Biomass Gasification

1. Biomass Gasification Presented by Dr. S.S. Sambi G.G.S.I.P.University, Delhi On 18 th December, 2010 At Fluor Daniel India Pvt. Ltd.

2. Biomass Constituents • Hemicellulose: 23-32%Polymer of 5 & 6 carbon sugar Lignin: 15-25% Complex aromatic structure Very high energy content Cellulose: 38-50% Polymer of glucose, very good biochemical feedstock Process CH 1.4 O 0.6 BIOMASS Gas Coke Aqueous Phase Oil Pratical applications require its trasformation into gas or liquid derived fuel

3. Inert Atmosphere 120 900 800 100 Aldehydes acids C=O 700 CO2 80 600 500 sample temperature (°C) weight loss (%) 60 Esters Formic acid C-O- 400 Absorbance 40 300 H2O H2O O-H Alkanes C-H 200 CO 20 800°C 100 0 0 35°C 0 50 100 150 200 Wavenumber (cm-1) time (min) Infrared stack plot of wood chip thermal decomposition Maple wood weight loss versus time and temperature program (25 mg, size range 125-212 microns) Maple wood chips Biomass Characterization TG/FTIR Perkin Elmer Spectrum GX oxidizing atmosphere

4. Biomass Feedstocks Forest Wood Residues Agricultural Residues Energy Crops • Thinning Residues • Wood chips • Urban Wood waste • pallets • crate discards • wood yard trimmings Corn cobs Rice hulls Sugarcane bagasse Animal biosolids Hybrid poplar Switchgrass Willow

5. Biomass

6. Waste Materials

7. Shape and Bulk of Biomass Energy Corn Waste Palm Waste Rice Husk Wooden Chip Sugarcane Wooden Chip Wooden Pellet Refuse Derived Fuel (RDF)

8. Bio-fuel Conversion Options

9. Air, Steam, CO2, and/or O2 CO, H2, CO2, H2O, CH4, C2H4 + unconverted tars (all organic compound with mass > C6H6) Biomass Gasification Process One of the best ways to optimize the extraction of energy from biomass and to obtain a standardized gas starting from very different materials BIOMASS Low Calorific Value: 4 - 6 MJ/Nm3 Using air and steam/air Medium Calorific Value: 12 - 18 MJ/Nm3 Using oxygen and steam • The main challenges of biomass gasification are: • Good control of temperature in the reactor • High heating rate (hundreds of degrees per second) and high temperatures (around 800°C) are necessary to maximize the gas yield • TARS conversion • TARs condense in the cold parts  plugging of tubes or agglomeration phenomena • TARS removal by filtration  lost of efficiency since they still contain energy

10. Gasification technology • The elements AIR Cooling and Cleaning system GASIFIER Engine Secondary Air BURNER PRODUCER GAS HEAT • Performance • Biomass consumption : 1 – 1.3 kg/kWh

11. Gasification Air (0.3) O2 (0.3) Steam Producer Gas (mol%) CO 24 H2 13 CH4 3 CO2 8 N2 52 (tars & particulate) Synthesis Gas (mol%) CO 39 H2 20 CH4 17 C2H2 6 CO2 18 N2 0 (tars & particulate) Fuel Gases Heat

12. Producer Gas - Composition

13. Biomass Gasification Basic Process Chemistry • Conversion of solid fuels into combustible gas Producer gas (CO + H2 + N2); Syngas(CO+H2) • Involves partial combustion of biomass • Four distinct processes in the gasifier viz. • Drying • Pyrolysis • Combustion • Reduction

14. Main Reactions • Wood (Pyrolysis) C slightly endothermic • C + O2 CO2 (ΔH0= -391,6 kJ mol-1) exothermic • C + H2O  CO+H2 (ΔH0 = + 131,79 kJ mol-1) endothermic • C + CO2 2 CO (ΔH0 = + 179,3 kJ mol-1) endothermic • CO + H2O  CO2 + H2 (ΔH0 = - 47,49 kJ mol-1) slightly exothermic • C + 2H2 CH4 (ΔH0= - 22 kJ mol-1) slightly exothermic • With the operating parameters (Pressure, Temperature) it is possible to select a gas containing more Syngas (CO+H2) or more SNG (CH4)

15. Gasification Thermochemical Reactions C + CO2 2 CO (Boudouard) 800° - 850° C C + H2O CO + H2 (Water gas shift)

16. Gasifier Types Design Basis: Fuel Properties, End Use, Scale, Cost • Updraft • Downdraft • Fluidized Bed • Bubbling • Circulating Flow • Entrained Flow • Staged (pyrolysis / steam reforming) • Rotary Steam Gasifier

17. Updraft Gasifier • Simple, reliable • Commercial history • High tars • Close coupled combustion

18. Downdraft Gasifier • Requires low moisture <20%) • Lowest Tar • Can use gas in engines (after conditioning) Biomass Air Pyrolysis Combustion Gas, Tar, Water Reduction Ash

19. Fluidized Bed Gasifier • Highest throughput • Fuel flexible • Tolerates moisture • Complex operation Product Gas Freeboard Fluid Bed Ash Biomass Plenum Air/Steam

20. : Bed hot particles :Biomass and char :Grid Bubbling fluidized bed (BFB) BFB combustion can be applied to a wide range of fuels, from dry-wood fuel and peat to high-moisture forest residues, sludge and even solid recovered fuels. BFB unit normally operates in a reducing atmosphere (less air than is needed for combustion), does not have as great an ability to absorb sulfur dioxide, and normally is used to burn lower-quality fuels with high volatile matter. Further, the BFB unit keeps most of the sand in the lower furnace. BFB generate power in the range of approx. 10-60 MW. Metso BFB

21. Circulating Fluidized Beds - CFBG The fast fluidization and continuous circulating of char enhance heat and mass transfer, raise reaction rate, strengthen fast pyrolysis, reduction and shift as well as other gas-solid reactions. The productivity and gas quality much better than other kinds of gasifiers i.e. 2000 kg/m²h and 7000 kJ/m³ Fast pyrolysis, reduction, shift and secondary reactions and higher heat efficiency are favoured at Equivalence Ratio: 0.2-0.28 and Reaction temperature :800-1000°C

22. Circulating Fluidized Beds Example: FERCO (Battelle) Numerous systems have been developed since 1980: - KUNII - FERCO - TNEE - RENET - Metso

23. Circulating Fluidized Beds

24. Fluidized Bed Boiler Technology for Renewable Energy

25. Entrained Flow Gasification (Steam Reforming) Flue Gas 850 C Synthesis gas Biomass Char Burner Gas Slip stream Steam Air

26. Staged Gasification Pyrolysis Steam Reforming 850 C Biomass + moisture Vapors + steam Synthesis Gas 700 C Burner Burner Carbon Conversion Technologies 2004

27. Rotary Steam Gasifier Medium Btu Gas Controlled Amount of Air Rice Husk Superheated Steam Rotary Drum Ignition Burner Driving Machinery Stoker Carbon -silica mixture Ash

28. Main kinds of Reactors for Gasification Updraft and Downdraft Gasifiershave been developed since ~ 1930.These produce a low BTU Gas (~ 6000 kJ/m3) with tars. Bubbling Fluidized Bed and Circulating Fluidised Bed are similar in that both use a "bed" of inert material (normally the bed is sand) which is then "fluidized" by high-pressure combustion air.  Advantages: Good gas and solid mixing, uniform temperatures and high heating rates, greater tolerance to particle size range and safer operation due to good temperature controlcompared to fixed bed gasification Drawbacks:Low density biomass fuel w.r.t. bed particles, segregation increases by the formation of volatiles and gaseous species bubbles around the fuel particle, reducing the conversion rate. Fine carbon particles produced in the reaction process elutriate (increasing the solid load to the cyclone and the filter). Fused ash and tar condensation provokes defluidization.

29. Biomass Thermal Conversion Developers Liquefaction Syngas (fuels) Producer gas (CHP) High Pressure Changing World Technologies GTI – U.S. Carbona – Finland Foster Wheeler – U.S. O2 10-25 MPa 1-3 MPa Ensyn -Canada Dynamotive- Canada ROI – U.S. BTG –Netherlands Fortum -Finland Carbona – Finland Lurgi – Germany Foster Wheeler – U.S. EPI – U.S. Prime Energy – U.S. FERCO – U.S. MTCI- U.S. Pearson – U.S. Carbon Conversion Technology – U.S. Indirect heat Low Pressure 0.2 MPa Air 300-600 C 700- 850 C

30. Possible Applications of the Product Gas • co-combustion in a coal power plant • co-combustion in a natural gas power plant without modifications at the burners • production of electric energy in a gas turbine • production of electric energy in a gas engine • production of electric energy in a fuel cell • as synthesis gas in the chemical industry • as reduction gas in the steel industry • for direct reduction of iron ore • for production of Synthetic Natural Gas by methanation • for production of Liquid Fuels by Fischer-Tropsch

31. The World Energy Demand is Growing Dramatically Biomass Energy Contribution

36. Emissions from Fossil Fuels This means combustion of increasing amounts of fossil fuels and release of considerable amounts of CO2 International Energy Outlook 2003, www.eia.doe.gov/oiaf/ieo/pdf/highlights.pdf, accessed July 30, 2004

38. Atmospheric CO2 forNovember 2010 Preliminary data released December 14, 2010 (Mauna Loa Observatory: NOAA-ESRL)

39. No Net Increase In Carbon Dioxide

40. Environmental Benefits • The burning of fossil fuels releases carbon dioxide captured by photosynthesis millions of years ago. • In contrast, carbon dioxide released through the consumption of biomass is balanced by carbon dioxide captured in the recent growth of biomass • Results in a far less net impact on greenhouse gas levels. • Millions of tons of waste that goes to landfills could be used for energy production • Preservation of agricultural land that would otherwise be sold for development. • Encourages sustainable agricultural techniques for bioenergy crops.

41. Assessment: Processes for use of Biomass Combustion processes ( λ> 1 ) are controlled best. Large plants available. Efficiency factors relatively low due to thermodynamic reasons, limits reached. Gasification processes (thermal ,0 < λ< 1) not yet marketable even after long period of research, but high efficiency factors foreseeable (2-3 times higher compared to combustion), Problems of gas purification largely solved. In small to average power range (up to 2 MW) fixed-bed gasifiers are advantageous, in average to high power range (>10 MW) fluidised bed gasifiers are of advantage. High utilization potential. Pyrolysis(λ = 0) to a mixture of gas, liquid and low-temperature coke in very differently designed procedures as „slow“, „fast” and „flash“ pyrolysis. The varying products are processed in very different ways. Fermentation (methane fermentation, microbial) is only partially an energetic utilization process (biogas), which originally served disinfection. Remarkable technical state, but compared to gasification small speed of reaction, low efficiency factor, great reactor volume required, and after-care of fermented liquid manure necessary. Liquefaction (alcoholic fermentation, extraction, compression)to bio-fuels is facing technical and economical difficulties. Mixing the products with conventional fuels is also being tested.

42. Electricity Production Costs The specific electricity production costs Ce are defined as the sum of the costs (costs of capital + operating costs + costs of materials), which has to be expended to generate one kWh of electricity. Way of Generation Ce in EuroCent/kWh Renewable photo-voltaic50 – 60 biomass10 – 12 wind 5 – 6 water 3 – 5 Conventional nuclear energy 2 – 3 coal2–3 gas 2 – 3

43. Conclusion • In view of the demand for sustainable development and the shortage of fossil fuels the possibilities of use of biomass are on the increase especially • The bio-energy will become competitive and play significant role because of the rapid increase of energy prices • The gasification of biomass is to be seen as especially profitable, because the gasification technology is considered the basis of extremely pure liquid fuels, which are able to fulfil all waste gas norms. • Global warming is already causing havoc still is remains doubtful whether the main part of the future energy supply will be made up of renewable energy. • The most important line of future energy supply should be through saving of energy

44. Thank You for Your Attention