State of the Art for Waste Incineration Plants

Transcription

1 State of the Art for Waste Incineration Plants

2

3 State of the Art for Waste Incineration Plants Vienna, November 2002

4 Authors: Josef Stubenvoll (TBU) Siegmund Böhmer (UBA) Ilona Szednyj (UBA) Coordination of the joint study: Gabriele Zehetner Note: The studie is also retrievable from the internet ( Impressum: Published by: Federal Ministry of Agriculture and Forestry, Environment and Water Management, Devision VI/3, Stubenbastei 5, 1010 Wien Printed by: Druckerei Berger, 3850 Horn, Austria Printed on Recyclingpaper Copyright: Federal Ministry of Agriculture and Forestry, Environment and Water Management All rights reserved ISBN X Cover photo: Bernhard Gröger (UBA), AVN, WAV, AVE RV Lenzing Reproduction is permissible if the source is quoted In case of having no use for this publication please return it for reuse resp. recovery to the Federal Ministry of Agriculture and Forestry, Environment and Water Management

5 1 State of the Art / Waste Incineration Content CONTENT CONTENT...2 SUMMARY INTRODUCTION Aims and Objectives The connection to the IPPC-Directive FIRING TECHNOLOGIES Delivery and pretreatment of waste Firing system and waste heat boiler Grate firing systems Rotary kiln Fluidised bed combustion Degassing and/or gasification of wastes TECHNOLOGIES FOR FLUE GAS CLEANING Separation of dust and non-volatile heavy metals Electrostatic precipitator Fabric filters Fine wet scrubbing HCl, HF, SO 2 and Hg removal Dry and semi-dry processes Wet flue gas cleaning NO x removal Primary Measures Secondary measures Reduction of organic emissions and PCDD/F Primary measures Secondary measures Simultaneous removal of acid gases, NO x and dioxins Moving bed adsorber with activated carbon Fluidised bed systems Avaibility and use in Austria WASTE WATER TREATMENT Gravity separation Neutralisation...43

6 State of the Art / Waste Incineration Content Increase of ph Reduction of ph Precipitation Flocculation Flotation Filtration Ion exchanger Activated coke filter DISPOSAL AND TECHNOLOGIES FOR WASTE TREATMENT Landfilling in big bags Solidification Separation of metals Washing processes Thermal treatment UTILISATION OF ENERGY Corrosion CROSS-MEDIA ASPECTS DESCRIPTIONS OF PLANTS Domestic waste incineration Waste incineration plant Flötzersteig Waste incineration plant Spittelau Waste incineration plant Wels Incineration of hazardous wastes Rotary kilns of the Plant Simmeringer Haide Waste incineration plant Arnoldstein Incineration of clinical waste Clinical waste incineration plant Baden Incineration of sewage sludge Fluidised bed reactors of the Plant Simmeringer Haide Incineration of treated waste fractions Combined waste incineration AVE - Reststoffverwertung (AVE-RVL) Lenzing Pyrolisis of wastes Gasification...109

7 1 State of the Art / Waste Incineration Content 8.9 Planned plants and plants under construction Waste incineration plant Zistersdorf Plant Simmeringer Haide: Fluidised bed reactor Waste incineration plant Dürnrohr Waste incineration plant Arnoldstein Thermal residue utilisation plant Niklasdorf ESTIMATION OF COSTS Discharge and storage Firing system and boiler Water-steam cycle Flue gas treatment Dry flue gas cleaning Absorption and adsorption plants for separation of HCl, HF and SO NO x reduction Posttreatment plants Cost estimations for whole plants Costs of fluidised bed combustion STATE OF THE ART Location of the waste incineration plant Emissions into the air Monitoring Emissions of air pollutants Emissions into the water Monitoring Emissions of water pollutants Accumulation of waste Utilisation of energy General State of the art NATIONAL AND EUROPEAN LEGISLATION Emissions to air National regulations Emissions to air from Austrian waste incineration plants Emissions to water National regulations European Community Solid waste from waste incineration Legal regulations for solid waste from waste incineration...178

8 State of the Art / Waste Incineration Content Waste and solid residues from Austrian waste incineration plants Monitoring Monitoring of operating parameters Monitoring of emissions to air national regulation Monitoring of emissions to air waste incineration plants Monitoring of emissions to water waste incineration plants Monitoring of waste from waste incineration and solid residues GLOSSARY AND ABBREVIATIONS REFERENCES Internet adresses...189

9 6 State of the Art / Waste Incineration Summary SUMMARY The aim of this study is to describe the state of the art for waste incineration plants with respect to the IPPC-Directive. The study deals with the complete process of waste incineration starting from the delivery of waste and ending with the treatment of solid residues from the incineration process. The following technologies are depicted in detail: - waste storage and pre-treatment, - introduction of waste into the combustion chamber, - applied firing technologies, - systems for energy utilisation, - applied technologies for flue gas cleaning, - treatment of waste water, - treatment and disposal of waste from combustion. Cost estimations splitted into investment costs, operating costs (including enumeration of relevant items) and maintenance costs are presented both for single technologies mentioned above and for whole waste incineration plants. This study should form the basis of the Austrian contribution to the exchange of information between Member States and the industries concerned on best available techniques (BAT) for waste incineration plants. This exchange of information is made in accordance with Article 16 paragraph 2 of European Council Directive 96/61/EC from 24 th September 1996 on Integrated Pollution Prevention and Control (IPPC-Directive). Presently about 190 plants for thermal treatment of waste with an overall capacity of about 2.7 Mio. t yr -1 are operated in Austria. In 135 of them only waste which is produced within the company is combusted. The operators of the other plants also accept waste fractions from other parties, however, some have contracts with certain partner companies. At present hazardous waste is incinerated in 14 plants with an overall capacity of about 233,000 tons per year, whereas the major part can be allocated to the Plant Simmeringer Haide of Fernwärme Wien GmbH. In addition to existing plants there is a number of plants under construction or planned. The sum of planned combustion capacity is estimated to be in the range of 1.4 to 1.7 Mio. t yr-1. In the study the following waste incineration plants are described in detail:! MVA Flötzersteig, MVA Spittelau Domestic waste incineration plants with grate firing! MVA Wels Grate firing for combustion of domestic and industrial waste! Rotary kilns of the Plant Simmeringer Haide Incineration of hazardous wastes! Fluidised bed reactors in Arnoldstein (ABRG Arnoldstein) Incineration of hazardous wastes! Pyrolysis plants in Baden Incineration of hospital wastes! Fluidised bed reactors of the Plant Simmeringer Haide Incineration of sewage sludge

10 State of the Art / Waste Incineration Summary 7! Fluidised bed reactor in Lenzing (AVE-RVL Lenzing) Combined waste incineration (e.g. treated household waste, sewage sludge)! Planned and already permitted waste incineration plants Dürnrohr, Arnoldstein, Zistersdorf, Niklasdorf, fourth fluidised bed reactor of the Plant Simmeringer Haide. Waste acceptance, treatment and introduction into the combustion chamber At grate firing plants for the combustion of household waste delivered waste is dumped into so-called acceptance bunkers and fed into the combustion chamber after mixing using bridge cranes without any further pretreatment. As to the processing of bulky refuse at most plants shears are provided in the vicinity of the bunker. Fresh air needed for combustion is sucked off from the waste bunker. Thus a slight vacuum is produced so that odour and dust emissions through the dumping devices to the ambient air are minimized. The maximum storage time is limited to a few days. Hazardous wastes are combusted in rotary kilns (and to a lower extent in fluidised bed reactors). After delivery hazardous wastes are visually examined whereby the accordance with accompanying documents is verified. Afterwards chemical and physical parameters are determined according to ÖNORM S2110 (1991). On the basis of analysis results single waste fractions are evaluated, stored in intermediate bunkers, mixed according to existing recipes and supplied to the combustion process. Also in this case combustion air is sucked off from the bunkers. In fluidised bed reactors usually a mixture of several waste fractions are combusted together. The waste fractions are visually examined before acceptance, randomly controlled, pulverized and mixed before combustion. Storage takes place in tanks or daily bunkers depending on the state of aggregation. Exhaust air from waste treatment and storage is either dedusted with fabric filters or introduced into the firing as combustion air. The fluidised bed boilers for exclusive combustion of sewage sludge are located directly to the main waste water treatment plant (WWTP) of Vienna. Thin sludge is supplied via pipelines and dewatered by means of centrifuges. Waste water from dewatering is pumped back to the WWTP and the remaining thick sludge is combusted. Pyrolysis for thermal treatment of hospital waste is performed discontinuously. Wastes are heated by means of gas burners until the distillation temperature is reached. At all described plants fuel oil, natural gas or coal can be introduced for starting up or shutting down as well as for satisfying the required minimum temperature for hazardous and non hazardous wastes using auxiliary burners. Use of energy With the exception of the small hospital waste incineration plants energy of flue gases is used at all waste incineration plants described in this study. The present spectrum of energy use can be described as follows: Pure electricity production (e.g. Wels), pure heat production (e.g. MVA Flötzersteig), Co-generation (CHP: Combined heat and power) (e.g. Plant Simmeringer Haide) and CHP with increased steam parameters (500 C, 80 bar: e.g. AVE- RVL Lenzing). If the energy of the flue gas is fully converted into heat a theoretical overall efficiency up to 80 % can be achieved. As to pure electricity production the overall efficiency (= net electrical efficiency) applying normal steam parameters will only be about 20 %. In case of increased

11 8 State of the Art / Waste Incineration Summary steam parameters and pure power generation an overall efficiency (= net electrical efficiency) up to 30 % can be achieved. At the waste incineration plant Dürnrohr that is presently under construction steam shall be fed into the steam cylce of the neighbouring coal power plant immediately before the intermediate superheater. With this concept the electric net efficiency shall be increased to 35 %. Technologies for flue gas cleaning At Austrian waste incineration plants dry and wet processes are combined for separation of the air pollutants dust, non-volatile and volatile (e.g. Hg) heavy metals, SO x, NO x, HCl, HF and organic compounds (dioxins and furans) (see Table 1). These processes can be implemented independent from the used firing system. Table 1: Combination of flue gas cleaning processes in existing waste incineration plants in Austria - electrostatic precipitator, - two-stage wet scrubber with precipitation, - wet removal of fine dust and - catalytic plant (low-dust circuit) - fabric filter with dosage of lime and activated coke, - two-stage wet scrubbing with gypsum scrubber and - downstream catalytic plant (low-dust circuit) - electrostatic precipitator, - two-stage wet scrubbing with precipitation, - activated coke adsorber (cross current) - downstream catalytic plant (low-dust circuit) - electrostatic precipitator, - two-stage wet scrubber, - wet removal of fine dust and - catalytic plant (low-dust circuit) - electrostatic precipitator, - two-stage wet scrubbing with NaOH scrubber, - fabric filter with dosage of lime and activated coke and - downstream catalytic plant (low-dust circuit) - electrostatic precipitator, - two-stage wet scrubber with precipitation, - wet removal of fine dust and - activated coke adsorber (counter current) Emission levels that can be achieved using these combinations of processes are presented in the following table (as half hourly mean values): Table 2: Emissions to air from Austrian waste incineration plants (as half hourly mean values in mg Nm -3 ; dioxin emissions are given in ng Nm -3 ; standardised at 11% O 2, dry gas, 273 K and kpa) Pollutant Type of measurement Range of emissions [mg Nm -3 ] Dust continuously < SO 2 continuously HCl continuously < HF continuously or discontinuously < CO continuously NO x continuously < 150

12 State of the Art / Waste Incineration Summary 9 Pollutant Type of measurement Range of emissions [mg Nm -3 ] Pb discontinuously < Cr discontinuously < Zn discontinuously Σ Pb + Cr + Zn 1 discontinuously < < As discontinuously < < Co discontinuously < Ni discontinuously < Σ As + Co + Ni 1 discontinuously < Cd discontinuously Hg continuously or discontinuously Σ As, Pb, Sb, Cr, Cu, Co, Mn, Ni, discontinuously V, Sn 1 Σ HC NH 3 continuously or discontinuously continuously or discontinuously PCDD/F (ng Nm -3 ) discontinuously Heavy metals have to be measured as single substance or as a sum depending on the permit. Waste water treatment Waste water from the first (acid) scrubber, the SO 2 scrubber and from the ash and slag treatment are cleaned in the waste water treatment plant. As the case may be this cleaning can be performed together for all partial flows. In Austria a multistage cleaning of waste water has become generally accepted. The first cleaning step, the heavy metal precipitation, usually comprises the processes precipitation, flocculation, sedimentation, neutralisation and sludge dewatering. The second cleaning step usually consists of a gravel filter, an activated coke filter and an ion exchanger. Applying the multistage cleaning of waste water emission limit values prescribed in the ordinance pertaining to the limitation of waste water emissions from the cleaning of combustion gas (Federal Legal Gazette 886/1995) can usually be easily attained (Table 3). Chemicals necessary for waste water treatment are stored and treated in chemical stations. Sludges accumulated during the particular processes are usually collected in sludge tanks and mostly dewatered to a water content of about 50 % by means of chamber filter presses. The occurring filter cake has to be disposed of as hazardous waste.

13 10 State of the Art / Waste Incineration Summary Table 3: Volumes and parameters of treated waste water from Austrian waste incineration plants after waste water treatment in the year 2000 [REIL, 2001; KROBATH, 2001; WACHTER, 2001; WERNER 2002] Cleaned waste water Temperature Electric conductivity Parameter Emission [mg l -1 ] ,657 [l t -1 waste] < [ C] [ms] Fish toxicity 2 ph [-] Undissolved compounds 10 < 30 Settleable solids < 0.3 < 10 Filterable substances 7 20 Residue on evaporation 1.4 g l -1 Salt content 35 [g l -1 ] Al 0.12 As < < 0.05 Ba 0.19 Ca < 5 [g l -1 ] Cd < < 0.05 Co < 0,05 Chlorides 7 < 20 [g l -1 ] Cyanides < < 0.1 Cr < 0.05 < 0.1 Cr (VI) < 0,05 Cu < 0.05 < 0.3 Fluorides < < 10 Hg < < 0.01 Mn < 0,05 NH 4 N Nitrate (NO 3 ) Nitrite (NO 2 ) 0.07 < 8 Ni < 0.05 < 0.5 P < 0.05 Pb < 0.01 < 0.1 Sn 0.06 Sulphate (SO 4 ) 325 8,000 Sulphides < 0.01 < 0.1 Sulphites < 1.0 < 8 Zn < 0.05 < 0.5 AOX / EOX 1.02 / 0.01 < 0.1 BTXE < COD < 75 Total Hydrocarbon 0.05 < 3

14 State of the Art / Waste Incineration Summary 11 Parameter Emission [mg l -1 ] Phenol < 0.01 < 0.1 TOC Tensides < 0,02 Volatile chlorinated hydro carbons < 0.1 Saponifiable fats and oils < 4 Sb 0.05 < 0.1 Tl < V 0.01 < 0.05 Chlorine (free) < 0.05 Chlorine total < 0.05 Non volatile lipophilic components < 20 Treatment of accumulated solid waste fractions By incineration wastes are reduced to one third of the original weight and to one tenth of the original volume. Fly ash, slag, ferrous scrap, filter cake from the waste water cleaning, gypsum and loaded activated coke primarily remain as wastes. These wastes are to a great extent classified as hazardous wastes and are treated and disposed of in Austria as follows:! Fly ash and the mixture slag/gypsum from the domestic waste incineration plants Spittelau and Flötzersteig are solidified and subsequently landfilled. Slags and fly ashes from the Plant Simmeringer Haide are landfilled too.! Slag from the waste incineration plant Wels is washed with water and landfilled. Fly ash from the waste incineration plant Wels is treated by a wet-chemical process and landfilled. Gypsum from this plant is also landfilled.! Bed ash and coarse ash from the fluidised bed reactor in Lenzing (AVE-RVL) are exempted and disposed of at landfills for residual waste. Ash from pre-dedusting devices, eco- and fabric filter ash and neutralisation sludge are exported as hazardous waste and disposed of underground.! Filter cake from waste water treatment is heavily charged with Hg. In general it is filled in so called big bags and disposed of underground. In addition to Hg also the concentrations of Zn and Cd as well as the residue on evaporation exceed the limit values for landfills for residual waste and mass waste landfills prescribed in the Austrian ordinance for landfills.! Separated metallic scrap is either delivered to a scrap dealer or returned to the steel industry.! In Wels, Arnoldstein and at the Plant Simmeringer Haide loaded activated coke is combusted together with waste. In addition to theses current practices various attempts (e.g. thermal treatment) were performed in order to utilize wastes from waste incineration plants or at least lower the hazardous potential. In most cases these attempts were terminated as on the one hand legal and economic conditions didn t justify the treatment and on the other hand technical problems complicated the permanent realization.

15 12 State of the Art / Waste Incineration Summary Costs The costs of a waste incineration plant basically depend on following factors:! Plant design! Size! Local infrastructure! Specific boundary conditions for waste disposal! Possibility for energy utilisation The main components are:! Repayment of investment! Maintenance and re-investment costs! Personnel costs! Other fix costs such as administration and insurance! Operating costs proportional to throughput such as chemical supply and waste disposal! Revenues from energy production proportional to throughput Basically it has to be considered that the thermal output is the important parameter for the investment and operating costs and not the mass throughput. The thermal output determines the size of the boiler and primarily the flue gas volume and therefore the size of the flue gas cleaning devices. Based on certain assumptions and on market prices of the last 5 years specific costs for following parts of a waste incineration plant have been estimated (in per ton combusted waste):! Discharge and storage! Firing system and boilers (various systems)! Water-steam cycle (various options)! Flue gas cleaning system (various processes) Additionally specific costs also based on certain boundary conditions for whole plants have been estimated as a function of plant size, type of energy utilisation and installed flue gas cleaning system. Estimated costs are between 91 and 148 per ton combusted waste depending on the plant. Cost calculation revealed that plants size has a great influence on overall costs. The maximum cost difference between identical plants of different size is about 37 per ton combusted waste. On the other hand different systems of energy utilisation result in cost differences of maximum 9 per ton, whereas different systems of flue gas cleaning cause cost differences of maximum 13 per t. If grate firing and fluidised bed combustion systems (equipped with the same system of energy utilisation and flue gas cleaning) are compared some general statements can be given:

16 State of the Art / Waste Incineration Summary 13 In Austria fluidised bed plants are exclusively charged with crushed or grinded wastes, whereas grate firings are operated with untreated waste. On the basis of certain assumptions and a capacity of 70,000 t yr -1 treated waste (Fluidised bed) respectively 100,000 t yr -1 untreated waste (grate firing) approximately the same specific treatment costs can be calculated based on the rated thermal input. Based on the mass throughput incineration costs of fluidised bed combustion systems are noticeably higher than those of a grate firing systems. In case of large plants with a throughput of 200,000 t yr -1 treated waste (for fluidised bed combustion) resp. 300,000 t yr -1 untreated waste (for grate firing) specific costs related to the rated thermal input will be more favourable if fluidised bed combustion is applied. It can be expected that in future even bigger units of fluidised bed firings can be built. That means that the fluidised bed technology represents a cost-efficient alternative for wastes with high calorific value. However, if waste has first to be separated into low and high calorific fractions and subsequently crushed and grinded, separation and subsequent combustion in a fluidised bed reactor will be uneconomic in comparison to a grate firing system.

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18 14 State of the Art / Waste Incineration Introduction 1 INTRODUCTION 1.1 Aims and Objectives The aim of this study is to describe the state of the art of waste incineration plants with respect to the European Council Directive 96/61/EC on Integrated Pollution Prevention and Control (IPPC-Directive). The main emphasis lies in the depiction of existing waste incineration plants in Austria. This includes a description of the type of the plants, demand of raw-materials and energy, type of incinerated waste fractions and installed systems for flue gas and waste water treatment (together with emission levels). Also, solid waste which accumulate from waste incineration are characterised with respect to volume and physical and chemical parameters. Applied techniques for treatment and disposal of accumulated waste are presented. Different systems of energy utilisation solely production of electricity, solely production of heat or co-generation of heat and power and how they influence cost efficiency of a waste incineration plant are discussed in detail. Cost estimations splitted into investment costs, operating costs (including enumeration of relevant items) and maintenance costs are presented both for single technologies (especially for flue gas cleaning systems which are installed at Austrian waste incineration plants) and for whole waste incineration plants. This study also deals with so-called Cross Media Effects, i.e. the transfer of pollutants between air, water and soil. The complex theme of Co-Incineration of waste is not dealt with in this study. 1.2 The connection to the IPPC-Directive In accordance with Article 16 paragraph 2 of European Council Directive 96/61/EC from 24 th September 1996 on Integrated Pollution Prevention and Control IPPC, the Commission organises the exchange of information between Member States and the industries concerned on best available techniques, associated monitoring and developments in them. The elaboration of the BAT documents for the categories of installation referred to in appendix I of the IPPC-Directive is carried out in Technical Working Groups which are set up by the European Commission in agreement with the Information Exchange Forum. The work of the Technical Working Groups is supported by the European Integrated Pollution Prevention and Control Bureau specially set up at the IPTS (Institute for Prospective Technological Studies) in Seville for this purpose. As defined in Article 2, Clause 11 of the IPPC-Directive, the term "Best Available Techniques" refers to the most effective and advanced stage in the development of activities and their methods of operation which indicate the practical suitability of particular techniques for providing in principle the basis for emission limit values designed to prevent and, where this is not possible, generally to reduce emissions and impacts on the environment as a whole. The term "techniques" includes both the technology used and the way in which the installation is designed, built, maintained, operated and decommissioned. "Available" techniques refers to those developed on a scale which allows implementation in the relevant industrial sector, under economically and technically viable conditions, taking into consideration cost and benefit analyses.

19 State of the Art / Waste Incineration Introduction 15 "Best" means most effective in achieving a high general level of protection of the environment as a whole. The following points should be given special attention when establishing Best Available Techniques in accordance with Annex IV of the Directive on "Integrated Pollution Prevention and Control": The use of low waste technology The use of less hazardous substances The promotion of the recovery and recycling of material and, where appropriate waste, produced and used in individual processes. Comparable processes, facilities and methods of operation which have been tried successfully on an industrial scale. Advances in technology and scientific knowledge. Type, impacts and volume of emissions involved. Date of commencement of operation of existing or new installations The length of time required for the introduction of a better available technology Type and consumption of raw materials (including water) used in individual processes and their energy efficiency. The necessity to prevent or at least reduce to a minimum the dangers and the overall impact of emissions on the environment. The necessity to prevent accidents and minimise their impact on the environment. The information publicised by international organisations or as set out in article 16 paragraph 2 by the Commission.

20 16 State of the Art / Waste Incineration Firing Technologies 2 FIRING TECHNOLOGIES As an introduction a general survey about the installations for handling and pre-treatment of waste is given. Afterwards descriptions of following firing technologies are presented: Grate firing Rotary kiln Fluidised bed combustion Degassing and/or gasification of wastes Particular descriptions of firing technologies include system-specific aspects of delivery, discharge, storage and conditioning of wastes for combustion. 2.1 Delivery and pretreatment of waste Waste can be delivered to the waste incineration plant either by truck or train. There it is dumped into bunkers, where it is stored before combustion or pretreatment. As far grate firing systems and rotary kilns are concerned no equipment for waste pretreatment or waste size reduction is required. Using these technologies waste from the bunker can directly be fed into the firing chamber. In case of fluidised bed combustion only crushed or grinded waste can be used. A direct feed as practiced at grate firing systems and rotary kilns can only be managed if specific operations (e.g. slowly rotating double screw) are provided. Therefore devices for waste conditioning (e.g. pulverizer, screens, magnetic separator) and another bunker for the intermediate storage of treated wastes are arranged after the first bunker. In Austria pyrolysis plants (degassing/gasification plants) are small plants which are charged discontinuously with waste either in unpacked form, in barrels or in bags. 2.2 Firing system and waste heat boiler During combustion of solid fuels including wastes four phases can be distinguished: Drying Degassing Gasification Complete burnout of gases and solids As to classic processes drying, degassing, gasification and burnout take place in the combustion and afterburning chamber. Processes described above happen slowly on the grate and in the rotary kiln and can be controlled by the combustion air supply. On the contrary, at fluidised bed reactors velocity of the combustion process cannot be controlled by this means because every single phase happens spontaneously. Main components of combustion gases are predominantly determined by the composition of incinerated wastes. Depending on the firing system composition of combustion gas varies according to the excess air and primary measures (e.g. temperature, residence time of combustion gases depending on the temperature). With firing specific measures, emissions of following pollutants can be reduced: Nitrogen oxides (NO x ), carbon monoxide (CO), hydro-

21 State of the Art / Waste Incineration Firing Technologies 17 carbons (C x H y ) and dust. Using fluidised bed combustion sulphur dioxide can be chemically bound into the combustion bed ash under certain conditions. At all waste incineration plants in Austria combustion heat introduced by wastes is totally transformed in waste heat boilers. Differences between particular processes occur concerning the height of radiation losses and other supplied energies (e.g. air preheating, auxiliary firing equipment). Therefore the overall efficiency of waste incineration plants (ratio from utilizable produced energy to totally applied (from waste, fuels and external sources) energy) mainly depends on the design parameters of the boiler but less on the kind of firing system. Quantity of solid wastes from waste incineration plants mainly depends on the composition of used wastes and the quality of burnout. Added chemicals such as limestone (fluidised bed combustion) or lime hydrate (into the waste gas stream before dust removal) only have small effects on total quantity of solid wastes from combustion Grate firing systems Presently in Austria three domestic waste incineration plants (Flötzersteig, Spittelau and Wels) are equipped with a grate firing system. This system should also be installed in the planned waste incineration plants Wels - Line 2, KRV Arnoldstein and Dürnrohr. Delivery, discharge and storage systems In municipal regions waste is directly delivered to the waste incineration plant by refuse collection vehicles and dumped into bunkers. In rural regions waste incineration plants are either planned or under construction. Delivery of waste should take place primarily by train. Planned transport systems for such plants include the use of modern refuse collection vehicles, which are equipped with containers. These containers are directly filled at the vehicle and subsequently transferred to the train. At the waste incineration plant, the containers are automatically emptied into the bunker. The logistic system also comprises external reload stations. Waste dumped into the bunker is stored 5 days at maximum. A considerable part of the combustion air is sucked off directly from the bunker in order to reduce odour nuisances to a minimum. This leads to a slight underpressure in the bunker so that ambient air is sucked into the bunker. Basically waste is not pretreated before combustion on the grate. In order to treat bulky refuse, at most plants shears are provided in the vicinity of the bunker. Waste is mixed in the bunker by using a bunker crane. Firing system and boiler Using a crane mixed waste is delivered from the bunker into the waste chute, which is located before the firing chamber. The waste pillar in the waste chute forms the airside sealing between the firing chamber and the bunker. If there is not enough waste in the chute, the waste chute will be closed by a pusher or a shutter. Actually waste is fed onto the grate by allocators that are arranged at the lower end of the chute and can be formed as pestles or as travelling grate. The velocity of the pestles or of the travelling grate is regulated according to the provided output. In Austrian waste incineration plants only pestles are used as allocators.

22 18 State of the Art / Waste Incineration Firing Technologies On the grate waste is moved further, stocked and contacted with primary air. Different grate velocities and air flow rates in various zones can be adjusted. In Austria following grate systems are used: Bar grates: In case of bigger grates more channels are arranged along the width. Stationary and moveable rows of bars alternate over the length. The moveable rows of bars are fixed to so-called grate slides. Forward feed grate: The movable row of bars pushes the waste forward. Applying different velocities in various zones the height of the waste bed can be controlled. Reciprocating grate: The movable row of bars pushes the waste, that directly lies on the grate, back. Waste in the upper regions of the waste bed is turned over by the slope of the grate. Combined forward and backward moving grate: Each second movable row of bars runs countercurrent to the row between. A movable row pushes the waste forward, the next pulls back and creates place for the waste pushed forward. Roller grates: In Austria no roller grate is presently operating or planned. At all times new surfaces for combustion are uncovered by stocking. Therefore velocity of solids burnout can be regulated by stoking and addition of primary combustion air. Secondary air injection into the combustion chamber at the side results in complete mixing of gases ignited by the primary combustion air and therefore complete burnout of combustion gases. At modern plants the coaction between allocator, grate movement, primary and secondary air supply and if needed by flue gas recirculation (for flue gas cooling, e.g. used at AVE - RVL Lenzing) is regulated by the controller of the firing performance depending on the firing parameters and the boiler output. Natural gas or heating oil is used for starting up and shutting down. Normally operation of auxiliary burners is not necessary for a continuous operation. Slag is used for heating the combustion air and thereby cooled. At the end of the grate slag is conveyed into the deslagger. Most of the deslaggers are built as wet deslagging systems. The chute is immersed in the water of the deslagger thereby establishing an air seal between the combustion chamber and the deslagging unit. In the slag bath the slag is cooled again. Pestles, dragline scrapers or plate conveyors are removing the slag from the deslagger. During this process the slag is simultaneously dewatered. Several plants (Flötzersteig, Wels) are equipped with a slag washing unit. There water is passed through the deslagger countercurrently to the slag, withdrawn from the deslagger being almost free from solids and further used for cleaning of flue gases. By this step the amount of soluble components remaining in the slag is minimized to a great extent. The delivered slag is classified by a coarse sieve and a magnetic separator. Firing system and boiler form a procedural unit. The combustion grate with the subsequent wet deslagger is integrated in a ceramically lined combustion chamber that is cooled by the tubes of the evaporator. A residence time of flue gases of two seconds at least at a temperature > 850 C is reached in the combustion chamber after the last combustion air supply. Subsequently flue gases pass a void zone of the boiler until they are cooled to a temperatur of about 650 C. This zone is followed by heating surfaces such as evaporators, superheaters and feedwater preheaters. Produced steam is expanded in a steam turbine. Depending on requirements low pressure steam can be withdrawn for a district heating system or for the use in an industrial plant. If

23 State of the Art / Waste Incineration Firing Technologies 19 there is no demand for heat, only electricity is produced. In this case the overall efficiency of a waste incineration plant is about 20 %. An overall efficiency of more than 80 % can be achieved with combined heat and power generation Rotary kiln In Austria a central waste incineration plant having two independent lines of rotary kilns (Plant Simmeringer Haide of Fernwärme Wien GesmbH) is in operation. Additionally to them there exist some small industrial waste incineration plants. Delivery, discharge and storage systems Delivery, discharge and storage systems of solid waste are basically similar to those of grate firings. In addition to solid wastes liquid and waste with high viscosity can be combusted in rotary kilns. In this case sedimentation facilites but also tanks and pump facilities are installed for treatment and interim storage. Firing system and boiler Mixed solid wastes are delivered from the bunker into the waste chute which is located in front of the firing using a crane. In most cases a sluice is integrated into the chute where waste can directly be fed into the rotary kiln. Highly viscous and liquid wastes can be inserted through the front wall of the rotary kiln. As a result of the slope and the rotation of the rotary kiln, wastes are transported and circulated, which leads to intensive contact with primary air, that flows through the rotary kiln. In contrast to grate firings rotary kilns are closed systems. Therefore also liquid and highly viscous materials can be inserted. Melted slag can be recirculated and/or discharged. Velocity of combustion cannot be regulated by zones as it is feasible at grate firing systems. Exhaust gases coming out of the rotary kiln are treated in an afterburning chamber. In order to assure high temperatures necessary for complete destruction of organic compounds ( C depending on the waste) afterburning chambers are equipped with burners that automatically start when the temperature falls below the given value. At the end of the rotary kiln slag arises either sintered or melted. By dropping into the water of the deslagging unit, granulated slag is formed. When the slag is sintered then this part of the plant is similar to that of a grate firing system. Rotary kilns and afterburning chambers are in most cases constructed as adiabatic, ceramically lined combustion chambers. After the combustion chamber flue gases pass a void zone until a temperatur range of about 700 C is reached. Subsequently heating bundles such as evaporators, superheaters and feedwater preheaters are arranged. Waste heat boiler and energy supply system is comparable to that of grate firing systems.

24 20 State of the Art / Waste Incineration Firing Technologies Fluidised bed combustion Fluidised combustion plants are in operation at three sites in Austria. They are exclusively used for waste incineration. Stationary fluidised bed reactors are installed at the Plant Simmeringer Haide and in the waste incineration plant Arnoldstein. A circulating fluidised bed reactor was erected by AVE - RVL Lenzing. In Austria fluidised bed reactors are used for the combustion of not utilizable plastic wastes, separately collected packaging wastes, fractions from waste separation plants, rejects from waste paper utilisation, separately collected wastes from trade and industry and for sewage sludge. In several industrial fluidised bed combustion plants wastes are co-combusted. In contrast to grate firings and rotary kilns the maximum grain size of wastes using fluidised bed combustion is limited so that usually treatment plants have to be installed. Wastes from the bunker or the storage depot are either classified by a sieve or directly put into the pulverizer. The fine fraction is classified by a magnetic separator and afterwards stored in a bunker. In Europe fluidised bed technology is playing a minor role in contrast to Japan. Above all two reasons are decisive: A fluidised bed combustion needs a good dosing of the waste which above all hardly can be realized using uncrushed or ungrinded municipal waste. The Japanese waste collection system is harmonized with combustion in fluidised bed reactors while the grain size is limited from the start. Without additional measures the major fraction of the non-combustible part of waste at fluidised bed combustion plants arises as fly ash that has to be landfilled at great expense. A precondition for the cost-effective use of fluidised bed reactors is the preseparation of dust with a separation efficiency of about 80 to 90 % at temperatures above 400 C so that the pollution burden of coarse and bed ash is lowered. In Austria fly ash and bed ash from waste incineration plants are hazardous wastes according to the waste classification ordinance (BGBl Nr. II 227/1997). Those wastes can be exempted (i.e. they are taken out of the scope of hazardous wastes) if it is proved that the hazardous properties don t apply (waste classification ordinance). A mixture of fabric filter ash and boiler ash doesn t meet the conditions for exempting in any case. Landfilling of hazardous wastes is noticeably more expensive than landfilling of non hazardous wastes because higher storage costs for underground depository arise. In Austria there are no underground depositories available. Compared with conventional grate firing systems and rotary kilns, fluidised bed combustion offers several advantages such as a smaller size at the same thermal output, a greater output of particular lines and a greater range of the calorific value of waste for combustion. Delivery, discharge, pretreatment and storage systems Systems for delivery, discharge and storage of solid wastes are basically similar to those of grate firings. Firing system and boiler Stationary fluidised bed combustion systems can be used for a rated thermal input up to 100 MW, for higher rated thermal inputs and in practice from 50 MW upwards circulating fluidised bed reactors are in use. Stationary fluidised bed reactors are equipped with a sand-

25 State of the Art / Waste Incineration Firing Technologies 21 bed that is held in abeyance by primary air introduced through nozzles. Using circulating systems sand is carried out of the combustion chamber by the flue gases and led to a cyclone. In the dip pipe of the cyclone flue gases with fine ash escape. Sand and coarse ash are separated in the cyclone and returned into the lower zone of the combustion chamber. Introduced wastes are mixed into the hot sandbed and combust spontaneously. Therefore a regulation of the combustion velocity by the air supply is not feasible. High demands that in general only can be achieved with crushed and grinded waste are made on the uniformity of the introduction system and the quality of mixing. Pulverized waste from the bunker is fed into the firing by dosing stations. Small ash particles enter the flue gas as fly ash. Heavy parts sink to the bottom of the bed and can be carried out in dry form together with bed material. Metallic parts accumulate dry, cooled and like sand blasted together with granular bed material and thus can be separated easily. Depending on the design combustion chambers of fluidised bed combustion plants can be constructed cooled or lined. The large amount of sand in the combustion chamber levels the temperature of the combustion chamber and supports a good mixing of wastes, additives and combustion gases. SO 2 can efficiently be bound by addition of lime or limestone so that under certain conditions a downstream desulphurisation step can be avoided. However the salt load is increased by addition of lime or limestone. Therefore a wet scrubbing for SO 2 separation after fluidised bed combustion may be reasonable because of economic reasons considering landfill properties of the produced wastes. The waste heat boiler and the waste gas treatment plant are similar to those of grate firings Circulating fluidised bed with upstream crushing and grinding AVE - RVL Lenzing operates a circulating fluidised bed reactor with upstream pulverization, that will be shortly described in the following text. The firing system mainly consists of: Uncooled combustion chamber with slightly conical shape at the bottom and cylindrical form at the top Cyclone Afterburning chamber Recirculation system for bed material with fluidised bed cooler Delivered wastes such as packaging materials, rejects, light fraction and waste wood are declared by the deliverer and randomly tested by the operator, crushed and grinded and interimly stored in two daily bunkers that are situated directly near the boiler. Feeding of waste into the pulverizer, distribution in the daily bunker and discharge from the daily bunker is carried out in view of good homogenization. Sewage sludge is directly dumped into two charging hoppers with discharge floor and interimly stored in a silo. Sewage sludge is usually stabilized and combusted a few hours after delivery. In all cases transport from the pretreatment site to the boiler house is established periodically with a pipe belt conveyor. Grinded wastes such as plastics, rejects, sieve overflow and waste wood can be fed from the charging hopper into the firing zone using 3 pneumatic conveyors. For sewage sludge, a separate conveyor line with a plug screw as feeder is available.

26 22 State of the Art / Waste Incineration Firing Technologies For oil and natural gas, burners and oil lances are provided. Coal can be fed with a separate dosing plant. Exhaust gas from the neighbouring viscose rayon production containing H 2 S (hydrogen sulphide) and CS 2 (carbon disulphide) is used as combustion air. Exhaust gas from waste treatment and storage is dedusted with fabric filters and discharged into the atmosphere. Combustion air is injected into the combustion chamber through the valve tray, two secondary air levels and several process-related places such as pneumatical conveyors and fluidising plates in the ash circle. Dosing of particular wastes, co-fired fuels and combustion air is regulated by a firing performance control system. The demand for air and fuel is calculated online. The most important parameters such as calorific value and demand on combustion air are calculated automatically from process data and adapted to the combusted wastes. Wastes are mixed homogeneously into the lower part of the combustion chamber and transported through the firing chamber with combustion air. In order to preseparate SO 2 limestone is continuously added to the fluidised bed reactor of AVE - Reststoffverwertung Lenzing. This is a necessary procedure, because the exhaust air of the viscose rayon production that is used as combustion air contains high amounts of sulphureous compounds. Bed material is separated from the flue gas by a cyclone and fed into the syphon and fluidised bed cooler. A regulated quantity of bed material is passed over the fluidised bed cooler in order to extract heat from bed material either for steam production and superheating of steam or temperature regulation of the combustion chamber. Flue gases leaving the cyclone are fully combusted in the afterburning chamber at sufficient temperature and residence time. Flue gases leaving the afterburning chamber are passing two vertical void zones with heating surfaces for evaporation, a horizontal zone with hanging heating surfaces for evaporation and superheating, a cyclone battery system and a preheater for feedwater Stationary fluidised bed combustion Stationary fluidised bed reactors for the combustion of sewage sludge and certain waste fractions are in operation at the Plant Simmeringer Haide. At the site Arnoldstein hazardous wastes are also combusted in such a combustion system. A stationary fluidised bed reactor consists of a bricked adiabatic combustion chamber with a valve tray, a stationary fluidised bed and an afterburning chamber. At the Plant Simmeringer Haide crushed and grinded wastes are delivered, interimly stored in receiver bunkers and fed into the fluidised bed by dosing conveyors. In Arnoldstein wastes also can be pulverized on site if necessary. Sewage sludges are pressed into the firing with high consistency pumps. Oil is directly combusted or mixed with wastes. In the lower part of the combustion chamber wastes are mixed homogeneously into the bed material and distributed in the fludized bed. In order to preseparate SO 2 it is possible to add limestone. Exhaust air from waste storage can be used as combustion air. Slightly contaminated exhaust air from waste treatment is dedusted in fabric filters. In Arnoldstein highly contaminated exhaust air, that doesn t pass the combustion, is purified with a continuously working countercurrent adsorber, that is filled with bark and activated coke. The charged adsorber material is subsequently combusted in the fluidised bed reactor.

27 State of the Art / Waste Incineration Firing Technologies 23 Combustion air is injected into the combustion chamber through the valve tray, two secondary air levels and a pneumatical conveyor. Dosing of particular wastes, co-fired fuels and combustion air is regulated by a firing performance control system. The demand for air and fuel is calculated online. The most important parameters such as calorific value and demand on combustion air are calculated automatically from process data and adapted to the combusted wastes. Flue gases leaving the cyclone are fully combusted in the afterburning chamber at a sufficient temperature and residence time. Flue gases leaving the afterburning chamber subsequently pass void zones with heating surfaces for evaporation, a horizontal zone with hanging heating surfaces for evaporation and superheating and a preheater for feedwater Degassing and/or gasification of wastes Pyrolysis plants with afterburning chambers are mainly used at small plants for thermal treatment of industrial and clinical waste. These small plants usually operate in a discontinuous mode. Waste is charged either in unpacked form, or packed in barrels or bags. At plants with degassing and/or gasification the processes drying, degassing and gasification take place in a reactor prior to combustion. Waste is introduced discontinuously into a distillation chamber that is heated up to a sufficient temperature in order to distill the waste. Gases leaving the distillation chamber are mixed with a continuous airflow in the afterburning chamber and held at a temperature of about 900 C by co-firing of natural gas. If the quantity of distilled gas is too high the volume of fired natural gas will be reduced automatically. Combustion gases leaving the afterburning chamber are cooled in a downstream hot water boiler and routed to a flue gas cleaning system. The smoldering process is done periodically. In order to ensure a sufficient burnout of the ash it is fired with gas burners before it is discharged from the distillation chamber. At small plants fluctuations of the throughput and inhomogeneities of combusted waste are compensated by the heat content and the large volume of flue gas from combustion of auxiliary fuels. As to pyrolysis plants the dust content of flue gases is small compared to conventional combustion systems. However, there is a great demand for additional fuels, so that consequently very high volumes of flue gas are formed.

28 24 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning 3 TECHNOLOGIES FOR FLUE GAS CLEANING In the following chapter flue gas cleaning technologies that are used in Austrian waste incineration plants are described. Generally they are applicable independant from the upstream combustion system and can be combined in every suitable manner. As to the separation of dust, non-volatile and volatile (e.g. Hg) heavy metals, SO x, NO x, HCl, HF and organic compounds (dioxins and furans) three processes can be distinguished: Dry processes In Austria dry processes are mainly applied for dedusting and separation of pollutants such as HCl, HF, SO 3, heavy metals and PCDD/F. Dedusting with electrostatic precipitators is almost exclusively applied in combination with downstream wet dedusting equipments, downstream solid bed adsorbers or downstream flow injection processes. Flow injection adsorbers with downstream fabric filters are arranged either directly after the waste heat boiler or after the scrubbers. Such plants mainly consist of a dry reactor, a fabric filter and additional systems for the handling of adsorbents and precipitated dusts. Generally, they are used for separation of heavy metals and PCDD/F. However, in special cases they are adapted for separation of HCl, HF and SO 2. Semi-dry processes In Austria presently no semi-wet or semi-dry processes are installed at waste incineration plants. Wet processes After waste incineration plants usually two-stage scrubbers are applied. In Austria exclusively wet scrubbers without incorporations are in operation. With wet scrubbers HCl, HF, SO x and heavy metals (Hg inclusive) can be removed from flue gas. 3.1 Separation of dust and non-volatile heavy metals Fabric filters, electrostatic precipitators and fine wet scrubbers are used for dust separation. Precleaning of flue gases can be done with cyclones, that are very efficient for separation of larger particles Electrostatic precipitator In a simplified version an electrostatic precipitator consists of a gas proof housing that contains discharge and collecting electrodes. With the aid of baffles and perforated metal plates the flue gas flow is splitted uniformly into particular segments. A dust bunker under the housing collects accumulating dust. The flue gas flow is channelled through passages of some cm wide which are formed by electrically charged metal plates (collecting electrodes). In the middle of the passages there are discharge electrodes which build an electrostatic field by means of DC voltage. The electrically charged dust particles give their charge to the collection electrodes and adhere to the metal plates. The collecting electrodes are regularly rapped. The deposited solid is removed by dust collecting hoppers. In order to prevent dust caking at the discharge electrodes they are continuously set into vibration.

29 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning 25 Electrostatic precipitators are connected to a high voltage supply and operated as close to the disruptive voltage as possible. Electrostatic precipitators are installed in the waste incineration plants Spittelau, Flötzersteig, Wels, Arnoldstein and in the installations of the Plant Simmeringer Haide Fabric filters Fabric filters are operated until a certain level of occupancy before they are regenerated or exchanged. The filtering medium consists of layers of fabric. Filters can be distinguished by the mode of operation: Off-Line cleaning interrupting the flue gas stream for the purpose of cleaning (back washing, vibration) On-Line cleaning no interruption of the flue gas stream for cleaning (compressed air blast) Filtering separators can also be built as jet pulse bag filter. In this case filter bags are hung with the opening face up (in the direction of the clean gas duct) whereas the raw gas flows through the bag from the outside inwards. The filter elements are cleaned by pressurized air blust. The filtering medium consists of fibrous materials which must show following properties: Sufficient mechanical strength Sufficient resistance to temperature Resistance to acids, caustic solutions and humidity Good air permeability Good dust collection (geometry of the gaps between the fibres) The filtering mediums can be carried out either as woven (right-angular weave) or nonwoven material. The lifetime of fabric filters is determined by fabric defects or an increased pressure drop caused by obstruction of the pores. Average lifetime of fabric filters is about 5 years. The resistance against acid or alkaline pollutants can be increased by the choice of filtering medium. The maximum possible permanent temperature of operation varies between 90 C for nylon and 260 C for teflon. In order to prevent formation of PCDD/F dust collectors shouldn t be operated in the temperature range of de novo synthesis ( C). Fabric filters are installed at the plant of AVE - RVL Lenzing and are intended to be installed in the planned waste incineration plants Wels line two and Dürnrohr.

30 26 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Fine wet scrubbing For wet separation of fine dust a combination of venturi scrubbers and wet electrostatic precipitators is applied in Austrian waste incineration plants. Each separation step consists of various venturi scrubbers. A high voltage electrode is arranged in the venturi scrubber. At the side away from the flow hollow cone jets are installed which generate a water jacket from the center to the wall. The circulation water is grounded. Therefore in addition to the inertia also the electrostatic attraction affects the dust particles charged by the high voltage electrode. Venturi scrubbers for separation of fine dust are used in the domestic waste incineration plants Spittelau, Flötzersteig and in the installations of the Plant Simmeringer Haide. 3.2 HCl, HF, SO 2 and Hg removal Dry and semi-dry processes Depending on the particular situation and the pollutant various adsorption media are used (e.g. activated coke, Ca(OH) 2 ). For separation of SO 2 mostly Ca(OH) 2 is applied. The adsorption medium reacts with pollutants along the whole flue gas path beginning at the place of injection until the downstream dust separation. In many cases part of removed dust is recirculated in order to reduce lime consumption. A mixture of calciumsulphit, calciumsulphate, lime, salts from separated acids such as CaCl 2 and CaF 2 as well as separated dusts that may contain heavy metals, organic pollutants and unreacted adsorption medium accumulates as waste. The basic reactions can be written in a simplified form as follows: Desulfurization: SO 2 + CaO + ½ H 2 O # CaSO 3 * ½ H 2 O HCl-adsorption: 2 HCl + CaO + x H 2 O # CaCl 2 * (x + 1) H 2 O Adsorption on activated coke of gaseous heavy metals and their compounds as well as gaseous organic compounds. If dry and semi-dry systems are installed directly after waste heat boilers the required operating temperature for dry adsorption can be adjusted by variation of the feedwater temperature at the entrance of the feedwater preheater (e.g. AVE - Reststoffverwertung Lenzing). If these systems are located after the scrubber flue gases have to be reheated. In this case a mixture of furnace coke, limestone and hydrated lime is injected into the firing in order to use unconverted lime for SO 2 preseparation. Residues from dry flue gas cleaning processes have to be disposed of as hazardous wastes. Presently the dry process for flue gas desulfurization is installed in the plants of AVE RVL Lenzing and of ABRG Arnoldstein. The application of the dry process (before the scrubber) is planned in the waste incineration plant Dürnrohr.

31 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Wet flue gas cleaning After waste incineration plants two-stage wet scrubbers are normally used. In Austria exclusively baffle-free spray scrubbers without incorporations are used First scrubbing stage The first scrubbing stage primarily serves the following functions: Saturation of flue gases, i.e. cooling of flue gases in contact with water to saturation temperature. Absorption of halogen and mercury compounds and of SO 3. Cooling of flue gases takes place in the so-called quenching zone by contact with scrubber recirculation water. The quenching nozzles are fed by two independant pump systems. Water demand is covered by two independent water systems via the emergency tank. In case of operating troubles and fresh water demand water is additionally fed into the quenching zone from this emergency tank. In the event of power failure a secured water supply for cooling of the temperature sensitive downstream plant components is provided. Emergency and circulation water are mostly conducted in separate pipes. The temperature after the quenching zone is observed by several measurements independent from each other. Absorption of halogen and mercury compounds and of SO 3 takes place in the scrubbing zone. Recirculation water is conveyed from the bottom of the scrubber by two independent water circuits to the nozzles. The nozzle levels are arranged in such a way that a homogeneous distribution of circulation water in the form of small droplets in the flue gas results. The major part of droplets directly falls into the bottom of the scrubber, the rest is separated from the flue gas by a droplet separator and also conveyed into the bottom of the scrubber. Conditioning of circulation water is achieved by Addition of process water Deduction of a partial stream into the waste water treatment plant Re-routing of cleaned water from the waste water treatment plant and Dosage of hydrated lime Water is supplied to the plant by the atomisation system of the droplet separator, as dilution water with chemicals, as rinsing water and by the quenching nozzles. A part of this water evaporates in the quenching zone, the rest is withdrawn as waste water and as moisture content of neutralisation sludge. Chemical reactions The pollutants HCl and HF are absorbed contacting the sprayed droplets of washing water. HF (g) + H 2 O (l) # HF (l) + H 2 O (l) HCl (g) + H 2 O (l) # HCl (l) + H 2 O(l)

32 28 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning A part of the absorbed acid ions can react to their corresponding salts in the washing water by addition of hydrated lime. Hydrated lime is added by the ph-regulation system in such an amount that the ph is held constant to a value of 1 by the remaining acids. 2 HF (l) + Ca(OH) 2 (s,l) # CaF 2 (l) + 2 H 2 O 2 HCl(l) + Ca(OH) 2 (s,l) # CaCl 2 (l) + 2 H 2 O In the wet scrubber mercury can be well absorbed as HgCl 2, Hg 2 Cl 2 and HgO whereas metallic mercury neither can be absorbed nor condensed. In the presence of Cl - and at combustion chamber temperatures above 850 C mercury is present as HgCl 2 to more than 95 % as far as waste incineration plants are concerned. HgCl 2 (g) + H 2 O # HgCl 2 (l) + H 2 O In the scrubber HgCl 2 can be reduced by SO 2 which may lead to disproportionation. Metallic mercury built by disproportionation would evaporate during atomization. Reduction: Reduction: SO 2 (l)+ 2 HgCl 2 (l)+ H 2 O # SO 3 (l)+ Hg 2 Cl 2 (l)+ 2 HCl Disproportionation: Hg 2 Cl 2 (l)# Hg(g,l) + HgCl 2 (l) In order to reduce the disproportionation rate measures such as a low ph value in the first scrubber and the permanent discharge of separated mercury into the waste water treatment is provided. Thus on the one hand separated SO 2 is mostly present as sulphate and on the other hand concentration of Hg 2 Cl 2 is held low Second scrubbing stage The second scrubbing stage serves the function of SO 2 removal. SO 2 scrubber using NaOH as reactant The SO 2 scrubber with NaOH is mostly designed as countercurrent scrubber with various atomization levels or as cross flow scrubber with double bore nozzles with hollow cone jets that are arranged in the centre of the scrubber. Circulation water from the bottom of the scrubber is conveyed to nozzles which are arranged in such a way that an even distribution of circulation water in the form of small droplets in the flue gas is guaranteed. The major part of droplets directly falls into the bottom of the scrubber. The rest is carried away with flue gas and is separated by a droplet separator and subsequently routed to the bottom of the scrubber. The ph value of circulation water is adjusted by addition of NaOH to slightly acid or neutral values. An almost constant concentration of sodium sulphate in circulation water can be achieved by a continuous discharge of waste water. Water for the SO 2 scrubbers arises from following sources: Atomization system of the droplet separator, dilution water for chemicals as well as rinsing and washing water of the dewatering unit. Water that is discharged from the circulating circle is conveyed into the first scrubbing stage. A high capacity droplet separator is arranged between the SO 2 stage and the secondary side of the gas/gas heat exchanger.

33 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning 29 In the second scrubber following reactions take place: SO 2 (g) + H 2 O # H + + HSO - 3 (l) H + + HSO ½ O 2 # SO H + HSO Na + # NaHSO 3 (l) SO Na + # Na 2 SO 4 (l) Related to efficiency NaOH is about seven times more expensive than lime (see 9.4.2). Another disadvantage is that there is not possibility to utilize the accumulated waste. As NaOH only forms soluble compounds with SO 2 the operation of this scrubbers is not problematic. Consequently investment costs are low. NaOH scrubbers are used at the small plants of ABRG Arnoldstein and in the clinical waste incineration plant Baden. A NaOH scrubber is intented to be installed after the planned second line of the waste incineration plant Wels. Precipitation using hydrated lime as reactant Most waste incineration plants in Austria that are presently operated with NaOH scrubbers have an external precipitation that follows a simplified double alkali process: Circulation water of the scrubber is held at a constant ph value of about 7 by dosage of NaOH and recirculation of alkaline process water. In an external precipitation plant a part of the sulphate ions that are contained in process water are precipitated as gypsum by addition of lime. Separation of gypsum takes place in the separation step. The gypsum suspension is drained for dewatering. The major part of the clear phase with a ph value of about 11,5 is recirculated into the scrubber. Only a small part of the clear phase is discharged from the process in order to balance the concentration of soluble compounds such as chlorides. The advantage of this arrangement is that circulation water below the solubility limit (clear phase) is used in the scrubber. Therefore problems connected with the suspension operation mode such as increased abrasion, sludge sedimentations in ph sensors and pipelines don t occur. Improvements in the operating behaviour of this type of scrubbers are bought with extra costs of NaOH compared to lime. However, overall costs of this technology are lower than those of the NaOH technology alone which is installed in some plants in Germany and Switzerland. Waste water from the SO 2 step is treated in a downstream waste water cleaning plant together with waste water from the first scrubber or is routed to the deslagging unit. There the ph of waste water is increased by dosage of hydrated lime to about 11,5. Thus sulphates that are dissolved in waste water are precipitated: HSO Ca(OH) 2 # CaSO 4 + H 2 O + OH - Two-stage wet scrubbing systems with precipitation are presently used in the domestic waste incineration plants Flötzersteig, Spittelau and Wels, as well as in one line of the Plant Simmeringer Haide. In the waste incineration plant Flötzersteig the wet scrubber using NaOH was retrofitted.

34 30 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Gypsum scrubber This scrubbing system is mostly designed as countercurrent scrubber with various atomization levels. Circulation water from the bottom of the scrubber is conveyed to nozzles that are arranged in such a way that an even distribution of circulation water in the form of small droplets in the flue gas is achieved. The major part of droplets directly falls into the bottom of the scrubber. The rest is carried away with the flue gas and is separated by a droplet separator and also conveyed into the bottom of the scrubber. There oxygen for oxidation is blowing in by a fan. The ph of the circulation water is adjusted to a slightly acid value by addition of limestone or hydrated lime. The concentration of solids in the circulation water is held at a certain value by the controlled discharge of gypsum. Discharged gypsum is dewatered by centrifuges. Water is withdrawn as filtrate from the dewatering of gypsum and as water content of the discharged gypsum. arge of waste water. Water is fed into the gypsum scrubber by following sources: Atomization system of the droplet separator, dilution water for chemicals as well as rinsing and washing water of the dewatering plant. As to this process following chemical reactions take place: SO 2 is absorbed by the recirculating water and exists as dissolved SO 2 or as hydrogensulphite which dissociates to some extent into sulphite. SO 2 (g) + H 2 O (l) $# SO 2 (l) + H 2 O (l) SO 2 (l) + H 2 O (l) # H + (l) + HSO - 3 (l) # 2 H + (l) + SO - 3 (l) The hydrogensulphite reacts with oxygen to sulphate. HSO ½ O 2 (g,l) # SO 4 (l) + H + (l) CaCO 3 is used as neutralisation medium that reacts with SO 2 in the washing water. SO 2 + CaCO 3 + x H 2 O # CaSO 3 * x H 2 O + CO 2 2 H + + SO CaCO H 2 O # CaSO 3 * 2 H 2 O + CO 2 + H 2 O HSO 3 and SO 3 originating from SO 2 react with CaCO 3. 2 H HSO CaCO 3 # Ca(HSO 3 ) 2 + CO 2 + H 2 O 2 H + + SO CaCO H 2 O # CaSO 3 * 2 H 2 O + CO 2 + H 2 O In the bottom of the scrubber sulphites and hydrogensulphites react with oxidation air and added limestone to calciumsulphate dihydrate. CaSO 3 * ½ H 2 O + ½ O H 2 O # CaSO 4 * 2 H 2 O + ½ H 2 O Ca(HSO 3 ) 2 + CaCO 3 + ½ O H 2 O # 2 CaSO 4 + CO 2 Gypsum scrubbers are in operation at the plant of AVE - Reststoffverwertung Lenzing. The installation is foreseen at the plant in Dürnrohr that is currently under construction and is planned at the fourth fluidised bed reactor in the Plant Simmeringer Haide.

35 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning NO x removal Nitrogen oxides (NO x ) can be formed in three different ways: Thermal NO x : During combustion a part of the air nitrogen is oxidized to nitrogen oxides. This reaction noteworthy only takes place at temperatures above 1,300 C. The reaction rate depends exponentially on the temperature and is directly proportional to the oxygen content. Fuel NO x : During combustion a part of the nitrogen contained in the fuel is oxidized to nitrogen oxides. Formation of NO x via radical reaction (prompt NO x ): Atmospheric nitrogen can also be oxidized by reaction with CH radicals and intermediate formation of HCN. However this way of formation is of small importance. Figure 1: Temperature dependence of NO x formation [VERBUNDGESELLSCHAFT, 1996] NO x emissions can be reduced by primary and secondary measures Primary Measures Primary measures basically have an impact on the formation of thermal NO x. At waste incineration plants following firing specific measures are available to reduce NO x emissions: Use of low-no x - Burners Formation rates of NO x can be lowered by reducing the oxygen content in the centre of the flame. With that measure a reducing atmosphere is created in the hottest parts of the flame so that the formation of thermal NO x is lowered. Complete combustion is achieved by increasing the oxygen content in the cooler zone, leading to a long flame.

36 32 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Staged combustion At certain plants staged combustion can be used in order to reduce NO x emissions. Air is supplied intentionally understoichiometrically to the first combustion zone. In this zone the formation of nitrogen oxides is reduced. A reduction of nitrogen oxides already formed by primary combustion seems to be possible to a small extent. Complete combustion is achieved at lower temperatures in the secondary zone, which is oxygen enriched by the second partial flow of air / oxygen. Flue gas recirculation Flue gas recirculation doesn t contribute substantially to the reduction of NO x emissions Secondary measures Following measures are available to remove already formed nitrogen oxides from flue gases. reaction with a reducing agent (NH 3 ): Reduction of NO x with NH 3 can be achieved in the temperature range of about C by good mixing without other measures. This technique is called selective non catalytic reduction (SNCR). At lower temperature ranges the same reaction takes place in the pores of catalysts and activated carbons (selective catalytic reduction SCR). wet chemical separation Wet chemical separation didn t succeed because of economical reasons on the one hand and secondary emissions at waste incineration plants on the other hand. Secondary measures can be applied as stand alone technologies for flue gas NO x removal or in combination with primary measures Selective non catalytic reduction (SNCR) In order to reduce nitrogen oxide ammonia or a reactant which produces ammonia is injected into the flue gas flow at temperatures of about 1,000 C. Without a catalyst the injected ammonia and the nitrogen oxide in the flue gas form nitrogen and water. A reduction efficiency of about % can be achieved. A plant using the SNCR process consists of the storage and the dosage station for the reactant, the apparatus for the injection of the reactant and the reactor that is integrated in the flue gas flow at a temperature range of about C. The injected and released ammonia reacts with NO x to nitrogen and water vapour. As unwanted side reaction a part of the ammonia combusts to NO x. A small part flows through as slip and can be found in fly dust and flue gases. Following overall reactions take place: NO x reduction: 4 NO + 4 NH 3 + O 2 # 4 N H 2 O NH x combustion: 4 NH O 2 # 4 NO + 6 H 2 O Ammonia slip: NH 3 # NH 3 These three reactions take place simultaneously whereas the reaction process heavily depends on flue gas temperature. In fact only a part of the injected ammonia is used for NO x reduction (Figure 2).

37 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning 33 Figure 2: Utilisation of injected ammonia [ZELLINGER & GRUBER] The SNCR process exceeds the stoichiometrical demand for ammonia because the nitrogen oxides that are formed by combustion of NH 3 have to be reduced in addition to those originally existent. The efficiency of this process is limited by the tolerable slip as too high NH 3 concentrations in the flue gas are inadmissible. If temperature decreases nitrogen oxides will not be reduced sufficiently and the NH 3 slip raises. At too high temperatures (> 1,200 C) NH 3 incinerates and forms NO x. In order to ensure an optimum utilisation of ammonia at varying degrees of load, which cause varying temperatures in the combustion chamber NH 3 can be injected at several layers. Important parameters for using the SNCR process is well mixing of the flue gases and NH 3 by turbulences and observing a minimum residence time. Further ammonia acts as an inhibitor for the de novo synthesis of dioxins and furans. No solid or liquid residues occur at the SNCR process. Presently the SNCR process only comes into operation in the installations of the Plant Simmeringer Haide. An aequous solution of ammonia (25 % ammonia) is used as reducing agent Selective catalytic reduction (SCR) The most important element of the SCR process (Selective Catalytic Reduction) is the catalyst that is passed by the hot flue gas mixed with a reducing agent. Catalytic plants in waste incineration plants are used for NO x reduction and oxidation of organic components. The principle of the SCR process is shown in Figure 3.

38 34 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Figure 3: Schematic of the SCR process [VERBUNDGESELLSCHAFT, 1996] On the catalyst nitrogen oxides are converted to elementary nitrogen and water vapour: 4 NO + 4 NH 3 + O 2 # 4 N H 2 O 6 NO NH 3 # 7 N H 2 O 2 NO NH 3 + O 2 # 3 N H 2 O The efficiency of NO x reduction, achieved by the SCR process is higher than 90%. The ratio of ammonia to nitrogen oxide must be regulated to an optimum both for denitrification as well as for full exploitation of injected ammonia. Dioxins and furans can be oxidized at the catalyst. Thereby following reactions take place: C 12 H n Cl 8-n O 2 + (9 + ½ n) O 2 # (n-4) H 2 O + 12 CO 2 + (8-n) HCl C 12 H x Cl 8-n O 2 + (9½ + ½ n) O 2 # (n-4) H 2 O + 12 CO 2 + (8-n) HCl An incomplete reaction of ammonia and oxidation of SO 2 to SO 3 on the catalyst (conversion) can result in the formation of ammoniumsulphate compounds that can deposit on the air preheater elements. 2 NH 3 + SO 3 + H 2 O # (NH 4 ) 2 SO 4 (ammoniumsulphate) NH 3 + SO 3 + H 2 O # NH 4 HSO 4 (ammoniumhydrogensulphate) In case of an excess of ammonia and SO 3 ammoniumsulphate condensates as dust that has little effect on the catalyst. In case of deficiency ammoniumhydrogensulphate is formed as an adhesive reaction product that may deposit on the surface of the catalyst. The condensation temperature of ammonium hydrogen sulphate gives the minimum working temperature of the catalyst. If the SO 3 concentration in the flue gas is less than 0,5 mg/nm 3 the condensation temperature is below 200 C, however if SO 3 concentrations are well above 20 mg/nm 3 the working temperature has to be increased to > 280 C. The required working temperature is mainly influenced by following boundary conditions: requirement on the efficiency for oxidation of organic compounds concentration of SO 3 in the flue gas If the concentration of SO 3 is low and the catalyst is installed for NO x reduction only, the working temperature can be decreased to 170 C.

39 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning 35 However, since activity is generally decreasing with decreasing temperature the specific volume of the catalyst must be increased. The following requirements are expected from DENOX catalysts (mostly TiO 2 catalysts) [KRATSCHMANN & NISTLER, 1988]: High activity and selectivity. Low conversion rate of SO 2 to SO 3. High resistance to temperature change. Minimum pressure loss and prevention of ash deposition by the shaping of the catalyst. Chemical and mechanical resistance. Resistance to erosion caused by ash. In Austrian waste incineration plants honeycombed full catalysts with activated titanoxide as substrate and catalytically active intercalations with the main components vanadium pentoxide V 2 O 5 and wolfram trioxide WO 3 are used as catalysts. The particular elements of the catalyst are combined to modules and arranged at several levels. According to VGB KRAFTWERKSTECHNIK (1992) a typical honeycombed catalyst has an effective surface of about 750 m 2 m -3. THOMĖ-KOZMIENSKY (1998) subdivides the individual reaction steps of catalysis as follows: Diffusion of the NO x and NH 3 molecules through the laminar boundary layer of the catalyst particulates to the latter's surface. Diffusion through the pores to the activated centres. Adsorption of NO x and NH 3 on the activated centres. Chemical reaction. Desorption of the products N 2 and H 2 O. Diffusion through the product pores to the catalyst surface. Diffusion through the laminar boundary layer into the gas stream. The key factor in the operating behaviour of an SCR system is the NH 3 slip that increases with increasing deactivation of the catalyst and depends on the homogeneity of NH 3 distribution. Depending on the position of denitrification unit it can be distinguished between the highdust circuit and the clean gas application. Due to the high mechanical stress of the catalysts the high-dust circuit is avoided at waste incineration plants. Clean gas application At first waste gas is cleaned in a flue gas cleaning plant, thereby usually cooled and afterwards reheated to the required temperature if necessary. The SCR plant with clean gas application consists of following components: Injection of ammonia with mixing equipment Catalyst box

40 36 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Heat transfer system (if necessary, temperature of the flue gas can be increased by about 40 C with external heating devices) and the corresponding ducts with forced draft Storage and dosage station for ammonia in aqueous solution All constructional measures required Electrotechnical equipment Applying the clean gas application flue gases usually have to be reheated before the catalyst. In case of a required temperature increase of about more than 40 C the use of thermal switching is economical at normal energy costs. Flue gases that enter the catalytic plant are heated in a gas/gas heat exchanger by flue gases coming out of the catalytic plant followed by the injection of ammonia water and another heating step, where natural gas, thermo-oil and high pressure steam are used. Afterwards the flue gas with adequate reaction temperature flows through the catalyst. In the pores of the catalyst injected ammonia reacts with nitrogen oxides to nitrogen and water vapour. Beyond it organic compounds are oxidized in case of a suitable catalyst layout. Thus a significant reduction of emissions of PCDD/F is achieved. Flue gases coming out of the catalyst are cooled in the gas/gas heat exchanger. In Austria the selective catalytic reduction with clean gas application is used in the waste incineration plants Flötzersteig, Spittelau, Wels, Lenzing and Arnoldstein. The second line of the plant in Wels as well as the plant in Dürnrohr will be equipped with an SCR plant too. Ammonia in an aqueous solution is used as reducing agent. Service life of catalysts is at least 10 years. High-dust circuit The catalysts are arranged in the particle loaded flue gas flow at a process-specific provided temperature range. This circuit was short-term tested at a plant and subsequently rebuilt to a clean gas application. Such a plant consists of: The storage and dosage station for ammonia in aqueous solution. The injection of ammonia with mixing equipment. Catalyst box. This arrangement has the advantage, that thermal switching and reheating is avoided and that the flue gas volume is smaller. On the other hand there is the serious disadvantage of the high dust load of the flue gas and as the case may be the presence of heavy metals and catalyst poisons. Thus the service life of the catalyst that is determined by the extent of erosion and deactivation is shortened. Additionally the channels of the catalyst have to be significantly larger so that the catalyst volume is strongly increased. Installations to blow off the dust from the catalysts are also unconditionally required. Presently no plant in Austria operates with high-dust circuits.

41 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Reducing agents for flue gas denitrification All monatomic nitrogen compounds can be used as reducing agent for denitrification, whereby ammonia and urea are mostly used [HARTENSTEIN & MAYER, 1995]. Ammonia NH 3 : Ammonia is a colourless pungent smelling gas and is mostly used in form of a watery solution. The use of gaseous NH 3 causes causticizations and makes handling difficult. Gaseous NH 3 is stored in liquefied form in pressure vessels. Urea (NH 2 ) 2 CO: Urea is delivered as a white crystalline, weakly hygroscope granulate with a grain size of 2 mm. The use of urea instead of ammonia displaces the optimum temperature window for the SNCR process to higher temperatures (about 50 K). Compared with the usage of ammonia emissions of carbon monoxide and laughing gas are considerably higher. According to KOEBEL et al. (2000) urea should not be used for new SNCR units. Urea can not be used for SCR because of the low temperature. 3.4 Reduction of organic emissions and PCDD/F Currently two major mechanisms for PCDD/F (dioxins and furans) formation are known [HÜBNER et al., 2000]: Formation of dioxins/furans in the presence of corresponding chlorinated precursors (such as PCBs, PCPs) by a homogenous gas phase reaction at temperatures between 300 and 800 C. De novo synthesis: The formation of PCDD/F will take place during cooling of the exhaust gas under the following conditions: Temperature range between some 200 and 500 C and adequate residence time in this temperature range. Presence of a chlorine source. Presence of oxygen in the exhaust gas. Presence of dust containing heavy metals and carbon which acts as catalyst. Emissions of organic pollutants and PCDD/F can be reduced by firing and plant specific measures (primary measures) and additionally by secondary measures.

42 38 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Primary measures Primary measures aim at the limitation of pollutant formation. Formation of dioxins/furans can be decreased by the construction and operation conditions of waste incineration plants. Limitation of the de novo synthesis Quick passing of the critical temperature range e.g. by installation of heat exchangers with high capacity. Reduction of the excess air by concerted combustion air input. Dust pre-precipitation to avoid the availability of catalytic active dusts. Frequently cleaning of plant sections, which are passed by the flue gas at the critical temperature range. Firing specific measures The most important measures to reduce the formation of PCDD/F are the reduction of the total excess air and an improvement of the combustion efficiency which means to lower the raw gas concentration of CO and C org as well as the loss on ignition of fly ash and slag. Reduction of the excess increases the temperature in the combustion chamber and improves burnout of gaseous organic compounds and particulates. However, this measure is limited by the inhomogeneity of the waste, which makes adjustment of excess air difficult. If combustion air is added under-stoichiometric CO and C org emissions will increase. Options for the reduction of the total excess air - without reducing the combustion air - are recirculating of the flue gas or using oxygen enriched combustion air. Preconditions for an optimum burnout are: High combustion temperatures (> 850 C) Sufficient residence time (> 2 seconds) High turbulence of exhaust gases and sufficient oxygen content Furnace modifications Furnace modifications aim to prevent sedimentation of fly dust in the critical temperature range of the furnace. To avoid cool corners (areas without air flow and temperatures in the critical range below 450 C) flow conditions in the furnace and heat transfer between gas and water/vapour have to be optimized. Also the quantities of active dust have to be reduced as well as dust sedimentation. Modification of the fuel input As far as technical possible the input of chlorinated compounds shall be significantly reduced since they are essential for PCDD/F formation.

43 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning Secondary measures Dust separation To a large extent once formed dioxins are fixed to particulate matter especially to the fine dust fraction. Therefore effective dust removal will lower the overall dioxins emissions. Activated coke fixed bed process In the fixed bed process pre-cleaned exhaust gases are channelled through an activated coke bed at temperatures between 100 and 130 C. The activated coke bed separates residual dust, aerosols and gaseous pollutants. It is moved cross current and counter current in order to prevent clogging of the bed by residual dust. Usually the dioxin-loaded coke is disposed of by internal combustion. Organic pollutants are destroyed to a great extent. Inorganic ones are released via slag or separated by the exhaust gas fine cleaning. Both gaseous and adsorbed dioxins can be removed from flue gas by the fixed bed process. This process is used at the MVA Wels and at the installations of the Plant Simmeringer Haide. It shall be installed in the planned plant KRV Arnoldstein. Flow injection process The flow injection process is suitable for precipitation of organic pollutants (e.g. dioxins and furans) and/or heavy metals. The separation is based on the principle of adsorption and filtration. For this purpose the pre-cleaned and non-acid flue gas is thoroughly mixed with a finely distributed powdered adsorbent at a temperature of about C. The best results are achieved in a fluidised bed reactor, which enables a large contact surface. The flue gas of the reactor is channelled to a downstream fabric filter, where the adsorbent forms a filter cake. For better utilisation a part of the cake is routed back into the reactor. In general, activated coke or furnace coke are used as adsorbent in combination with lime hydrate. Both of them are suitable for separation of organic pollutants such as PCDD/F, but activated coke is more effective for Hg adsorption, besides the efficiency is improved by impregnation with sulphur. As to the application in waste incineration plants the adsorbent is usually disposed of by internal combustion. Both gaseous and adsorbed dioxins can be removed from flue gas with this process that is used at the plants of AVE-RVL Lenzing and ABRG Arnoldstein. The application is planned at the plants KRV Arnoldstein and Zistersdorf. Catalytic oxidation Catalytic oxidation processes, which are normally used for reducing nitrogen oxide emissions, are applied for dioxin reduction as well. In general, the installations operate in clean gas circuits. Dust and heavy metals have to be removed first to prevent rapid wear and poisoning of the catalyst. In principle only gaseous dioxins can be oxidized what means that dioxins and furans contained in dust have to be removed by efficient dust separation devices. As to the catalytic oxidation no wastes are produced since dioxins are converted to gaseous oxidation products. Normally spent catalysts are taken back by the producers. The efficiency of dioxin removal is between 90 and 95 % as a rule. Often the catalyst is used in combination with the flow injection process. In order to reduce dioxin emissions catalysts are used in the domestic waste incineration plants Flötzersteig and Spittelau. Catalysts in combination with the flow injection process are

44 40 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning used at the plants of AVE-RVL Lenzing and ABRG Arnoldstein. In the planned plants Dürnrohr, KRV Arnoldstein (respectively in combination with the flow injection process) and Wels, line 2, catalysts will come into operation. 3.5 Simultaneous removal of acid gases, NO x and dioxins Moving bed adsorber with activated carbon These systems are used for the removal of SO 2, HCl, NO x, heavy metals and organic compounds from flue gases of power plants, waste incineration plants and other industrial incineration plants. The are constructed as counter current or cross current adsorbers. As to the countercurrent adsorber flue gases enter the horizontal bulk material bed from the bottom through suction funnels and escape through the free space above the bulk material bed. The bulk material (activated coke or activated carbon) is introduced via a charging hopper or chutes and slowly passes through the bed from the top to the bottom. The migration velocity is determined by the discharge system. As to cross flow adsorbers bulk material is distributed in a vertical bed and supported by blinds or bar sieve constructions. The flue gases horizontally flow through the bed that can be divided into several layers using perforated metal plates or blinds. Pollutants are removed from the flue gas following different reaction mechanisms (for furnace coke) SO 2 chemisorption to H 2 SO 4 and fixation into ash as sulphates HCl adsorption and fixation into ash as chlorides HF adsorption and fixation into ash as fluorides Hg adsorption and chemisorption PCDD/F adsorption and filtration NO x catalytic reduction of NO x with NH 3 (like in SCR-units) Process temperatures of activated coke systems are in the range of 100 to 140 C Fluidised bed systems Fluidised bed systems are a dry flue gas cleaning systems for the removal of pollutants such as sulphur dioxide, hydrochloric acid, heavy metals, dioxins and furans. The main principle of this process is to bring the flue gas in an intensive contact with sorbents such as calcium hydroxide, open-hearth furnace coke, water and recirculated material in the turborecactor. The turboreactor operates as circulating fluidised bed in the fast fluidisation regime. The gas/solid mixture leaves the turboreactor at the top. The solid is separated from the flue gas in a fabric filter or electrostatic precipitator. In the filter cake of the fabric filter a further reaction between sorbents and pollutants takes place. The major part of the separated solids is recirculated into the fluidised bed reactor while the remaining leaves the process. Due to the high percentage of sorbent recirculation high sorbent utilisation and low stoichiometric ratios are achieved.

45 State of the Art / Waste Incineration Technologies for Flue Gas Cleaning 41 For a flue gas desulphurisation process after coal/oil fired boilers only slaked lime is used as sorbent. It is injected between the reactor outlet and the filter or directly into the reactor. For the flue gas cleaning process after waste incineration plants open-hearth furnace coke is additionally injected at the same position (between the reactor outlet and the fabric filter). This systems are operated in a temperature range between 70 and 160 C. It is intended to use this technique in the planned waste incineration plant of KRV Arnoldstein. However, to guarantee the compliance with emission limit values also an activated coke filter will be installed. 3.6 Avaibility and use in Austria All plants in Austria that are presently in operation with the exception of AVE-RVL Lenzing were retrofitted with various systems for flue gas cleaning and waste water treatment. As an example some important facts concerning the history of the domestic waste incineraton plant Flötzersteig are summarised: The waste incineration plant Flötzersteig was built in the years by the municipality Vienna and was equipped according to the state of the art at that time with a masoned grate combustion chamber, a waste heat boiler, an electrostatic precipitator and a cyclone separator. In 1985 a retrofitting program was started, which comprised the erection of a three stage wet flue gas treatment plant and a waste water treatment plant for the separation of heavy metals, HCl, SO 2 as well as for fine dust separation. At the beginning of the ninties the firing grate, the combustion chamber as well as the electrostatic precipitators were renewed. In order to comply with the state of the art the selective catalytic reduction for NO x removal as well as the dioxin destruction were built. Experiences at Austrian waste incineration plants show that all technologies for reduction of emissions into air and water that are described in this study can be integrated into existent plants. Potential limitations may solely result from space requirements of the particular installations. The additional installation of a SNCR process can be limited by the given geometry of the combustion chamber as well as by the temperature control. However this process doesn t comply with the state of the art anyway, as the limit values for NO x emissions according to the Austrian law but not the actual limit values prescribed in the actual permits can be met.

46 42 State of the Art / Waste Incineration Waste Water Treatment 4 WASTE WATER TREATMENT Waste water arising from the first and second scrubbers as well as from the ash and slag treatment is treated in the waste water treatment plant. If precipitation of salts is unlikely all partial flows can be combined and treated together. In Austria multiple stage cleaning of the waste water has become widely accepted. The first cleaning step, the heavy metal precipitation, normally includes processes such as precipitation, flocculation, sedimentation, neutralisation and sludge dewatering. The second cleaning step mostly comprises a sand filter, an activated coke filter and an ion exchanger. Chemicals that are necessary for waste water treatment are stored and prepared in a chemical station. As a rule sludges accumulating at the particular processes are collected in a sludge tank and are in most cases dewatered in chamber filter presses to a moisture content of about 50 %. The remaining filter cake has to be disposed of as hazardous waste. 4.1 Gravity separation Solid particulates can be separated by means of gravitation settling. The velocity of incoming waste water is reduced thus enabling sedimentation of solids, which are then removed from the bottom as sludge. Floating materials are skimmed from the surface. Sludge contains carbonates, sulphides or hydroxides of heavy metals, oily scum and under certain circumstances even dioxins. Basically different types of sedimentators can be distinguished: Sedimentation tanks designed to allow a residence time of about 1.5 to 2.5 hours. Laminar separators, where plates are used to enlarge the sedimentation surface. Tanks with vertical flow that are usually not equipped with a mechanical sludge removal system. In any case storage facilities for sedimented sludge have to be provided. Limits and restrictions Sedimentation is usually used as a pretreatment method, but it is not suitable for separation of fine particles. For smalll particles or if their density is similar to that of water or if they form emulsions, flocculent and/or coagulant chemicals have to be added. These chemicals cause destabilisation of emulsions and agglomeration of particles that can be separated as flocs. If the waste water contains volatile compounds emissions of VOCs may occur due to high residence times in the separator.

47 State of the Art / Waste Incineration Waste Water Treatment Neutralisation Increase of ph In order to separate SO 2 waste water must must have a slightly acid or neutral ph value. Heavy metals are separated at higher ph. The increase in ph is achieved by adding chemicals such as limestone, quicklime, slaked lime or sodium hydroxide. The choice of chemical depends on the volume and the composition of waste water. Limestone (CaCO 3 ): Limestone is only used for pretreatment of waste water with a very low ph (<1) or for neutralisation of single batches of waste water. Limestone is added to waste water either as a powder or as slurry. It is available at a low price, but handling of the powder is difficult. Further disadvantages are the need of large quantities and the release of CO 2. Quicklime/lime (CaO): Quicklime can be used as an alternative to limestone. By using lime smaller quantities are needed, there is no release of CO 2 and the reaction velocity is higher. Handling of the hygroscope and alkaline powder as well as the large heat production in the course of dissolution can cause problems. Slaked lime (Ca(OH) 2 ): Slaked lime is commonly used in waste water treatment plants. It is added either as a powder or as slurry (milk of lime). Slaked lime is cheap, but handling of powder causes problems. Sodium hydroxide: Sodium hydroxide (NaOH) is also commonly used as neutralisation agent. It is always added to waste water as a solution Reduction of ph If necessary, hydrochloric or sulphuric acid at a convenient concentration can be used for reduction of ph. 4.3 Precipitation Chemical precipitation is a process in which dissolved components (heavy metals, phosphates, sulphates and fluorides) react with added chemicals to form very slightly soluble or insoluble compounds. Flocculent or coagulant chemicals might support precipitation. The precipitate will be separated from the waste water by sedimentation, optionally followed by filtration or microfiltration. Heavy metals are precipitated as slightly soluble hydroxides by addition of lime milk. Precipitation of heavy metals (especially Hg) is completed by subsequent or simultaneous addition of sulphides (e.g. Na 2 S) or organic sulphureous complexing agents (e.g. trimercapto-striazine TMT 15). Subsequently excessive sulphides are separated by addition of FeCl 3 that serves as flocculant. Often polymer flocculants are added simultaneously. A precipitation system usually consists of one or two stirred mixing tanks, where the agent and possibly other chemicals are added, and a sedimentation tank. Process differences arise by the use of different chemicals: Using lime, the mass of sludge increases. Operating and maintenance problems may occur by handling, storage and feeding of lime. The advantages of using lime are: prevention of increasing salt content in the waste water, improvement in sludge sedimentation and dewatering.

48 44 State of the Art / Waste Incineration Waste Water Treatment Advantages of using chemicals are, that pre- or posttreatment is not necessary and that the amount of accumulated sludge is comparable low. Some chemicals are also highly efficient at removing suspended and dissolved metals from a waste water stream. 4.4 Flocculation Flocculation usually follows precipitation. The purpose of waste water flocculation is to induce suspended particles or emulsions to agglomerate to settleable flocs. The flocculation process takes about 10 to 20 minutes. In order not to destroy the formed flocs mixing must be done gently. However a slight movement of the waste water is necessary in order to bring the particles in contact with each other. Flocculation basins mostly have the form of mixing reactors. Various reagents can be used as flocculation agents: Air Polyelectrolytes: cationic, anionic and non-ionic Aluminium compounds such as alum or sodium aluminate Iron compounds such as ferric chloride, ferric sulphate and melanterite Lime Partial recycling of flocs back into the flocculator can result in a better floc structure and an optimum exploitation of flocculent. In order to achieve an optimum separation performance disturbing compounds can be removed by an oil separator, by splitting of emulsions and other processes. Flocculation is often applied in combination with sedimentation, flotation and filtration. Limits and restrictions If metal compounds are used as flocculents, an exact ph range will be a key issue for a good separation performance. Stable emulsions cannot be broken by chemicals. Another disadvantage are the high costs of flocculation agents. 4.5 Flotation Flotation is a process where solid or liquid particulates are separated from the waste water phase by attachment to gas bubbles. The buoyant particles accumulate at the water surface and are collected with skimmers. Additives, such as aluminium and ferric salts, activated silicic acid anhydride and various organic polymers, are commonly used to support the flotation process. Their function is to create a surface or a structure able to absorb or entrap the air bubbles. Flotation is used when gravity settlement is not appropriate, e.g. when the particulates have poor gravity settling characteristics the density difference between suspended particulates and water is too low oil and grease are to be removed or the recovery of the material is required.

49 State of the Art / Waste Incineration Waste Water Treatment 45 There are three methods of flotation that can be distinguished: Vacuum flotation: Air is dissolved at atmospheric pressure in the waste water, followed by a pressure drop to allow the formation of bubbles. Induced air flotation: Fine bubbles are drawn into the waste water via an induction device such as a venturi or orificed plate. Dissolved air flotation: Pressurized air is dissolved into the waste water and subsequently released to form small bubbles. Flotation is unaffected by changes of flow rate and temperature. The installed flotation tanks are smaller as compared to gravity separation. Further advantages are the high separation efficiency and the possibility to recover removed material. Restrictions Using flotation, soluble substances and gross free oil cannot be removed. There are higher operational costs than using sedimentation, because more expensive flocculent and coagulant chemicals are needed. 4.6 Filtration Filtration describes the separation of solids from waste water effluents passing through a porous medium. Used filters have to be cleaned by backwashing with reverse water or fresh water. If low particulate emissions are required, filtration will be used as final separation step. Commonly types of filter systems are, e.g. the granular or sand filter for waste water treatment the belt filter press, which is used for sludge dewatering, but also for liquid/solid separation operations filter presses, which are used for sludge dewatering, but also for the separation of solids. Sand filters consist of a granular filter bed with either downward or upward flow. The operation can be performed semicontinuously filtration followed by backwashing or continuously simultaneous filtration and backwashing. Restrictions Colloids or emulsions cannot be separated without additional chemical treatment. Finely dispersed or slimy solids will block the filter medium, if filter aids are not used. Filters have a high separation efficiency and operate under a wide range of conditions, but they can not be used for dissolved pollutants. A disadvantage of semi-continuous sandfilters is that clogging and fouling processes are possible. Furthermore a breakthrough can cause additional pollution of the previously cleaned water.

50 46 State of the Art / Waste Incineration Waste Water Treatment 4.7 Ion exchanger With ion exchangers undesirable ionic constituents of waste water can be removed and substituted by other ions. Substituted ions are retained in the resin and ejected into the regeneration liquid or the backwash water in concentrated form when starting the ion exchanger regeneration. Heavy metallic ions, anions such as halogens, sulphates, nitrates or cyanides as well as soluble ionic organic compounds can be removed with high efficiency. Ion exchanger are also used as last step in a complex waste water cleaning system because all ions can be removed from the waste water due to the existing variety of resins. The main advantage of an ion exchanger is the potential to recover the exchanged ions. Thus the production of sludge is prevented. However the sol that is generated during regeneration has to be treated and disposed of. Ion exchanger enable high separation performances and can be adapted to the particular requirements. Furthermore they are not sensitive to flow rate fluctuations. Restrictions Application limits may occur if resin particles swell because of too high ion strength. Furthermore an irreversible adsorption to the resin what means destruction may be caused by an excess of inorganic (e.g. ferrous sediments) or organic compounds (e.g. aromatics). At a temperature level of about 60 C anionic resins loose activity due to thermal stress. The presence of nitrogen acids, chromic acids, hydrogenperoxide, iron, magnesium and copper will lead to chemical and physical destruction of resins. The operation of ion exchangers is associated with high costs and can be noticeably impaired by the presence of competitive ions in the waste water. 4.8 Activated coke filter Activated coke filters are used for the efficient removal of organic compounds from waste water. Activated coke is added to waste water either alone or in combination with flocculents. After the adsorption of pollutants it is removed by sedimentation or filtration. Dosage of actived coke is applied only in case of need so that this process can be applied in a flexible manner. Normally used activated coke is not regenerated but combusted or landfilled together with accumulated sludge. The adsorption capacity of activated coke can be significantly reduced by the existence of various organic compounds in waste water.

51 State of the Art / Waste Incineration Disposal and Technologies for Waste Treatment 47 5 DISPOSAL AND TECHNOLOGIES FOR WASTE TREATMENT Waste incineration leads to weight and volume reduction of wastes. Main waste fractions are fly ash, slag, metallic scrap, filter cake from the waste water treatment, gypsum and loaded activated carbon. These wastes are predominantly hazardous wastes. In Austria they are treated or disposed of as follows: Fly ash and the mixture of slag/gypsum from the waste incineration plants Spittelau and Flötzersteig are solidified and subsequently landfilled. Slag, fly ash and gypsum from the waste incineration plant Wels as well as slags and fly ashes from the Plant Simmeringer Haide are landfilled too. In general the filter cake from waste water treatment is heavily charged with Hg. In most cases it is filled in so called big bags and disposed of underground. Other critical parameters are the Zn and Cd concentration as well as the residue on evaporation. Separated metallic scrap is either delivered to a scrap dealer or returned to the steel industry. In Wels, Arnoldstein and at the Plant Simmeringer Haide loaded activated coke is combusted together with waste. In addition to these current practices various tests were performed with the goal to utilize wastes from waste incineration plants or at least to lower the hazard potential. In the waste incineration plant Wels slags and ashes were washed and afterwards thermally treated using a rotary kiln. In Lenzing (AVE-RVL) thermal treatment was done in trial operation. These experiments were terminated as on the one hand legal and economic conditions didn t justify the treatment and on the other hand technical problems complicated permanent realization. In the following chapters several technologies that were tested or are applied shall be presented. 5.1 Landfilling in big bags Filter dust, filter cake and mixed solid waste can be filled in so called big bags and disposed of underground. Big bags are constructed as double-walled plastic container with a volumetric capacity of 1,5-2 m 3 (corresponding to one ton). The outer layer of the plastic container consists of polypropylene that ensures the required stability. The inner layer is waterproof and consists of polyethylene. Storage of big bags out of doors without covering is not possible, as the stability of polypropylene decreases by UV radiation. In addition to big bags steel container can be used too. Big bags are comparatively expensive and can be used only for relatively dry waste. The filter cake from the waste water treatment of Austrian waste incineration plants is commonly packed into big bags and disposed of underground.

52 48 State of the Art / Waste Incineration Disposal and Technologies for Waste Treatment 5.2 Solidification They aim of solidification of ashes and slags is to reduce the mobility or the mobilisation potential of certain pollutants. However this process doesn t represent a utilisation of wastes. Solidified material shall meet following criterias: Low permeability for water No chemical reaction with water Mechanical long-term stability Chemical and biochemical long-term stability No pollutant release into the eluate in case of erosion and corrosion or changes in the disposal conditions No emission of reaction products or metabolites from biochemical reaction products Compatibility with follow-up processes It is possible that an immobilisation procedure only immobilises certain pollutants. Therefore a thorough knowledge of immobilisation mechanisms is of utmost importance. The basic mechanisms are: Encapsulation Integration into homogenous solidifying phases, e.g. polymers, glass or other silicates Solidification by chemical reaction with waste, e.g. lime or cement It has to be decided individually which mechanism is most suitable for a special problem. Most of the binding systems are based on inorganic matter, therefore inorganic pollutants such as heavy metals can be immobilised easier than organic compounds. Often used processes are the Schlacke-Reststoff-Additiv Verfahren and the Zement- Additiv Verfahren. Slag, gypsum and filter ash from the domestic waste incineration plants Spittelau and Flötzersteig are solidified with cement and subsequently used as material for the erection of side walls of the landfill Rautenweg. 5.3 Separation of metals In Austrian waste incineration plants ferrous metals are removed from slag by means of magnetic separators. The separated metals are either returned to the steel industry or delivered to a scrap dealer. 5.4 Washing processes Soluble pollutants (e.g. chlorides, sulphates, heavy metals) shall be extracted from the solid wastes by washing processes. In the waste incineration plant Wels slag and filter ash are treated by the so called MR (Multi Recycling) process. MR Process In the wet deslagging unit slag is washed with water from the second scrubber of the flue gas cleaning plant or with fresh water when gypsum is removed separately in order to extract chlorides, sulphates and base-forming ions.

53 State of the Art / Waste Incineration Disposal and Technologies for Waste Treatment 49 Treatment of filter ash is carried out in two steps. In the first step ash is suspended in water whereby a ph value of 9 12 is attained. The solid is separated from the solution, that contains slightly soluble salts (primarily Na-, K-, Ca-, Cl- and SO 4 -compounds) by means of a vacuum belt filter. In the following washing step soluble heavy metals are extracted using the acid washing water of the first scrubber of the flue gas cleaning system. The heavy metal containing waste water is cleaned in the waste water treatment plant. The washed ash can be thermally post-treated. However, substances that are introduced into the waste water treatment plant may cause problems with precipitation in the post treatment step. That was the case at the waste incineration plant Wels. 5.5 Thermal treatment In Wels the washed filter ash was thermally treated in a rotary kiln for further reduction of dioxins and mercury. Flue gases from the rotary kiln were cooled, cleaned with a fabric filter and subsequently led back into the combustion chamber of the waste incineration plant. At this time the thermal treatment is not performed as in this case no significant improvements of ash quality in regard to current Austrian regulations can be achieved as far as landfilling is concerned. In Austria loaded activated carbon from flue gas cleaning is combusted in grate firings as well as in rotary kilns directly or after a low temperature treatment together with the waste.

54 50 State of the Art / Waste Incineration Utilisation of Energy 6 UTILISATION OF ENERGY Energy is supplied to the combustion chamber by waste, auxilliary fuels and by preheated air. This energy is converted in the combustion chamber by combustion. A part is released to the heating surfaces of the combustion chamber, the rest is conducted away from the combustion chamber with the exhaust gases. In special cases heat is delivered to the heating surfaces by ash. In the waste heat boiler heat is transferred to the water steam cycle by cooling the exhaust gases. The energy content of the exhaust gases at the exit of the waste heat boiler is called exhaust gas loss. The ratio of the energy that is taken up by the water steam cycle to the energy that is introduced into the combustion chamber is called boiler efficiency. Hence the boiler efficiency significantly depends on the exhaust gas flow and with that on the air excess and the temperature of the exhaust gases leaving the boiler. The minimal exhaust gas temperature is limited by the acid dew point. Fluidised bed combustions with exhaust gas temperatures of about 160 C can achieve boiler efficiencies of about 90 %. Costumary grate firings have a boiler efficiency of about 80 %. The water steam system that is applied in Austrian waste incineration plants is comparable to that of medium-sized steam boiler plants of the industry in the range of 20 to 120 MW th. Solely at small plants purely high temperature boilers are installed. All steam boilers that are used in Austrian waste incineration plants are natural circulation boilers. At all plants the water steam process happens as follows: Water is deionised in the water treatment plant and fed into a feedwater tank. There it is used for the first filling of the pipes of the feedwater system and for balancing of losses during operation. The deionised water is degassed in a degasser that is located above the feedwater tank by impact with steam and then heated to a temperature of about 105 C. The boiler feedwater is pumped into the steam drum by water pumps through steam and flue gas heated feedwater heaters. Water from the steam drum runs over the downspout to the collectors that are placed at the lower part of the boiler. From the collectors water is routed to the feedwater evaporators which they pass from bottom up. On the upper side of the evaporators a water-steam mixture arises which is then piped into the steam drum. There the steam is separated, removed from the steam drum and conducted over the superheater surfaces. Injection coolers are used to regulate the steam outlet temperature. The steam parameters are limited by the contents of flue gases. At flue gas temperatures above 500 C and pipe wall temperatures above 420 C corrosions are caused by sodium and potassium chloride. For this reason higher temperatures in the superheater only can be driven with special measures. In order to prevent high temperature chlorine corrosion steam parameters with pressures less than 60 bar and temperatures less than 420 C are applied at most plants. In Austria only one plant is operated with superheater temperatures up to 500 C and a pressure of approximately 80 bar. In return steam in the flue gas flow is superheated to about 380 C. The final superheating is performed in a so called fluidised bed cooler: Circulating ash of a circulating fluidised bed is fluidised with air and cooled at a syphon. The ash contains corrosive salts. Therefore corrosion damages often occur. The higher power generation rate is accompanied with a lower availability of the superheater. Enhancement measures are under development. In case of pure power generation fresh steam leaving the boiler is conducted over a turbine and subsequently condensated. If heat is needed steam can be withdrawn from the turbine at a lower pressure level. In case of a large heat demand the outlet pressure from the turbine will be held at a higher level. Thus the power generation rate is reduced. As to the power generation on the one hand partly pure condensation turbines and on the other hand mainly at Viennese plants back-pressure turbines are used.

55 State of the Art / Waste Incineration Utilisation of Energy 51 If heat-controlled cogeneration (CHP) is applied what means that the waste heat is fully utilized about 85 % of the energy converted in the steam generator is delivered as heat and about 15 % is delivered as electricity from the turbine, depending on the steam parameters (Figure 4 and Figure 5). In case of no heat demand electricity delivered from the turbine will be about 25 % of the energy converted in the steam generator if normal steam parameters are applied. In this case excess energy has to be dissipated by the cooling system. Combined Heat and Power (normal steam parameters) waste 10 MJ/kg combustion air 0,1 MJ losses through radiation 0,2 MJ condensate losses via exhaust gas 1,2 MJ internal consumption of high-pressure steam 0,2 internal consumption of electrical energy 0,4 MJ produced electrical energy 0,8 MJ useful heat 7,2 MJ loss on condensate 0,2 MJ Figure 4: Energy flow chart diagram of cogeneration (CHP) with normal steam parameters In Austria there is a plant under construction where the produced steam shall be fed into the water-steam cycle of a neighbouring power plant. In combination with the power plant a theoretical power generation of up to 35 % of the energy converted in the steam generator is calculated. Thus an equivalent coal amount of 80 % of the thermal output of wastes can be substituted.

56 52 State of the Art / Waste Incineration Utilisation of Energy Combined Heat and Power (increased steam parameters) waste 10 MJ/kg combustion air 0,1 MJ losses through radiation 0,2 MJ condensate losses via exhaust gas 1,2 MJ internal consumption of high-pressure steam 0,2 internal consumption of electrical energy 0,4 MJ produced electrical energy 1,3 MJ useful heat 6,7 MJ loss on condensate 0,2 MJ Figure 5: Energy flow chart diagram of cogeneration (CHP) with high steam parameters Main consumers of electricity in a waste incineration plant are the combustion air fans, the feedwater pumps, the circulating pumps of the wet flue gas cleaning system and the forced draft fan. As to grate firings and rotary kilns own needs of electricity lie between 2 and 3 % of the thermal output. The own electricity demand of fluidised bed combustion plants is about 50 % higher due to higher initial pressure of combustion air and the additional energy demand for waste pretreatment. Main heat consumers are the reheating steps of the flue gas cleaning system. Flue gases leaving the wet scrubbers have to be reheated before they enter the dry systems. Reheating is performed by means of gas/gas heat exchangers and steam preheaters that are heated with low pressure steam. High pressure steam and natural gas are used for the final heating of flue gases before the catalyst. Required energy for reheating can be held low by application of large heat exchanger surfaces.

57 State of the Art / Waste Incineration Utilisation of Energy 53 Uncoupled heat can be used for the production of fresh steam by heating the condensate and the combustion air with low pressure steam, so that the rate of power generation can be increased. The overall efficiency of a waste incineration plant is defined as the ratio of utilizable energy (heat and power) to supplied energy. If waste heat is fully used (heat-controlled cogeneration) a theoretical overall efficiency up to 80 % can be achieved. If heat is not used the overall efficiency applying normal steam parameters will only be about 20 % (Figure 6). Pure electricity production (normal steam parameters) waste 10 MJ/kg combustion air 0,1 MJ losses through radiation 0,2 MJ condensate losses via exhaust gas 1,2 MJ internal consumption of high-pressure steam 0,2 internal consumption of electrical energy 0,4 MJ produced electrical energy 1,8 MJ produced heat 5,2 MJ Figure 6: Energy flow chart diagram of pure power generation with normal steam parameters In case of increased steam parameters and pure power generation an overall efficiency up to 30 % can be achieved (Figure 7).

58 54 State of the Art / Waste Incineration Utilisation of Energy Pure electricity production (increased steam parameters) waste 10 MJ/kg combustion air 0,1 MJ losses through radiation 0,2 MJ condensate losses via exhaust gas 1,2 MJ internal consumption of high-pressure steam 0,2 internal consumption of electrical energy 0,4 MJ produced electrical energy 2,2 MJ produced heat 5,8 MJ Figure 7: Energy flow chart diagram of pure power generation with high steam parameters However a comparison of efficiencies can give only a rough estimate as in the first case mainly heat at a low temperature level and in the other case electricity is produced. For example electricity can be converted to low level heat by heat pumps with a performance coefficient of about 4. This would give an overall efficiency similar to cogeneration (CHP). Therefore not only the energetic efficiency but also the environmental effects that result from substitution of energy should be considered. Thus it is self-evident that an optimal use of energy from waste incineration can be influenced not only by the choice of the suitable process but also by the choice of the suitable site.

59 State of the Art / Waste Incineration Utilisation of Energy Corrosion As to waste incineration plants important factors for corrosions are the chloride content of the flue gases and the steam parameters. The steam parameters have to be chosen in such a way that under all operating conditions the superheater surfaces are operated in the corrosionfree zone corresponding to Figure 8. Flue gas temperature [ C] 1000 Corrosion zone 800 Transition zone Corrosionfree zone Surface temperature of the heating surface [ C] Figure 8: Corrosion zones of the heating surfaces

60 56 State of the Art / Waste Incineration Cross-Media Aspects 7 CROSS-MEDIA ASPECTS The IPPC Directive follows the approach of the integrated prevention and reduction of pollution and provides measures for the reduction of emissions to air, water and soil among this also measures for waste leading to a high level of protection of the environment as a whole. The purely shifting of pollution from one medium to another shall be prevented. In the course of the information exchange about best available techniques a working group was installed that deals with costs and cross-media aspects. Results of this working group are not present yet. As to the BAT reference documents that are already finished emission of pollutants are discussed separately for the media air, water and soil (including waste/residues), followed by evaluation of BAT in the so-called consensus mode of experts. The integrated approach, that particularly also includes the prevention of emissions and the formation of wastes, was mainly chosen in view of the production of material goods and can be extended in this domain to the product evaluation and life cycle analysis. The application of the integrated approach within the scope of the Directive 96/61/EC (IPPC Directive) is limited to plants that are listed in annex I. In addition to the industrial operations of the producing sectors power plants (above 50 MW) as well as waste treatment plants and landfills are also included in annex I. The special feature of a power plant consists in the fact that the product is energy. Waste treatment plants including waste incineration plants don t generate a product. They are errected for the disposal of wastes from municipal and producing sectors. However, in most cases the produced heat is utilized. The shifting between particular environmental media at a waste incineration plant that is operated according ot the state of the art can be described as follows: During combustion of waste a part of the waste is transformed into the gaseous phase, exhaust gases have to be cleaned in order to separate fly ash, acidic gases, heavy metals and dioxins whereby solid wastes and waste water accumulates. The non-combustible parts of the original waste remain as ash or slag. This ash and slag and solid waste from dry and wet flue gas cleaning are landfilled, in some cases after a further treatment. Heat produced during combustion is mostly used as such and also partly converted to electricity. Combustion reduces the volume of domestic waste by about 90 % and the weight by about two thirds. The calorific value of domestic waste lies between 7 and 15 MJ per ton. Some fractions of waste from trade and industry have higher calorific values (up to 40 MJ t -1 ). However, in some cases hardly combustible or even non-combustible waste is also combusted in order to destroy combustible toxic compounds. Therefore shifting effects are quantitatively determined by the input material, the combustion technology and the flue gas cleaning technology as well as by the characteristics of energy utilisation. At waste incineration plants built and operated according to the state of the art pollutants are shifted between media as given below. With regard to amounts and costs it is referred to chapter 9.4. Details about energy utilisation are described in chapter 6 and potential profits are presented in chapter 9.3. Cross-media aspects of flue gas scrubbing Applied auxiliary materials: water, sodium hydroxide, hydrated lime, limestone, electricity, precipitation chemicals (flocculants, polyelectrolytes), hydrochloric acid, heat for reheating Air: Clean gas Water: treated waste water Accumulated wastes: sludge from waste water cleaning (filter cake), gypsum

61 State of the Art / Waste Incineration Cross-Media Aspects 57 Cross-media aspects of dry flue gas cleaning Dust separation (preseparation) Applied auxiliary materials: electricity Air: Clean gas Accumulated wastes: Filter dust, fly ash Combinated separation of dust, Hg, and PCDD/F Applied auxiliary materials: burnt lime, activated coke, electricity Air: Clean gas Accumulated wastes: mixture of salt containing filter dust, fly ash, loaded activated carbon Cross-media aspects of denitrification Applied auxiliary materials: ammonia solution (or urea), electricity, catalyst (possibly) Air: Clean gas Accumulated wastes: catalyst abrasion (possibly) Cross-media aspects of the separation of dioxins Applied auxiliary materials: activated carbon or coke, electricity Air: Clean gas Accumulated wastes: dioxin containing activated carbon/coke Shifting of particular elements and substances Objective: concentration of pollutants At the beginning of the ninties the transfer of single substances, such as heavy metals, S, Cl, F and phosphorous was investigated at the waste incineration plant Spittelau [Schachermayer et al. 1995]. The objective of this study was the determination of transfer coefficients for the mentioned substances and the development of determination methods. Investigations are still running, the results obtained until now allow the optimization of the plant with regard to accumulated solid waste from combustion and give information about the composition of the delivered domestic waste over a long period. This work showed that the sulphur content of the clean gas after wet flue gas cleaning was less than 1 % of the input. About 47 % of the sulphur that is contained in the waste is transferred into the slag, about 39 % into the filter ash and 6-8 % both into the waste water and into the filter cake. Introduced P distributes among slag (83 %) and ash (17 %) and to a very low extent among clean gas, waste water and filter cake. As to heavy metals mass balances were made for iron, copper, zinc, lead, cadmium and mercury. Less than 1 % of the heavy metals of combusted waste reaches the cleaned gas. Iron can be separated to about 80 % by scrap separation, about 18 % can be found in the slag. Copper its concentration in the waste is much lower than that of iron is found in the slag (about 94 %) and in the filter dust (about 6 %). Zinc and lead also can be found mainly

62 58 State of the Art / Waste Incineration Cross-Media Aspects in the filter dust and the slag. However the distribution between slag and filter dust was about 1 : 1 in the case of zinc and 3 : 1 in the case of lead. According to these investigations about 90 % of cadmium is found in the filter dust and about 9 % in the slag. About 30 % of mercury is discharged with the filter dust, about 66 % with the filter cake and about 5 % with the slag.

63 State of the Art / Waste Incineration Descriptions of Plants 59 8 DESCRIPTIONS OF PLANTS The Waste Management Plant and Substance Database of the Federal Environment Agency currently lists 188 plants for the thermal recycling and treatment of waste with a total capacity of around 2.7 million tons [BMLFUW, 2001]. Since the capacities of all plants are not known, this total capacity must be regarded as a minimum value that in reality may be much higher. Of a total of 188 plants, 135 treat waste generated exclusively within their own enterprise. The remaining 53 plants are partly publicly accesssible. However, others only treat waste of specific partner enterprises, the so-called selected third parties. Hazardous waste is presently combusted in 14 plants with an overall capacity of about 233,000 tons a year. The main part can be attributed to Fernwärme Wien GmbH, Plant Simmeringer Haide [BMLFUW, 2001]. Waste for combustion can be classified to applied technologies and plants as follows: Domestic waste incineration plants MVA Flötzersteig, MVA Spittelau, MVA Wels Combustion of hazardous wastes Rotary kilns of the Plant Simmeringer Haide and of ABRG Arnoldstein Combustion of clinical waste Pyrolysis Plant Baden, rotary kilns of the Plant Simmeringer Haide Combustion of sewage sludge Fluidised bed reactors of the Plant Simmeringer Haide and of AVE-RVL Lenzing Combustion of treated waste fractions AVE-RVL Lenzing, Steyrermühl, Funder Combined waste incineration AVE - Reststoffverwertung Lenzing, Wels, (planned) 4 th fluidised bed reactor of the Plant Simmeringer Haide Pyrolysis of waste (compare to combustion of clinical waste) Planned and already permitted waste incineration plants Dürnrohr, Arnoldstein, Zistersdorf, Niklasdorf, Wels (2 nd line), Plant Simmeringer Haide (4 th fluidised bed reactor) Gasification No plant in Austria Most of these plants are described in detail in the following chapters.

64 60 State of the Art / Waste Incineration Descriptions of Plants 8.1 Domestic waste incineration Waste incineration plant Flötzersteig 196,605 t domestic waste from Vienna City were incinerated in the waste incineration plant Flötzersteig in the year General data of this plant are presented in Table 4. Table 4: General data of the waste incineration plant Flötzersteig (reference year: 2000) [REIL, 2001] Operator Waste incineration plant Flötzersteig Fernwärme Vienna GmbH Start up 1963 Firing technology Grate firing Waste throughput 196, t Average net calorific value 8,862 kj kg -1 Average gross calorific value 9,400 kj kg -1 Theoretical rated thermal input 62 MW Working hours line 1 8,011 Working hours line 2 8,066 Working hours line 3 8,207 Plant concept A process flow diagram of one of the three incineration lines is shown in Figure 9. Each line basically consists of the following units: Waste bunker Firing system: Combined forward and backward moving grate Waste heat boiler Flue gas cleaning devices consisting of: Electrostatic precipitator, three-stage wet scrubber, catalytic flue gas cleaning system for NO x and dioxin removal Multistaged waste water treatment plant Steam distribution system

65 cf State of the Art / Waste Incineration Descriptions of Plants 61 HO 2 Boiler Economiser Electrostatic precipitator Scrubber Natural gas Air 4 bar NH4OH TMT FeCl3 PE HCL NaOH Ca(OH) 2 Lime milk Lime milk precipitation ag. Precipitation agents Condensate returns Steam to consumers Slag bunker Filter ash Sludge tank Chamber filter press Filter cake box Sewerage Figure 9: Process flow scheme of the waste incineration plant Flötzersteig

66 62 State of the Art / Waste Incineration Descriptions of Plants Table 5 shows an input / output balance of the waste incineration plant Flötzersteig related to one ton of waste. Table 5: Input and output flows of the waste incineration plant Flötzersteig (reference year: 2000) [REIL, 2001] Input related to one ton of waste Output related to one ton of waste Heat kwh Heat 1,980 kwh Electricity 79.0 kwh Electricity - Natural gas m³ Steam (p = 16 bar; T = 270 C) 2.75 t Fresh water 825 l Slag kg Lime 2.46 kg Metal scrap - Sodium hydroxide, 30% 3.48 kg Fly ash 15.6 kg Ammonia, 25% 1.87 kg Filter cake (20 30 % H 2 O) 0.93 kg Precipitating agents 0.25 kg Cleaned waste water l Polyelectrolyte kg Cleaned flue gas (dry) 5,100 Nm³ Hydrochloric acid kg Acceptance, treatment and storage of waste Domestic waste from Vienna is delivered by 230 refuse collection vehicles. Each vehicle contains 4-5 t waste on an average. After weighing waste is dumped into the waste bunker that consists of a so-called daily bunker and a storage bunker. The size of the storage bunker is equivalent to the volume of a waste delivery over a period of three days. Waste introduction and supply with combustion air The storage bunker as well as three chutes (funnel tubes) are fed with waste grapples from two cranes. Waste is introduced by chutes, pushed onto the combustion grate by allocators and combusted with preheated air. Utilisation of energy The combustion grate is followed by a steam boiler (evaporator heating surface: 1,695 m 2 ) with superheater (370 m 2 ) and economiser (220 m 2 ). The produced superheated steam has a temperature of 270 C and 16 bar. Steam pipelines in accessible canals lead to proximate bulk purchasers. Residual heat is fed into the remote district heating network via two converting stations. Flue gas cleaning system and emissions to the air Electrostatic precipitator: Each line is equipped with an electrostatic precipitator with two fields for separation of coarse particles. The dust load is reduced from about mg Nm -3 to mg Nm -3 and finally reduced to about 2 mg Nm -3 by the flue gas cleaning system before the stack. Wet flue gas cleaning: Flue gas from each line is washed by three scrubbers. In the first scrubber flue gases are cooled from a temperature of 200 C to C and saturated with

67 State of the Art / Waste Incineration Descriptions of Plants 63 steam. In the lower part of the scrubber a water film is created by circular nozzles so that HCl, HF, heavy metals, Hg and part of the residual dust are washed out. The ph of the washing water is held constant by addition of lime milk to a value of 1.5. In the second (ph neutral) scrubber SO 2 is separated by addition of NaOH whereby a mixture of Na 2 SO 4 and Na 2 SO 3 is produced. A part of the wash water is routed to the wet slag removal where gypsum is precipitated and removed together with slag. Fine dust is separated in the third treatment step by a venturi scrubber. Catalytic NO x removal and dioxin destruction: Before entering the catalyst the flue gas is reheated from 60 to 130 C by means of steam heat exchangers. Previously after the entrance valve an evaporated aequous ammonia solution is added to the raw gas. After reaction in the catalyst the flue gas is cooled by a heat pipe and conducted to the stack via the flue gas fan. Emission levels that can be achieved by these plants are presented in Table 6. Table 6: Emissions to air from the waste incineration plant Flötzersteig (reference year: 2000) [REIL, 2001] Parameter Emission [mg Nm -3 ] a Minimum Average value Maximum Total mass [kg yr -1 ] b,d Specific emissions [g t -1 ] c,d Dust * , HCl * , HF SO 2 * C org * , CO * , NO x as NO 2 * , Pb Cr < Zn Σ Pb + Cr + Zn < As < Co < Ni < Σ As + Co + Ni < Cd Hg NH 3 * PCDD+PCDF ng Nm mg yr µg t -1 * Continuous measurement a Half hourly average values in mg Nm -3 ; dioxin emissions are given in ng Nm -3 (11% O 2 ; dry flue gas; standard conditions) b In kg yr -1, dioxins in mg yr -1 c Emissions related to one ton used waste in g t -1 ; dioxin emissions in µg t -1 d Total mass and specific emissions are calculated based on average half hourly mean values, using the quantity of dry flue gas (5,100 Nm³ t -1 waste) and the waste quantity (196,605 t yr -1 ).

68 64 State of the Art / Waste Incineration Descriptions of Plants Waste water treatment and emissions to water Waste water first passes a neutralisation step where a part of the heavy metals precipitates. The other part is precipitated in the precipitation step which is then followed by a flocculation step. Accumulated sludge is separated in a baffle plate thickener before it is dewatered in a chamber filter press. A partial flow of the cleaned waste water is routed to the clean water tank, the rest is conducted into the sewage. Following values presented in Table 7 can be achieved by this multistaged waste water treatment system. Table 7: Waste water parameters of the waste incineration plant Flötzersteig after the waste water treatment (reference year: 2000) [REIL, 2001] Parameter Measured value [mg l -1 ] Temperature < 30 C Electric conductance 20 ms ph 7.6 Undissolved matter < 30 Settleable solids < 10 As < Cd Chlorides (Cl) 10,000 Cyanides < Cr < 0.05 Cu 0.11 Fluorides (F) < Hg < NH 4 (N) 3.16 Nitrate (NO 3 ) 33 Nitrite (NO 2 ) 0.14 Ni < 0.05 Pb < 0.01 Sulphate (SO 4 ) 325 Sulphides < 0.1 Sulphites < 1.0 Zn 0.4 AOX / EOX 1.02 / < 0.02 BTXE < Total HC 0.05 Phenol < 0.01

69 State of the Art / Waste Incineration Descriptions of Plants 65 Waste Slag: At the end of the grate slag falls into the water filled wet deslagger where it is cooled. Afterwards it is transported to the slag bunker by a plate conveyor. From there slag is loaded onto trucks by using a crane and transported to a landfill. Fly ash: Fly ash is transported to an intermediate silo using conveying screws. From there it is pneumatically conveyed into two ash silos. Slag and ash are solidified by addition of water and cement and used for the erection of sidewalls for the landfill Rautenweg in Vienna. Filter cake from waste water treatment: The filter cake from waste water treatment is filled into big bags and disposed of underground. The composition of above mentioned waste fractions is shown in Table 8. Results of leaching tests are given in Table 9. Table 8: Chemical data of wastes from the waste incineration plant Flötzersteig (reference year: 2000) [REIL, 2001] Parameter Measured value Slag Fly ash Filter cake Bulk density [kg m -3 ] 800-2, TOC [%] (air dried basis - ad) Σ(SO 4 +SO 3 ) [%] (ad) Cl [%] (ad) F [%] (ad) CO 3 [%] (ad) SO 4 [%] (ad) Total moisture [%] (ad) Loss on ignition [%] (ad) Main components [mg kg -1 ] (dry basis) Si 130, ,000 65, ,000 Al 40, ,000 40,000-70,000 27,500 Mg 10,000-25,000 10,000-25,000 29,700 Fe 20,000-40,000 10,000-20,000 55,100 Ca 120, , , , ,000 Na 15,000-30,000 30,000-50,000 2,250 K 10,000-25,000 45, ,000 3,040 Heavy metals [mg kg -1 ] (dry basis) Zn 1,500-5,000 12,000-25,000 15,000 Pb 1,000-3,500 3,000-7,000 5,900 Mn 400-1, Cr Cd

70 66 State of the Art / Waste Incineration Descriptions of Plants Parameter Measured value Slag Fly ash Filter cake As Hg ,590 Ni Organic compounds [µg kg -1 ] Total PCDF Total PCDD TEQ Total PCB < 600 < 600 Total PAH < 50 < 50 Table 9: Leaching tests; waste incineration plant Flötzersteig (reference year: 2000) [REIL, 2001] Parameter Concentration [mg kg -1 ] a Slag Fly ash Mg < 10 < 10 Ca 1,300 15,000 SO 4 1,600 25,000 Cl 1, ,000 NH 3 as N 7 3 NO 3 as N < 3 < 3 NO 2 as N DOC Fe < 0.5 < 0.5 Mn < 0.5 < 0.5 Ni < 0.5 < 0.5 Cd < Cr < 0.5 < 0.5 Cu Pb Zn Hg < 0.01 < 0.01 a Test details: Increased liquid to solid ratio (10 : 1); distilled water (T = 20 C); no ph control; maximum particle size 10 mm; results in mg per kg dry residue.

71 State of the Art / Waste Incineration Descriptions of Plants Waste incineration plant Spittelau In the year ,912 tons of waste were combusted in the waste incineration plant Spittelau. General data of the waste incineration plant Spittelau are shown in Table 10. Table 10: General data of the waste incineration plant Spittelau (reference year: 2000) [REIL, 2001] Operator Waste incineration plant Spittelau Fernwärme Vienna GmbH Start up 1971 Firing technology Grate firing Waste throughput 268, t Average net calorific value 8,822 kj kg -1 Average gross calorific value 9,400 kj kg -1 Theoretical rated thermal input 85 MW Working hours line 1 7,812 Working hours line 2 7,882 Plant concept A process flow diagram of the waste incineration plant Spittelau is shown in Figure 10. Each line basically consists of the following units: Waste bunker Firing system: Reciprocating grate Waste heat boiler Flue gas cleaning devices consisting of: Electrostatic precipitator, three-stage wet scrubber, catalyst for NO x removal and dioxin destruction Multistaged waste water treatment plant Steam turbine, generator and heat decoupling system

72 cf 68 State of the Art / Waste Incineration Descriptions of Plants Fließbild MVA Spittelau HO 2 Boiler Electrostatic precipitator Scrubber DeNox Stack Erdgas Luft 4 bar NH4OH TMT FeCl3 PE HCL NaOH Ca(OH) 2 Lime milk Lime milk precipitation ag. Lime milk precipitation ag. G Slag bunker Scrap container Filter ash Sludge tank Chamber filter press Filter cake box Receiving water (Donaukanal) Figure 10: Process flow scheme of the waste incineration plant Spittelau

73 State of the Art / Waste Incineration Descriptions of Plants 69 Table 11 shows an input-output balance of the waste incineration plant Spittelau related to one ton of waste. Table 11: Input-output flows of the waste incineration plant Spittelau (reference year: 2000) [REIL, 2001] Input related to 1 t waste Output related to 1 t waste Heat 27.6 kwh Heat 1,857 kwh Electricity 78.5 kwh Electricity 150 kwh Natural gas 20.1 m³ Steam (p= 32 bar; T = 240 C) 2.6 t Fresh water 730 l Slag 207 kg Lime 2.9 kg Metal scrap 22 kg Sodium hydroxide, 30 % 2.25 kg Fly ash 19 kg Ammonia, 25 % 2.9 kg Filter cake (15 20 % H 2 O) 1 kg Precipitating agents 0.17 kg Cleaned waste water 415 l Cleaned flue gas (dry) Nm³ Acceptance, treatment and storage of waste Domestic and similar industrial waste is delivered to the waste incineration plant Spittelau by 250 refuse collection vehicles per day. The vehicles are weighed on two weigh-bridges before waste is dumped into the waste bunker that has a volume of about m³. Waste introduction and supply of combustion air After mixing in the bunker waste is supplied to both combustion lines by two bridge cranes. Each crane grab has a capacity of 4 m³. Waste is fed onto the grate that is located at the lower end of the combustion chamber through a filling slot using hydraulic allocators. Fresh air needed for combustion is sucked off from the waste bunker. Thus a slight vacuum is produced so that odour and dust emissions through the dumping devices to the ambient air are minimized. Grate firing system Up to 16 t waste per hour can be thermally treated on the sloped reciprocating grate with a total surface of 35 m 2. With the heat content of the combustion gases 90 tons of saturated steam per hour are produced. Utilisation of energy For electricity production steam is expanded in a backpressure turbine from 33 to 4,5 bar. The remaining energy of the steam is transferred to the return water of the remote district heating network in heat exchangers. On an yearly average more than 5 MW electricity for covering of own needs and for feeding into the public electricity network as well as 60 MW of district heat are produced.

74 70 State of the Art / Waste Incineration Descriptions of Plants Flue gas cleaning system and emissions to the air Electrostatic precipitator: Hot flue gas with a temperature of 180 C leaves the heat exchanger, that follows the waste heat boiler. Then it is dedusted in a three field electrostatic precipitator to a concentration < 5 mg Nm -3. Wet flue gas cleaning: Dedusted flue gas enters the quenching zone of the first wet scrubber, where it is cooled to saturation temperature (60-65 C) by injection of fresh water. The first wet scrubber is built as cross flow scrubber working at a ph value of 1. Due to intensive contact between wash water and flue gas HCl, HF, dust as well as heavy metalls are separated. The second wet scrubber is designed for desulphurization and is operated at a ph of 7. Flue gas is adiabatically expanded in the downstream electrodynamic venturi scrubber where fine dust particles are separated after charging by an electrode. Catalytic NO x removal and dioxin destruction: After reheating by a heat exchanger an evaporated aequous solution of ammonia is added to the flue gas. Flue gas is further reheated to a reaction temperature of 280 C by means of heat pipes and gas burners. In the catalyst (three layers) nitrogen oxides are converted to nitrogen and dioxins/furans are destroyed. In a third heat exchanger flue gases are cooled to 115 C and discharged to the atmosphere via a 126 m high stack. The concentration of certain pollutants in the flue gas is presented in Table 12. Table 12: Emissions to air from the waste incineration plant Spittelau (reference year: 2000) [REIL, 2001] Parameter Emission [mg Nm -3 ] a Minimum Average value Maximum Specific emissions Total mass [kg yr -1 ] [g t -1 ] c,d b,d Dust * HCl * HF < 0.02 < 0.1 < 27.8 SO 2 * , CO * ,144 NO x as NO 2 * C org * , Pb Cr < Zn Σ Pb+Cr+Zn < As < Co < Ni < Σ As+Co+Ni < Cd Hg NH PCDD+PCDF 0.02 ng Nm mg yr µg t -1

75 State of the Art / Waste Incineration Descriptions of Plants 71 * Continuous measurement; discontinuous values are arithmetic average values from a TÜV measurement ( ) a Half hourly average values in mg Nm - ³; dioxin emissions in ng Nm -3 (11 % O 2 ; dry flue gas; standard conditions) b In kg yr -1, dioxins in mg yr -1 c Emissions related to one ton used waste in g t -1, dioxin emissions in µg t -1 d Total mass and specific emissions are calculated based on average half hourly mean values, using the quantity of dry flue gas (5,170 Nm³ t -1 waste) and the waste quantity (269,375 t yr -1 ). Waste water treatment and emissions to water Dissolved heavy metals from the first scrubber become insoluble by adding lime milk, precipitating and flocculation agents. Then they are separated by means of a downstream laminar clarifier. After the precipitation and the separation step has been passed repeatedly the hydroxide sludge is dewatered. Gypsum from the discharged water of the second scrubbing step is precipitated by addition of lime milk and then sedimented in the clarification basin. Gypsum sludge is pumped into the wet deslagger. Sodium hydroxide that is recovered is recycled into the second scrubber. The cleaned waste water is directly released into the receiving water. Values that can be achieved by this multistaged waste water treatment plant are shown in Table 13. Table 13: Waste water parameters of the waste incineration plant Spittelau after treatment (reference year: 2000) [REIL, 2001] Parameter Measured value [mg l -1 ] Temperature 47.8 C Fish toxicity GF 2.0 ph value 7.8 Filterable substances < 20 Settleable solids < 0.3 ml/l Sight depth > 30.0 cm Residue on evaporation 1.4 g l -1 Color Odour clear neutral Al 0.19 Ag 0.12 Ammonia (N) 3.3 As < Ba 0.19 Ca 5,056 Cd < Co < 0.05 Cr total < 0.05 Cr (VI) < 0.05 Chlorine (free) < 0.05

76 72 State of the Art / Waste Incineration Descriptions of Plants Parameter Measured value [mg l -1 ] Chlorine (total) Cl 2 < 0.05 Chloride (Cl) 7,085 Cyanides (CN) < Cu < 0.05 Fe < 0.05 Fluorides (F) 2.2 Hg < Mn < 0.05 Nitrate (NO 3 ) 4.8 Nitrite (NO 2 ) 0.07 Ni < 0.05 P < 0.05 Pb < 0.01 Sb 0.04 Sn 0.06 Sulphate (SO 4 ) 1,183 Sulphide < 0.1 Sulphite < 1.0 Tl < 0.01 V < 0.05 Zn < 0.06 EOX < 0.02 CSB < 75 BTX < Total HC 0.21 Phenol < 0.01 Tensides < 0.02 Non-volatile lipophilic components < 20 TOC 4.3 Waste Slag: At the end of the combustion grate slag falls into a water filled wet deslagger. From there the cooled slag is transported to the slag bunker by a belt conveyor. Filter ash: Filter ash is transported to a silo using a mechanical-pneumatical conveying system. Slag and filter ash are mixed with water and cement and used as slag/filter ash concrete in the landfill construction.

77 State of the Art / Waste Incineration Descriptions of Plants 73 Ferrous scrap: Ferrous scrap is separated from cooled slag by an magnetic separator and supplied to the steel industry. Filter cake from waste water treatment: Filter cake is filled into big bags and disposed of underground. The composition of above mentioned waste fractions is shown in Table 14. Results of leaching tests are presented in Table 15. Table 14: Chemical data of waste fractions from the waste incineration plant Spittelau (reference year: 2000) [REIL, 2001] Parameter Measured value Slag Fly ash Filter cake Bulk density [kg m -3 ] 800 1, TOC [%] (air dried basis - ad) Σ(SO 4 +SO 3 ) [%] (ad) Cl [%] (ad) F [%] (ad) CO 3 [%] (ad) SO 4 [%] (ad) Total moisture [%] (ad) Loss on Ignition [%] (ad) Main components [mg kg -1 ] (dry basis) Si 140, ,000 70, ,000 10,000 70,000 Al 30,000 75,000 40,000-80,000 1,500 20,000 Mg 10,000 23,000 70, ,000 1,500 30,000 Fe 30,000 80,000 10,000-20,000 10,000 50,000 Ca 120, , , , , ,000 Na 10,000 45,000 15,000-65,000 1,000 10,000 K 10,000 25,000 30,000-75, ,000 Heavy Metals [mg kg -1 ] (dry basis) Zn 1,200-5,500 7,000-20, ,500 Pb 500 5,500 2,500-7, ,000 Mn 300 1, Cr Cd As Hg ,000 Ni

78 74 State of the Art / Waste Incineration Descriptions of Plants Parameter Measured value Slag Fly ash Filter cake Organic compounds [µg kg -1 ] Total PCDF Total PCDD TEQ Total PCB < 600 < 600 Total PAH < 100 < 100 Table 15: Leaching tests; waste incineration plant Spittelau (reference year: 2000) [REIL, 2001] Parameter Concentration [mg kg -1 ] a Slag Fly ash Gypsum Mg < 10 < Ca 2,000 15,000 10,300 SO ,000 1,900 Cl 2, ,000 4,400 NH 3 as N 10 5 NO 3 as N < 3 < 3 13 NO 2 as N DOC Fe < 0.7 Mn < 0.5 < 0.5 < 0.7 Ni < 0.5 < 0.5 < 0.7 Cd Cr < 0.5 < 0.5 < 0.7 Cu < 0.7 Pb Zn < 0.7 Hg < 0.01 < 0.01 < 0.01 a Test details: Increased liquid to solid ratio (10 : 1); distilled water (T = 20 C); no ph control; maximum particle size 10 mm; results in mg per kg dry residue.

79 State of the Art / Waste Incineration Descriptions of Plants Waste incineration plant Wels In the year ,094 tons of domestic and trade waste, about 10,000 tons of trade waste, building waste and bulky refuse each as well as about 4,000 tons of residues from mechanical treatment and 1,251 tons of feeding stuff were combusted in the waste incineration plant Wels. General data of the waste incineration plant Wels - line 1 are shown in Table 16. Table 16: General data of the waste incineration plant Wels (reference year: 2000) [WACHTER, 2001] Waste incineration plant Wels Operator Welser Abfallverwertung Betriebsführung GmbH Start up 1995 Firing technology Grate firing Waste throughput 75,681 t Average gross calorific value 9.5 MJ kg -1 Theoretical rated thermal input 33.5 MW Working hours line 1 8,183 Plant concept A process flow diagram of the waste incineration plant Wels is shown in. The plant basically consists of the following units: Waste bunker Firing system: Grate firing (Combined forward and backward moving grate) Waste heat boiler Power generation and possibility of decoupling of district heat Flue gas cleaning devices: Electrostatic precipitator, two-stage wet scrubber, activated coke filter, catalytic flue gas cleaning system Residue treatment: Wet chemical/thermal ash treatment (thermal treatment not in operation), slag treatment Multistaged waste water treatment plant Table 17 shows an input-output balance of the waste incineration plant Wels related to one ton of waste.

80 76 State of the Art / Waste Incineration Descriptions of Plants Table 17: Input and output of the waste incineration plant Wels (reference year: 2000) [WACHTER, 2001] Input related to 1 t waste Output related to 1 t waste Electricity 130 kwh Electricity 599 kwh Natural gas 4.5 m³ Steam (p = 40 bar; T = 400 C) 3.15 t Fresh water 850 l Slag 274 kg Lime 6.4 kg Ferrous scrap 17.2 kg Sodium hydroxide, 30% 3.0 kg Fly ash 35 kg Ammonia, 25% 1.4 kg Filter cake (28 % H 2 O) 2.25 kg Coke 1.2 kg Gypsum 4.7 kg Polyelectrolyte kg Cleaned waste water 358 l Hydrochloric acid, 30% 0.5 kg Cleaned flue gas (dry) 5,692 Nm³ FeCl 3, 40% Na 2 S 0.65 kg 0.19 kg

81 cf State of the Art / Waste Incineration Descriptions of Plants 77 Boiler G HO 2 Stack Electrostatic precipitator Denox plant Air 4 bar NH4OH Na2S FeCl3 PE HCL NaOH Waste water treatment plant Ca(OH) 2 Receiving water Neutralization Precipit. Neutralization Floccul. Sedimentation Sand filter SM - ion exchanger Activated coke filter Neutralization sludge Gypsum Figure 11: Process flow scheme of the waste incineration plant Wels line 1

82 78 State of the Art / Waste Incineration Descriptions of Plants Acceptance, treatment and storage of waste Waste for combustion is delivered by refuse collection vehicles, weighed and afterwards dumped into the waste bunker that has a capacity of m³. Waste is mixed using a grab crane. Waste introduction and supply of combustion air Every 15 minutes about 2 tons of waste are fed from the waste bunker via a slot and an allocator onto the combined forward and backward moving grate. The main part of the primary combustion air is sucked off from the waste bunker by a fan and blown through the cooled grate bars into the waste bed lying beyond. When waste with low calorific value is combusted primary air is preheated to enhance combustion and ensure a high combustion temperature. A part of the cooled flue gas is withdrawn after the electrostatic precipitator and recirculated into the combustion chamber. Thereby the oxygen content in the flame and thus formation of thermal NO x is lowered. Grate firing system Combined forward and backward moving grate. Waste heat boiler The combustion grate is followed by a boiler system, where flue gases are cooled from a temperatur of 950 C to 650 C. Afterwards flue gases pass the convection zone where their energy content is used for steam production. There their temperature is reduced to 200 C. Utilisation of energy A turbine with a rated power of 7,2 MW produces 45.5 Mio. kwh electricity (reference year: 2000) which are partly used for covering own needs. The surplus of produced energy is fed into the public electrical system. Flue gas cleaning system and emissions to the air Electrostatic precipitator: The major part of dust is separated from the flue gas by electrostatic precipitation. Wet flue gas cleaning: In the first acid step hydrochloric and hydrofluoric acid as well as mercury compounds and residual dust are absorbed in the acid washing water. The occurring absorption liquor is collected in the lower part of the scrubber. A partial flow of process water is continuously fed into the waste water cleaning system in order to prevent the concentration of pollutants. In the second scrubber SO 2 is removed from flue gas using lime and sodium hydroxide. A partial flow of circulating water is conducted over a precipitation station where a part of the formed sulfates is precipitated as gypsum. Activated coke filter: In the activated coke filter traces of mercury, organic compounds, HCl and SO 2 are adsorbed to activated coke. A part of the loaded filter material is continuously withdrawn and new activated coke is added. Catalyst: After leaving the activated coke filter flue gases are reheated to a temperature that is sufficient for catalytic denitrification and oxidation of organic compounds by means of a

83 State of the Art / Waste Incineration Descriptions of Plants 79 heat transfer system and a high pressure steam heat exchanger. Nitrogen oxides are reduced by injection of an aequous solution of ammonia. After cooling flue gases are routed to the stack. Emission levels that can be achieved by the described flue gas cleaning system are presented in Table 18. Table 18: Emissions to air from the waste incineration plant Wels (reference year: 2000) [WACHTER, 2001] Parameter Emission [mg Nm -3 ] a Total mass [kg yr -1 ] b,d Specific mass [g t -1 ] c,d Dust * < 0.5 < < 2.85 HCl * < 0.1 << << 0.57 HF * < 0.05 << << 0.28 SO 2 * < 2 < < CO * 20 8, NO x as NO 2 * 54 23, Pb < < 0.86 < Cr < < 0.86 < Zn < < 0.86 < As < < 0.86 < Co < < 0.86 < Ni < < 0.86 < Cd < < 0.86 < Hg < < 0.86 < Sb < < 0.86 < Cu < < 0.86 < Mn < < 0.86 < V < < 0.86 < Sn < < 0.86 < Tl < < 0.86 < Se < < 0.86 < Σ HC * < 1 < < 5.69 NH , PCDD + PCDF ng Nm mg yr µg t -1 (I-TEF) * Continuous measurement a Half hourly average values in mg Nm -3 ; dioxin emissions are given in ng Nm -3 (11% O 2 ; dry flue gas; standard conditions) b In kg yr -1, dioxin loads in mg yr -1 c Emissions related to one ton used waste in g t -1 ; dioxin emissions in µg t -1 d Total mass and specific emissions are calculated based on average half hourly mean values, using the quantity of dry flue gas (5,692 Nm³ t -1 waste) and the waste quantity (75,681 t yr -1 ).

84 80 State of the Art / Waste Incineration Descriptions of Plants Waste water treatment and emissions to water The waste water treatment plant consists of a precipitating zone (neutralisation, precipitation, flocculation, sedimentation and sludge dewatering) and a filter zone, which has been erected in two lines (two-layer filter, activated coke filter, ion exchanger, pure water filter). The parameters of cleaned waste water are shown in Table 19. The cleaned waste water is released into the receiving water.. Table 19: Waste water parameters of the waste incineration plant Wels after waste water treatment (reference year: 2000) [WACHTER, 2001] Parameter Measured value [mg l -1 ] Temperature < 30 C ph value 6.8 < ph < 9.0 Undissolved compounds < 25 Settleable solids < 0.2 Salt content < 35 g l -1 As < 0.05 Cd < 0.05 Chlorides (Cl) < 20 g l -1 Cyanides < 0.05 Cr < 0.1 Cu < 0.3 Fluorides (F) < 10 Hg < 0.01 NH 4 N < 8 Nitrate (NO 3 ) < 40 Nitrite (NO 2 ) < 8 Ni < 0.5 Pb < 0.1 Sulphate (SO 4 ) < 1,200 Sulphides < 0.1 Sulphites < 8 Zn < 0.5 AOX / EOX < 0.1 Total HC < 3 Volatile chlorinated hydro carbons < 0.1 Saponifiable fats and oils < 4

85 State of the Art / Waste Incineration Descriptions of Plants 81 Waste Slag: Slag is washed with water and landfilled. Gypsum: Gypsum occurring by desulfurization is dewatered and landfilled. Ash: Ash that occurs in the electrostatic precipitators is conveyed to a silo for fly ash where it is intermediate-stored before wet chemical treatment. Slag, ash and gypsum are landfilled. Ferrous scrap: Ferrous scrap is separated from slag and delivered to a scrap dealer. Sludges: Sludges that occur during waste water treatment are dewatered using a chamber filter press, filled into big bags and disposed of underground. 8.2 Incineration of hazardous wastes Rotary kilns of the Plant Simmeringer Haide Two rotary kilns of the Plant Simmeringer Haide are operated for incineration of hazardous wastes. In the year ,964 tons of wastes were combusted. A detailed list of treated types of waste and quantities is given in Table 20. Table 20: Types of waste and waste quantities incinerated in the rotary kilns of Plant Simmeringer Haide (reference year: 2000) [KROBATH, 2001] Types of waste Waste quantity [t yr -1 ] Waste oil 9,521 Oil-water mixture, oil content % 28 Oil-water mixture, oil content 50-85% 1,655 Oil-water mixture, oil content <50% 6,384 Oil-water mixture, oil content <10% which can be separated 759 Separator content 1,216 Other waste, internal waste 1,902 MA 48; collection of hazardous waste 1,059 Liquid organic waste 10,703 Solid or pasteous organic waste 11,100 Liquid inorganic waste 10,005 Solid or pasteous inorganic waste 328 Oil contaminated soil 115 Trade and industrial waste 16,308 Hospital waste 2,360 Old medicines 768 Herbicides 802 Hazardous household waste 2 Chemically contaminated soil 56

86 82 State of the Art / Waste Incineration Descriptions of Plants Types of waste Waste quantity [t yr -1 ] Laboratory waste 344 Biofilter from the main WWTP Vienna, residual waste 3,256 Screening DRO 5,008 Sand and crushed stone, canal waste 4,829 General data of the two rotary kilns of the Plant Simmeringer Haide are shown in Table 21. Table 21: General data of the rotary kilns of the Plant Simmeringer Haide (reference year: 2000) [KROBATH, 2001] Operator Rotary kilns of the Plant Simmeringer Haide Fernwärme Vienna GmbH Years of commissioning 1980 Firing technology Waste throughput Theoretical rated thermal input rotary kiln 89,964 t 50 MW Working hours line Working hours line Plant concept A process flow diagram of one of the rotary kilns is shown in Figure 12. Each combustion line basically consists of the following units: Delivery and acceptance zone Firing system: Rotary kiln (length: 12 m, outer diameter 4.5 m, rotations per minute: ) Waste heat boiler Flue gas cleaning devices: SNCR process, electrostatic precipitator, four-stage wet scrubber, activated coke filter Multistaged waste water treatment plant Steam distribution system

87 cf State of the Art / Waste Incineration Descriptions of Plants 83 AVA Simmeringer Haide - DRO Emergency stack Emergency stack Activated coke filter Boiler Scrubber Slag Boiler ash Figure 12: Process flow scheme of the rotary kilns of the Plant Simmeringer Haide

88 84 State of the Art / Waste Incineration Descriptions of Plants Table 22 presents an input/output balance of the rotary kilns of the Plant Simmeringer Haide related to one ton of waste. Table 22: Input and output flows of the rotary kilns of the Plant Simmeringer Haide (reference year: 2000) [KROBATH, 2001] Input related to 1 t waste Output related to 1 t waste Electricity 234 kwh Heat 1,459 kwh Fresh water 6,158 l Electricity 269 kwh Heavy fuel oil, 1 % S m³ Steam (p = 52 bar; T = 350 C) 3.7 t Lime 23.2 kg Slag 190 kg Coke 5.0 kg Metal scrap 13.4 kg Sodium hydroxide, 50 % 5.2 kg Fly ash 14.6 kg Ammonia, 25 % 3.0 kg Filter cake (54.7 % H 2 O) 17 kg Precipitating agents, 15 % 0.32 kg Cleaned waste water 1,657 l FeCl 3, 40 % 1.53 kg Cleaned flue gas (dry) 7,900 Nm³ Hydrochloric acid, 30 % Sand Liquid nitrogen, 98.5 % 1.0 kg 35.6 kg 3.6 kg Acceptance, treatment, storage and introduction of waste After delivery hazardous wastes are visually examined whereby the accordance with accompanying documents is verified. Afterwards chemical and physical parameters according to ÖNORM S2110 (1991) are determined. On the basis of analysis results waste fractions are evaluated, intermediately stored, mixed according to existing recipes and fed into the rotary kiln. Solid Waste: Solid waste is delivered in containers and vats by trucks and dumped into the waste bunker. Waste from the waste bunker is directly supplied either to the combustion process over a feeding chute or is homogenized first. Liquid Waste: Liquid waste is delivered in tank lorries and stored depending on their properties. Combustible liquids are either directly supplied to the combustion process or after previous mixing using combustion lances. Container: Containers are intermediately stored, sorted and directly supplied to the combustion process or to the homogenization process using roller conveyors and lifts. Infectious clinical waste: This waste fraction is delivered in sealed plastic containers, intermediately stored and supplied to the combustion chamber by a fully automatic conveyor. Supply of combustion air Combustion air is sucked off from the bunker and supplied to the rotary kiln over the front wall as primary air and over the afterburning chamber as secondary air.

89 State of the Art / Waste Incineration Descriptions of Plants 85 Rotary kilns with afterburning chamber The steel tubes are refractory lined and have a length of 12 meters and an outer diameter of 4.5 m. Waste is mixed by slow rotation ( rotations per minute), transported through the rotary kiln and combusted at a temperature of about 1,200 C. Flue gases of the rotary kiln are fully combusted in the afterburning chamber. If the combustion temperature in the afterburning chamber falls below C two side wall burners using extra light and heavy fuel oil can be additionally switched on. In the middle respective upper end of the afterburning chamber secondary and tertiary air is injected. Utilisation of energy Electricity is produced to cover the own needs of the Plant Simmeringer Haide. Additionally heat is fed into the remote district heating system of Vienna. Flue gas cleaning system and emissions to the air Electrostatic precipitator: In this first flue gas cleaning step dust emissions are reduced to mg/nm -3. Wet flue gas cleaning: The wet flue gas cleaning system consists of two cross flow scrubbers for separation of acid, water soluble gases as well as dust and heavy metals. The subsequent venturi scrubber is operated for separation of fine dust and for preconditioning of flue gases for the electrodynamic venturi scrubber. SNCR: Nitrogen Oxides are reduced by injection of an aequous solution of ammonia into the flue gas. Activated coke filter: Post-treatment takes place in a counter current plant using activated coke separately for each combustion line. This unit consists of two parallel arranged adsorbers that are filled with lignite-furnace coke. The adsorbers for the rotary kilns consist of 8 moduls each, whereby each modul is filled with 15 t adsorbent. Flue gas flows through the layer from the bottom up while the coke slowly moves downwards. Using these flue gas cleaning system emission levels shown in Table 23 can be achieved. Table 23: Emissions to air from the rotary kilns of the Plant Simmeringer Haide (reference year: 2000) [KROBATH, 2001] Parameter Emission [mg Nm -3 ] a Total mass [kg yr -1 ] b, d Specific emissions [g t -1 ] c,d Dust * < HCl * HF < SO 2 * CO * 33 23, NO x as NO 2 * , Cr As < Ni Cd Hg

90 86 State of the Art / Waste Incineration Descriptions of Plants Parameter Emission [mg Nm -3 ] a Total mass [kg yr -1 ] b, d Specific emissions [g t -1 ] c,d Cu C org * 2.2 1, NH , PCDD+PCDF ng Nm mg yr µg t -1 PAH * Continuous measurement a Half hourly average values in mg Nm -3 ; dioxin emissions are given in ng Nm -3 (11% O 2 ; dry flue gas; standard conditions) b In kg yr -1, dioxin loads in mg yr -1 c Emissions related to one ton used waste in g t -1 ; dioxin emissions in µg t -1 d Total mass and specific emissions are calculated based on average half hourly mean values, using the quantity of dry flue gas (7,900 Nm³ t -1 waste) and the waste quantity (89,964 t yr -1 ). Waste water treatment and emissions to water Waste water from both rotary kilns is precleaned together with those of the three fluidised bed reactors. Afterwards it is conducted into the main sewage treatment plant of Vienna. Waste water cleaning is performed using gravity separation, neutralisation, flocculation, filtration and precipitation processes. Using these cleaning steps emission levels shown in Table 24 can be achieved. Table 24: Waste water parameters of the rotary kilns of the Plant Simmeringer Haide after waste water treatment (reference year: 2000) [KROBATH, 2001] Parameter Measured value [mg l -1 ] Temperature < 30 C Electric conductivity 24.6 ms cm -1 ph value 9.2 Undissolved compounds 10 As < 0.02 Ca 3.86 g l -1 Cd Chlorides (Cl) 8.86 g l -1 Cyanides < 0.1 Cr 0.01 Cu 0.01 Fluorides (F) 5.2 Hg NH 4 N 63 Nitrate (NO 3 ) 50 Ni 0.01 Pb < 0.02 Sulphate (SO 4 ) 912

91 State of the Art / Waste Incineration Descriptions of Plants 87 Parameter Measured value [mg l -1 ] Sulphides < 0.01 Sulphites < 5 Zn 0.05 AOX / EOX 0.01 Phenol 0.11 Sb Tl 0.02 V 0.01 Waste Slag and filter ash: Slag and filter ashes are landfilled. Filter cake: The filter cake from the waste water cleaning plant is filled into big bags and landfilled. Ferrous scrap: Separated ferrous metals are delivered to a scrap dealer. Activated coke: Loaded activated coke is removed into a silo by conveying installations and combusted internally. Chemical data of waste fractions from the rotary kilns are shown in Table 25. Results from leaching tests are presented in Table 26. Table 25: Chemical data of wastes from the rotary kilns (reference year: 2000) [KROBATH, 2001] Parameter Measured value Slag Fly ash Filter cake TOC [%] (air dried basis - ad) Cl [%] (ad) 3.4 SO 3 [%] (ad) 21.4 Main components [mg kg -1 ] (dry basis) SiO % 12.2 % 2.9 % Al 22,217 13,576 3,308 MgO 3.1 % 1.4 % 0.5 % Fe 97,815 46,928 26,619 CaO 12.1 % 8.2 % 31.4 % Na 2 O 17.9 % K 2 O < 0.4 Heavy Metals [mg kg -1 ] (dry basis) Zn 1,868 52,921 9,399 Pb ,162 1,062 Mn 826 1, Cr

92 88 State of the Art / Waste Incineration Descriptions of Plants Parameter Measured value Slag Fly ash Filter cake Cd As Hg ,088 Ni Table 26: Leaching tests according to ÖNORM S 2115; rotary kilns of the Plant Simmeringer Haide (reference year: 2000) [KROBATH, 2001] Leached concentrations [mg kg -1 ] Slag Fly ash Gypsum ph value SO ,717 1,441 Cl 30 5, NH 3 as N NO NO Fe Mn Ni < < 0.1 Cd Cr Cu < 0.01 Pb Zn ,178 0,18 Hg < < Waste incineration plant Arnoldstein Fluidised bed reactors of the waste incineration plant Arnoldstein The fluidised bed reactor of the waste incineration plant Arnoldstein was adjusted to the state of the art in 2000 and is continuously operated since January In ,000 tons of hazardous and non hazardous wastes (oily waste, solvent-water mixtures, treated and untreated wood waste, wood packaging, plastic waste, sludge and waste water) were combusted. The catalogue of key numbers of wastes permitted for thermal treatment can be found on the homepage of the waste incineration plant ( General data of the fluidised bed reactor of the waste incineration plant Arnoldstein are given in Table 27.

93 State of the Art / Waste Incineration Descriptions of Plants 89 Table 27: General data of the fluidised bed reactor of the waste incineration plant Arnoldstein (reference year: 2001) [Werner, 2002] Operator Fluidised bed reactor Arnoldstein Asamer Becker Recycling Gesellschaft mbh Start-up 1994 Start-up after overhaul Firing technology Waste throughput Fluidised bed reactor t Average calorific value of the waste kj kg -1 Thermal output 8 MW Operating hours (test operation) Plant concept A process flow diagram is shown in Figure 13. The plant basically consists of the following units: Treatment hall for crushing and grinding and mixing of wastes Hall for intermediate storage of wastes Firing system: Stationary fluidised bed reactor with waste heat boiler Flue gas cleaning devices: Electrostatic precipitator, two-stage wet scrubbing with NaOH scrubber, flow injection process and catalytic flue gas cleaning system (clean gas application) Central waste water treatment plant If necessary oil is used as additional fuel for start up and shut down.

94 cf 90 State of the Art / Waste Incineration Descriptions of Plants Fließbild Arnoldstein Fluidized bed Waste heat boiler Economiser Electrostatic precipitator Scrubber Fabric filter Catalyst Steam NH4OH to WWTP Feedwater Figure 13: Process flow scheme of the waste incineration plant Arnoldstein

95 State of the Art / Waste Incineration Descriptions of Plants 91 In Table 28 output flows of the fluidised bed reactors of the waste incineration plant Arnoldstein are shown. Table 28: Output flows of the fluidised bed reactors of the waste incineration plant Arnoldstein (reference year: 2001) [WERNER, 2002] Output Steam (25 bar; 180 C) 4.5 t h -1 Ash 9,000 t yr -1 Ferrous scrap 170 t yr -1 Filter cake 200 t yr -1 Waste water 13,000 m 3 yr -1 Flue gas 15,500 Nm 3 h -1 Acceptance, treatment and storage of waste Incoming wastes are declared by the deliverer and always controlled optically by the operator of the waste incineration plant. Depending on the waste and on the deliverer singular or mixed samples are taken regularly in order to determine various parameters such as ph, calorific value, ignition loss, halogens, heavy metals, density and others. Waste is intermediately stored in boxes. Immediately before combustion they are transported to the waste bunker using a crane. Liquid waste fractions are intermediately stored in tanks. Waste introduction and supply of combustion air Mixed, crushed and grinded solid wastes are fed into the bunker by means of a crane. The bottom of this bunker is constructed as slowly moving conveyer belt. Waste discharged from the bunker falls onto another conveyor belt and is conveyed into a charging hopper for a dosing screw. Using the dosing screw solid wastes are charged regularly onto a so-called throw feeder, which distributes the waste uniformly across the fluidised bed. Liquid wastes are injected by means of a lance. For start up of the plant two burners firing fuel oil are installed. Exhaust air from the waste storage facilities and the tanks are used as combustion air. The combustion air is introduced into the combustion chamber as secondary air through nozzles and as conveying air for recirculated bed ashs. In order to regulate the dosage of waste, fuel oil and combustion air, a control system for the regulation of the firing performance is installed. Combustion chamber The combustion chamber is constructed as an uncooled, brick-lined stationary fluidised bed system. Immediately above the stationary fluidised bed reactor the afterburning zone with secondary air injection is arranged. Hydrated lime and limestone from the flow injection process are pneumatically conveyed into the combustion chamber for preseparation of SO 2.

96 92 State of the Art / Waste Incineration Descriptions of Plants Waste heat boiler The waste heat boiler is constructed as a horizontal boiler with radiation heating surfaces in the first and convection surfaces in the second part. These heating surfaces are pure evaporating heating surfaces. The horizontal waste heat boiler is followed by a feedwater preheater. In the energy system saturated steam is produced which is fed into the local steam network using a pressure reducing valve. Flue gas cleaning system and emissions into the air Dedusting: Dedusting of flue gases leaving the boiler is performed by means of an electrostatic precipitator. The temperature of flue gases entering the electrostatic precipitator depends on the boiler load and the travel time. Wet flue gas cleaning: The wet flue gas cleaning system consists of a co-current scrubber with acid circulation water and a counter current scrubber with NaOH as neutralizing agent. Each scrubber is followed by a droplet separator. Heat from the flue gases entering the scrubber is transferred to the flue gases leaving the scrubber by means of a gas/gas heat exchanger. The outlet temperature can be regulated by a downstream steam heated gas preheater. Flow injection process: The flow injection unit consists of a flue gas channel with injection of furnace coke, limestone and hydrated lime and a fabric filter. The operating temperature is about 120 C. Added chemicals are recirculated several times and then injected into the combustion chamber. Catalytic flue gas cleaning: The catalytic flue gas cleaning system is constructed as clean gas application with heat transfer system (gas/gas heat exchanger). It exclusively serves the function of NO x reduction An aequous solution of ammonia (25 %) is used as reducing agent. After the catalytic flue gas cleaning system flue gases are cooled in a heat exchanger. The heat is used for preheating water for the feedwater tank. Using these cleaning steps emission levels shown in Table 29 can be achieved. Table 29: Emissions to air from the waste incineration plant Arnoldstein (reference year: 2001) [WERNER; 2002] Parameter Emission [mg Nm -3 ] a Total mass [kg yr -1 ] b, d Specific emissions [g t -1 ] c,d Dust * 1, HCl HF SO 2 * C org * < < CO * < NO x as NO 2 * < , Cd Hg PCDD+PCDF ng Nm mg yr µg t -1 * Continuous measurement a Half hourly average values in mg Nm -3 ; dioxin emissions are given in ng Nm -3 (11% O 2 ; dry flue gas; standard conditions)

97 State of the Art / Waste Incineration Descriptions of Plants 93 b In kg yr -1, dioxin loads in mg yr -1 c Emissions related to one ton used waste in g t -1 ; dioxin emissions in µg t -1 d Total mass and specific emissions are calculated based on average half hourly mean values, using the quantity of dry flue gas (5,388 Nm³ t -1 waste; calculated from the hourly flue gas volume of 15,500 Nm³, the operating hours and the waste input) and the waste quantity (26,000 t yr -1 ). Waste water treatment and emissions to water Waste water from the fluidised bed reactors (13,000 m³ yr -1 resp. 36 m³ h -1 ) and landfill leachate are cleaned in the waste water treatment plant. After cleaning using heavy metal precipitation, neutralisation and gypsum precipitation the waste water is released into the receiving water. Using these cleaning steps emission levels shown in Table 30 can be achieved. Table 30: Waste water parameters (composite sample) of the waste incineration plant Arnoldstein after waste water treatment (reference year: 2001) [WERNER, 2002] Parameter Measured value [mg l -1 ] ph value 7.2 Filterable substances 7 As < 0.01 Cd < 0.05 Total Cr < 0.05 Cu < 0.05 Fluoride 8 Ni 0.06 Hg < Pb < 0.1 Sb < 0.1 Sulphate (SO 4 ) 8,000 Zn < 0.5 Cyanides (easy releasable) < 0.1 NH 4 N 127 TOC 25 Phenol < 0.1 EOX < 0.1

98 94 State of the Art / Waste Incineration Descriptions of Plants Waste Wastes arising from the whole process (bed ash, fly ash, gypsum and filter cake) are mixed, exempted and disposed of on a landfill for residual waste. Occurring metal scrap is recycled. Table 31: Chemical data of ash from the fluidised bed combustion of the waste incineration plant Arnoldstein (reference year: 2001) [WERNER, 2002] Parameter Measured value [mg kg -1 ] (dry basis) Limit value Hg < 1 20 / 3,000 As 55 5,000 Pb 2,550 10,000 Cd 20 5,000 Table 32: Concentration of pollutants in the eluate of ash from the waste incineration plant Arnoldstein (reference year: 2001) [WERNER, 2002] Parameter Limit value eluate [mg kg -1 ] (dry basis) concentration Limit value concentrate [mg l -1 ] (dry basis) Measured value [mg kg -1 ] (dry basis) Residue on evaporation 100,000 30,000 46,000 ph value Sb As 50 5 < 1 Pb < 1 Total Cr < 0.5 Cr (VI) as Cr 20 2 < 0.2 Co < 0.5 Cu < 0.5 Ni < 0.5 Hg < 0.05 Tl 20 2 < 0.5 V < 1 Zn 1, < 0.5 Sn 1, < 1 F Ammonia as N 10,000 1,

99 State of the Art / Waste Incineration Descriptions of Plants Incineration of clinical waste Clinical waste incineration plant Baden Plant concept A process flow diagram of the clinical waste incineration plant Baden is shown in Figure 14. The plant basically consists of the following units: Shaft furnace Afterburning chamber Hot water boiler One-stage wet scrubbing Downstream flow injection process Waste water treatment plant

100 96 State of the Art / Waste Incineration Descriptions of Plants hot water out scrubber fabric filter in CaOH 2 CaOH 2 NaOH TMT FeCl 3 PE chamber filter press sand filter activated coke filter slag filter cake filter ash Figure 14: Process flow scheme of the clinical waste incineration plant Baden

101 State of the Art / Waste Incineration Descriptions of Plants 97 Exclusively wastes from hospitals are combusted. All auxilliary burners are operated with natural gas, whereby fluctuations of the flue gas temperature and the flue gas volume caused by different waste compositions are balanced. The process itself takes place discontinuously. Wastes are introduced into the shaft furnace periodically and heated to the distillation temperature using a gas burner. At the end of the distillation process solid residues are completely burnt out by means of gas burners. Combustion gases formed in the shaft furnace are burnt out in the afterburning chamber with injected air and subsequently cooled in the horizontal hot water boiler. Flue gases leaving the hot water boiler first pass the quenching zone and then the scrubbing zone of a one-stage NaOH scrubber. In this scrubber HCl, HF, SO 2 and part of the dust are separated. Flue gases are post-treated by means of a flow injection process after reheating with a gas burner. Activated coke and hydrated lime are used as adsorbent. Waste water that is discharged from the scrubber is treated in a multistage waste water treatment plant. The following waste fractions accumulate: Ash from the firing system and the waste heat boiler, filter cake from the waste water treatment and waste from the flow injection process. 8.4 Incineration of sewage sludge Fluidised bed reactors of the Plant Simmeringer Haide In the year ,390 tons of sewage sludge and 3,378 tons of waste oils as well as about 1,000 tons of feeding stuff and solvents each were combusted in three fluidised bed reactors. General data of the fluidised bed reactors are shown in Table 33. Table 33: General data of the fluidised bed reactors of the Plant Simmeringer Haide (2000) [KROBATH, 2001] Operator Fluidised bed reactors in the plant Simmeringer Haide Fernwärme Vienna GmbH Start-up 1980/1992 Firing technology Sludge throughput Average net calorific value Average gross calorific value Theoretical rated thermal input Stationary fluidised bed reactors System Copeland 54,390 t dry substance, corresponding to 1,656,000 m 3 thin slurry 15.7 MJ kg -1 dry substance 17.1 MJ kg -1 dry substance 50 MW Working hours line 1 2,484 Working hours line 2 5,603 Working hours line 3 8,784

102 98 State of the Art / Waste Incineration Descriptions of Plants Plant concept A process flow scheme of one fluidised bed reactor is shown in Figure 15. One incineration line basically consists of the following units: Fluidised bed reactor Waste heat boiler Flue gas cleaning devices: SNCR process, electrostatic precipitator, acid and alkaline scrubber, activated coke filter Multistaged waste water treatment plant Steam distribution system

103 State of the Art / Waste Incineration Descriptions of Plants 99 AVA Simmeringer Haide - WSO Emergency stack Emergency stack Stack Activated coke filter Boiler Electrostatic filter Scrubber Boiler ash Figure 15: Process flow scheme of the fluidised bed reactors of the Plant Simmeringer Haide

104 100 State of the Art / Waste Incineration Descriptions of Plants Table 34 presents an input/output balance of the three fluidised bed reactors of the Plant Simmeringer Haide related to one ton of waste. Table 34: Input and output flows of the fluidised bed reactors (reference year: 2000) [KROBATH, 2001] Input related to 1 t waste Output related to 1 t waste Electricity 590 kwh Heat 1.98 MWh Heavy fuel oil (1 % S) m³ Electricity kwh Fresh water 15,530 l Steam (p = 52 bar; T = 350 C) 5.22 t Lime 4.7 kg Fly and bed ash 264 kg Sodium hydroxide, 50 % 16.5 kg Filter cake (54.7 % H 2 O) 23 kg Ammonia, 25 % 4.1 kg Cleaned waste water 1,104 l Precipitating agents, 15 % 0.05 kg Cleaned flue gas (dry) 13,110 Nm³ FeCl 3, 40 % Coke Polyelectrolyte Hydrochloric acid, 30% Quartz sand Liquid nitrogen, 98.5 % 2.1 kg 3.4 kg 4.45 kg 1.4 kg 13.7 kg 2.5 kg Acceptance, treatment, storage and introduction of waste The three fluidised bed reactors are constructed for the incineration of sewage sludge from the main waste water treatment plant of Vienna. Supplied thin sludge is dewatered by means of centrifuges. The resulting thick sludge has a dry substance content between 30 and 36 % and is supplied to the fluidised bed reactors. Supply of combustion air Combustion air is preheated by means of an air preheater. Fluidised bed reactors The three fluidised bed reactors of the plant Simmeringer Haide are constructed according to the principle of the stationary fluidised bed technology. The temperature of the fluidised bed is 750 C. The combustion chamber is equipped with an oil burner. Utilisation of energy Energy from the flue gas is used for the production of steam (53 bar). Steam produced by the rotary kilns and the fluidised bed reactors is combined and converted to electricity by two turbines. Electricity is used for covering the own needs of the installation of the Plant Simmeringer Haide. Additionally the oven lines are equipped with a cogeneration (CHP) system which decouples heat for the district heating system of Vienna.

105 State of the Art / Waste Incineration Descriptions of Plants 101 Flue gas cleaning system and emissions to the air Electrostatic precipitator: In the first flue gas cleaning step dust emissions are reduced to mg Nm -3. Flue gas scrubbing: The wet flue gas cleaning system consists of two cross flow scrubbers for separation of acid, water soluble gases as well as dust and heavy metals. The subsequent venturi scrubber is used for separation of fine dust and for preconditioning of flue gases for a electrodynamic venturi scrubber. SNCR: Nitrogen oxides are reduced by injection of an aequous solution of ammonia into the flue gas. Activated coke filter: Post-treatment takes place in a counter current plant using activated coke separately for each combustion line. This unit consists of two parallel arranged adsorbers that are filled with lignite-furnace coke. The adsorbers for the fluidised bed reactors consist of 4 moduls each, whereby each modul is filled with 15 t adsorbent. Flue gas flows through the layer from the bottom up while the coke slowly moves downwards. Using these flue gas cleaning measures emission levels shown in Table 35 can be achieved. Table 35: Emissions to air from the fluidised bed reactors (reference year: 2000) [KROBATH, 2001] Parameter Emission [mg Nm -3 ] a Total mass [kg yr -1 ] b,d Specific emissions [g t -1 ] c,d Dust * HCl * HF < SO 2 * e CO * 4 3, NO x as NO 2 * , ,311 Cr As < Ni Cd Hg Cu PAH NH , PCDD+PCDF ng TE Nm mg yr µg t -1 * Continuous measurement a Half hourly average values in mg Nm -3 ; dioxin emissions are given in ng Nm -3 (11% O 2 ; dry flue gas; standard conditions) b In kg yr -1, dioxin loads in mg yr -1 c Emissions related to one ton used waste in g t -1 ; dioxin emissions in µg t -1 d Total mass and specific emissions are calculated based on average half hourly mean values, using the quantity of dry flue gas (13,110 Nm³ t -1 waste) and the waste quantity (63,390 t yr -1 ). e below detection limit (0.3 mg Nm -3 )

106 102 State of the Art / Waste Incineration Descriptions of Plants Waste water treatment and emissions to water The waste water from the three fluidised bed reactors is precleaned together with those of the two rotary kilns. Afterwards it is conducted into the main waste water treatment plant of Vienna. Waste water cleaning is performed using gravity separation, neutralisation, flocculation, filtration and precipitation processes. Neutralisation is performed in order to separate HCl and HF. Using these cleaning steps emission levels shown in Table 24 can be achieved. Waste Bed- and filter ash: Bed- and filter ashes are landfilled. Filter cake: The filter cake from the waste water cleaning plant is filled into big bags and landfilled. Chemical data of wastes from the fluidised bed reactors are shown in Table 36. Results from leaching tests are presented in Table 37. Table 36: Chemical data of wastes from the fluidised bed reactors (reference year: 2000) [KROBATH, 2001] Parameter Fly ash TOC [%] (air dried basis - ad) 0.97 Cl [%] (ad) 0.18 SO 3 [%] (ad) 3.3 Main components [mg kg -1 ] (dry basis) SiO Al 41,948 MgO 25 Fe 179,107 CaO 164 K 2 O 1.3 Heavy metals [mg kg -1 ] Zn 2,738 Pb 378 Mn 414 Cr 108 Cd 10.4 As 11.6 Hg 0.76 Ni 87

107 State of the Art / Waste Incineration Descriptions of Plants 103 Table 37: Leaching tests according to ÖNORM S 2115 fluidised bed reactors (reference year: 2000) [KROBATH, 2001] Parameter Concentration [mg kg -1 ] ph value 9.5 SO 4 1,284 Cl 58 NH 3 as N 0.75 NO 3 5 NO Fe 0.01 Mn < 0.01 Ni < 0.1 Cd < 0.01 Cr 0.03 Cu < 0.01 Pb 0.1 Zn 0.04 Hg Incineration of treated waste fractions Treated waste fractions are combusted in the plant of AVE-RVL Lenzing (description see chapter 8.6.1) and in the installations of the Plant Simmeringer Haide (description see chapter and 8.2.1). 8.6 Combined waste incineration Combined waste incineration is performed at the waste incineration plant Wels (description see chapter 8.1.3), at the plant of AVE-RVL Lenzing (description see chapter 8.6.1) and at the planned 4 th fluidised bed reactor of the Plant Simmeringer Haide AVE - Reststoffverwertung (AVE-RVL) Lenzing Following types of waste are combusted at AVE - Reststoffverwertung Lenzing: Packaging materials from the separated collection Rejects Light fractions/sieve overflow from mechanical-biological plants Waste wood, particularly contaminated Sewage sludge In ,715 tons of waste were treated on the whole (Table 38) [SCHNOPP, 2002].

108 104 State of the Art / Waste Incineration Descriptions of Plants Table 38: Types of waste and waste quantities treated at AVE - Reststoffverwertung Lenzing (reference year: 2000) [SCHNOPP, 2002] Types of waste Waste quantity [t yr -1 ] Plastic wastes 34,454 Rejects 19,464 Sewage sludge 31,986 Mixed plastic fractions 41,913 Old wood 6,898 General data of the fluidised bed reactor of AVE-RVL Lenzing are presented in Table 39 Table 39: General data of the fluidised bed reactor of AVE-RVL Lenzing [SCHNOPP, 2002] AVE - Reststoffverwertung Lenzing Operator RVL GmbH Start up September 1998 Technology Circulating fluidised bed reactor Waste throughput (2000) 134,715 t Calorific value of the waste MJ kg -1 Rated thermal input 110 MW th Operating hours (2000) About 6,100 Fuel oil, natural gas and coil are used as additional fuels for start up and shut down if necessary. The maximum rated thermal input of the plant is about 110 MW as continuous load. The plant is constructed for the treatment of wastes with a mixed calorific value of MJ kg -1. The required waste quantity is defined by the thermal output and is about 7-60 tons per hour. Plant concept A process flow diagram of AVE - Reststoffverwertung Lenzing is shown in two following figure. The plant basically consists of the following units: Delivery Treatment and storage of waste Fluidised bed combustion with fluidised bed cooler and afterburning chamber Waste heat boiler Dry, wet and catalytic flue gas cleaning devices Waste water treatment

109 cf State of the Art / Waste Incineration Descriptions of Plants 105 fabric filter pretreatment plant line 1 sewage sludge afterburning chamber coal gas air boiler feed water steam economizer SO srubber 2 HO 2 DeNoxplant bed material sand limestone HCl scrubber air 4 bar induced draught NH4OH line 2 gypsum offgases from viscose rayon production fresh air thermal treatment of accumulated waste Na2S FeCl3 PE HCL NaOH fresh air waste water treatment plant (WWTP) WWTP CaCO 3 HOK Ca(OH) 2 neutralization flocculation precipitation sedimentation sand filter SM - ion exchanger activated coke filter ash silos sludge from neutralization Figure 16: Process flow scheme of AVE-Reststoffverwertung Lenzing

110 106 State of the Art / Waste Incineration Descriptions of Plants Acceptance, treatment and storage of waste Delivered wastes such as packaging materials, rejects, light fraction and waste wood are declared by the deliverer and randomly tested by the operator, crushed and grinded and interimly stored in two daily bunkers that are situated directly near the boiler. Feeding of waste into the pulverizer, distribution in the daily bunker and discharge from the daily bunker is carried out in view of good homogenization. Sewage sludge is directly dumped into two charging hoppers with discharge floor and interimly stored in a silo. Sewage sludge is usually stabilized and combusted a few hours after delivery. In all cases transport from the pretreatment site to the boiler house is performed periodically with a pipe belt conveyor. Waste introduction and supply of combustion air Grinded wastes such as plastics, rejects, sieve overflow and waste wood can be fed from the charging hopper into the firing zone using 3 pneumatic conveyors. For sewage sludge, a separate conveyor line with a plug screw as dosing device is provided. For oil and natural gas, burners and oil lances are installed. Coal can be fed with a separate dosing plant. Exhaust gas from the neighbouring viscose rayon production containing H 2 S (hydrogen sulphide) and CS 2 (carbon disulphide) is used as combustion air. Exhaust gas from waste treatment and storage is dedusted with fabric filters and discharged into the atmosphere. Combustion air is injected into the combustion chamber through the valve tray, two secondary air levels and several process-related places such as pneumatical conveyors and fluidising plates in the ash circle. Dosing of particular wastes, co-fired fuels and combustion air is regulated by a firing performance control system. The demand for air and fuel is calculated online. The most important parameters such as calorific value and demand on combustion air are calculated automatically from process data and adapted to the combusted wastes. Fluidised bed combustion with afterburning chamber The firing system mainly consists of: Uncooled combustion chamber with slightly conical shape at the bottom and cylindrical form at the top Cyclone Afterburning chamber Recirculation system for bed material with a syphon and a fluidised bed cooler Wastes are mixed homogeneously into the lower part of the combustion chamber and transported through the firing chamber with combustion air. In order to preseparate SO 2 limestone is continuously added to the fluidised bed reactor of AVE - Reststoffverwertung Lenzing. This is a necessary procedure, because the exhaust air of the viscose rayon production that is used as combustion air contains high amounts of sulphureous compounds. Bed material is separated from the flue gas by a cyclone and fed into the syphon and fluidised bed cooler. A regulated quantity of bed material is passed over the fluidised bed cooler

111 State of the Art / Waste Incineration Descriptions of Plants 107 in order to extract heat from bed material either for steam production and superheating of steam or temperature regulation of the combustion chamber. Flue gases leaving the cyclone are fully combusted in the afterburning chamber at sufficient temperature and residence time. Waste heat boiler Flue gases leaving the afterburning chamber are passing two vertical void zones with heating surfaces for evaporation, a horizontal zone with hanging heating surfaces for evaporation and superheating, a cyclone battery system and a preheater for feedwater. The steam system is connected to that of the adjacent Lenzing AG. Feedwater is pumped from the existing feedwater system into the boiler drum through the feedwater preheater. The water passes in the so-called natural circulation the evaporator surfaces in the fluidised bed cooler and the waste heat boiler and evaporates to some extent. Steam is separated from water in the steam drum and conducted into the steam network of Lenzing AG via the superheater. The first superheaters are arranged in the waste heat boiler, the last superheaters are arranged in the fluidised bed cooler. Utilisation of energy The steam parameters of the produced fresh steam are 78 bar and 500 C. Electricity is produced by the turbines of Lenzing AG. The major part of the steam is withdrawn at 4 bar from the turbines and introduced into the process steam system of Lenzing AG. The overall demand for process steam is several times higher than the produced amount, exists all over the year and is covered by another fluidised bed reactor, two waste liquor boilers and an oil and gas fired reserve boiler. Flue gas cleaning and emissions into the air Dry flue gas: The dry flue gas cleaning system is constructed as transport reactor with downstream fabric filter. The flue gas temperature is regulated by the boiler to a constant value of about 160 C. The dry flue gas cleaning system is used for dedusting, heavy metal precipitation and preseparation of acid components such as HCl, HF and SO 3. Lime, limestone and activated coke can be dosed into the ducts before the fabric filter. Separated dust is recirculated to some part. Wet flue gas cleaning: The wet flue gas cleaning system consists of a co-current scrubber with acid circulating water, a countercurrent scrubber with gypsum suspension, droplet separators after each scrubber and a downstream steam heated gas preheater. The first step is used for the separation of acid components such as HCl, HF, SO 3 and for separation of volatile components. The second step is used for the separation of SO 2. The gypsum suspension of a partial flow is dewatered. Waste water from both scrubbers is treated by the waste water treatment plant. Cleaned waste water is partly returned to the first step. Limestone is injected in dry form as neutralizing agent. Catalytic flue gas cleaning: The catalytic flue gas cleaning system is arranged in clean gas application with preheating by a gas/gas heat exchanger and a high pressure steam preheater. It is used for reduction of NO x and oxidation of organic pollutants such as dioxins and furans.

112 108 State of the Art / Waste Incineration Descriptions of Plants The whole plant is designed in terms of precautionary environmental protection what means that the particular plant elements are dimensioned and arranged in such a way that the prescribed emission limit values can be observed even in cases of highest possible pollutant loads of combusted wastes. Achieved emission values of the fluidised bed reactor are shown in Table 40. Table 40: Emissions to air from the fluidised bed reactor of AVE - Reststoffverwertung Lenzing [SCHNOPP, 2002] Parameter Emission a [mg Nm -3 ] Dust 0.6 HCl 0.8 HF 0.02 SO C org 0.6 CO 2.3 NO x as NO Σ Pb, Cr, Zn Σ As, Co, Ni, Sb, Cu, Mn, V, Sn Cd+Tl Hg NH PCDD+PCDF 0.05 ng Nm -3 a Half hourly average values in mg Nm -3 ; dioxin emissions are given in ng Nm -3 (11% O 2 ; dry flue gas; standard conditions) Waste water treatment The waste water treatment plant consists of following units: Neutralisation, precipitation, flocculation and sedimentation and post treatment with gravel filters, ion exchanger and activated coke filter. For neutralisation lime milk is added. Waste As far as waste from combustion is concerned a process concept was chosen by AVE-RVL Lenzing with the following goals: Minimizing the amount of waste Concentration of pollutants in small amounts of waste Low concentration of volatile heavy metals in the main part of the ash Minimization of the PCDD/F content in the predominant part of the ash Reduction of the metallic Al content in the ash

113 State of the Art / Waste Incineration Descriptions of Plants 109 For that purpose the major part of the ash is separated in a cyclone battery at the end of the superheater zone. A part of this fine ash is recirculated into the combustion chamber again, in order to reduce volatile components and oxidize the major part of metallic Al. Following wastes accumulate: Bed ash: Coarse ash and interfering materials such as ferrous fragments and stones, that are separated by a coarse sieve and a magnetic separator. Coarse ash: Overflow of the coarse sieve of the bed ash. Ferrous scrap: Separated with magnetic separators from bed ash. Ash from pre-dedusting: Fine ash with a grain size between 40 and 100 µm, that is separated in the cyclone battery in the temperature range of 900 to 400 C. Additionally fine ash can be withdrawn by the air separator in the ash cycle of the firing system. Eco- and fabric filter ash: Very fine ash (< 40 µm) that arises in the flue gas zone after prededusting in the temperature range between 400 and 160 C and in the dry flue gas cleaning system. The mass fraction of very fine ash is less than 30 % of the overall ash but contains the main part of the volatile heavy metal and PCDD/F load. Very fine ash can be thermally post-treated in a rotary kiln. As this ash is disposed of underground anyway and already has the required properties without treatment, the rotary kiln was in operation only at the beginning of the test operation. Neutralisation sludge from the waste water treatment plant: Inorganic sludge dewatered in chamber filter presses. Gypsum: Arising in the suspension scrubber and dewatered in the centrifuge. Bed ash, coarse ash and pre-dedusting ash are exempted and disposed of at landfills. Eco- and fabric filter ash and neutralisation sludge are exported as hazardous wastes and disposed of underground. 8.7 Pyrolisis of wastes See combustion of clinical wastes 8.8 Gasification Gasification is not applied in Austria.

114 110 State of the Art / Waste Incineration Descriptions of Plants 8.9 Planned plants and plants under construction Waste incineration plant Zistersdorf The planned waste incineration plant Zistersdorf is designed for the treatment of about 120,000 t yr -1 domestic waste and similar industrial waste as well as for the treatment of about 10,000 t yr -1 sewage sludge (25 % dry substance). General data of the waste incineration plant Zistersdorf are shown in Table 41. Table 41: General data of the waste incineration plant Zistersdorf [SCHLEDERER, 2000] Operator Permit Firing technology Waste incineration plant Zistersdorf A.S.A. Abfall Service AG according to 17 UVP-G, notification from 20 th April, 1999 Grate firing Waste throughput 130,000 t yr -1 Average net calorific value 8.96 MJ kg -1 Theoretical rated thermal input 45.4 MW Steam production 54 t h -1 Operating hours 7,128 full-load operation hours for each of the two lines Decoupling of heat for district heating additionally to electricity production is intended but realisation is not guaranteed at the moment. Plant concept Each line basically consists of the following units: Waste bunker Firing system: Grate firing Waste heat boiler for steam production and turbine for electricity production and heat decoupling Flue gas cleaning devices consisting of: Fabric filter (including a flow injection absorber), two-stage flue gas scrubbing, catalytic flue gas cleaning system (both lines together) Waste water treatment plant including an evaporation plant Plant for waste treatment Heavy metals in the waste water from the wet scrubbers will be removed by flocculation and precipitation. Then the waste water is evaporated in a two-stage evaporation plant. Thus the incineration plant will operate waste water free. The particular steps of slag treatment are: Sieving (grain size = 70 mm), crushing and grinding of the coarse fraction, separation of ferrous and non-ferrous metals. As an alternative a melting plant for slag, boiler ash and filter dusts can be built.

115 State of the Art / Waste Incineration Descriptions of Plants 111 The limit values of the flue gas cleaning system are shown in Table 42 and compared to those laid down in the Austrian Clean Air Ordinance for Steam Boiler Units (LRV-K). Table 42: Emission limit values for the waste incineration plant Zistersdorf (Values in mg Nm -3, dioxins in ng Nm -3, referred to 11 % O 2 and dry flue gas) [SCHLEDERER, 2000] Parameter Limit value given in the permit [mg Nm -3 ] 1 Dust 8 HCl 7 HF 0.3 SO 2 20 CO 50 NO 2 70 ΣSb+As+Pb+Cr+Co+Cu+Mn+ Ni+V+Sn 0.5 Cd + compounds 0.01 Hg + compounds 0.05 Tl + compounds Zn + compounds 0.5 C org 8 NH 3 5 PCDD + PCDF 0.1 ng Nm -3 1 Within the first year of operation some air pollutants have to be measured periodically: Heavy metals: monthly; PCDD/PCDF: twice a year and 12 monthly average values; PCB: twice a year; PCBz: twice a year; PCPh: twice a year; PAH: twice a year Plant Simmeringer Haide: Fluidised bed reactor 4 The fluidised bed reactor 4 of the Plant Simmeringer Haide has already been permitted according to 29 AWG. The building commission has already been placed. The reactor is constructed as stationary rotating fluidised bed. 90,000 tons of waste per year with a calorific value between 8 and 16 MJ kg -1 and 6,000 tons sewage sludge as dry substance shall be combusted. The plant is equipped with a waste heat boiler and flue gas cleaning devices consisting of an electrostatic precipitator, a two-stage wet scrubbing with gypsum precipitation, an activated coke filter and an SCR process. A flue gas flow of 80,000 m -3 h -1 is expected Waste incineration plant Dürnrohr The waste incineration plant Dürnrohr is planned with an average capacity of 300,000 t waste per year, whereby according to the feasibility study about 150,000 t household waste and similar industrial waste, 70,000 t industrial waste and about 25,000 t bulky refuse and building wastes each as well as approximately 20,000 t sewage sludge shall be used. General data of the waste incineration plant Dürnrohr are presented in Table 43.

116 112 State of the Art / Waste Incineration Descriptions of Plants Table 43: General data of the waste incineration plant Dürnrohr [GRAF, 2000] Waste incineration plant Dürnrohr Operator AVN Planned start-up 2003 Start of building 2001 Firing Technology Grate firing Number of lines 2 Average waste throughput Approximately 300,000 t Average net calorific value 9.8 MJ kg -1 Theoretical rated thermal input 120 MW (both lines) Efficiency at the estate boundaries % Plant concept A process flow diagram of one of the two lines is shown in Figure 17. Each line basically consists of the following units: Waste bunker Firing system: Grate firing designed for the combustion of 24 tons of waste per hour Waste heat boiler designed for the production of 80 t superheated steam (400 C, 50 bar) per hour Flue gas cleaning devices consisting of: Fabric filter, two-stage flue gas scrubbing, selective catalytic NO x removal and dioxin destruction Some components are used by both lines: Multistage waste water treatment plant Slag treatment Steam distribution system Steam produced in the boilers is fed into the steam cycle of the power plant Dürnrohr unit 2 (about 140 t h -1 ). In this case steam from the waste incineration plant is introduced into the steam cycle of the power plant immediately before the intermediate superheater and superheated in the power plant again. Thus the produced steam can be better utilized and relevant quantities of fossil fuel (approximately 50,000 t coal and 10 Mio m³ natural gas per year) can be substituted. In case of standstill of the power plant the medium pressure steam is converted to electricity using an own turbine. Low pressure steam is decoupled from this turbine and delivered to the power plant for heat-keeping and long distance heat. Slag is discharged into a wet deslagger. Afterwards washed slag is splitted into oversized particles, scrap and raw slag by means of a rod sieve and a magnetic separator. The crude slag is transported away and landfilled or externally treated. Following legal limit values (LRV-K) that are shown in Table 44 have to be met with the flue gas cleaning devices under construction consisting of a fabric filter, a two-stage scrubbing and a SCR process.

117 State of the Art / Waste Incineration Descriptions of Plants 113 Table 44: Proposed limit values for emissions to air of the waste incineration plant Dürnrohr Parameter Limit value [mg Nm -3 ] NO x 70 CO 50 SO 2 50 Dust 8 C org 8 HCl 7 Σ Pb, Zn, Cr 0.5 Σ As, Co, Ni 0.3 HF 0.3 Hg 0.05 Cd 0.02 PAH 0.01 Bap 0,0001 PCB 0.1 ng Nm -3 PCDD + PCDF 0.1 ng Nm -3

118 cf 114 State of the Art / Waste Incineration Descriptions of Plants evaporator boiler superheater steam economizer flue gas treatment water fabric filter wet scrubber DeNoxplant grate firing NH4OH deionized water gypsum TMT FeCl3 PE HCL NaOH waste water treatment plant (WWTP) CaCO 3 HOK Ca(OH) 2 WWTP slag neutralization flocculation precipitation sedimentation sand filter SM - ion exchanger activated coke filter metallic scrap boiler ash filter ash sludge from neutralization Figure 17: Process flow scheme of the planned waste incineration plant Dürnrohr

119 State of the Art / Waste Incineration Descriptions of Plants Waste incineration plant Arnoldstein Approximately 80,000 t household waste and similar industrial waste per year are foreseen for thermal treatment. General data of the waste incineration plant Arnoldstein are given in Table 45. Table 45: General data of the planned waste incineration plant Arnoldstein [GRUBER, 2000] Operator Waste incineration plant Arnoldstein Planned start-up 2004 Firing technology Kärntner Restmüllverwertungs GmbH (KRV) Grate firing Waste throughput 10.7 t h -1 nominal throughput Average net calorific value 10,000 kj kg -1 Theoretical rated thermal input 107 GJ h -1 Steam production Operating hours > 7,500 Appr. 35 t h -1 (400 C, 40 bar) Plant concept A process flow diagram of the waste incineration plant Arnoldstein is shown in Figure 18. The plant basically consists of the following units: Waste bunker Waste heat boiler Firing system: Grate firing with Syncom process (oxygen enrichement) Flue gas cleaning devices consisting of: Fluidised bed process, fabric filter, activated coke filter (cross current), SCR process Waste is conveyed to the grate through the charging hopper. At the lower end of the charging hopper a dosing device continuously moves the waste forward onto the grate. Real combustion takes place on the reciprocating grate according to the Martin Syncom process. Combustion with oxygen enriched air results in a decrease of the specific flue gas volume. Ferrous and non ferrous metals shall be separated from the slag. Options for utilisation of the pretreated slag (road and earth construction) are searched. The slag will be landfilled, if no other options for utilisation can be found. The flue gas treatment plant works waste water free.

120 116 State of the Art / Waste Incineration Descriptions of Plants Figure 18: Process flow scheme of the planned waste incineration plant Arnoldstein (source: Flue gases are first cooled in the boiler and subsequently fed into the fluidised bed reactor. After passing further cleaning steps (fabric filter, activated coke filter, SCR process) emission values shown in Table 46 are expected. Table 46: Expected emissions from the waste incineration plant Arnoldstein (Values in mg Nm -3, dioxins in ng Nm -3, related to 11 % O 2, dry flue gas) [GRUBER, 2000] Parameter Expected emission Limit value according to LRV-K 18 medium plants Dust 5 20 HCl 7 15 HF SO CO NO Σ Pb + Zn + Cr Σ As + Co +Ni Cd Hg Σ HC 5 20 NH 3 16 (0 % O 2 ) PCDD + PCDF

121 State of the Art / Waste Incineration Descriptions of Plants Thermal residue utilisation plant Niklasdorf Depending on the calorific value about 60,000 to 100,000 t of residues and wastes shall be thermally used in the fluidised bed reactor. Sewage sludges, fibre sludges, rejects, sieve overflows from mechanical biological plants and composting, old wood, packaging materials and screenings shall be treated. In most cases wastes are sorted in external plants and treated before fluidised bed combustion. General data of the thermal residue utilisation plant Niklasdorf are given in Table 47. Table 47: General data of the thermal residue utilisation plant Niklasdorf [SPIEGEL, 2000] Operator Thermal residue utilisation plant Niklasdorf ENAGES Start of building 2002 Planned start-up End of 2003, beginning of 2004 Firing technology Number of lines 1 Waste throughput Operating hours 8,000 Fluidised bed reactor 60,000 to 100,000 t The plant will have a rated thermal input of approximately 25 MW and is constructed to supply the paper mill with electricity and heat (steam). Plant concept The plant basically consists of the following units: Fluidised bed reactor Waste heat boiler, designed for the production of approximately 30 t steam per hour Flue gas cleaning devices consisting of: Fabric filter, two-stage flue gas scrubbing, selective catalytic NO x removal Multistage waste water treatment plant Waste shall be incinerated at atmospheric pressure or at low vacuum in a fluidised bed reactor. Subsequently combustion gases remain in the combustion chamber at a temperature > 850 C for at least two seconds so that all components of the combustion gas can react. Bed material is withdrawn from the reactor to avoid accumulation of coarse material. Withdrawn bed material is cooled with water by means of cooling screws. Coarse material is separated and the bed material is either transported directly to the bed material silo or conveyed into the ash silo. Ashes shall be separated at different temperature levels with 400 C being the major range. The combination of these first flue gas cleaning steps shall lead to a concentration of pollutants in the fabric filter ash. After the dry flue gas cleaning system flue gas is conducted through a conventional twostage wet flue gas cleaning system. In the first scrubber acid gases such as HCl, HF and heavy metals are removed from the flue gas whereas in the second one primarily SO 2 is separated. NO x emissions are reduced by selective catalytic reduction (SCR). Emission limit values given by the permit are shown in Table 48.

122 118 State of the Art / Waste Incineration Descriptions of Plants Process water multiply used in the flue gas cleaning system is routed to a waste water treatment plant, which basically consists of following techniques: Precipitation, flocculation, filtration and neutralisation. Table 48: Emission levels of the planned thermal residue utilisation plant Niklasdorf compared with the limit values of the Clean Air Ordinance for Steam Boiler Units (Values in mg Nm -3, dioxins in ng Nm -3, related to 11 % O 2, dry flue gas) [SPIEGEL, 2000] Parameter Limit value given in the permit [mg Nm -3 ] Limit value according to LRV-K 1989 for medium plants [mg Nm -3 ] Dust HCl HF SO CO NO Σ Pb + Cr + Zn Σ As + Co + Ni 0.7 ΣSb+As+Pb+Cr+Co+Cu +Mn+Ni+V+Sn 0.5 Cd 0.05 Cd+Tl 0.05 Hg Σ HC NH PCDD + PCDF 0.1 ng Nm ng Nm -3

123 State of the Art / Waste Incineration Estimation of Costs ESTIMATION OF COSTS The costs of a waste incineration plant basically depend on following factors:! Plant design! Size! Local infrastructure! Specific boundary conditions for waste disposal! Possibility for energy utilisation The main components are:! Repayment of investment! Maintenance and re-investment costs! Personnel costs! Other fix costs such as administration and insurance! Operating costs proportional to throughput such as chemical supply and waste disposal! Revenues from energy production proportional to throughput Basically it has to be considered that the thermal output is the important parameter for the investment and operating costs and not the mass throughput. The thermal output determines the size of the boiler and primarily the flue gas volume and therefore the size of the flue gas cleaning devices. For a better understanding of this chapter some parameters were fixed as follows: calorific value of the waste: 10 MJ kg -1 ash content of the waste: 30 % chlorine concentration in the raw gas before flue gas cleaning: 1,000 mg Nm -3 SO 2 concentration in the raw gas: 600 mg Nm -3 specific air requirement per ton waste: 4,500 m 3 specific flue gas volume after flue gas cleaning: 5,500 Nm 3 t -1 For calculation of the required fan power combustion air with a temperature of 50 C and a pressure increase of 40 mbar is taken as a basis. The fan efficiency is uniformly assumed to be 70 %. On the basis of these assumptions specific costs for particular plant subunits have been estimated and are given per ton of combusted waste. As in practise different boundary conditions for the particular plants apply and each plant represents more or less a prototype only a rough estimate can be presented in this chapter. Only the plant operator knows the exact cost structure which as a rule are not available to the public because of competition reasons. The investment costs that are described in this paper are based on order prices of the last five years (predominantly Austrian and German plants, that were constructed under comparable boundary conditions).

124 120 State of the Art / Waste Incineration Estimation of Costs 9.1 Discharge and storage In densely populated regions waste is delivered to the waste incineration plants by refuse collection vehicles. There it is directly dumped into the waste bunker. Therefore only weighing installations, traffic areas and waste bunkers have to be erected as installations for delivery and storage. The size and consequently the costs of these traffic areas and waste bunkers are mainly determined by the plant capacity and the storage volume of the bunker. Primarily these costs arise from expenses for building above ground level and foundation work. In this case investment costs aren t directly proportional to the bunker and plant sizes but have to be calculated with the exponent 0.7. For example doupling the bunker volume will increase costs by a factor 2 0,7. As to a plant with a yearly waste throughput of about 300,000 tons the construction costs for traffic areas and bunkers are about 10 Mio Euro. For different plant sizes costs presented in Table 49 have been estimated. Table 49: Specific costs for discharge and storage facilities as a function of throughput when waste is delivered by refuse collection vehicles Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 4.6 Mio. about 7.5 Mio. about 10 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Specific costs for delivery with refuse collection vehicles [ t -1 ] In less densely populated regions a part of the waste is delivered by train. That makes the erection of track works and installations for discharge, such as container crane systems and dump devices necessary. Investment costs for a complete crane system are about 3.5 Mio. referred to a transshipment of 300,000 t yr -1. Crane systems for smaller plants are not much cheaper, since their costs depend on the standardized dimensions of the containers. However, costs for tracks are will decrease with decreasing plants size. For different plant sizes costs presented in Table 50 have been estimated. Yearly maintenance costs uniformly were rated at 3 % of investment costs. Table 50: Specific costs for discharge and storage facilities as a function of throughput when waste is delivered by train Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 3 Mio. about 4 Mio. about 5 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Specific costs of train discharge [ t -1 ] If one part of the waste is delivered by train and the other part is delivered by refuse collection vehicles overall costs have to be added (see Table 72 and next pages).

125 State of the Art / Waste Incineration Estimation of Costs Firing system and boiler The firing system and the boiler comprises the following components: Installation for feeding and dosing of waste Supply of combustion air Combustion grate with combustion chamber Transport and storage installations for ash and slag Flue gas ducts until feedwater preheater Waste heat boiler including feedwater supply and fresh steam delivery Cost determining factors for the firing system and the boiler are the type of the grate system, the desired boiler efficiency and the design of the waste heat boiler. If water-cooled grates should be installed and if the flue gas temperature after the waste heat boiler should be 160 C (which increases boiler efficiency to 90 %) and if high steam parameters should be applied, average investment costs can be up to 20 % higher than those of conventional plants. For a line with a yearly throughput of about 150,000 tons investment costs for the firing system and the boiler without costs for construction and for electronic, monitoring, regulation and control equippment are about 16 Mio.. Costs for heating surfaces are almost proportional to the size of the plant, whereas costs for other equippment depend on the plants size, so that on average investment costs will depend from size by a factor of about 2 0,8. Thus for different plant sizes specific costs shown in Table 51 have been estimated. Costs are widely independent from the number of combustion lines. Table 51: Specific costs for a grate firing system and the boiler of waste incineration plants as a function of throughput Parameter Investment costs [ ] about 9.2 Mio. Throughput 75,000 t yr ,000 t yr ,000 t yr -1 about 11.6 Mio. about 16 Mio. Specific investment costs [ yr -1 ] Yearly maintenance costs in percent of investment costs [% yr -1 ] Specific maintenance costs [ yr -1 ] Average overall consumption of electricity (normal operation) [kwh t -1 ] Costs of electricity [ t -1 ] Accumulating slag and boiler ash [kg t -1 ] Disposal costs of slag and boiler ash [ t -1 ] Specific costs for firing and boiler [ t -1 ] Operating costs for the firing system that are directly proportional to the waste throughput arise from: Energy consumption for air and flue gas conveying and for feedwater supply Disposal costs for slag and ash

126 122 State of the Art / Waste Incineration Estimation of Costs The specific energy consumption for the firing system and the boiler is about 27 kwh t -1 at a steam pressure of about 50 bar. In case the steam pressure is increased to 75 bar the energy demand will rise by about 4 kwh t -1. As to the disposal costs for slag and ash it was assumed that both can be disposed of on a landfill for residual waste. If boiler ash couldn t be exempted it would have to be disposed of underground. Thus disposal costs would rise by about 2 t -1. About 3.2 tons of steam per ton waste are produced in general. Proceeds from steam production are treated in the chapter water-steam cycle. 9.3 Water-steam cycle The water-steam cycle of a waste incineration plant comprises the following components: Water treatment plant, condensate system, turbine with cooling system and heat decoupling system. Different systems are installed in Austrian waste incineration plants. At Viennese plants the major part of the energy is fed into the district heating network and electricity is only produced to cover the own need. At most other plants emphasis lies on the production of electricity. The kind of plant and the possibilities for energy delivery primarily determine the proceeds from energy production. Therefore the cost overview is presented in such a way that energy proceeds can totally be attributed to the water-steam cycle. Therefore five technical systems have been distinguished. As can be already seen at the particular plant descriptions none of these options can directly be related to an existing plant or to a plant under construction. The energy yield attained in practise depends on a great number of parameters such as boiler design, heat exchanger surfaces, utilisation of low pressure steam for feedwater and air preheating and turbine design. In the following chapter a comparison of different systems shall be made under standardized boundary conditions. In Table 52 to Table 59 main cost factors of the water-steam cycle are described on the basis of the following assumptions: Yearly operating hours: 7,500 h. In every case a boiler efficiency of about 80 % is assumed so that an energy output of 2.2 MWh per ton waste results (calorific value of the waste: 10 MJ kg -1 ). This value can vary by plus/minus 10 % depending on the plant. The investment costs were derived from that of comparable plants. Depending on the actual boundary conditions significant deviations may occur. The specific investment costs were calculated on the basis of a rate of interest of 6 % over a duration of 15 years. This period was chosen as the propability for re-investment costs are high after 15 years operation. Yearly maintenance costs uniformly were rated at 3 % of investment costs. Heat and electricity delivery were adjusted to the steam parameters. Depending on the type of turbine and the type and operation of the water-steam cycle deviations may occur. Proceeds from delivered energy mainly depend on the kind of energy and the particular energy demand. For feeding electricity into the grid normally a price of about 25 per MWh (selling price) is paid. In case of feeding heat into the district heating system about

127 State of the Art / Waste Incineration Estimation of Costs per MWh are paid. If the plant is situated at a site, where a demand for electricity and heat exists about 45 per MWh (purchase price) for electricity and about 10 per MWh for heat can be saved. Consequently for the options 1 to 5 25 per MWh for electricity and 6 per MWh for heat delivery were taken as relevant values. In comparison to that 45 per MWh for electricity and 10 per MWh for heat delivery are paid in case of options 6, 7 and 8. Option 6 technically corresponds to option 2, option 7 technically corresponds to option 4 and option 8 technically corresponds to option 5. Option 1: Pure heat decoupling If only heat is produced the investment costs comprise expenses for water and condensate treatment and for heat transformation. If no other infrastructure exists, also cooling systems for emergency situations have to be installed (Figure 19). produced steam (high pressure) heat for internal and external use recycling of condensate Figure 19: Water-steam cycle option 1 Table 52: Specific costs of a water-steam cycle with pure heat decoupling and feeding into district heating systems as a function of waste throughput Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 3 Mio. about 4.5 Mio. about 6 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ]

128 124 State of the Art / Waste Incineration Estimation of Costs Option 2: Steam extraction turbine applying steam parameters of 50 bar and 400 C In this case investment costs comprise costs for water and condensate treatment, for heat decoupling, for the turbine and cooling systems. If no other infrastructure exists also recooling systems for emergency situations have to be installed (Figure 20). G heat for internal use Figure 20: Water-steam cycle option 2 and 6 Table 53: Specific costs of a water-steam cycle comprising a steam extraction turbine as a function of waste throughput Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 8 Mio. about 12 Mio. about 16 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Electricity delivery [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ]

129 State of the Art / Waste Incineration Estimation of Costs 125 Option 3: Steam extraction turbine combined with steam introduction into an adjacent thermal power plant In addition to the investment costs given in option 2 costs for retrofit measures in the power plant minus the existent infrastructure have to be considered (Figure 21). G heat for internal use G power plant waste incineration Figure 21: Water-steam cycle option 3 Table 54: Specific costs of a water-steam cycle comprising a steam extraction turbine in combination with the steam system of an adjacent power plant as a function of waste throughput Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 8,5 Mio. about 12,5 Mio. about 15 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Electricity delivery [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ]

130 126 State of the Art / Waste Incineration Estimation of Costs Option 4: Cogeneration (CHP) applying steam parameters of 50 bar and 400 C In addition to the investment costs given in option 2 also costs for the heat decoupling system have to be considered (Figure 22). G produced steam (high pressure) heat for internal and external use recycling of condensate Figure 22: Water-steam cycle option 4, 5, 7 and 8 Table 55: Specific costs of a water-steam cycle comprising cogeneration (CHP) and low steam parameters as a function of waste throughput Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 9 Mio. about 14 Mio. about 18 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Electricity delivery [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ]

131 State of the Art / Waste Incineration Estimation of Costs 127 Option 5: Cogeneration (CHP) applying steam parameters of 80 bar and 400 C In addition to the investment costs given in option 2 also the cost increases for raised steam parameters and costs for the installations for heat decoupling have to be considered (Figure 22). Table 56: Specific costs of a water-steam cycle comprising cogeneration (CHP) and high steam parameters as a function of waste throughput Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 10 Mio. about 15,5 Mio. about 20 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Electricity delivery [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ] Option 6: Steam extraction turbine applying steam parameters of 50 bar and 400 C On the contrary to option 2 the waste incineration plant is located at a site where energy can be substituted which otherwise has to be purchased (Figure 20). Table 57: Specific costs of a water-steam cycle comprising a steam extraction turbine (normal steam parameters) as a function of waste throughput when energy can be substituted Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 8 Mio. about 12 Mio. about 16 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Electricity delivery [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ]

132 128 State of the Art / Waste Incineration Estimation of Costs Option 7: Cogeneration (CHP) applying steam parameters of 50 bar and 400 C On the contrary to option 4 the waste incineration plant is located at a site where energy can be substituted which otherwise has to be purchased (Figure 22). Table 58: Specific costs of a water-steam cycle comprising cogeneration (CHP normal steam parameters) as a function of waste throughput when energy can be substituted Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 9 Mio. about 14 Mio. about 18 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Electricity delivery [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ] Option 8: Cogeneration (CHP) applying steam parameters of 80 bar and 400 C On the contrary to option 5 the waste incineration plant is located at a site where energy can be substituted which otherwise has to be purchased (Figure 22). Table 59: Specific costs of a water-steam cycle comprising cogeneration (CHP high steam parameters) as a function of waste throughput when energy can be substituted Parameter Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Investment costs [ ] about 10 Mio. about 15.5 Mio. about 20 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Heat delivery [MWh t -1 ] Specific proceeds from heat production [ t -1 ] Electricity delivery [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam cycle [ t -1 ]

133 State of the Art / Waste Incineration Estimation of Costs 129 Survey of specific proceeds from the water-steam-cycle Table 60: Survey of specific proceeds from different options of the water-steam cycle as a function of waste throughput Option Throughput 100,000 t yr ,000 t yr ,000 t yr -1 Option Option Option Option Option Option Option Option As shown in Table 60 increasing plant sizes result in higher proceeds from the water-steam cycle. In case of lower investments (pure heat decoupling option 1) the dependence on the plant size is only marginal. On the basis of rated costs higher investments for a higher rate of electricity production as is presumed in option 3 and 5 would be economically favourable. However, option 3 can only be realized at a site adjacent to a power plant with an approximately ten times higher thermal output and a yearly operating time of at least h. Option 5 is problematic insofar as corrosion problems occure when increased steam parameters are applied. These problems are not sufficiently solved until now. In Table 60 a high availability is assumed for all options which is not reflected in practice in the case of option 5. Here higher revision costs within the boiler system and additional standstills have to be considered. If these facts cause addittional expenses of about 2 Mio per year specific costs will increase by 7 per ton in the case of a plant with a waste throughput of 300,000 t yr -1. Thus this option obviously looses economically attractiveness. The difference between sites with and without heat demand at the same cost levels for energy (option 2 and 4) referred to a througput of 300,000 tons per Jahr is only about 5.5 /t. Proceeds from electricity production in a power plant and cogeneration (CHP) are similar. A significant increase of proceeds will be achieved by a suitable choice of the plants location if produced energy can be used for substitution of fossil fuels or if an existing energy demand can be covered (option 6 to 8).

134 130 State of the Art / Waste Incineration Estimation of Costs 9.4 Flue gas treatment In Austria following combinations of flue gas cleaning technologies are in operation or should be installed: - electrostatic precipitator, - two-stage wet scrubber with and without precipitation, - wet removal of fine dust and - catalytic plant (low-dust circuit) - fabric filter with dosage of lime and activated coke, - two-stage wet scrubbing with gypsum scrubber and - downstream catalytic plant (low-dust circuit) - electrostatic precipitator, - two-stage wet scrubbing with NaOH scrubber, - fabric filter with dosage of lime and activated coke and - downstream catalytic plant (low-dust circuit) - electrostatic precipitator, - two-stage wet scrubbing with precipitation, - activated coke adsorber (cross current) - downstream catalytic plant (low-dust circuit) - electrostatic precipitator, - two-stage wet scrubber, - wet removal of fine dust and - activated coke adsorber (counter current) - Fluidised bed process - Fabric filter - Activated coke filter - Selective catalytic reduction Dry flue gas cleaning As to dry flue gas cleaning it was generally assumed, that the dust concentration in the raw gas is 5 g Nm -3 and the flue gas volume is 5,500 Nm 3 t -1. The investment costs for the dedusting device include expenses for the filter itself as well as for silos, dust conveyors and dosing devices (if installed).

135 State of the Art / Waste Incineration Estimation of Costs 131 Operating costs mainly consist of costs for electricity consumption, disposal costs for the separated dust and costs for the adsorption reagents. Costs for the adsorption media also comprise disposal costs of accumulated waste. At Austrian plants dedusting with an electrostatic precipitator is only used in combination with a downstream wet electrostatic precipitator or a downstream activated coke plant. Specific costs of an electrostatic precipitator as a function of waste throughput are presented in Table 61, specific costs of wet dedusting systems are shown in Table 62. Table 61: Specific costs for dedusting with an electrostatic precipitator as a function of waste throughput Parameter Consumption of electricity Unit Throughput per line 75,000 t yr t yr ,000 t yr -1 Specific consumption kwh t Specific costs of energy consumption t Disposal costs Specific amount of accumulated waste kg t Specific costs for waste disposal t Maintenance and wear Share of investment costs % Specific costs of maintenance t Investment costs 1,000,000 1,200,000 1,600,000 Specific investment costs t Rated specific overall costs t Wet dedusting system Table 62: Specific costs for wet dedusting as a function of waste throughput Parameter Consumption of electricity Average overall consumption (normal operation) Unit Throughput per line 75,000 t yr t yr ,000 t yr -1 kwh t Costs of electricity consumption t Maintenance and wear Share of investment costs % Specific costs of maintenance t Investment costs 1,500,000 2,000,000 2,500,000 Specific investment costs t Rated specific overall costs t

136 132 State of the Art / Waste Incineration Estimation of Costs It has been shown that a dry flue gas cleaning system with dosage of activated coke is the most cost-effective solution for preseparation of mercury, PCDD/F and for dedusting (Table 63). Another advantage of this process is that a great part of heavy metals and dioxins and furans are already removed before the flue gas enters the wet scrubbing system. For that reason pollutant concentration in the accumulated gypsum is low. Dry flue gas cleaning with fabric filter Table 63: Specific costs of a dry flue gas cleaning system with fabric filter as a function of waste throughput Parameter Consumption of electricity Unit Throughput 75,000 t yr ,000 t yr ,000 t yr -1 Specific consumption kwh t Specific costs of energy consumption t CaO-consumption incl. waste disposal Specific consumption kg t Stoichiometric factor Specific costs for adsorption t Activated coke consumption Specific consumption kg t Specific costs of activated coke t Disposal costs Specific amount of accumulated waste kg t Specific costs for waste disposal t Maintenance and wear Share of investment costs % Specific costs of maintenance t Specific costs of filter wear t Investment costs 1,150,000 1,450,000 2,000,000 Specific investment costs t Rated specific overall costs t Absorption and adsorption plants for separation of HCl, HF and SO 2 Presently only wet processes are used for separation of HCl, HF and SO 2. At one plant preseparation can be performed using a dry process, at another plant the installation of a dry process is planned. In case wet processes are applied operating costs are influenced by the type and amount of adsorption media, by the energy consumption and by disposal costs of waste. In the investment costs expenses for flue gas ducts and for scrubbers, droplet separators, heat ex-

137 State of the Art / Waste Incineration Estimation of Costs 133 changers and reactors and for the whole infrastructure for handling of water, waste water, chemicals and residues are included. It was basically assumed, that 600 mg Nm -3 SO 2 and 1,000 mg Nm -3 HCl have to be separated. Under these conditions specific costs of a NaOH scrubber are about 11 t -1, costs of scrubbers with precipitation are between 8 and 9 t -1 and costs of a gypsum scrubber are between 5 and 6 t -1. The combination of a gypsum scrubber with a dry flue gas cleaning system with activated coke adsorption is slightly more expensive than a dry plant for the separation of HCl, HF and SO 2 only (13.19 vs t -1 ) based on a throughput of 75,000 t yr -1. In case of plants with a waste throughput of about 100,000 t yr -1 per line costs are approximately the same (12.69 vs t -1 ), in case of a throughput of about 150,000 t yr -1 per line lower costs arise for the combination gypsum scrubber plus dry flue gas cleaning system compared to dry adsorption only (12.15 vs t -1 ). Costs of absorption and adsorption plants are given in Table 64 to Table 67. Dry flue gas cleaning with adsorption Table 64: Specific costs of a dry flue gas cleaning system with adsorption as a function of waste throughput Parameter Consumption of electricity Unit Throughput per line 75,000 t yr ,000 t yr ,000 t yr -1 Specific consumption kwh t Specific costs of energy consumption t CaO-consumption incl. waste disposal Specific consumption kg t Stoichiometric factor Specific costs for adsorption t Activated coke consumption Specific consumption kg t Specific costs of activated coke t Disposal costs Specific amount of accumulated waste kg t Specific costs for waste disposal t Maintenance and wear Share of investment costs % Specific costs of maintenance t Specific costs of filter wear t Investment costs 1,725,000 2,175,000 3,000,000 Specific investment costs t Rated specific overall costs t

138 134 State of the Art / Waste Incineration Estimation of Costs Gypsum scrubber Table 65: Specific costs of a gypsum scrubber as a function of waste throughput Parameter Unit Throughput per line 75,000 t yr ,000 t yr ,000 t yr -1 Consumption of electricity Specific consumption kwh t Specific costs of energy consumption t Reheating Temperature increase C Heat demand MWh t Specific costs t CaCO 3 consumtion Specific consumption kg t CaO-consumption Specific consumption kg t Costs of neutralizing agent t Disposal costs Specific amount of accumulated gypsum kg t Specific amount of filter cake kg t Specific costs t Maintenance and wear Share of investment costs % Specific costs t Investment costs 2,500,000 3,000,000 4,000,000 Specific investment costs t Rated specific overall costs t

139 State of the Art / Waste Incineration Estimation of Costs 135 Scrubber with precipitation Table 66: Specific costs of a scrubber with precipitation as a function of waste throughput Parameter Unit Throughput 75,000 t yr ,000 t yr ,000 t yr -1 Consumption of electricity Specific consumption kwh t Specific costs of energy consumption t Reheating Temperature increase C Heat demand MWh t Specific costs t NaOH- consumption Specific consumption kg t CaO-consumption Specific consumption kg t Costs neutralizing of agent t Disposal costs Specific amount of accumulated gypsum kg t Specific amount of filter cake kg t Specific costs t Maintenance and wear Share of investment costs % Specific costs t Investment costs 2,500,000 3,000,000 4,000,000 Specific investment costs t Rated specific overall costs t

140 136 State of the Art / Waste Incineration Estimation of Costs NaOH scrubber Table 67: Specific costs of a NaOH scrubber as a function of waste throughput Throughput per line Parameter Unit 75,000 t yr ,000 t yr ,000 t yr -1 Consumption of electricity Specific consumption kwh t Specific costs of energy consumption t Reheating Temperature increase C Heat demand MWh t Specific costs t NaOH- consumption Specific consumption kg t CaO-consumption Specific consumption kg t Costs for neutralizing agent t Disposal costs Specific amount of accumulated gypsum kg t Specific amount of filter cake kg t Specific costs t Maintenance and wear Share of investment costs % Specific costs t Investment costs 1,800,000 2,200,000 3,000,000 Specific investment costs t Rated specific overall costs t

141 State of the Art / Waste Incineration Estimation of Costs NO x reduction For catalytic flue gas cleaning (SCR) only the clean gas application that is used in Austria was considered. In addition to investment costs and costs for maintenance, also costs for reheating, catalyst-exchange, ammonia and electricity are the main positions. In the investment costs the whole flue gas path with heat transfer system, flue gas pipe, catalyst box and bypass pipe as well as the whole NH 4 OH system consisting of detanking equipment, storage, dosing station, evaporation and mixing units were included. The overall costs of catalytic flue gas cleaning (Table 68) are about 3 t -1 which is two times higher than the costs for non-catalytic flue gas cleaning (SNCR, Table 69). However, with SNCR an emission limit value of 100 mg Nm -3 as is prescribed by Austrian law cannot be observed. If the catalyst is also used for dioxin oxidation the catalyst volume and thus the position specific volume/catalyst wear will increase. However differences in overall costs are small. Catalytic flue gas cleaning (SCR) Table 68: Specific costs of SCR as a function of waste throughput Throughput per line Parameter Unit 75,000 t yr ,000 t yr ,000 t yr -1 Consumption of electricity Specific consumption kwh t Specific costs of energy consumption t Reheating Temperature increase C Heat demand MWh t Specific costs t NH 4 OH consumption (as NH 3 solution 25 %) Specific consumption kg h Specific costs t Maintenance and wear Share of investment costs % Specific t Average life cylce a Specific costs catalyst wear t Investment costs 1,200,000 1,500,000 2,000,000 Specific investment costs t -1 1,65 1, Rated specific overall costs t -1 3,32 3,

142 138 State of the Art / Waste Incineration Estimation of Costs Non-catalytic flue gas cleaning (SNCR) Table 69: Specific costs of SNCR as a function of waste throughput Throughput per line Parameter Unit 75,000 t yr ,000 t yr ,000 t yr -1 Consumption of electricity Specific consumption kwh t Specific costs of energy consumption t NH 4 OH consumption (as NH 3 solution 25 %) Specific consumption kg h Specific costs t Maintenance and wear Share of investment costs % Specific t Investment costs 700, ,000 1,000,000 Specific investment costs t Rated specific overall costs t Posttreatment plants At some plants systems for posttreatment of flue gases are installed after dedusting and gas absorption or adsorption: Flow injection adsorber (Table 70) with activated coke and lime or limestone as reagents and fixed bed adsorber (Table 71) using furnace coke. Reacted or loaded chemicals are reouted into the combustion system. Thus operating costs are primarily costs for adsorption media and electricity consumption. In the investment costs expenses for flue gas ducts, heat exchangers, reactors and filters and for the required infrastructure for delivery, storage and dosage of chemicals and for conveying, storage and filling of residues are included.

143 State of the Art / Waste Incineration Estimation of Costs 139 Flow injection adsorber Table 70: Specific costs of a flow injection adsorber as a function of waste throughput Throughput per line Parameter Unit 75,000 t yr ,000 t yr ,000 t yr -1 Consumption of electricity Specific consumption kwh t Specific costs of energy consumption t CaO-consumption incl. salt disposal Specific consumption kg t Stoichiometric factor Specific costs for adsorption t Activated coke consumption Specific consumption kg t Specific costs of activated coke t Disposal costs Specific amount of accumulated waste kg t Specific costs for waste disposal t Maintenance and wear Share of investment costs % Specific costs of maintenance t Specific costs of filter wear t Investment costs 1,150,000 1,450,000 2,000,000 Specific investment costs t Rated specific overall costs t

144 140 State of the Art / Waste Incineration Estimation of Costs Activated coke plant Table 71: Specific costs of an activated coke plant as a function of waste throughput Throughput per line Parameter Unit 75,000 t yr ,000 t yr ,000 t yr -1 Consumption of electricity Specific consumption kwh t Specific costs of energy consumption t Activated coke consumption Specific consumption kg t Specific costs t Maintenance and wear Share of investment costs % Specific t Investment costs 2,800,000 3,600,000 5,000,000 Specific investment costs t Rated specific overall costs t Cost estimations for whole plants In order to estimate the costs of whole plants following assumptions were made. At a plant with a waste throughput of 100,000 t yr -1 an arrangement based on one line, in case of 200,000 t yr -1 two lines with 100,000 t yr -1 each and in case of 300,000 t yr -1 two lines with 105,000 t yr -1 each are assumed. The investment costs that have been estimated for the particular plant components only refer to the systems engineering. In addition to that also proportional costs for construction, EMC and other infrastructure measurements have to be considered. The construction costs were rated 20 % and the costs for EMC were rated 15 % of the plants cost. Other investment costs such as costs for planning of the plant and e.g. other infrastructure differ marginally with particular plant sizes. Personnel costs were calculated for the whole plant and thus haven t been considered in the estimations for the particular plant components. In the cost calculations only expenses for personnel that is directly necessary for the plants operation are included. Differences in the distribution and administration systems have been neglected. The investment costs were calculated statically based on a duration of 15 years and a rate of interest of 6 %. Furthermore full load operation of the plant with a yearly operation time of 7,500 h was supposed. In the rated costs some positions such as costs for construction interests, leading personnel, administration, advertising and insurance aren t included. Thus costs calculated under these assumptions are at least 30 to 40 % too low and therefore accounted as rated specific overall costs. To make cost estimations more realistic a share of 40 % were added to the rated specific overall costs and the resulting cost were named estimated specific overall costs. Cost estimations for different plants are based on the same simplified assumptions. Thus the relations of different plants correspond to practical experiences.

145 State of the Art / Waste Incineration Estimation of Costs 141 In the tables below following differences between plants have been elaborated: Different plant size Different energy utilisation on the basis of uniform prices Different flue gas cleaning systems The assumptions made are described in the titles of Table 72 to Table 77. Figure 23 shows the cost structure as a function of plant size and energy utilisation. 160,00 140,00 /t 120,00 100,00 option 1 option 2 option 3 upper range low er range 80,00 60, t yr-1 Figure 23: Cost structure of the same systems as a function of plant size and energy utilisation The size has a great influence on the overall costs of a plant. The maximum difference between small and large plants is about 37 per ton incinerated waste. On the other hand the way of energy utilisation shifts the costs by about 9 per ton. Integration of steam in existing power plant (options 1) and cogeneration (option 3) lead to lower overall costs than pure electricity production (option 2).

146 142 State of the Art / Waste Incineration Estimation of Costs Figure 24 shows the cost structure in case of different plant design and same energy utilisation. 160,00 /t 140,00 120,00 100,00 option 2 option 4 option 5 option 6 upper range low er range 80,00 60, t yr-1 Figure 24: Cost structure in case of different plant design and the same energy utilisation In the options that are shown in Figure 24 only electricity is produced from waste incineration. Again it is shown that the overall costs of a plant mainly depend on the size (maximum difference: 37 per t), whereas the maximum difference as a function of the flue gas cleaning system is 13 per ton. On the whole the range of overall costs shown in both figures is between 92 an 148 per ton incinerated waste. In the rural regions between Vienna and Salzburg a plant capacity of 300,000 t yr -1 corresponds to a catchment area with a radius of about km. In case of small plants the cost difference between direct delivery with the refuse collection vehicle and delivery with an overall logistic of collection, reloading to train and transport by train is between 10 an 15 /t. Thus lower logistic costs at small plants can compensate the higher specific treatment costs only to a small part.

147 State of the Art / Waste Incineration Estimation of Costs 143 Table 72: Whole plant - option 1: Costs of a grate firing system with delivery by train, dry, wet and catalytic flue gas treatment and with the steam cycle connected to that of an adjacent power plant as a function of throughput Parameter Costs for discharge and storage using refuse collection vehicles Additional costs for discharge and storage using the train Unit Throughput 100,000 t yr ,000 t yr ,000 t yr -1 t t Firing system and boiler t Water steam cycle (option 3) t Dry flue gas cleaning t Gypsum scrubber t Catalytic flue gas cleaning t Investment costs of systems engineering 33,650,000 59,100,000 78,000,000 Construction 6,730,000 11,820,000 15,600,000 EMC 5,047,500 8,865,000 11,700,000 Other investment costs 6,000,000 7,000,000 8,000,000 Specific costs for construction, EMC + others t Personnel costs yr -1 1,700,000 1,800,000 2,000,000 Specific personnel costs t Rated overall costs t Estimated overall costs t

148 144 State of the Art / Waste Incineration Estimation of Costs Table 73: Whole plant - option 2: Costs of a grate firing system with delivery by train, dry, wet and catalytic flue gas treatment with power generation as a function of throughput Parameter Costs for discharge and storage using refuse collection vehicles Additional costs for discharge and storage using the train Unit Throughput 100,000 t yr ,000 t yr ,000 t yr -1 t t Firing system and boiler t Water steam cycle (option 2) t Dry flue gas cleaning t Gypsum scrubber t Catalytic flue gas cleaning t Investment costs of systems engineering 33,150,000 58,600,000 79,000,000 Construction 6,630,000 11,720,000 15,800,000 EMC 4,972,500 8,790,000 11,850,000 Other investment costs 6,000,000 7,000,000 8,000,000 Specific costs for construction, EMC + others t Personnel costs yr -1 1,700,000 1,800,000 2,000,000 Specific personnel costs t Rated overall costs t Estimated overall costs t

149 State of the Art / Waste Incineration Estimation of Costs 145 Table 74: Whole plant - option 3: Costs of a grate firing system with delivery by train, dry, wet and catalytic flue gas treatment with cogeneration (CHP) as a function of throughput Parameter Costs for discharge and storage using refuse collection vehicles Additional costs for discharge and storage using the train Unit Throughput 100,000 t yr ,000 t yr ,000 t yr -1 t t Firing system and boiler t Water steam cycle (option 4) t Dry flue gas cleaning t Gypsum scrubber t Catalytic flue gas cleaning t Investment costs of systems engineering 34,150,000 60,600,000 81,000,000 Construction 6,830,000 12,120,000 16,200,000 EMC 5,122,500 9,090,000 12,150,000 Other investment costs 6,000,000 7,000,000 8,000,000 Specific costs for construction, EMC + others t Personnel costs yr -1 1,700,000 1,800,000 2,000,000 Specific personnel costs t Rated overall costs t Estimated overall costs t

150 146 State of the Art / Waste Incineration Estimation of Costs Table 75: Whole plant - option 4: Costs of a grate firing system with delivery by train, electrostatic precipitator, NaOH scrubber, flow injection adsorber and catalytic plant with power generation as a function of throughput Parameter Costs for discharge and storage using refuse collection vehicles Additional costs for discharge and storage using the train Unit Throughput 100,000 t yr ,000 t yr ,000 t yr -1 t t Firing system and boiler t Water steam cycle (option 2) t Electrostatic precipitator t NaOH scrubber t Flow injection adsorber t Catalytic flue gas cleaning t Investment costs systems of engineering 37,250,000 59,400,000 80,200,000 Construction 7,450,000 11,800,000 16,040,000 EMC 5,587,500 8,910,000 12,030,000 Other investment costs 6,000,000 7,000,000 8,000,000 Specific costs for construction, EMC + others t Personnel costs yr -1 1,700,000 1,800,000 2,000,000 Specific personnel costs t Rated overall costs t Estimated overall costs t

151 State of the Art / Waste Incineration Estimation of Costs 147 Table 76: Whole plant - option 5: Costs of a grate firing system with delivery by train, electrostatic precipitator, precipitation, activated coke adsorber and catalytic plant with power generation as a function of throughput Parameter Costs for discharge and storage using refuse collection vehicles Additional costs for discharge and storage using the train Unit Throughput 100,000 t yr ,000 t yr ,000 t yr -1 t t Firing system and boiler t Water steam cycle (option 2) t Electrostatic precipitator t Scrubber with precipitation t Activated coke adsorber t Catalytic flue gas cleaning t Investment costs of systems engineering 40,500,000 65,300,000 88,200,000 Construction 8,100,000 13,060,000 17,640,000 EMC 6,075,000 9,795,000 13,230,000 Other investment costs 6,000,000 7,000,000 8,000,000 Specific costs for construction, EMC + others t Personnel costs yr -1 1,700,000 1,800,000 2,000,000 Specific personnel costs t Rated overall costs t Estimated overall costs t

152 148 State of the Art / Waste Incineration Estimation of Costs Table 77: Whole plant - option 6: Costs of a grate firing system with delivery by train, dry adsorption, activated coke adsorber and catalytic plant with power generation as a function of throughput Parameter Costs for discharge and storage using refuse collection vehicles Additional costs for discharge and storage using the train Unit Throughput 100,000 t yr ,000 t yr ,000 t yr -1 t t Firing system and boiler t Water steam cycle (option 2) t Dry adsorption t Activated coke adsorber t Catalytic flue gas cleaning t Investment costs of systems engineering 38,475,000 61,250,000 83,000,000 Construction 7,695,000 12,250,000 16,600,000 EMC 5,771,000 9,187,500 12,450,000 Other investment costs 6,000,000 7,000,000 8,000,000 Specific costs for construction, EMSR + others t Personnel costs yr -1 1,700,000 1,800,000 2,000,000 Specific personnel costs t Rated overall costs t Estimated overall costs t Costs of fluidised bed combustion In Austria fluidised bed reactors for combustion of waste are exclusively charged with crushed and grinded wastes. The calorific value of these wastes as well as their ash content vary in wide ranges. However the specific costs for combustion strongly depend on these two parameters. In order to obtain reproducible figures the following assumptions were made: Ash content of the waste: 10 % Calorific value of the waste: 15 MJ/kg These parameters roughly correspond to those of sorted fractions from waste. For a comparison with the specific costs of combustion of unsorted waste on a grate firing system, plants with the same rated thermal input were investigated. In case of fluidised bed combustion estimations were based on a stationary fluidised bed reactor with a capacity of 70,000 t yr -1 and a circulating fluidised bed with a capacity of 200,000 t yr -1 in one line each using the waste parameters above. These data correspond to grate firing systems with a capacity of 100,000 t yr -1 and 300,000 t yr -1 (calorific value of waste: 10 MJ/kg). However, in the latter case two combustion lines were assumed. Plants with a yearly capacity of 300,000 t per line are only offered by a few plant constructors.

153 State of the Art / Waste Incineration Estimation of Costs 149 As to the energy utilisation option 2 was the basis for both firing systems. Costs for flue gas treatment will be the same for both systems, if the same emission limit values have to be obtained. On the basis of certain assumptions and a capacity of 70,000 t yr -1 treated waste (fluidised bed) respectively 100,000 t yr -1 untreated waste (grate firing) approximately the same specific treatment costs will arise based on the rated thermal input. Based on the mass throughput incineration costs of fluidised bed combustion systems are noticeably higher than those of a grate firing systems (Table 80). In case of large plants with a throughput of 200,000 t yr -1 treated waste (for fluidised bed combustion) resp. 300,000 t yr -1 untreated waste (for grate firing) specific costs related to the rated thermal input will be more favourable if fluidised bed combustion is applied. It can be expected that in future even bigger units of fluidised bed firings can be built. That means that the fluidised bed technology represents a cost-efficient alternative for wastes with high calorific value. However, if waste has first to be separated into low and high calorific fractions and subsequently crushed and grinded, separation and subsequent combustion in a fluidised bed reactor will be uneconomic in comparison to a grate firing system. Table 78: Costs for the firing system and the boiler of waste incineration plants with fluidised bed combustion as a function of throughput Parameter Throughput 70,000 t yr ,000 t yr -1 Investment costs [ ] about 10 Mio. about 23 Mio. Specific investment costs [ t -1 ] Yearly maintenance costs as share of investment costs [% yr -1 ] 3 3 Specific maintenance costs [ t -1 ] Average overall consumption of electricity (normal operation) [kwh t -1 ] Costs of electricity [ t -1 ] Amount of slag and boiler ash [kg t -1 ] Disposal costs of slag and boiler ash [ t -1 ] 6 6 Specific costs of firing and boiler [ t -1 ]

154 150 State of the Art / Waste Incineration Estimation of Costs Costs of a steam cycle: steam extraction turbine applying steam parameters of 50 bar and 400 C (corresponding to option 2 and a grate firing system) In addition to the presumptions made in option 2 for grate firing systems the higher calorific value is considered. Table 79: Specific costs of a water-steam cycle comprising a steam extraction turbine (normal steam parameters) as a function of waste throughput Parameter Throughput 70,000 t yr ,000 t yr -1 Investment costs [ ] about 8 Mio. about 16 Mio. Specific investment costs [ t -1 ] Specific maintenance costs [ t -1 ] Delivery of heat [MWh t -1 ] 0 0 Delivery of electricity [MWh t -1 ] Specific proceeds from electricity production [ t -1 ] Rated proceeds from water-steam [ t -1 ] Comparison of costs of grate and fluidised bed systems with the same thermal output Table 80: Specific costs and proceeds of waste treatment, firing, boiler and energy utilisation Parameter Unit Throughput [t yr -1 ] 70, , , ,000 Grate firing system t Fluidised bed without waste crushing and grinding GJ t GJ Fluidised bed with waste t crushing and grinding 1 1 For crushing and grinding of waste an expense of 20 t -1 was assumed.

155 State of the Art / Waste Incineration State of the Art STATE OF THE ART In this chapter state of the art for end of pipe techniques such as flue gas cleaning and waste water treatment are summarised. These techniques can be generally implemented in new and existing waste incineration plants of every size from a technical point of view. However specific investment and operating costs will be lower for large plants (see chapter 9). Achieved emission levels associated with these techniques do not depend on the firing system or on the kind or composition of waste being incinerated but only on the construction, layout and way of operation of single units. In addition to end of pipe techniques generall measures are given in keywords only, whereby a more detailled description can be found within the respective chapters Location of the waste incineration plant The choice of the plants location should be determined amongst others by the following factors:! Geographic proximity to the site where waste for incineration accumulates! Possibility for waste delivery by train! Secured utilisation of decoupled steam and/or residual heat of the flue gases (use as district heat or as process heat)! Neighborhood to a river with a high water throughput to decrease impacts by discharge of thermal loads! Minimisation of the thermal load released to rivers by efficient use of energy! Meteorological situation and background pollution of the site 10.2 Emissions into the air As an introduction some keywords about the general interaction between pollutants and flue gas cleaning systems are given:! Sour components, such as SO 2, HCl, and HF are reduced either by wet systems or by dry systems. In general effective removal of one pollutant leads to separation of the other components.! In the first stage of wet scrubbers also mercury ions are removed.! Effective reduction of dust and fine particles leads to a decrease of the emissions of nonvolatile heavy metals and particle bound dioxines.! In the catalyst NO x is reduced to nitrogen, whereas gaseous dioxines are oxidised to CO 2 and H 2 O.! In an activated coke filter combined adsorption and oxidation of sour components, Hg, PCDD/F and NO x takes place.

156 152 State of the Art / Waste Incineration State of the Art Monitoring Continuous emission measurement of the following pollutants in the stack is state of the art: dust, SO 2, NO x (NO and NO 2 ), HCl, HF, CO, CO 2, TOC (total organic carbon) and Hg. If HCl is controlled by means of efficient flue gas cleaning devices, HF can be measured discontinuously. Continuous measurement of the following operating parameters at representative positions within the flue gas channel is state of the art: oxygen content, temperature within the combustion chamber, temperature of the flue gas, water content of the flue gas, pressure and volume of the flue gas. Emissions of the pollutants N 2 O, NH 3 can be measured continuously. Dioxines and furanes can be monitored quasi-continuously over a period of 8 hours up to 14 days. Heavy metals (with the exception of Hg) are measured discontinuously. Emissions measured continuously should be given as half hourly mean values. Emissions measured discontinuously should be given as concentration with respect to the analysis time. To enable optimum operation of the firing and the flue gas cleaning system, additional measurements of certain parameters and pollutant concentrations at various sites within the flue gas ducts are necessary. These are, amongst others, temperature, oxygen content, CO content, NH 3 and NO x content. Emissions have to be given in the following three ways:! As mass concentration in milligram per cubicmetre (mg/m 3 ) or nanogram per cubicmetre (ng/m 3 ) referred to standard conditions (0 C, 1013 mbar; dry conditions) and to a given oxygen content (11 % for waste incineration).! As mass flows in kilogram per hour (kg/h), gram per hour (g/h) or milligram per hour (mg/h).! As specific emissions in kilogram, gram or milligram per ton of incinerated waste (kg/t; g/t or mg/t). State of the art entails the erection of air quality measuring stations for the automatic recording of concentrations of SO 2, dust, ozone, nitrogen oxide as well as meteorological data and operating parameters of the waste incineration plant Emissions of air pollutants In the following text emissions of pollutants are presented unless otherwise stated as half hourly mean values (hmv) referred to standard conditions (0 C, 1013 mbar, dry) and an oxygen content of the flue gas of 11 %. Dust Dust emissions are reduced by means of electrostatic precipitators (ESP) in combination with subsequent wet scrubbers, subsequent fixed bed adsorbers or subsequent flowinjection processes. Flow-injection adsorbers are in every case connected to a bag filter. In one Austrian waste incineration plant cyclones are used for pre-separation of particles with a diameter > 100 µm, whereas fine dust is removed by the flow-injection process. With an ESP a reduction rate of 99,9 % can be achieved, with a wet scrubber > 80 % of the remaining dust are separated from the flue gas.

157 State of the Art / Waste Incineration State of the Art 153 With those combined systems dust and ultra-fine particles can be effectively removed from the flue gas. Coming from a raw gas concentration of maximum mg/nm 3 emission values of < 0,1 2 mg/nm 3 are achievable, which corresponds to a reduction rate of > 99,96 %. Example plants: Wels: maximum half hour mean value during two week operation ( ): 1,2 mg/nm 3 ; most of the other waste incineration plants in Austria achieve these values during normal operation. SO 2 SO 2 is removed from the flue gas by means of wet scrubbers. In some cases (fluidised bed systems) also dry-systems (flow-injection process) are used in addition to the scrubbers. In some plants traces of SO 2 are adsorbed in an activated coke filter. In wet scrubbers reduction rates of 96 98,4 % are achievable (data from four plants in Austria). With a raw gas concentration of maximum 600 mg/nm 3, a clean gas concentration of < 10 mg/nm 3 is achievable. At higher raw gas concentrations, emission values < 50 mg/nm 3 can be attained. Example plant: Wels: maximum half hour mean value during two week operation ( ): 3 mg/nm 3 ; most of the other waste incineration plants in Austria achieve these values during normal operation. NO x NO x emission are reduced by SCR in five (out of seven) described waste incineration plants. Efficiencies of SCRs in Austrian waste incineration plants are between %. Maximum raw gas concentration was reported to be in the range of 500 mg/nm 3. On the basis of these data an emission value < 50 mg/nm 3 is achievable in general. Example plant: Spittelau, Flötzersteig, Lenzing NH 3 With a well designed and operated SCR-unit an emission value < 5 mg/nm 3 can be attained. Example plants: All Austrian waste incineration plants equipped with SCR. HCl HCl is almost completely absorbed in the liquid phase of the wet scrubber (reduction rate: > 99,9 %). It is also removed by dry processes (flow injection process). With a raw gas concentration of mg/nm 3, emission values < 1 are achievable. At higher raw gas concentrations (up to mg/nm 3 ) emissions can be reduced to < 5 mg/nm 3. Example plants: Wels: HCl was not detectable in the clean gas of the waste iincineration plant in the period from Most of the other waste incineration plants in Austria achieve these values during normal operation.

158 154 State of the Art / Waste Incineration State of the Art HF HF emissions are corresponding to the emissions of HCl. They are reduced by wet scrubbers and by dry processes. Raw gas concentration after a waste incineration plant is about 3 mg/nm 3, reduction rate of a wet scrubber is in the range of 99,3 %. Achievable emission values are < 0,03 mg/nm 3. Example plants: Wels: HF was not detectable in the clean gas of the waste incineration plant in the period from The plants Spittelau and AVE Reststoffverwertung Lenzing emit less than 0,03 mg/nm 3 during normal operation. CO CO is not a pollutant per se, but a benchmark for the quality of the combustion. Emissions depend to some extent on the firing technolgy. Emissions lower than 30 mg/nm 3 can be attained in general (Wels in the period ). Unburnt hydrocarbons Emissions of unburnt hydrocarbons strongly depend on the quality of combustion. In general values < 2 mg/nm 3 can be attained (Wels in the period ; most other waste incineration plants in Austria during normal operation). Hg Mercury is removed in the first stage of the wet scrubber, sometimes in combination with an activated coke filteror with the flow-injection process. Achievable levels with a wet scrubber and an activated coke filter are < 0,002 mg/nm 3. A combination of the flow injection process and a wet scrubber leads to emission values of 0,004 mg/nm 3, whereas a wet scrubbing system alone reduces Hg emissions to 0,036 mg/nm 3. Example plants: Wels: 0,0009 < 0,002 (lower value is a mean value from 6 single measurements); rotary kilns of the plant Simmeringer Haide: 0, < 0,002 (12 single measurements); fluidised bed systems of the plant Simmeringer Haide: 0, < 0,002 (12 single measurements). Cd Removal of Cd strongly correlates with the separation of dust and fine particles. Achievable levels are from 0,0003-0,013 mg/nm 3 (referred to a period of 0,5 to 6 hours; attained by all described waste incineration plants).

159 State of the Art / Waste Incineration State of the Art 155 Heavy metals Heavy metals are separated together with dust by means of ESP, bag filters, wet scrubbers, or by an activated coke filter.! Pb, Cr, Zn For incineration of domestic waste, values from < 0,006 - < 0,1 mg/nm 3 are achievable (referred to a period of 0,5 to 6 hours). The lower value is reached with a combination of ESP, wet scrubber and activated coke filter. Other waste incineration plants can achieve values < 0,15 mg/nm 3.! As, Co, Ni Achievable levels are < 0,003 0,11 mg/nm 3. The higher concentrations are emitted by the rotary kilns of the plant Simmeringer Haide. PCDD/F Dioxines and furanes are oxidised by the catalyst (only gaseous dioxines and furanes) or adsorpted by an activated coke filter (both gaseous and particle bound dioxines and furanes) or in the flow-injection process. An efficient preseparation of dust is essential to achieve low emission values. In general achievable values are < 0,05 ng/nm 3, with an activated coke filter levels of 0, ,009 ng/nm 3 can be attained Emissions into the water State of the art is cleaning of the waste water (such as waste water from wet flue gas cleaning, from wet deslagging or form boiler feedwater preparation) in a multistaged waste water treatment plant (WWTP). If precipitation of salts is unlikely all partial flows can be combined and treated together. The first cleaning step, the heavy metal precipitation, normally includes processes such as precipitation, flocculation, sedimentation, neutralisation and sludge dewatering. The second cleaning step mostly comprises a sand filter, an activated coke filter and an ion exchanger. Chemicals that are necessary for waste water treatment are stored and prepared in a chemical station. As a rule sludges accumulating at the particular processes are collected in a sludge tank and are in most cases dewatered in chamber filter presses to a moisture content of about 50 %. The remaining filter cake has to be disposed of as hazardous waste. Waste water from flue gas cleaning The following measures are state of the art: Separation of solid particles from the flue gas before it enters the wet systems for flue gas cleaning. Recycling of (partially) cleaned waste water or of low polluted waste water from other processes (e.g. as feed for the first scrubber).! Separation of solid particles from the flue gas before it enters the wet systems for flue gas cleaning.! Recycling of (partially) cleaned waste water or of low polluted waste water from other processes (e.g. as feed for the first scrubber).

160 156 State of the Art / Waste Incineration State of the Art! Recycling of used chemicals (e.g. NaOH for the second scrubber) as far as possible! Not using ground water or drink water as input water whenever possible.! Use of physical, physical and chemical or chemical waste water treatment systems for neutralisation, for stripping of ammonia, for precipitation of heavy metals, gypsum and fluorid and for solid particle removal.! Separated disposal of waste from waste water treatment Monitoring The parameters flow, ph, electrical conductivity and temperature should be measured continuously. The pollutants chlorides, fluorides, mercury and TOC should be controlled daily, whereas all other parameters should be measured weekly. All parameters and pollutant concentrations which are not continuously monitored should be measured in a flow proportional representative sample of the discharge over a maximum period of 24 hours Emissions of water pollutants With a well designed and operated waste water treatment plant the following emission levels can be attained: Table 81: Emissions of pollutants into water from Austrian Waste Incineration Plants Parameter Emission Temperature [ C] < 30 Electric conductivity < 25 ms Fish toxicity 2 ph [-] Undissolved compounds 10 < 25 Settleable solids < 0.3 ml l -1 Filterable substances 7 20 Residue on evaporation 1.4 g l -1 Salt content [g l -1 ] 35 Al 0.12 As < < 0.05 Ba 0.19 Ca [g l -1 ] < 5 Cd < < 0.05 Co < 0,05 Chlorides [g l -1 ] 7 < 20 Cyanides < < 0.1 Cr < 0.05 < 0.1 Cr (VI) < 0,05 Cu < 0.05 < 0.3 Fluorides < < 10

161 State of the Art / Waste Incineration State of the Art 157 Parameter Emission Hg < < 0.01 Mn < 0,05 NH 4 N < 8 Nitrate (NO 3 ) < 5 Nitrite (NO 2 ) < 8 Ni < 0.05 < 0.5 P < 0.05 Pb < 0.01 < 0.1 Sn 0.06 Sulphate (SO 4 ) < 1,200 Sulphides < 0.01 < 0.1 Sulphites < 1.0 < 8 Zn < 0.05 < 0.5 AOX / EOX 1.02 / < 0.1 BTXE < COD < 75 Total Hydrocarbon 0.05 < 3 Phenol < 0.01 < 0.1 TOC Tensides < 0,02 Volatile chlorinated hydro carbons < 0.1 Saponifiable fats and oils < 4 Sb 0.05 < 0.1 Tl < V 0.01 < 0.05 Chlorine (free) < 0.05 Chlorine total < 0.05 Non volatile lipophilic components < Accumulation of waste By incineration wastes are reduced to one third of the original weight and to one tenth of the original volume. Besides that waste incineration should also aim at the complete destruction of organic compounds and at the concentration of pollutants in small volumes of waste. The following measures are considered state of the art:! Separation of metallic scrap from slag and ash from fluidised bed combustion.! Concentration of mercury salts in the filter cake of the waste water treatment plant followed by underground disposal of the filter cake.! Incineration of loaded activated coke under conditions sufficient for complete destruction.

162 158 State of the Art / Waste Incineration State of the Art! Posttreatment of slag and fly ash (e.g. washing, wet-chemical process) to reduce the heavy metal content. Polluted waste water is treated in the WWTP, accumulated filter cake is disposed of underground.! Fly ash, slag and bed ash from fluidised bed combustion is classified as hazardous waste which has to be disposed of underground. However, if pollutant concentration is low these waste fractions can be exempted. When solidification is applied, long term stability of the solid waste have to be proven. Landfill sites chosen for final disposal of solidified waste fractions should be designed and operated according to the state of the art Utilisation of energy The energy content of the waste (and of cofired conventional fuels) should be converted into electricity and/or heat with the highest possible efficiency. The form of produced energy should be adjusted to the existing demands. When heat is produced, care should be taken, that demand for heat exists throughout the year. State of the art for energy utilisation is summarised below:! If the energy of the flue gas is fully converted into heat a theoretical overall efficiency up to 80 % can be achieved.! As to pure electricity production the overall efficiency (= net electrical efficiency) applying normal steam parameters can be about 20 %. Under particular circumstances the proportion of recovered energy can be increased:! In case of increased steam parameters and pure power generation an overall efficiency (= net electrical efficiency) up to 30 % can be achieved.! If steam is fed into the steam cylce of a neighbouring coal power plant the electric net efficiency shall be increased to 35 % General State of the art! Acceptance and control provisions of incoming waste: A basic requirement for an environmental safe waste incineration process which includes acceptance, storage, handling, good combustion and minimisation of emissions - is the exact knowledge of the origin, of the physical and chemical characteristics and of the hazardous potential of the waste. Physically and chemically parameters and other properties of wastes can be checked in accordance with national or international standards (e.g. ÖNORMEN S 2110 and S 2111). Especially when waste is delivered to an incineration plant the first time the following parameters should be checked: Name and adress of the deliverer, origin of the waste, volume, water and ash content, calorific value, concentration of chlorides, fluorides, sulfur and heavy metals. For repeated delivery of waste exemptions can be granted with respect to frequency and extent of controls. However to enable good combustion conditions, the parameters volume, water and ash content, calorific value and concentration of chlorides should be known in every case.

163 State of the Art / Waste Incineration State of the Art Domestic waste should be weighed before dumping into the bunker - Hazardous wastes should be visually examined to verify the accordance with accompanying documents. Chemical and physical parameters should be determined according to existing standards (e.g. ÖNORM S2110 (1991)). - Other waste fractions should be visually examined before acceptance and periodically controlled. - Sewage sludge should be dewatered as far as possible. Waste water should be treated in a WWTP.! Storage and handling of waste Storage facilities should be kept as small as possible by logistically measures. Different waste fractions should be separately stored. Emissions of odour and dust of storage and dumping devices should be prevented e.g. by sucking off fresh air needed for combustion from the waste bunker or by installation of fabric filters or activated coke filters. Storage facilities should be sealed to prevent leakage of pollutants into groundwater, arising waste water should be treated in a WWTP.! Use of natural gas or light heating oil as auxiliary fuels! Sufficient residence time of the flue gases at high temperature (e.g. at least two seconds at a temperature level of 850 C or C when the content of halogenated organic compounds of the waste exceeds 1 %) have to be guaranteed if necessary by installation of afterburners.! Domestic waste incineration (grate firing systems): - Sufficient capacity of storage bunkers (at least four days) - Bunker crane system with at least two cranes - Possibilities for waste mixing inside the bunker - Minimisation of storage time of domestic waste (five days maximum) - Prevention of introduction of false air into the combustion chamber: the airside seals should be the waste pillar or shutters and the wet deslagging unit. - Controlled waste feed, grate movement and combustion air supply to enable complete combustion! Fluidised bed combustion: - Classification and pulverization of waste before combustion - Uniform waste introduction and good mixing of the waste

164 160 State of the Art / Waste Incineration National and European Legislation 11 NATIONAL AND EUROPEAN LEGISLATION 11.1 Emissions to air A number of pollutants are emitted into air from waste incineration plants, the level and extend of emission depend on the many factors, such as storage and handling conditions, quality of combustion and flue gas cleaning. Table 82 presents a non comprehensive list of air pollutants, which may be emitted by waste incineration plants. Table 82: Non comprehensive list of air pollutants which may be emitted to air by waste incineration plants CO 2 NO x N 2 O Pollutant SO 2, dust (including PM 10 ) CO, NMVOC, CH 4 HCl, HF As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, Sb, others PCDD/F PAH (6 or 16 single substances, inclusively BaP) NH 3 POPs (PCB, TRI, PER, TCE) Reason for emission, Emission source Combustion: C-content of the waste and of auxiliary fuels Combustion: Thermal and fuel nitrogen Low combustion temperature; SCR; SNCR Combustion: S- and ash-content of the waste Uncomplete combustion (low excess air, low combustion temperature), inadequate mixing of the flue gas Combustion: halogen content of the waste Heavy metal content of the waste Combustion conditions; content of precursors of the waste Low combustion temperature, inadequate mixing of the flue gas Flue gas cleaning: ammonia slip Combustion: chlorinated compounds in the waste National regulations With the Steam Boiler Emission Act of 1980 legislative regulation for limitation of emissions to the atmospere came into effect in Austria. This law was superseded by the Clean Air Act for Steam Boilers in 1988 (LRG-K, Fed. Law Gaz. No. 380/1988 as amended by Fed. Law Gaz. No. I 158/1998) and by the Clean Air Ordinance for Steam Boiler Units (LRV-K, Fed. Law Gaz. No. 19/1989 as amended by Fed. Law Gaz. No. II 342/1997). Amongst basic requirements the Clean Air Act for Steam Boiler Units prescribes emission limit values for stationary steam boiler units in annex 1 (such as large combustion plants, domestic waste incineration plants, recovery boilers from the pulp and paper industry) that were commissioned before the 1 st of January 1989 (old plants). Legal basis for plants commissioned or licensed after the 1 st of January 1989 is the Clean Air Ordinance for Steam Boiler Units (new plants). Emission limit values for domestic waste incineration plants are given as half hourly average values and are referred to standard conditions (0 C; 1,013 mbar; dry conditions) and 11 vol% O 2 in the exhaust air. They are listed in Table 83.

165 State of the Art / Waste Incineration National and European Legislation 161 For incineration of hazardous wastes two ordinances were put into force:! Ordinance of the Federal Ministry of Environment, Youth and Family Affairs on incineration of hazardous waste (Fed. Law Gaz. II No. 22/1999)! Ordinance of the Federal Ministry of Economic Affairs on incineration of hazardous waste in industrial plants (Fed. Law Gaz. II No. 32/1999) On 28 th of December 2000 the European Directive on the Incineration of Waste (2000/76/EC) came into force. This directive replaces - although transition periods are foreseen - every existing European legislation concerning incineration of waste. Therefore a revision of existing national legislation became necessary. Table 83 also presents emission limit values of the Austrian Waste Incineration Collective Ordinance which will come into force on 1 st of November This ordinance will transpose general and specific requirements of the European Directive on the Incineration of Waste (2000/76/EC) into national law. It is based on existing national regulations concerning waste, trade and air and should harmonise legal regulations with respect to incineration and coincineration of hazardous and non-hazardous waste (including waste oil) within different plants (such as cement kilns, large combustion plants) and should reflect state of the art for thermal treatment of waste. Besides that it should enable Austria to fulfill requirements given in the European Emission Ceiling Directive (2000/81/EC) and to meet limits for ambient air quality European Directive on the Incineration of Waste (2000/76/EC) The European Directive on the Incineration of Waste (2000/76/EC) lays down limit values for emissions of pollutants into air (compare Table 83) and for the discharge of waste water from flue gas cleaning (chapter ).

166

167 State of the Art / Waste Incineration National and European Legislation 163 Table 83: Emission limit values as prescribed in the Austrian Clean Air Ordinance for Steam Boilers and the Draft of the Austrian Waste Incineration Ordinance as well as the EU Directive on the Incineration of waste Pollutant Small plants a Clean Air Ordinance for Steam Boilers [mg m -3 ] Medium plants b Large plants c EU Directive on the Incineration of waste [mg m -3 ] Daily average Half hourly average value o Average values Daily average value n A (100%) g B 97% g value Austrian Waste Incineration Collective Ordinance [mg m -3 ] Half hourly average value Average value Dust HCl HF SO CO p, q p, q NO d,e 400 e,f 400 d,e 200 d,e m 200/150/70/100 l 300/200/100 Σ Pb,Cr,Zn + compounds Σ As,Co,Ni + compounds Heavy metals Σ Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V: 0,5 h /1 h,i Cd + compounds Hg + compounds Σ Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V, Sn: 0.5 h Cd, Tl: 0.05 h /0.1 h,i Cd, Tl: 0.05 h h /0.1 h,i PCDD+PCFF 0.1 ng m ng m ng m ng m -3 k 0.1 ng m -3 k C org NH 3 5 h a Small plants: On average the mass flow rate of incinerated waste is below 750 kg h -1 b Medium plants: On average the mass flow rate of incinerated waste is between 750 and 15,000 kg h -1 c Large plants: On average the mass flow rate of incinerated waste is higher than 15,000 kg h -1 d For existing waste incineration plants with a nominal capacity exceeding 6 tonnes per hour or new incineration plants e Until the 1 st of January 2007 and without prejudice to relevant (Community) legislation the emission limit value does not apply to plants only incinerating hazardous waste f For existing incineration plants with a nominal capacity of 6 tonnes per hour or less

168 164 State of the Art / Waste Incineration National and European Legislation g Either non of the half hourly average values exceeds any of the emission limit values of column A, or, where relevant, 97 % of the half hourly average values over the year do not exceed any of the emission limit values column B h Average values over the sample period of a minimum of 30 minutes and a maximum of 8 hours i Until the 1 st of January 2007 average values for existing plants for which the permit to operate has been granted before the 31 st of December 1996 and which incinerate hazardous waste only k Sample period of a minimum of 6 hours and a maximum of 8 hours. The limit value refers to the total concentration of dioxins and furans calculated using the concept of toxic equivalence l for a nominal capacity up to 2 t waste h -1 : 300 mg m -3 ; for a nominal capacity between 2 and 6 t waste h -1: 200 mg m -3 ; for a nominal capacity of more than 6 t waste h -1 : 100 mg m -3 ; m for a nominal capacity up to 2 t waste h -1 : 200 mg m -3 ; for a nominal capacity between 2 and 6 t waste h -1: 150 mg m -3 ; for a nominal capacity of more than 6 t waste h -1 : 100 mg m -3 (existing plants) and 70 mg m -3 (new plants) n Exemptions for NOx may be authorised by the competent authority for existing incineration plants: - with a nominal capacity of 6 tonnes per hour, provided that the permit foresees the daily average values do not exceed 500 mg m -3 and this until 1 January 2008, - with a nominal capacity of > 6 tonnes per hour but equal or less than 16 tonnes per hour, provided the permit foresees the daily average values do not exceed 400 mg m -3 and this until 1 January 2010, - with a nominal capacity of > 16 tonnes per hour but < 25 tonnes per hour and which do not produce water discharges, provided that the permit foresees the daily average values do not exceed 400 mg m -3 and this until 1 January Until 1 January 2008, exemptions for dust may be authorised by the competent authority for existing incinerating plants, provided that the permit foresees the daily average values do not exceed 20 mg m -3. o Until 1 January 2010, exemptions for NOx may be authorised by the competent authority for existing incineration plants with a nominal capacity between 6 and 16 tonnes per hour, provided the half-hourly average value does not exceed 600 mg m -3 for column A or 400 mg m -3 for column B. p 150 mg m -3 of combustion gas of at least 95 % of all measurements determined as 10-minute average values or 100 mg m -3 of combustion gas of all measurements determined as half-hourly average values taken in any 24-hour period. q Exemptions may be authorised by the competent authority for incineration plants using fluidised bed technology, provided that the permit foresees an emission limit value for carbon monoxide (CO) of not more than 100 mg m -3 as an hourly average value.

169 State of the Art / Waste Incineration National and European Legislation Emissions to air from Austrian waste incineration plants Emission limit values prescribed in the permits of existing waste incineration plants are given in Table 84. Limit values given in the permit are fixed during the licensing process of a plant. Considering local circumstances such as poor ambient air quality or areas with high background pollution of soil and water stricter limit values than in the Austrian law are often prescribed in the permit. This is especially true for new waste incineration plants, which have been already licensed or which are currently under construction (Table 85). Table 84: Emission limit values prescribed in the permits of existing waste incineration plants Parameter Spittelau Wels Simmeringer Haide (Fluidised Bed) Lenzing Flötzersteig Arnoldstein Simmeringer Haide (Rotary Kiln) Dust HCl HF SO CO NO x as NO Pb 1.3 Zn Cr 1 b Σ Pb+Cr+Zn 4 Σ Pb+Zn: 4.0 Σ Sb,As,Co,Cu, Mn,V,Ni,Sn As 1 Co Ni b b b Σ As+Co+Ni Cd Cd, Tl: Hg Σ HC NH PCDD+PCFF 0.1 ng m -3 a 0.1 ng m ng m ng m ng m ng m -3 a Daily mean immission level of 20 fg m -3. Fulfilled if the daily mean emissions are below 0.4 ng m -3. b < 0.2 mg Nm -3 as three hourly average value c Concentration in the exhaust gas in mg m -3 ; dioxin emissions are given in ng m -3 (11 % O 2 ; dry flue gas; standard conditions; half hourly average values) d LV...Limit value according to the permit of the plant: Concentration in the exhaust gas in mg m -3 ; dioxin emissions are given in ng m -3 (11 % O 2 ; dry flue gas; standard conditions)

170 166 State of the Art / Waste Incineration National and European Legislation Table 85: Emission limit values given in the permits of plants under construction Parameter Zistersdorf 1 [mg Nm -3 ] Dürnrohr [mg Nm -3 ] Niklasdorf [mg Nm -3 ] Dust HCl HF SO CO NO Σ Pb, Zn, Cr Σ As, Co, Ni 0.3 ΣSb+As+Pb+Cr+Co+Cu+Mn+ Ni+V+Sn Cd + compounds Cd+Tl: 0.05 Hg + compounds Tl + compounds Zn + compounds 0.5 C org NH PAH 0.01 Bap PCB 0.1 ng Nm -3 PCDD + PCDF 0.1 ng Nm ng Nm ng Nm -3 1 Within the first year of operation some air pollutants have to be measured periodically: Heavy metals: monthly PCDD/PCDF: twice a year and 12 monthly average values PCB: twice a year PCBz: twice a year PCPh: twice a year PAH: twice a year

171 State of the Art / Waste Incineration National and European Legislation Emissions to water Table 86 shows a non-comprehensive list of pollutants, which may be emitted by waste incineration plants into water. Table 86: Non comprehensive list of pollutants emitted to water by waste incineration plants Emission to water As, Pb, Cd, Cr, Cu, Ni, Hg, Sn, Zn, N, Cl, CN, F, P, TOC, BTX, phenol DCE, DCM, Chloralkane, BTXE, PAH Emission source Scrubbing of flue gas from waste incineration National regulations I. Ordinance pertaining to the general limitation of waste water emissions to running waters or public sewage networks (Fed. Law Gaz. No. 186/1996) In the interests of this ordinance, the authorities shall, based on the origin as well as the definitive substances contained and properties thereof, decide upon which parameter should be used to monitor the quality of the waste water. The following types of waste water relevant for waste incineration plants are exempted from this ordinance and are treated separately: Waste water from the cleaning of combustion gases. Waste water from water conditioning. Waste water from cooling systems and steam production. The permissible limit values of this ordinance for the discharge of waste water are given in Table 87. II. Ordinance pertaining to the limitation of waste water emissions from the cleaning of combustion gas (Fed. Law Gaz. No. 886/1995) This ordinance prescribes which emission threshold limit values apply when the waste water from gas cleaning is to be licensed for discharge from power plants (either lignite-, coal- or oil-fired), from municipal waste incineration plants or from plants for incineration of liquid and solid waste to running waters or drainage systems. Waste water may only be discharged to running waters if there is no other possibility, in accordance with the rules, for recovery or disposal of the residues contained in the waste water. Discharge into the drainage system is only allowed when unavoidable. The permissible limit values of this ordinance for the discharge of waste water are given in Table 87. To attain the limit values the following measures may be applied: Use of fuels low in sulphur, chlorines and heavy metals. Disintegration and homogenisation of fuels. Recycling of waste water to reduce the consumption of fresh water. The untreated water for wet flue gas cleaning can be waste water with low load from other areas (e.g. cooling water, water from wet slag removal,...) Not using ground water or drinking water as input water. Use of techniques, which produce valuable by-products (e.g. gypsum).

172 168 State of the Art / Waste Incineration National and European Legislation Removal of solid matter by dry techniques prior to wet scrubbing. Use of physical, chemical or physical and chemical waste water cleaning processes for neutralisation, stripping of ammonia, precipitation of heavy metals and for removal of solid matter and fluoride. Separation of waste water and waste resulting from waste water cleaning operations and disposal of the waste. III. Ordinance pertaining to the limitation of waste water emissions from water conditioning (Fed. Law Gaz. No. 892/1995) In the case of legal approval of a particular discharge of waste water from plants for water conditioning the authorities shall prescribe the threshold limit values set out in Table 87. The ordinance applies to waste water from cleaning, rinsing, regeneration or disinfection of facilities for the purpose of physical, chemical or combined physical and chemical conditioning of rain water, ground water or surface water up to a defined level of quality for drinking, bathing or water for industrial or domestic use. To attain the limit values the following measures may be applied: Minimising the salt load to be discharged by preferential use of membrane processes (e.g. micro-filtration, reverse osmosis, ). Separate recapture of the concentrate from ion-exchange processes or from reverse osmosis plants. Separate cleaning of concentrates or regenerates before discharge. Preferential use of treatment technologies which produce the least possible treatment residues or which produce residues which can be recycled or further exploited (e.g. iron slurries). Preferential use of non-toxic treatment chemicals which can be totally broken down by aerobic micro-organisms. The use of flocculents that have little or no mineral oil content. The use of treatment or regeneration chemicals with the lowest possible content of organic halogen compounds. Not using the following chemicals: 1. Ethylenediaminetetraacetate, their homologues or salts 2. Polycarbon amino acids, their homologues or salts 3. Organometallic compounds 4. Chromates 5. Nitrites 6. Organic polyelectrolytes (based on acrylamide, acrylonitrile, and others) with a monomer content higher than 0.1 % by mass. Use of mixing or buffer basins for the purpose of quantity and concentration compensation. Use of physical, physical and chemical or chemical (screening, sedimentation, filtration, flotation, precipitation/flocculation) or even, with direct pass, biological waste water cleaning processes. The use of physical or chemical processes for the conditioning and dewatering of solid residues from water treatment and waste water cleaning

173 State of the Art / Waste Incineration National and European Legislation 169 IV. Ordinance pertaining to the limitation of waste water emissions from cooling systems and steam production (Fed. Law Gaz. No. 1072/1994) The authorities shall prescribe the threshold limit values set out in the ordinance for the discharge of waste water from power plant cooling systems to running waters or drainage systems. Emission limit values are prescribed for the operation of once-through cooling systems, of circulating cooling systems (inclusive desalination and evacuation of the system) and of the following processes (Table 87): Desalination (flooding), clarification or condensate treatment Ash and slag removal Scouring Combustion gas end cleaning (including combustion gas ducts) Wet preservation To attain the limit values the following measures may be applied: Separated channelling of cooling and process water. Not using ground water or drinking water for continuous cooling systems. Only using continuous cooling when located near a source of running water with a high throughput. Protection against corrosion and sediments by constructive measures and not using chemical admixtures (not using chromates, nitrites, mercaptobenzthiazoles, imidazole compounds and zinc compounds as anti corrosive agents). Prevention of microbial growth using constructive measures (disconnecting clearance volumes, not using organic polymer materials with high monomer content). If use of biocides is necessary: the use of intermittent processes, not discharging the effluent during shock treatment, not continually using biocides with the exception of hydrogen peroxide, ozone or UV. Generally not using organo-mercury, organo-tin or other organometallic compounds, mainly not using quaternary ammonium compounds. Recycling of waste water to reduce the consumption of fresh water. Water discharged from the cooling cycle can be used for wet slag removal, flue gas cleaning or as moistening agent for ash accumulations. Comprehensive energetic exploitation of the waste heat from the waste water (district heating, power-heat coupling, low temperature heating,...). Preferential use of circulating cooling systems with optimised exchange rate for discharge water (less than 5 % of the daily circulated volume). When dispersion agents have to be used: Use of non-toxic substances with an overall aerobic biodegradability of 80 % within 14 days; generally not using ethylenediaminetetraacetate (EDTA) diethylenetriamine pentaacetic acid (DTPA), their homologues or their salts; largely not using other polycarbon amino acids, their homologues or salts. Dosage on a 'need only basis of all cooling water additives by mechanical dosing equipment and supported by analytical monitoring of the resulting concentrations in the cooling circuit.

174

175 State of the Art / Waste Incineration National and European Legislation 171 Table 87: Limit values for emissions into the hydrosphere Fed. Law Gaz. No. 186/1996 Running waters Drainage system Incineration of waste Running waters Incineration of waste except municipal waste Chloride content of waste <0.75 weight % Fed. Law Gaz. No. 886/1995 Chloride content of waste >0.75 weight % Incineration of waste Drainage system Incineration of waste except municipal waste Chloride content of waste <0.75 weight % Chloride content of waste >0.75 weight % Temperature 30 C 35 C 30 C 30 C 30 C 35 C 35 C 35 C Reheating range bacteria toxicity k Daphnia toxicity k Fish toxicity < 2 h - g, h g, h g, h f f f Algae toxicity k Interference of biodegradation - g Filterable substances 30 mg l -1 ; i 30 mg l mg l mg l mg l mg l mg l mg l -1 g Settling solids 0.3 ml l ml l -1 i ph-value Al 2 mg l -1 g Sb mg l mg l mg l mg l mg l mg l -1 Sb a mg t mg t -1 8 mg kg mg t mg t -1 8 mg t -1 As 0.1 mg l -1 0,1 mg l mg l mg l mg l mg l mg l mg l -1 As a mg t mg t -1 4 mg kg mg t mg t -1 4 mg kg -1 Ba 5 mg l -1 5 mg l Pb 0.5 mg l mg l mg l mg l mg l mg l mg l mg l -1 Pb a mg t mg t -1 4 mg kg mg t mg t -1 4 mg kg -1 Cd 0.1 mg l mg l mg l mg l mg l mg l mg l mg l -1 Cd a mg t mg t -1 2 mg kg mg t mg t -1 2 mg kg -1 Cr total as Cr 0.5 mg l mg l mg l mg l mg l mg l mg l mg l -1 Cr a total as Cr mg t mg t mg kg mg t mg t mg kg -1 Cr(VI) as Cr 0.1 mg l mg l Co 1.0 mg l mg l mg l mg l mg l mg l mg l mg l -1

176 172 State of the Art / Waste Incineration National and European Legislation Fed. Law Gaz. No. 186/1996 Running waters Drainage system Incineration of waste Running waters Incineration of waste except municipal waste Chloride content of waste <0.75 weight % Fed. Law Gaz. No. 886/1995 Chloride content of waste >0.75 weight % Incineration of waste Drainage system Incineration of waste except municipal waste Chloride content of waste <0.75 weight % Chloride content of waste >0.75 weight % Co a mg t mg t mg kg mg t mg t mg kg -1 Fe 2.0 mg l -1 g Cu 0.5 mg l mg l mg l mg l mg l mg l mg l mg l -1 Cu a mg t mg t mg kg mg t mg t mg kg -1 Mn 1.0 mg l mg l mg l mg l mg l mg l -1 Mn a mg t mg t mg kg mg t mg t mg kg -1 Ni 0.5 mg l mg l mg l mg l mg l mg l mg l mg l -1 Ni a mg t mg t mg kg mg t mg t mg kg -1 Hg 0.01 mg l mg l mg l mg l mg l mg l mg l mg l -1 Hg a mg t -1 3 mg t mg kg -1 3 mg t -1 3 mg t mg kg -1 Ag 0.1 mg l mg l -1 Zn 2.0 mg l mg l mg l mg l mg l mg l mg l mg l -1 Zn a mg t mg t mg kg mg t mg t mg kg -1 Sn 2.0 mg l mg l mg l mg l mg l mg l mg l mg l -1 Sn a mg t mg t mg kg mg t mg t mg kg -1 Tl 0.1 mg l mg l mg l mg l mg l mg l -1 Tl a mg t mg t -1 4 mg kg mg t mg t -1 4 mg kg -1 V 0.5 mg l mg l mg l mg l mg l mg l -1 V a mg t mg t mg kg mg t mg t mg kg -1 Cl free as Cl mg l mg l Cl total as Cl mg l mg l Ammonia as N 10 mg l -1 j 10 mg l mg l mg l mg l mg l mg l -1 Cyanide as CN b 0.1 mg l mg l mg l mg l Chloride as Cl g Fluoride as F 10 mg l mg l mg l mg l mg l mg l mg l mg l -1 N bounded as N j j j j j j Nitrate as N k k Nitrite as N 1.0 mg l mg l

177 State of the Art / Waste Incineration National and European Legislation 173 Fed. Law Gaz. No. 186/1996 Running waters Drainage system Incineration of waste Running waters Incineration of waste except municipal waste Chloride content of waste <0.75 weight % Fed. Law Gaz. No. 886/1995 Chloride content of waste >0.75 weight % Incineration of waste Drainage system Incineration of waste except municipal waste Chloride content of waste <0.75 weight % Chloride content of waste >0.75 weight % P total as P 2.0 mg l mg l mg l mg l -1 Sulphate as SO 4 k 200 mg l -1 2,500 mg l -1 2,500 mg l -1 2,500 mg l -1 j j j Sulphide as S 0.1 mg l mg l mg l mg l mg l mg l mg l mg l -1 Sulphide as S a mg t mg t -1 8 mg kg mg t mg t -1 8 mg kg -1 Sulphite as SO 3 1 mg l mg l mg l mg l mg l mg l mg l mg l -1 TOC as C 25 mg l mg l -1 ; 30 mg l -1 ; 30 mg l -1 ; mg l -1 g 50 mg l -1 g 50 mg l -1 g CSB as O 2 75 mg l mg l -1 ; 90 mg l -1 ; 90 mg l -1 ; mg l -1 g 150 mg l -1 g 150 mg l -1 g BSB 5 as O 2 20 mg l AOX as Cl 0.5 mg l mg l EOX as Cl mg l mg l mg l mg l mg l mg l -1 EOX as Cl a,g mg t mg t -1 4 mg kg mg t mg t -1 4 mg kg -1 Hardly volatile lipophilic 20 mg l mg l substances Σ HC 10 mg l mg l POX as Cl 0.1 mg l mg l Phenol index as phenol 0.1 mg l mg l mg l mg l mg l mg l mg l mg l -1 Surfactants total 1.0 mg l -1 i BTX 0.1 mg l mg l

178 174 State of the Art / Waste Incineration National and European Legislation Fed. Law Gaz. No. 892/1995 Running waters Sewage system Flow pass cooling system Fed. Law Gaz. No. 1072/1994 e Running waters Sewage system Running waters Sewage system Running waters Sewage system Temperature 30 C 35 C 30 C 35 C 30 C 35 C 30 C 35 C Reheating range K Bacteria toxicity f 12 f - - Daphnia toxicity Fish toxicity 2 h f < 2 h f < 2 g f < 2 g f Algae toxicity Interference of biodegradation Filterable substances 30 mg l -1 g 150 mg l -1 g i 30 mg l -1 i 50 mg l -1 I g Settling solids ph-value Al 2 mg l -1 g Sb As 0.1 mg l mg l Ba Pb 0.5.mg l mg l mg l mg l -1 Cd 0.1 mg l mg l mg l mg l -1 Cr total as Cr mg l mg l mg l mg l -1 Cr(VI) as Cr Co Fe 2.0 mg l -1 g mg l -1 g Cu 0.5 mg l mg l mg l mg l mg l mg l -1 Mn 1.0 mg l -1 g Ni mg l mg l -1 Hg 0.01 mg l mg l Ag Zn 2.0 mg l mg l mg l mg l mg l mg l -1 Sn c d

179 State of the Art / Waste Incineration National and European Legislation 175 Fed. Law Gaz. No. 892/1995 Running waters Sewage system Flow pass cooling system Fed. Law Gaz. No. 1072/1994 e Running waters Sewage system Running waters Sewage system Running waters Sewage system Tl V mg l mg l -1 Cl free as Cl mg l mg l mg l -1 g 0.2 mg l -1 g 0.3 mg l mg l mg l mg l -1 Cl total as Cl Ammonia as N mg l -1 g - Cyanide as CN b Chloride as Cl g Fluoride as F N bounded as N 20 mg l -1 g Nitrate as N Nitrite as N mg l mg l mg l P total as P 2.0 mg l g mg l -1 g - Sulphate as SO mg l g Sulphide as S Sulphite as SO mg l mg l -1 TOC as C 30 mg l mg l -1 g - 25 mg l -1 g - CSB as O 2 90 mg l mg l -1 g - 75 mg l -1 g - BSB 5 as O 2 20 mg l AOX as Cl 0.2 mg l mg l mg l -1 g 0.15 mg l -1 g 0.15 mg l -1 g 0.15 mg l -1 g 0.5 mg l mg l -1 EOX as Cl Hardly volatile lipophilic substances Σ HC mg l mg l mg l mg l mg l mg l -1 POX as Cl Phenol index as phenol Surfactants total 1.0 i BTX c d

180 176 State of the Art / Waste Incineration National and European Legislation a b c d e f g h i j Referred to 1 t installed incineration capacity for waste Released easily Waste water from closed circuit cooling systems, that is introduced during desalination or partial or complete system clearance Valid for waste water from desalination, elutriation or condensate cleaning, ash and slag removal, corroding, cleaning on the side of combustion and wet conservation For waste waters, occurring during depletion of closed circuit-cooling systems Fed. Law Gaz. No. 186/1996 is valid No interference of bio-decomposition Specification see Directive No interference of the drainage system and the waste water treatment plant Specification in the individual case In case of need

181 State of the Art / Waste Incineration National and European Legislation European Community The Directive on the Incineration of Waste (2000/76/EC) gives also emission limits for the discharge of waste water from flue gas cleaning (Table 88). Table 88: Emission limit value for discharge of waste water from the cleaning of exhaust gas according to the European Directive on the Incineration of Waste Parameter Total suspended solids as defined by Directive 91/271/EEC Emission limit values expressed in mass concentrations for unfiltered samples [mg l -1 ] 95 % 30 mg l % 45 mg l -1 Hg + compounds 0.03 Cd + compounds 0.05 Tl + compounds 0.05 As + compounds 0.15 Pb + compounds 0.2 Cr + compounds 0.5 Cu + compounds 0.5 Ni + compounds 0.5 Zn + compounds 1.5 Dioxins and furans, defined as the sum of individual dioxins and furans calculated using the concept of toxic equivalence 0.3 Comparing the European Directive on the Incineration of Waste with the Austrian Ordinance pertaining to the limitation of waste water emissions from the cleaning of combustion gas some differences can be highlighted: In the Austrian ordinance it is distinguished weather the water is routed to the drainage system or to running waters. The Austrian ordinance prescribes emission limit values and additionally limit values referred to the tons installed incineration capacity The European Directive limits the dioxins and furans contained in the waste water. In Austria no limit value is prescribed The Austrian Directive also includes limit values for the heavy metals Sb, Co, Mn, Sn, V and for further water parameters (compare Appendix I) Solid waste from waste incineration Depending on the waste input and the process technologies used for incineration and flue gas cleaning solid waste from waste incineration can be classified into the groups given in Table 89. Different waste fractions are allocated to key numbers, which are established in the Austrian standard ÖNORM S2100.

182 178 State of the Art / Waste Incineration National and European Legislation Table 89: Types of solid waste generated by waste incineration Separation of ferrous and non ferrous metals Ash removal NO x removal Desulphurisation Waste water treatment Process Waste pre-treatment and separation from ash and slag Removal in the boiler ESP, bag filter Primary measures SCR / SNCR Dry and spray absorption Wet limestone scrubbing SN: Waste key numbers according to ÖNORM S2100 (1997) Residue (key number) Ferrous metal scrap (SN non hazardous) Non ferrous metal scrap (SN non hazardous) Bottom ash and slag (SN hazardous waste) Fly ash and dust (SN hazardous waste) No residue No residue SCR: spent catalyst Dry and spray absorption products (SN hazardous waste) Gypsum (SN non hazardous) Filter cake (SN hazardous waste) Legal regulations for solid waste from waste incineration All waste fractions generated by waste incineration plants except gypsum from flue gas desulphurisation and ferrous and non-ferrous metal scrap are classified as hazardous waste according to the Waste Management Act (Fed. Law Gaz. No. 325/1990). According to this Act hazardous waste and waste oil have either to be disposed of in underground landfills or have to be treated before final disposal according to the state of the art to reduce impacts on human health and the environment as a whole. On demand of the owner or producer of the waste some types of hazardous waste (labelled in the Austrian Standard ÖNORM S2100) can be exempted according to the Waste Determination Ordinance (Fed. Law Gaz. No. 227/1997). There limit values for some pollutants in the waste are given. If the concentration of all pollutants of the hazardous waste is below these limit values the waste will then be handled as non hazardous waste. The procedure of exemption has to be repeated every four month in each individual case. Waste disposal of non hazardous waste on landfills is regulated by the Ordinance on Landfill (Fed. Law Gaz. No. 164/1996). The Ordinance on Landfill focuses mainly on the establishment of limit values for the total content of pollutants and for the content of pollutants in the eluate. It also includes strict requirements for waste evaluation and acceptance inspection. Depending on the type of waste and its leaching characteristics four different types of landfills are distinguished by the Ordinance on Landfill: Landfills for excavated soil: for disposal of inert waste with a very low content of pollutants (e.g. not recoverable excavated soil). Landfills for construction and demolition waste: for disposal of inert waste fractions with a low content of pollutants. Landfills for residual matter: for disposal of waste with high concentrations of pollutants, which are not elutable (e.g. wastes after thermal treatment).

183 State of the Art / Waste Incineration National and European Legislation 179 Mass waste landfills: for disposal of waste fractions with a limited content of pollutants, including by-products of mechanical-chemical pre-treatment The main difference between mass waste landfills and landfills for residual matter are the limit values. For the latter one the limit values for the eluate is more important, whereas for mass waste landfills the limit values for the total content of pollutants is more significant. The limit values for these four landfill classes are listed in Table 90. This Ordinance on Landfill does not apply to underground storage and temporary waste storage sites. Export of waste is regulated by the European Regulation on the Supervision and Control of Waste Shipment within, into and from the European Community (Waste Shipment Regulation 93/259/EEC). Adaptation of the Waste Management Act in terms of waste import, export and transit was undertaken by the amendment to the Waste Management Act (Fed. Law. Gaz. No. 1996/434).

184 I II a Soluble compounds and ph value 180 State of the Art / Waste Incineration National and European Legislation Table 90: Total content of pollutants and pollutants in the eluate for the four Types of landfills (Fed. Law Gaz. No. 196/1996) Landfills for excavated soil Landfills for construction and demolition waste Landfills for residual material Mass waste landfills Total content Pollutants in the eluate Total content Pollutants in the eluate Total content Pollutants in the eluate Total content Pollutants in the eluate ph value d k 6-13 Electrical conductivity 150 ms m -1 d 300 ms m -1 i j 1,000 ms m -1 i n Residue from evaporation 8,000 mg kg -1 ds 25,000 mg kg -1 ds Inorganic substances [mg kg -1 ds] 30,000 mg kg - 1 ds Al 5.0 e o As , Ba ,000 Pb f ,000 B 30.0 Cd , Cr total f ,000 Cr(VI) as Cr Co f Fe 10.0 e 20.0 o m Cu f ,000 Ni f ,000 Hg l Ag Zn 500 1, ,500 f , ,000 mg kg -1 ds

185 State of the Art / Waste Incineration National and European Legislation 181 I Landfills for excavated soil Total content II a Pollutants in the eluate Landfills for construction and demolition waste Total content Pollutants in the eluate Landfills for residual material Total content Pollutants in the eluate Sn Mass waste landfills Total content Pollutants in the eluate Ammonium as N ,000 Chloride as Cl 2,000 5,000 Cyanide, easily set free, as CN Fluoride as F Nitrate as N Nitrite as N ,000 Phosphate as P Sulphate as SO 4 5,000 k 25,000 Organic total values [mg kg -1 ds] TOC as C 20,000 b c 20,000 b c ,000 g h 500 h 30,000 g k ,000 p k m Σ HC 20 c 20 c h 50.0 h 5, ,000 Σ PAH h m 100 EOX as Cl m 30 Anionic-active tensides m as TSB POX as Cl 1,000 The limit value for one waste parameter will be met, if the arithmetic average value of all single values in one bulk sample does not exceed the limit value. Only the ph value has to be in the given range. How to take samples, test the waste and calculate the total content of pollutants is fixed in the Ordinance on Landfill. Ds Dry substance a if the content of one pollutant in the excavation or soil is caused geogen an exceeding of the limit value up to the value of column II will be permitted m m m

186 182 State of the Art / Waste Incineration National and European Legislation b This value will be met if the ignition loss is not larger than 3 weight per cent c For not contaminated, natural excavation higher limit values will be possible, if the humic or peat content in the soil is lower than 10% of the waste, deposited on this landfill. Furthermore tuned by the geogen background of a landfill higher limit values are possible. d If total values of column I are met, a ph value of will be allowed. In such a case and a ph value of the limit value for electrical conductivity is 250 ms m -1 e In case of a geogen back ground charge exceedings of 100% are allowed f For disposition of glassed, mineral smelting in single cases higher limit values are possible g This value will be met if the ignition loss is not larger than 5 weight per cent h Higher limit values for soil and earth will be possible, if the humic or peat or the structural material impurity content in the soil is lower than 10% of the waste, deposited in this landfill. i For wastes compacted by hydraulic fixing agents the limit value has to be met after 28 days curing time j For unset concrete, concrete residues and bentonite slurries: 800mS m -1 k (further) specifications see Directive l In case of Hg in form of hardly soluble sulphured compounds, which are solidified a mercury content up to 3,000 mg kg -1 ds is allowed m If this parameter is relevant for the deposited waste it will be fixed during the licensing procedure, n Higher limit values for some types of waste are possible o Only valid for wastes, compacted by hydraulic fixing agents p This value will be met if the ignition loss is not larger than 8 weight per cent

187 State of the Art / Waste Incineration National and European Legislation Waste and solid residues from Austrian waste incineration plants Table 91 shows the specific masses of waste fractions from Austrian waste incineration plants referred to 1 t of waste input in the year Table 91: Specific volumes of waste fractions from Austrian waste incineration plants referred to 1 t of waste input in the year 2000 [REIL, 2001; KROBATH, 2001; WACHTER, 2001] Simmeringer Haide Waste fraction Flötzersteig Spittelau Wels Arnoldstein Fluidized bed Rotary kiln combustion Slag [kg t -1 waste] Gypsum [kg t -1 waste] Fly ash [kg t -1 waste] Filter cake [kg t -1 waste] 4, Ash 9,000 t yr (incl. bed ash) t yr Water content [%] Metal scrap [kg t -1 waste] t yr An overview of different waste treatment processes carried out in Austria is given in Table 92. Table 92: Treatment of solid residues of Austrian waste incineration plants [REIL, 2001; KROBATH, 2001; WACHTER, 2001] Plant Slag Fly ash Gypsum Filter cake Metal scrap Flötzersteig Slag concrete; sealing material for a landfill 1 Underground disposal Spittelau Slag concrete; sealing material for a landfill 1 Underground disposal Wels Landfilled in Wels after wet chemical treatment Underground disposal Lenzing Arnoldstein Simmering rotary kiln Bed ash, coarse ash, prededusting ash landfilled landfilled Mixed and landfilled Simmering landfilled Fluidized bed 1 Is mixed with slag and fly ash during flue gas cleaning +eco and fabric filterash: underground disposal Underground disposal Steel industry Scrap dealer Scrap dealer recycled

188 184 State of the Art / Waste Incineration National and European Legislation 11.4 Monitoring Emissions into air, water and soil can be measured continuously and/or discontinuously. In many European countries pollutants are continuously measured in flue gases or waste water with high volumetric flows. This type of emission measurement reflect the actual concentration of a pollutant in the flue gas or in the waste water. The results can be described as half hourly-, hourly-, daily-, monthly- or yearly-average values. The shorter the averaging period the more accurate are the actual emissions reflected, but the wider is the range of emission levels. The difference between half hourly average values, monthly average values and yearly average values is given in Table 93: Table 93: Emissions in relation to reporting period [ Pollutant (2001) Half hour mean value Monthly mean value Yearly mean value Min (mg/nm 3 ) Max (mg/nm 3 ) Min (mg/nm 3 ) Max (mg/nm 3 ) (mg/nm 3 ) Dust Spittelau Flötzersteig Sim. Haide FBR 1 Sim. Haide RK 1 0,0 0,5 < 0,1 < 0,1 12,6 13,6 19,5 29,7 0,4 1,8 0,1 0,5 1,8 3,1 0,3 0,6 0,8 2,4 0,2 0,5 HCl Spittelau Flötzersteig Sim. Haide FBR 1 Sim. Haide RK 1 0,0 0,1 < 1 < 1 8,2 9,7 < 1 7,1 0,6 0,5 < 1 < 1 1,1 3,0 < 1 < 1 0,8 1,7 < 1 < 1 SO 2 Spittelau Flötzersteig Sim. Haide FBR 1 Sim. Haide RK 1 0,0 0,1 < 0,3 < 0,3 16,4 80,3 0,5 60,6 1,2 5,9 < 0,3 0,3 3,5 15,2 0,3 0,8 2,1 8,5 < 0,3 0,6 CO Spittelau Flötzersteig Sim. Haide FBR 1 Sim. Haide RK 1 1,4 2,2 5,8 2,9 91,2 150,6 53,0 246,0 16,6 10,5 12,5 14,3 31,1 14,3 17,7 18,0 26,3 12,0 14,8 15,5 NO x Spittelau Flötzersteig Sim. Haide FBR 1 Sim. Haide RK 1 0,0 0,5 9,9 17,2 92,8 94,9 183,7 281,1 7,6 23,3 96,2 89,3 31,8 55,9 110,2 108,7 22,9 38,8 106,1 102,0 C org Spittelau Flötzersteig Sim. Haide FBR 1 Sim. Haide RK 1 0,0 0,1 < 0,2 < 0,2 19,2 19,1 19,9 63,8 0,2 0,4 < 0,2 < 0,2 1,2 1,3 0,4 0,2 0,5 0,7 < 0,2 0,2 FBR: Fluidised bed reactor; RK: Rotary kiln 1 reporting period: January 2001 to May 2001

189 State of the Art / Waste Incineration National and European Legislation 185 Besides control of emissions continuous emission measurements gives the operator the possibility to react on unstable firing conditions (e.g. CO, NOx), complete or partial breakdown of abatement systems (e.g. dust) or on extremely high input loads (e.g. chlorides, mercury). The influence of the corresponding time average on real emissions should be considered when determining BAT levels Monitoring of operating parameters At Austrian waste incineration plants the following operating parameters have to be measured continuously according to the Austrian Waste Incineration Collective Ordinance:! Temperature near the inner surface of the boiler or at a representative side within the combustion chamber.! Temperature of the flue gas.! Volume of the flue gas! Oxygen content of the flue gas.! Pressure of the flue gas.! Water content of the flue gas Monitoring of emissions to air national regulation Emissions to the air can be given in the following three ways: As concentration in milligram per cubicmeter [mg m -3 ] or nanogram per cubicmeter [ng m -3 ] referred to standard conditions (0 C; 1,013 mbar; dry conditions) and to a given o- xygen content (11 % for waste incineration). This is the standard procedure for Austrian waste incineration plants laid down in Austrian Waste Incineration Collective Ordinance. As mass flow in tons a year [t y -1 ], kilogram per hour [kg h -1 ], gram per hour [g h -1 ] or milligram per hour [mg h -1 ]. In Austria waste incineration plants have to report mass flows according to the Austrian Waste Incineration Collective Ordinance. As specific mass flows in kilogram per ton of fuel input (waste) [kg t -1 ], gram per ton fuel input (waste) [g t -1 ] or milligram per ton fuel input (waste) [mg t -1 ]. Specific mass flows are normally based on calculations and are a tool for the comparison of different plants and for the estimation of the plants (energy-, combustion- or reduction-) efficiency. Continuous monitoring of the following air pollutants is prescribed by the Austrian Waste Incineration Collective Ordinance: Carbon monoxide SO 2 HCl HF (not necessary, if HCl is controlled by effective flue gas cleaning) Nitrogen oxides Organic C Dust Hg

190 186 State of the Art / Waste Incineration National and European Legislation Monitoring of emissions to air waste incineration plants The frequency of the emission measurement of hydrogen fluoride is plant specific, varying from one measurement a year (e.g. as it is done in the waste incineration plant Spittelau or Flötzersteig) to continuous monitoring (e.g. in the waste incineration plant Wels). In most cases it depends from the efficiency of the plants sulphur dioxide and HCl removal system. Hg is continuously monitored at the fluidised bed reactor of AVE RV Lenzing. Ammonia is measured once a year in Wels, twice a year after the rotary kilns in the plant Simmeringer Haide and continuously in the plant Flötzersteig. All other air pollutants not given in are monitored discontinuously. The number of measurements depends on local conditions. For example, dioxine and furan emissions are measured twice a year in Wels and the rotary kilns of the plant Simmeringer Haide, but 6 times a year in the waste incineration plant Flötzersteig. PAH are monitored twice a year in the waste incineration plant for hazardous wastes in the plant Simmeringer Haide and once a year at the fluidized bed reactors of the plant Simmeringer Haide. Heavy metals are either measured once or twice a year Monitoring of emissions to water waste incineration plants The waste water of the waste incineration plant Wels is controlled 4 times a year by external experts. Additionally some parameters, such as SO 4, Cu or Cl are measured weekly by the plant operator. The temperature and the ph value of the waste water are monitored continuously. In the plant Simmeringer Haide, where waste water of the fluidized bed reactors and of the rotary kilns is treated together, temperature, ph and electrical conductivity are controlled continuously. Chlorides, fluorides and mercury are controlled daily, whereas all other parameters are checked weekly Monitoring of waste from waste incineration and solid residues The total content of pollutants in slag, fly ash and filter cake are monitored twice a year by the operators of the plants Flötzersteig and Spittelau. Residues converted to slag concrete are controlled twelve times a year before final disposal at the landfill site. Chemical parameters of solid waste from the waste incineration plant Simmeringer Haide are controlled every month. Leaching tests of the fly ash are performed monthly, whereas pollution levels of filter cake and slag are controlled by leaching tests periodically.

191 State of the Art / Waste Incineration Glossary and Abbreviations GLOSSARY AND ABBREVIATIONS Ad: air dried basis AOX: Adsorbable Organic Halogen BAT: Best Available Techniques Big Bag: Double-walled plastic or steel container for waste storage BTXE: Benzene, Toluol, Xylene, Ethyl benzene CHP: Combined heat and power COD: Chemical oxygen demand DeNO x : Denitrification EMC: Electronic, measurement and control EOX: Extractable organic bound halogens Overall efficiency: Ratio of utilizable carried off energy to supplied energy HC: Hydrocarbon IPPC-Directive: European Council Directive on Integrated Pollution Prevention and Control (96/61/EC) IPTS: Institue for Prospective Studies MA 48: Magistratsabteilung der Stadt Wien, competent authority for the Viennese waste management PAH: Polycyclic aromatic Hydrocarbons PE: Polyelectrolyte PCB: Polychlorinated Biphenyl PCPh: Polychlorinated Phenols PCDD/F: Polychlorinated Dibenzo-p-dioxins/furans; group of 75 resp. 135 isomers SCR: Selective catalytic reduction of nitrogen oxides SNCR: Selective non catalytic reduction of nitrogen oxides TEQ: Toxic Equivalent TOC: Total Organic carbon TMT: Trimercapto-s-triazine VOC: Volatile Organic Carbon

192 188 State of the Art / Waste Incineration References 13 REFERENCES BMLFUW (2001): Federal Waste Management Plan HARTENSTEIN, A.; MAYER A (1995): SCR Katalysatortechnik mit Harnstoff für Industrie und Heizkraftwerke. In VGB Kraftwerkstechnik 75, Heft 2, p HÜBNER C., BOOS R., BOHLMANN J., BURTSCHER K., WIESENBERGER H. (2000): In Österreich eingesetzte Verfahren zur Dioxinminderung. Monographie 116, Umweltbundesamt GmbH, Wien 2000 KOEBEL, M.; ELSENER, M.; MARTI, T. (2000): Reduzierung von Stickoxiden in Abgasen mittels Harnstoff. Paul Scherrer Institut; Villingen CH, KRATSCHMANN, H; NISTLER W. (1988): Die Maschinentechnik im Kraftwerk Dürnrohr. In: ÖZE; Jahrgang 41, Heft 9/10, p KROBATH, P. (2001): Schriftliche Mitteilung REIL, E. (2001): Written information, 17 th July, ROLLAND, C.; GRECH, H. (2001): Stand der Abfallbehandlung in Österreich in Hinblick auf das Jahr Bericht des Umweltbundesamts Wien. (BE-182;2001). SCHACHERMAYER, E.; BAUER G.; RITTER; E. et al. (1995): Messung der Güter- und Stoffbilanz einer Müllverbrennungsanlage. Monographie des Umweltbundesamts. (UBA-M- 56). SCHNOPP, K (2002): Written information. THÓME-KOZMIENSKY, K. J. (1994): Thermische Abfallbehandlung. Berlin: EF-Verlag für Energie- und Umwelttechnik, UMWELTERKLÄRUNG (1999): Environmental statement according to the Council Regulation (EEC) No 1836/93 of 29 June 1993 allowing voluntary participation in the industrial sector in a Community eco-management and audit scheme of Assamer Becker Recycling Gesellschaft mbh. VERBUNDGESELLSCHAFT (1996): Umweltbericht. VGB KRAFTWERKSTECHNIK (1995): Lehrheft für die Ausbildung zum Kraftwerker Feuerungen und Dampferzeuger. Heft 7, 2. Auflage, Essen. WACHTER, R. (2000): Written Information, 14 th November, WACHTER, R. (2001): Written Information, 5 th July, WERNER, T. (2002): Written Information, 6 th February, WIESER, P. (2000): Written information, 3 rd July, 2000.

193 State of the Art / Waste Incineration References Internet adresses Asamer Becker Recycling GmbH Abfallverwertungs und entsorgungs GmbH Fernwärme Wien GmbH Kärntner Restmüllverwertungs GmbH Welser Abfallverwertung Betriebsführung GmbH