Gasification and Pyrolysis

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International Academy of Wood Science Meeting 2006
Has Thermo-chemical Conversion of Wood a Future
? by Xavier DEGLISE Emeritus Professor at
University Henri Poincaré, Nancy 1
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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

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Forest Biomass represents 2230 MTOE/year (without
deforestation) around 65 of 3365 MTOE in
potential Renewable Energies. Biomass could
fulfill 22 of the actual world energy needsand
Wood is the major biomass!
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But, there is a lot of issues for Forests!
3. Nature oriented management
Vulnerability and extremes
1. Climate change
2. Increased demand incl. bio energy
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Forests resources are increasing vs time! C
sequestration
European forest sector carbon balance 1950 1999
(Nabuurs et al. 2003) Pg C y-1 Petagram C / year
1015 gram / year
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In EU 25, still fellings remain rather stable,
and the resource is growing fast!
Latest German inventory gave a net annual
increment of 12 m3.ha-1.y-1
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Bio energy will lead to an extra demand
Current oil price rise 100 /ton CO2 carbon
tax
Value added will be very low but the stove
needs to burn
Suitability of residue extraction from EU 25
forests
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Extra Resource Wood Biomass ?
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Wood Residues
Source of Residue Type of Residue
Forest operations Branches, needles, leaves, stumps, roots, low grade and decayed wood, slashings and sawdust
Pulp industry, Sawmilling and planning Bark, sawdust, trimmings, split wood, planer shavings
Plywood production Bark, core, sawdust, veneer clippings and waste, panel trim, sanderdust
Particleboard production Bark, screening fines, panel trim, sawdust, sanderdust
Wood Wastes Packing material, old wooden furniture, wooden building waste (demolition wood)
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Estimated potential of Wood Residuesin the World

• Overall quantity of WR 2,000 MT/y or 650
  MTOE/y to compare with
• 7,000 MT/y of Forest biomass or 2 230 MTOE/y
• WR 30 of potential Forest Biomass

Matti Parikka, Biomass and Bioenergy 27 (2004)
613620
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Wood Residues vs Clean Woodin France

• Overall quantity of WR 16 MT / year to compare
  with
• 23 MT / Year of processed wood (5 MT/y
  imported)
• 40 MT / Year of Wood biologically produced by
  the forest
• 20 MT / Year of Fuel Wood (estimated) with 80
  domestic consumption
• WR represent an important source of Biomass (5.5
  MTOE)but is scattered!
• WR corresponds only to 6 of the oil consumption
  (96 MT/y)

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Biomass upgrading into Energy or Chemicals

Co-combustion
Electricity Heat
Biomass
Direct Combustion
Fuel cells
SNG DME H2 Fischer Tropsch hydrocarbons Alcohol
s Methanol Ethanol Bio-fuel
Engine Turbine
Gasification
Pyrolysis
Direct Liquefaction
N/A ?
Bioprocesses
N/A ?
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Overview of Wood thermal Processes
Wood
(Co) combustion
Gasification
Pyrolysis
Direct Liquefaction
slow fast, flash
Atmospheric or pressurized O2, air, H2O
H2O, critical conditions, Hydro liquefaction
(H2) High Pressure
Direct heating
Indirect Heating
Flue gas
char oil gas
Liquid biomass Heavy bio-oil
syngas
Upgrading treatment
Synthesis/cleaning
Engine or Turbine
Bio-fuels
Charcoal
Heat and Electricity
CH3OH, CnHm, H2
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Operating conditions of the thermal processes
Thermal Process Temperature Atmosphere Products Mean overall Yield
Combustion gt 900C O2 (air) CO2 H2O N2 ashes to be treated 65
Pyrolysis lt 500C Inert gas or Low pressure char tars gas, which proportions are related to the pyrolysis parameters 45
Gasification by Fast pyrolysis gt 700C Inert gas or Low pressure Mainly gas (CO, H2, CH4, C2H4 ) with low quantity of char used 75
Gasification gt 800C Air or H2O vapour Gas (H2, CO, CO2, CH4, N2) ashes to be treated 50-60
Liquefaction by Fast Pyrolysis lt 550C Low pressure High viscosity liquid (phenols) 75
Direct Liquefaction 300C- 350C Slurry in water CO High pressure High viscosity liquid (phenols) non soluble in water 80
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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

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Pyrolysis is the Key Reaction of all the thermal
Processes
WOOD
Cutting or Grinding
Drying
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Mechanism of the pyrolysis
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Operating conditions of the pyrolysis process
PAH
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To lower the PAHs

• Naphtalene, Anthracene, Pyrene, Benzopyrene
  which are formed during the pyrolysis step of the
  thermal conversion, it is compulsory
• to decrease the Residence Time
• to increase the Temperature
• when it is possible!

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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

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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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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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Main kinds of Reactors for Gasification
Updraft and Downdraft reactors have been
developed since 1930. They produce a low BTU
Gas ( 6000 KJ/m3) with tars. Actually the new
systems use mainly fluidized beds and circulating
fluidized beds.but they are often too
complicated energy output lt energy in put!
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Problems with Tars!
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Circulating Fluidized Bed
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Advantages of Gasification by fast Pyrolysis in
a Circulating Fluidized Bed System

• product gas nearly free of nitrogen
• calorific value higher than 13 MJ/Nm³
• very low tar content due to steam gasification
• gas quality is independent of water content in
  biomass feed
• now, the apparatus are compactnot enough!
• a wide range of feedstock can be gasified
• possibility to use a catalyst as bed material
  (regeneration of catalyst in combustion zone) to
  influence the gas composition and gasification
  kinetic in a more positive way
• But sometimes energy output lt energy input!

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Circulating Fluidized Beds
Numerous systems have been developed since
1980 - KUNII - FERCO - Our (TNEE) - RENET
(Güssing) - .
Example FERCO (Battelle)
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We have an old expertise in wood gasification in
dual fluidized bed pyrolysis, until the pilot
scale A pilot with a capacity of 500Kg/H pine
barks was operating in a pulp mill in
1984/1985. Its power was around 2 MW and it
produces a medium BTU Gas (HHV around 16000 KJ/m3)
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20 Years later.always the same process developed
in the RENET Biomass Power Station, Güssing,
Austria (Schematic layout)
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Photos of the RENET Pilot which start in Austria
in 2001
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Circulating Fluidized Bed with CO2 Absorber
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Complete Syngas Process
Flue Gas
Fly Ash removal
Shift Reactor
Wet scrubber
CO2 elimination
Heat Exchangers
Gas compression
Gasifier
Combustor
Catalyst heat carrier
Water treatment steam production unit
Synthesis Gas
Bottom Ash Extraction
Air
Dried Biomass
Steam
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Optimum Capacity of Gasification Processes
10t/h could be a great maximum for RW
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• To solve the problem of capacity, it is necessary
  to have a pre-treatment process producing a char
  from different kinds of biomass, which could be
  then transformed at a larger scale.
• Such a system is proposed for the production of
  Hydrogen from Biomass
• The Philosophy of this two step process could be
  adapted, as the optimum input feed of the
  gasification must be over 10T/H

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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

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Van KREVELEN Diagram giving the elementary
Composition and yield of Charcoal vs
carbonization temperature It is possible to
select which kind of Char you want high
Carbon content high Yield .. Porosity
depends on the heating Rate
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Low temperature Pyrolysis for Wood Residues The
Chartherm Process

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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

Liquid fuels from Syngas
Liquid fuels from Pyrolysis
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With Syngas we can produce Hydrocarbons or
Methanol
For hydrocarbons the main Reaction of Fischer
Tropsch Synthesis
n CO (m/2 n) H2 CnHm nH20
Catalyst (metal oxides)
The relative proportion of CO and H2 vary as a
function of what you want gas or diesel
This process is used in RSA, its name is SASOL,
producing around 15 Mio T/y of liquid fuel
For methanol the main reaction is
CO2H2 CH3OH
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Biomass-derived Fischer-Tropsch diesel production

• energy efficiency from tree-to-barrel 44light
  products 11, power 14overall energetic
  efficiency about 69

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Stepwise gasification to bio-diesel production
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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

Liquid fuels from Syngas
Liquid fuels from Pyrolysis
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Wood Liquefaction via Fast Pyrolysis

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Wood Liquefaction via Fast Pyrolysis

Bubbling fluid bed reactor with electrostatic
precipitator
Circulating fluid bed reactor
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Wood Liquefaction via Fast PyrolysisProduct
Yield vs temperature

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Bio-oil from fast Pyrolysis
The crude pyrolysis liquid or bio-oil is dark brown and approximates to biomass in elemental composition. Ready substitution for conventional fuels in many stationary applications such as boilers, engines, turbines Heating value of 17 MJ/kg at 25 wt. water, is about 40 that of fuel oil / diesel Does not mix with hydrocarbon fuels Not as stable as fossil fuels

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• Direct Hydrothermal Liquefaction
• Direct hydrothermal liquefaction involves
  converting Wood to an oily liquid (crude oil), in
  a pressurized reactor with CO
• The reaction was
• CO wood product CO2 reduced wood
• Wood react with CO, (in fact H2 coming from a
  shift reaction, COH2O CO2H2) in water at
  elevated temperatures (300-350C) with sufficient
  pressure to maintain the water primarily in the
  liquid phase (12-20 MPa) for residence times up
  to 30 minutes.

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• Direct Hydrothermal Liquefaction (continued)
• The overall approx. stoichiometry is
• 100 Kg wood 1 mol CO 2.2 mol CO2 1 mol H2O
  55 Kg of non vapor product.
• oil yield was 33 of dry wood feed with a rather
  high energy content, giving a high energy yield,
  around 65 of the HHV of wood.
• Hydrothermal treatment is based on early work
  performed by the Bureau of Mines Albany
  Laboratory in the 1970s.

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• Introduction
• Pyrolysis
• Gasification
• Carbonisation
• Liquefaction
• Conclusion

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• Actually, all the thermo-chemical processes are
  not able to convert wood into liquid fuels.
• The main problems are
• Capacity of the plant in relationship with the
  input feed
• How to use different sources of dry biomass
  (residues from forest and wood industries,
  treated wood, wastes)
• What to do with the by-products of the different
  steps of the conversions (gas, liquid or solid)
• Energy efficiency

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Idea ?
Charcoal
Treated Wood wastes
SNG
Untreated Wood Wastes Primary Processing
Charcoal
Methanol
Gasification CO H2
Recovered wood from Forest Operations Thinnings.
Charcoal
Bio-diesel (FT)
Hydrocarbons (FT)
Charcoal
Dry urban Wastes Paper, cardboard
Pyrolysis
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Questions?