Biomass Gasifier: Principle and application

Transcription

1 Training programme on Energy Efficient technologies for climate change mitigation in Southeast Asia Biomass Gasifier: Principle and application

2 Biomass as a Fuel Age-old and most widely used fuel source Annual consumption was estimated to be of the order of 20 million tonnes a few years ago A Cheap, abundantly available fuel A very Clean fuel Biomass has no Sulphur content Short CO 2 fixation cycle Renewable

3 Why Biomass Gasification? Biomass Producer Gas Allows better process control and convenience Cleaner combustion in connected equipment Elimination of all pollution related to Biomass use Gasification is highly efficient process Can be applied over a range of output ratings (few to hundreds of kws) Can be used for thermal applications & electricity generation Low initial investment and cost of power production Biomass is CO 2 neutral fuel Organized biomass feedstock supply can contribute to rural livelihood and uplift of rural economy

4 Comparative energy cost for different fuels (For Q useful = 10,000 kcal/hr)

5 What is Gasification? Basic Process Chemistry Conversion of solid fuels into combustible gas mixture called producer gas (CO + H2 + CH4) Involves partial combustion of biomass Four distinct process in the gasifier viz. Drying Pyrolysis Combustion Reduction

6 Gasification Basic Process Chemistry Schematic

7 Biomass gasification

8 Types of gasifier Up-draft gasifier: Efficient but gives comparatively dirty gas, good for thermal applications Down-draft: Comparatively clean gas, good for power generation Cross draft: in between above two.

9 Producer Gas Properties

10 Comparison of producer gas characteristics Component Wood Gas (vol. %) Charcoal Gas (vol. %) Rice Husk gas (vol. %) Nitrogen Carbon monoxide Carbon dioxide Hydrogen Methane Up to 4 Gas heating value KCal/m³ > 1000 Rated gas production per kg husk : Nm³ Gasification temperature : oc Fuel feed for 120 kw : 300 kg/hr Fuel feed for 58 kw : 150 kg/hr

11 Gasifier system performance specifications Biomass consumption < 1.3 kg/hr/kwe (woody biomass) < 2.4 kg/hr/kwe (non-woody biomass) Gas production 2 ± 0.2 Nm3 / hr/kwe Turn down ratio 3:1 Gas quality Tar<100 mg Nm3 Particulate matter <50 mg//nm3 Diesel replacement >65% Avg. CV from woody biomass >1075 KCal/NM3 Avg. CV from non woody biomass >955 KCal/NM3

12 Gasifier : Performance Rated Electrical output in KW Wood/ rice husk consumption in kg/hr Acceptable moisture content % < 20 < 20 < 20 < 20 Average gas calorific value (kcal/nm 3 ) >1100 >1100 Gas flow required Nm 3 /hr Thermal rating (000 kcal/hr) Diesel replacement (lt/hr) Hopper capacity in kgs Auxiliary power consumption in kw Water requirement in lt/hr 250 Gas composition CO H 2 CH 4 CO 2 N 2 V/V % < Approximate price of gasifier (US $) Total project cost ( US $ )

13 Cost Economics of fuel replacement in Updraft gasifier

14 Cost Economics of fuel replacement in Updraft gasifier

15 Applications

16 Thermal use of producer gas Thermal energy of the order of 4.5 to 5.0 MJ/m 3. Flame temperatures as high as 1200 o C can be obtained by optimal pre-mixing of air with gas. Few of the applications: Dryers: Drying applications in farm products, food and spices industry like large cardamom, ginger, rubber and tea (Temp. requirement oC). Kilns: Baking of tiles, potteries(temperature requirement oC). Furnaces:For melting metals and alloys in non-ferrous (Temperature requirement ~ oC). Boilers: Process industries, which require steam or hot water like silk reeling, dyeing, turmeric boiling, cooking, jaggery making etc.

17 Electricity generation from producer gas Electric power generation from few kw to MW, either for local consumption or for grid power To operate diesel engine on dual fuel mode with 80-85% diesel replacement To operate gas engine on 100% mode To operate water pumps for irrigation purpose

18 Range of applications

19 Schematic : Power generation mode

20 Schematic : Thermal mode (scrubbed gas)

21 Schematic : Thermal hot gas mode

22 Case :Gasifer based dual fuel power generation in rural areas, India Why gasifier based Dual fuel power generation is suitable for rural area? Employment issues : Diversion of excess manpower to rice husk transportation and preparation Utilization of the rice residues unsuitable for industrial processing Considerably lower costs per produced kwh electricity with wood-gas dual fuel than with diesel oil. Low capital cost involvement compared to even min/micro hydel project and no threat to ecological balance as in the case of every hydel project A renewable & clean non polluting fuel suitable for rural environment.

23 Operating Economics Diesel Dual fuel Diesel Dual fuel Diesel Dual fuel DG set capacity (KW) Gross Heat Rate on LCV at standard reference conditions Diesel fuel required in lt/hr Qty. of bio-gasified gas required in NCM Equivalent wood mass kg/hr (70% DR) Available energy KWH (10% loss) per hour Available energy KWH per year (10 hr x 300 days) Cost of diesel per hour (@ Rs per ltr) US $ Cost of wood per hour (@ Rs.2.5/kg) US $ Total running cost Rupees per hour US $ Running Cost per unit (Rs. Per KWH) US Cents

24 Capital Expenditure Diesel Dual fuel Diesel Dual fuel Diesel Dual fuel DG set capacity (KW) Miscellaneous and commissioning cost Gasifier dual fuel project cost Bank loan Maintenance cost (Cents/kWh) Interest cost per unit (cents/kwh) Depreciation cost per unit (cents/kwh) Cost of generation cents/kwh Total cost (cents/kwh) Benefit per unit (cents/kwh)

25 Payback period Diesel Dual fuel Diesel Dual fuel Diesel Dual fuel DG set capacity (KW) Payback for 10 hours, 300 days operation Total yearly kwh generated and available Total savings per year by dual fuel operation (US $) Pay back period in months for total investment Payback for 16 hours, 300 days operation Total yearly kwh generated and available Total savings per year by dual fuel operation (US $) Pay back period in months for total investment

26 *Case : Tobacco curing, Myanmar Tobacco curing is a traditional industry practiced Tobacco plantations are traditionally livelihoods activity in and along the banks of Ayeyarwadi River. Tobacco planting period is from October to January. Tobacco leaves are to be cured within 72 hours after picking them up from the plants. The curing season is usually from February to May. There are about 108 tobacco plants running in Myingyan Township. * Project implemented by TERI India

27 Case.Contd. The maximum temperature needed is 80 C In curing of tobacco, hot air is used by passing through the flue pipes. Fuel wood consumption for one process is 7500 kg. At present, firewood, obtained by cutting and collecting the trees Prosopies, juliflora from the remaining natural forest.

28 Curing Plant : front View

29 Different views

30 Comparison between Traditional Method and Gasifier Method No Description Traditional Method Gasifier Method 1 Type of fuel Wood-fuel Biomass (Pigeon bean stalk) 2 Wt. of tobacco to be cured 3500 kg About 3500 kg 3 Total wt. of fuel required kg 1600 kg 4 Working days for curing 5 6 days Max. 5 days 5 Total time of curing 110 hours 120 hours About 90 hours 6 Wt. of cured tobacco (expected) kg About 575 kg 7 Labor requirement 3 5 workers 1 2 workers 8 Quality of output Good grades than traditional method

31 Case : Large cardamom drying Large cardamom is major cash crop of Sikkim Cardamom is small farmers business (more than 85% with small <2ha area) Still primitive smoking method used for in poor quality product Traditional bhatti system: low (5--10%) efficiency: huge fuel wastage (estimated wastage: 20,000 MT in Sikkim)

32 Improved system More than 60% fuel wood saving Retains 35% more volatile oil Retains natural colour (better appeal) Pays back itself in one curing season

33 Important lessons: Thermal Applications Introduction of a gasifier is not just an addition, but an integration (both technological and cultural) with the existing traditional/conventional practice Strong QA/QC (specially material selection, welding quality, casting and curing of high temperature insulation) needs to be enforced User education/training is critical for ensuring Use of properly sized/dried wood Safety Options for short term/long term linkages for sustainable biomass supply need to be explored

34 Important lessons: Gasifier power plant Major scope where biomass is produced in-situ e.g. rice mills High degree of social mobilization needed for running rural power plants sustainably. Tariff collection on a continued basis is a big challenge, which can probably be leveraged by livelihood and income generation activities (Needs substantial state support). The capital costs of establishing distributed generation and microgrids are about 50% higher than centralized power at present and can be brought down further. The economic costs of providing electricity to remote users are also comparable for both routes. Plant availability can be made as high as desired through training of local operators. Increasing the PLF, however, needs sustained efforts. Control of engine is largely manual. Servicing of engines and gasifier systems is a major cost item at present

35 Other implemented cases Wood/coconut shells/cashew shells/stalks etc replacing Wood Charcoal ENTERPRISE TYPE MICRO SMALL COMMUNITY Silk,Cardamom in India Nepal, Bhutan: Arecanut processing MgCl 2 ; PoP, Tobacco curing Green brick drying, Bamboo mat factory CO2 manufacturing Community cooking, Residential Hostels, Crematoria (D) Diesel/Furnace Oil Silk dyeing Rubber drying Canteens Bakeries Electricity Crematoria Water heaters in hostels LPG Other Fuels (tyres /rice husk) Sweet making Puffed rice

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