Spittelau. The thermal waste treatment plant.

Transcription

1 Spittelau. The thermal waste treatment plant.

2 History of the Spittelau thermal waste treatment plant. In 1969 the newly-founded Fernwärme Wien GmbH (formerly Heizbetriebe Wien) was commissioned by the City of Vienna to secure the city s district heating supply. With the operation of the Sipttelau thermal waste treatment plant which was under construction at that point in time Fernwärme Wien also assumed responsibility for the orderly disposal of municipal wastes. Today, the successively expanded district heating network is fed by a total of ten generating plants with an installed output of more than,800 MW, and its pipeline length of over 1,000 km makes it one of the largest in Europe. More than 6,000 dwellings and over 5,300 industrial consumers are currently supplied with district heating for space heating and water heating. The Spittelau thermal waste treatment plant was erected at its current location in order to supply the new General Hospital, some two kilometres distant, with district heating. With its total output of 460 MW the Spittelau plant is the second-largest generator in the City of Vienna s district heating network. The thermal waste treatment plant integrated in the works has a throughput capacity of more than 50,000 tonnes per annum and is part of the supply network, feeding in an annual average of 60 MW (basic load coverage). In addition, five further gas- or gas/oil-fired hot water boilers can produce 400 MW of thermal output to cover peak demand. The ongoing updating to the state of the art in flue gas cleaning technology has meant continuous modernisation of the thermal waste treatment plant with a flue gas wet scrubber (1986/1989) and a denox and dioxin destruction system (1989).

3 Friedensreich Hundertwasser. At the time of the modernisation of the Spittelau thermal waste treatment plant the famous painter and architect Friedensreich Hundertwasser completely redesigned the façade of the whole works. The previously sober, functional building became an internationally unique, spectacular work of art: a successful example of a harmonious symbiosis of technology, ecology and art together with an important contribution to the reduction of the optical environmental pollution in the urban living space. home. The example of the Spittelau thermal waste treatment plant is proof that, rather than the existing rational, impersonal architecture under which we all suffer, a creative spirit in harmony with nature can be inspired. It should be a statement against the anonymity in our cities. I know, that future-oriented action demands courage to implement that which is still derided and opposed by the establishment today. Friedensreich Hundertwasser on the design of façades: Einstein said: if the formula is not neat, it can also not be correct. That is precisely the opposite of what the functionalists, rationalists and technocrats preach. Today we are experiencing the triumph of rationalism and the depressing, aggressive and soulless monotony and are confronted simultaneously with nothingness. The sins are particularly prominent in industrial construction. More sinned-against than the cities were the people who spend more time in sterile, inhumane industrial buildings than at In the meantime, a familiar Viennese sight, widely admired by tourists and locals alike: the Spittelau thermal waste treatment plant. 3

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5 Layout of the Spittelau thermal waste treatment plant. Firstly the delivered waste arrives at the waste bunker. Two bridge cranes feed the feeding hoppers (filling shafts) of the plant. A dispatcher thrusts the waste onto the grate of the com-bustion chamber. From the overhead stream boiler the flue gases flow through an electrostatic precipitator and a three-stage flue gas scrubber into the catalytic denox and dioxin destruction system. They finally leave the works via the chimney. The in-house waste water treatment plant cleanses the waste water resulting from the flue gas cleaning process. The remaining solid residues are disposed of in an orderly manner Waste bunker Feeding hopper Grate Combustion chamber Waste heat boiler Wet slag remover Electrostatic precipitator Flue gas wet scrubber (two-stage) Fine dust separator (electrodynamic Venturi) SCR denox system Chimney Magnetic separator Slag bunker Filter ash silo Emission control

6 Waste delivery. Orange-coloured transporters of Vienna City Council (the 48er ) unloading municipal waste The main delivery of Viennese municipal waste (domestic waste and industrial wastes similar to household waste) to the Spittelau thermal waste treatment plant takes place from Monday to Friday between 7.00 am and 3.00 pm. Up to 50 delivery vehicles pass over one of the two weighbridges daily. After weighing, they empty their contents at one of the total of eight dumping stations into the waste bunker which has a capacity of some 7,000 m 3. Following thorough mixing in the bunker in order to keep the heating value constant, two bridge cranes, each of whose polyp grabs have a capacity of some 4 m 3, transfer the waste to the two incinerators

7 Thermal waste treatment. The thermal waste treatment plant consists of two incinerators, each with a flue gas cleaning system as well a common denox and dioxin destruction system that serves both incinerators. Connected to this is a treatment plant for the waste water from the flue gas wet scrubber. Via the feeding hopper and the hydraulic dispatcher the waste is moved from the bunker to the grate at the lower end of the combustion chamber. Up to 17 tonnes of waste per hour can be thermally treated on the sloping, 35 m area of the two-track reverse-acting stocker grate. During the start-up and run-down phase of a boiler two 9 MW gas burners ensure the necessary combustion chamber temperature and thus the burn-off of the flue gases required by law. In normal operation the use of the gas burners is not necessary: the average waste heating value of 9,500 kj/kg is more than sufficient to ensure self-combustion of the waste. The crane transports the waste to the feeding hopper Waste bunker Feeding hopper Grate Combustion chamber Waste heat boiler Wet slag remover 7

8 Annual energy balance 006 of the Spittelau thermal waste treatment plant Natural gas 5,607 t waste 665,300 MWh Natural gas for auxiliary firing 3,400 MWh Natural gas for denox plant 50,400 MWh Flue gas losses 16,000 MWh Effective energy 55,00 MWh Waste water losses 67,900 MWh Net current 17,900 MWh In-house power demand,600 MWh In-house heat demand 5,700 MWh 7 7 % Losses 69 % Energy output 4 % Energy demand Net heat 479,000 MWh 8

9 District heating and power generation. Waste combustion creates hot flue gases. These give off their heat content to the boiler heating surfaces of the incinerators. The two incinerators generate a total of 90 tonnes of saturated steam (33 bar) per hour. For power generation this steam volume is first reduced to 4.5 bar in a backpressure turbine. In the downstream heat exchanger group the return water from the district heating network is reheated by condensation. The non-combustible waste components (slag) that arrive at the end of the grate fall into the wet slag remover. From there the cooled slag is transported to the slag bunker by a conveyor belt, with ferrous scrap being removed beforehand for recycling by overhead electromagnets. In the waste bunker there is constant negative pressure caused by the extraction of the necessary fresh air for the combustion process, thus minimising the escape of odours and dust via the dumping stations into the ambient air. In addition, the use of a complex combustion control system which has been developed over many years ensures an optimum combustion process on the grate and thus maximum burn-out of slag and flue gas. In an average year large amounts of power are generated from domestic waste and household-like wastes: approximately 6 MW of power to meet in-house requirements and feeding into the public grate as well as 60 MW district heating. This amount of energy is equivalent to a space heating equivalent of some 60,000 dwellings with 80 m floor area Waste bunker Feeding hopper Grate Combustion chamber Waste heat boiler Wet slag remover 1 st heat exchanger 6 1 9

10 Flue gas cleaning. Dust separation and wet scrubbing. The thermal waste treatment plant has had a highly efficient dust separation system (electrostatic precipitator) since initial commissioning in This was augmented in 1986 by a two-stage flue gas wet scrubber with attached fine dust separator (electrodynamic Venturi). With the modification of these three treatment stages as well as the installation of the Europe s first SCR denox system downstream from a wet scrubber in 1989 the Spittelau plant was the international pioneer in the field of flue gas cleaning and emission reduction relating to thermal waste treatment. The emission limit values in accordance with the Waste Incineration Directive that apply today relating to domestic waste-fired steam boiler plants were significantly undercut with the existing process concept from the very beginning.

11 8. The flue gas leaves the first heat exchanger downstream of the waste heat boiler at a temperature of 180 C. A threestage electrostatic precipitator cleans the flue gas to a dust content of < 5 mg/dscm. A mechanical-pneumatic conveyor system transports the thus-deposited fly ash to a 15 m 3 - capacity silo. The almost completely de-dusted flue gas then enters the quenching system of the first wet scrubber. Here it is cooled down to saturation temperature (60-65 C) by fresh water injection. Operating with a ph value of 1, with intensive gas-liquid contact in the cross-flow the first wet scrubber ensures the separation of hydrogen chloride (HCl), hydrogen fluoride (HF) and dust, as well as particle-bound and gaseous heavy metals The second wet scrubber is designed as a counter-current scrubber and is operated with a ph value of 7. This causes the unloading of sulphur dioxide (SO ) fro the flue gas. In the next cleaning stage, the electrodynamic Venturi, adiabatic expansion of the flue gas takes place and then the fine dust particles, which have been moistened and charged by a central electrode, are removed to reduce the residual dust content to values < 1 mg/dscm. The second heat exchanger reheats the flue gas to 5 C and passes it over an induced draft fan to the denox and dioxin destruction system. 7 The electrodynamic Venturi causes the almost complete dedusting of the flue gas Electrostatic precipitator Flue gas wet scrubber / 1 st scrubber Flue gas wet scrubber / nd scrubber Fine dust separator (electrodynamic Venturi) nd heat exchanger 11

12 Flue gas cleaning. DeNOxing and dioxin destruction. The denox plant operates with the selective catalytic reduction (SCR) process. The denox plant represents the last stage of the flue gas cleaning process and serves for the removal of NOxes, dioxins and furans from the flue gas. The flue gas flows from the two cleaning lines are first combined. The flue gas is then mixed with vaporised ammonia water (NH3). Heating tubes and natural gas surface burner heats this gas mixture to a reaction temperature of up to 80 C before it is passed to the catalytic converter. With the introduced ammonia and the oxygen contained in the flue gas, on flowing through the three catalytic converter plants the nitrous gases (NOx) are converted to harmless nitrogen a steam and the dioxins and furans are destroyed. In this cleaning process the catalytic converter used accelerates the chemical reaction and works with utmost efficiency in the smallest possible space: with a volume of just a few cubic metres it provides a reaction surface of several square kilometres. The flue gases purified in the catalytic converter cool off to 130 C in the attached heat exchanger. The purified gases are then ready for passing into the atmosphere via the 16 m high chimney of the Spittelau plant. 1

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14 Flow chart of the thermal waste treatment plant. Lime slurry Sodium hydroxide solution G Milk of lime, precipitation chemicals Lime slurry, precipitation chemicals Waste bunker 6 Wet slag remover 11 Chimney 16 Fly ash silo Feeding hopper 7 Electrostatic precipitator 1 Feed water tank 17 Slag bunker 3 Grate 8 Flue gas wet scrubber (two-stage) 13 Turbine & generator 18 Scrap metal container 4 Combustion chamber 9 Fine dust separator 14 Heat exchanger group 19 Multi-recycling plant 5 Heat recover boiler SCR denox system 15 Electro-magnetic separator 0 Waste water treatment plant 14

15 Fresh water Natural gas Detail view of the induction draft fan 9 Ammonia 11 Mass balance 006. Input flows (data related to 1 t of waste) Heat demand (covered by in-house production): 5 kwh Power demand (covered by in-house production): 90 kwh Natural gas demand: 0 m 3 Fresh water demand: 746 l 0 Lime consumption: Sodium hydroxide solution consumption, 30 %:,6 kg,4 kg 1 Ammonia consumption, 5 %: Precipitation chemicals consumption: 3,0 kg 0, kg Lime slurry, precipitation chemicals Output flows (data related to 1 t of waste) Heat output: 1,896 kwh 5 Power output: Slag and gypsum: 34 kwh 05 kg 4 Ferrous scrap: kg Fly ash: 17 kg Filter cakes: 1kg Purified waste water: 357 l Chamber filter press Pure water tank Sludge tank Filter cake box Receiving water course (Danube Canal) Fresh water Basic process water Acid process water Saturated steam Fly ash/slag Hydroxide sludge Gypsum sludge District heating Purified flue gas (dry): Waste throughput rate: Operational hours incineration line 1: Operational hours incineration line : 4,400 dscm 5,607 ttt 7,859 ttt 7,784 ttt 15

16 Waste water treatment and residues. A multi-stage treatment plant processes all the waste water arising in the flue gas wet scrubbing system. This is then passed into the receiving water course (Danube Canal). With the addition of lime slurry as well as special precipitation and flocculation chemicals, a precipitation reactor first converts the dissolved heavy metal compounds present in the waste water into an insoluble form. In the downstream lamella clarifier the suspension formed is separated into or overflow water and heavy metal hydroxide sludge. After repeatedly passing through precipitation and separation stages, the hydroxide sludge dewatered in a chamber filter press to a residual moisture of approx. 30 % and filled into dumper trucks as filter cakes. Following final control of the throughflow volume, temperature, ph value and freed of any remaining ferrous scrap, mixed with cement and water and used as slag concrete, with an eluate quality approaching that of drinking water, in landfill site preparation (perimeter wall formation). The ferrous scrap previously separated from the raw slag in the Spittelau plant is returned to the material cycle (steel production). The residues from the waste water treatment plant, the filter cakes and the fly ash are transported abroad by train in covered skips or silo transporters and deposited in a decommissioned salt mine. Multi-recycling plant Chamber filter press conductivity the purified waste water is passed into the receiving water course. The multi-recycling plant processes the sodium sulphate discharge water of the second wet scrubber stage. The dissolved sodium sulphate (gypsum) is precipitated by the addition of lime slurry, sedimented in the settling tank and pumped into the wet slag remover as gypsum sludge. The sodium hydroxide solution reclaimed during the course of the sedimentation process is fed back into water cycle of the second wet scrubber. The solid residues of the thermal waste treatment are slag, ferrous scrap, fly ash and filter cakes with a total mass of some 50 kg per tonne of waste utilised. After the slag has been removed to a special treatment plant (in covered dumper trucks), this residue is sifted, 16

17 Precipitation stage Precipitation stage 1 Pure water tank Sludge tank 17

18 Waste management. In the Austrian Waste Management Act, 1990, for the first time particular attention was paid to a sustained waste management system by the establishment of a series of targets. Priority was given to: 1) Protection of the environment; ) Resource conservation; 3) Economical handling of landfill volumes; and 4) Depositing of exclusively inert wastes. But already years before that the City of Vienna had drawn up a sustainable, environmentally sound waste management concept. With the decision in favour of thermal waste treatment in 1961 Vienna took the first, decisive step towards an ecologically responsible waste disposal concept. In the meantime, this tried and tested basic model has been augmented in an optimum manner with a spatially inclusive and comprehensive recycled materials collection system in combination with material recycling of the separately collected waste glass, waste paper, metal, plastic and biological waste fractions. Since 1 January 004, in accordance with the terms of the Austrian Landfill Directive whereby only wastes with an maximum organic carbon content of 5 % may be dumped in landfills, pre-treatment measures must be undertaken in all cases prior to final disposal. Today, thermal waste treatment is regarded as the most economically and ecologically sensible version of all disposal technologies. Thermal waste treatment sets itself apart from other disposal methods with a series of advantages: 1) Exploitation of the energy contained in the waste for power and heat generation; ) Continuous plant availability; 3) High degree of operational safety; and 4) Ensures achievement of the targets stipulated by the Waste Management Act. 18

19 Environmental protection. Compared with the direct disposal of untreated municipal waste, thermal waste treatment offers a wide range of advantages: 1) Reduction of the amount of waste to be disposed of to % of the initial volume; ) Destruction of organic pollutants (e.g. dioxins) contained in the waste; 3) Extensive inertisation of the inorganic components contained in the waste; 4) Specific extraction of pollutants from the environment; 5) Extraction of recyclable or easy-to-dispose-of inert residues; 6) Possibility of easy control of ongoing processes as well as emissions released into the environment; 7) Primary energy substitution due to the exploitation of energy contained in the waste (generation of power and heat); Thanks to the ongoing improvement in flue gas and waste water treatment measures, today the 1971-commissioned Spittelau waste treatment plant has achieved the (for the present) highest level of emission reduction. 8) Reduction of greenhouse-effective gases (particularly methane). The current emission values of the Spittelau thermal waste treatment plant can also be viewed on the Internet under: 19

20 Air pollution control. The continuously-measured emission values of the air pollutants carbon monoxide (CO), sulphur dioxide (SO), nitrous oxides (NOx), hydrogen chloride (HCl), dust and hydrocarbons (Corg) in the purified flue gas are transmitted online to the City of Vienna environmental agency, thus enabling ongoing monitoring of the maintenance of limit values. In normal operation, the emission limit values stipulated by law relating to air pollution control are significantly undershot (even compliance with the Austrian Clean Air Act 1988, the first worldwide and widelydiscussed emission limit values for dioxins and furans represent no problem). Thus, for the purpose of a total ecobalance, current research work is focusing on optimisation measures relating to solid residues. Not least due to its high flue gas cleaning standard, the incorporation of the Spittelau plant into the City of Vienna s district heating network and the thus-enabled substitution primary energy sources such as gas or oil by waste as a fuel has resulted in a improvement in the municipal emission and immission balance sheet. Emission values in the purified flue gas 006. Dust Hydrogen chloride (HCI) Hydrogen fluoride (HF) Sulphur dioxide (SO ) Carbon monoxide (CO) Nitrous oxides (NO x ) Hydrocarbons Lead, zinc, chrome (Pb, Zn, Cr) Arsenic, cobalt, nickel (As, Co, Ni) Antimony, arsenic, lead, chrome, cobalt, copper, manganese, nickel, vanadium, tin (Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V, Sn) Cadmium (Cd) Cadmium and thallium (Cd, TI) Mercury (Hg) < < < 1 < < 0.00 < < < Reduction compared with notification of permission 98.0 % 9.0 % 85.7 % 98.0 % 67.0 % 7.0 % 90.0 % mg/dscm % 99.8 % 96.4 % 99.0 % 96.0 % 78.0 % mg/dscm 4 4 Polychlorated dioxins and furans (PCDD/PCDF) Austrian Waste Incineration Directive 00 Act on Protection against Emissions from Boiler plants 004 Notification of permission Mean value % ng/dscm 0

21 Technical data. 1. Weighing device:. Waste bunker: 3. Combustion chamber feed: 4. Firing: 4.1. Grate: 4.. Combustion chamber: 4.3. Additional firing: 5. Slag removal: 6. Waste heat boiler: 7. Turbine & generator: 8. Flue gas cleaning: 8.1. Electrofilter: 8.. Flue gas wet scrubber: 8.3. DeNOx & dioxin destruction system: 9. Induced draft fan:. Chimney: Weighbridge, number: Capacity: Tipping points: Bridge crane with hydraulic polyp grabs, number: Capacity of each grab: Number of combustion lines: Maximum throughput capacity per line: Air-cooled twin-track reciprocating grate Grate length: Grate width: Inclination: Fuel thermal output per line: Waste thermal value: Primary air heating: Fire resisting material: Firing rate regulation: Gas burners, number per line: Fuel thermal output per line: Ram-wet slag remover Slag remover volume: Natural circulation radiation boiler Maximum steam output per line: Maximum operating pressure: Maximum operating temperature: Heating surface: Saturated steam back-pressure turbine Maximum electrical output: Back-pressure: Number of lines: Flue gas volumes per line: Operating voltage: Dust separation efficiency: 1 st stage: Design: Absorption agents: HCI separation rate: nd stage: Design: Absorption agent: SO separation rate: SCR catalytic converter, number of catalytic converter systems: Operational temperature: NOx destruction rate: Dioxin destruction rate: Rotary fan, number per line: Maximum delivery rate: Electrical power: Design: Height: Diameter: 7,000 m m 3 18 t/h 7.5 m 4.6 m MW 8,00 9,600 kj/kg C SiC rammed-layer lining material Steam output, O -concentration, Combustion chamber temperature 9 MW 5 m 3 55 t/h (saturated steam) 34 bar 45 0 C,40 m 6.4 MW 4.5 bar (denox plant:1) 85,000 dscm/h (wet) 60 kv > 99.5 % Quench/separation of Hydrogen chloride (HCI), hydrogen fluoride (HF), dust, heavy metals Cross-flow scrubber Water/lime slurry > 98 % Separation of sulphur dioxide (SO ) Counter-current scrubber Sodium hydroxide solution > 98 % 3 bis 80 0 C > 95 % > 95 % 1 137,000 dscm/h (wet) 1 MW Steel/brick 16 m.5 m 1

22 Supply security. The Vienna heating ring. With its eye-catching façade designed by Friedensreich Hundertwasser the Spittelau thermal waste treatment plant has become the symbol of district heating in Vienna. Technically, together thermal waste treatment plants Flötzersteig and Simmeringer Haide, the Spittelau plant is one of the three base power stations that form the backbone of Vienna s district heating supply. The base power stations exploit the domestic waste accruing in Vienna and hazardous wastes from Austria as well as sewage sludge from the main waste water treatment plant in Vienna. The energy acquired from the thermal waste treatment is exploited as valuable heat energy for the district heating system. Spittelau thermal waste treatment plant Danube The cogeneration plants of Wien Energie Wienstrom together with OMV s Schwechat refinery generate the major proportion of the district heating requirement also known as medium load. Besides the production of electrical energy, with their combined heat and power plants these power stations provide a decisive advantage over conventional caloric power stations: the waste heat arising from the combustion of the primary energy sources oil and gas does not go unexploited, but is used for the production of heating energy. Industrial building General Hospital Fernwärme Wien covers up to 96 % of the heat energy demand of its customers with the heat recovered from the base and medium load power stations. The peak load power stations only go on-line with outdoor temperatures under C: but their gas- and oil-fired hot water boilers not only provide peak period coverage in winter, they also represent a downtime backup, for example when a district heating station has to be withdrawn from the network for maintenance. Thus they ensure an all-year-round district heating supply. The district heating is distributed from the plants to customers via a network consisting of more than 1,000 km of underground pipelines. After the so-called primary water in the boilers of the plants has been heated up to 150 C, the district heating water flows to the converter stations distributed throughout the city. There, in heat exchangers the primary water heats water which is passed via the secondary network to dwellings in order to feed radiators and water taps with hot water. Flötzersteig thermal waste treatment plant Dwellings Converter station City Hall The rising CO concentration in the Earth s atmosphere is one of the main causes of climate change. Three-quarters of CO emissions can be attributed to the combustion of oil, coal or gas. The production of greenhouse gases can be reduced significantly by the utilisation of cogeneration systems and the heat energy produced from thermal waste treatment. Fernwärme Wien exploits all available energy sources in an ecologically and economically sound manner according to the spirit of a cleaner environment, and in this way achieves

23 Leopoldau cogeneration plant Kagran district heating works Geothermal plant UNO-City Donaustadt cogeneration plant Office building Arsenal district heating works Simmering cogeneration plant Simmeringer Haide thermal waste treatment plant Pfaffenau thermal waste treatment plant Inzersdorf district heating works OMV cogeneration plant a two-thirds reduction in the otherwise required primary energy sources. Some 365,000 tonnes of heating oil are saved annually. Thus Fernwärme Wien is not only one of the safest, but also one of the most efficient forms of energy production. 3

24 WIEN ENERGIE Fernwärme Spittelauer Lände Vienna Austria Phone: +43 (0) Fax: +43 (0) APPOINTMENT ARRANGEMENTS FOR GUIDED TOURS: Phone: +43 (0) / 0008 /.000 / WEF / Grö 1st edition Errors and omissions excepted. Subject to alterations. WIEN ENERGIE Fernwärme, a company of WIEN ENERGIE.