Biomass Gasification

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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.

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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
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Biomass Characterization
Biomass fuel characteristics Biomass fuel characteristics Biomass fuel characteristics Biomass fuel characteristics Biomass fuel characteristics
Moisture Volatiles Fixed carbon Ash Lower heating value (wet fuel)
8.9 wt 74 wt 16.5 wt 0.6 wt 16.6 MJkg-1
TG/FTIR Perkin Elmer Spectrum GX
oxidizing atmosphere
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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
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Biomass
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Waste Materials
Material name Heat value (kcal/kg)
Paper 4,000
News paper 5,100
Craft paper 3,800
Polyethylene (PE) 11,000
Polypropylene (PP) 11,100
Polystyrene 9,600
Styrofoam 10,000
Fiber reinforced plastic (FRP) 3,900
Phenol resin 5,800
Thermal plastic resin 10,000
PET bottle 5,600
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Shape and Bulk of Biomass Energy
Corn Waste
Palm Waste
Rice Husk
Wooden Chip
Sugarcane
Wooden Chip
Wooden Pellet
Refuse Derived Fuel (RDF)
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Bio-fuel Conversion Options
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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 800C) 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

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Gasification technology

• The elements

Cooling and Cleaning system
AIR
GASIFIER
Engine
Secondary Air
BURNER
PRODUCER GAS
HEAT
Performance Biomass consumption 1 1.3
kg/kWh
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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 CO
2 18 N2 0 (tars particulate)
Fuel Gases
Heat
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Producer Gas - Composition
Particulars Rice Husk Woody Biomass
CO 15-20 15-20
H2 10-15 15-20
CH4 Upto 4 Upto 3
N2 45-55 45-50
CO2 8-12 8-12
Gas C.V. (kcal/Nm3) Above 1050 Above 1100
Gas generated in Nm3/kg of biomass 2 2.5
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Biomass Gasification

• Basic Process Chemistry
• Conversion of solid fuels into combustible gas
  Producer gas (CO H2 N2) Syngas (COH2)
• Involves partial combustion of biomass
• Four distinct processes in the gasifier viz.
• Drying
• Pyrolysis
• Combustion
• Reduction

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Main Reactions

• Wood (Pyrolysis) C slightly endothermic
• C O2 ? CO2 (?H0 -391,6 kJ mol-1) exothermic
• C H2O ? COH2 (?H0 131,79 kJ mol-1)
  endothermic
• C CO2 ? 2 CO (?H0 179,3 kJ mol-1)
  endothermic
• CO H2O ? CO2 H2 (?H0 - 47,49 kJ mol-1)
  slightly exothermic
• C 2H2 ? CH4 (?H0 - 22 kJ mol-1) slightly
  exothermic
• With the operating parameters (Pressure,
  Temperature) it is possible to select a gas
  containing more Syngas (COH2) or more SNG (CH4)

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

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Updraft Gasifier

• Simple, reliable
• Commercial history
• High tars
• Close coupled combustion

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Downdraft Gasifier

• Requires low moisture lt20)
• Lowest Tar
• Can use gas in engines
• (after conditioning)

Biomass
Air
Pyrolysis
Combustion
Gas, Tar, Water
Reduction
Ash
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Fluidized Bed Gasifier

• Highest throughput
• Fuel flexible
• Tolerates moisture
• Complex operation

Product Gas
Freeboard
Ash
Fluid Bed
Biomass
Air/Steam
Plenum
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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
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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 800-1000C
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Circulating Fluidized Beds
Example FERCO (Battelle)
Numerous systems have been developed since
1980 - KUNII - FERCO - TNEE - RENET - Metso
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Circulating Fluidized Beds
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Fluidized Bed Boiler Technology for Renewable
Energy
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Entrained Flow Gasification
(Steam Reforming)
Flue Gas
850 C
Synthesis gas
Biomass
Char
Burner
Gas Slip stream
Steam
Air
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Staged Gasification
Pyrolysis
Steam Reforming
850 C
Biomass moisture
Vapors steam
Synthesis Gas
700 C
Burner
Burner
Carbon Conversion Technologies 2004
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Rotary Steam Gasifier
Controlled Amount of Air
Medium Btu Gas
Rice Husk
Superheated Steam
Rotary Drum
Ignition Burner
Driving Machinery
Stoker
Carbon -silica mixture
Ash
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Main kinds of Reactors for Gasification
Updraft and Downdraft Gasifiers have 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 control compared to fixed bed
gasification DrawbacksLow 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.
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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
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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

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The World Energy Demand is Growing Dramatically
Biomass Energy Contribution
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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
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GLOBAL MEAN ANNUAL SURFACE TEMPERATURE WITH UNCERTAINTY BANDS Per Year from 1855 through 2005

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    Atmospheric CO2 for November 2010 Preliminary
data released December 14, 2010 (Mauna Loa
Observatory NOAA-ESRL)
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No Net Increase In Carbon Dioxide
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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.

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Assessment Processes for use of Biomass
Combustion processes ( ? gt 1 ) are controlled
best. Large plants available. Efficiency factors
relatively low due to thermodynamic reasons,
limits reached. Gasification processes (thermal ,
0 lt ? lt 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 (gt10 MW) fluidised
bed gasifiers are of advantage. High utilization
potential. Pyrolysis (? 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.

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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-voltaic
50 60 biomass 10 12 wind 5
6 water 3 5 Conventional nuclear
energy 2 3 coal 2
3 gas 2 3
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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

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Thank You for Your Attention