Transcript Gasification and Pyrolysis

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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1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
6. 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 needs…and 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
Forest owner
behavior
1. Climate
change
4. Forestry in
broader context
of all land uses
2. Increased demand;
incl. bio energy
New giants:
New services &
functions:
Russia, China
C sequestration
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-1
Components of the total forest sector sink (Pg C y )
Forests resources are increasing vs time!: C sequestration
0,170
Tree Biomass
Coarse woody debris
Forest floor
0,120
Mineral soil
Wood Products
Total
0,070
0,020
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
-0,030
European forest sector carbon balance 1950 –1999 (Nabuurs
Pg C y-1= Petagram C / year =1015 gram / year
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et al. 2003)
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In EU 25, still fellings remain rather stable,
and the resource is growing fast!
Mil. m3 over bark
800
700
600
500
Net annual increment
400
Fellings
300
200
100
0
1950
1960
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1970
1980
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2000
Latest German inventory
gave a net annual
increment of 12 m3.ha-1.y1
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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
Forest operations
Pulp industry, Sawmilling
and planning
Type of Residue
Branches, needles, leaves, stumps, roots,
low grade and decayed wood, slashings and
sawdust
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 Residues
in 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) 613–620
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Wood Residues vs “Clean Wood”
in France

Overall quantity of WR: 16 MT / year to compare with
o
~ 23 MT / Year of processed wood (5 MT/y imported)
o
~ 40 MT / Year of Wood biologically produced by the
forest
o
~ 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
Biomass
Direct
Combustion
Gasification
Pyrolysis
Direct
Liquefaction
Electricity
Heat
Fuel cells
Engine
Turbine
N/A ?
SNG
DME
H2
Fischer Tropsch
hydrocarbons
Alcohols
Methanol
Ethanol
Bio-fuel
Bioprocesses
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N/A ?
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Overview of “Wood thermal Processes”
Wood
(Co) combustion
Flue gas
Pyrolysis
Direct Liquefaction
slow
fast, flash
H2O, critical conditions,
Hydro liquefaction (H2)
High Pressure
Gasification
Atmospheric or pressurized
O2, air, H2O
char
oil
gas
Liquid biomass
Heavy bio-oil
Direct
heating
Indirect
Heating
syngas
Upgrading treatment
Engine or Turbine
Heat and Electricity
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Synthesis/cleaning
Bio-fuels
Charcoal
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CH3OH, CnHm, H2
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Operating conditions of the thermal processes
Thermal Process
Temperature
Atmosphere
Products
Mean
overall
Yield
Combustion
> 900°C
O2 (air)
CO2 + H2O + N2
+ ashes to be treated
~ 65 %
Pyrolysis
< 500°C
Inert gas or
Low pressure
char + tars + gas, which
proportions are related to
the pyrolysis parameters
~ 45 %
Gasification by
Fast pyrolysis
> 700°C
Inert gas or
Low pressure
Mainly gas (CO, H2, CH4,
C2H4 …) with low quantity of
char used
~ 75 %
Gasification
> 800°C
Air or H2O
vapour
Gas (H2, CO, CO2, CH4, N2)
+ ashes to be treated
50-60 %
Liquefaction by
Fast Pyrolysis
< 550°C
Low pressure
High viscosity liquid (phenols)
~ 75 %
Direct
Liquefaction
300°C- 350°C
Slurry in water
CO High
pressure
High viscosity liquid (phenols)
non soluble in water
~ 80 %
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1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
6. Conclusion
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Pyrolysis is the Key Reaction of
all the thermal Processes
WOOD
Cutting or Grinding
Drying
Pyrolysis
Combustion
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Gasification
Liquefaction
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Charcoal making
Heated Wood
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Mechanism of the pyrolysis
Primary degradation
Char, H2O,
CO, CO2
low T
high T
fragmentation,
decarbonylation(CO),
dehydration(H2O)
acids, acetol,
furfural, lactons,
hydroxyacetaldehyde
Secondary degradation
HOLOCELLULOSE
Secondary
degradation
depolymerization
transglicosilation
levoglucosan
and sugars
high T
LIGNIN
low T
depolymerization
phenols,
methoxyphenols(guaiacols),
dimethoxyphenols(syringols)
Secondary
degradation
Carbonyl
compounds,
furans, phenols,
CO, CO2
Char, CO, C
O2
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Operating conditions of the pyrolysis process
PAH
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To lower the PAH’s
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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1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
6. 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 + 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)
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C slightly endothermic
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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 < energy in put!
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Problems with Tars!
air/quartz
vapeur/quartz
vapeur/olivine
Güssing
vapeur/catalyseur
EC project
0
5
10
15
Tar content (g/Nm3 dry gas) in the fuel gas
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Circulating Fluidized Bed
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 compact……not 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 < energy input!
Circulating Fluidized Beds
Numerous systems
have been developed
since 1980:
- KUNII
- FERCO
- Our (TNEE)
- RENET (Güssing)
- ………….
Example: FERCO (Battelle)
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)
fumées
(950°C)
cyclone
dépoussièreur
gaz de pyrolyse
(850°C)
caloporteur
(950°C)
lit transporté
de combustion
(950°C)
bois
char + caloporteur
lit en pyrolyse
( ~ 800°C)
gaz de pyrolyse
recyclé (300 - 400°C)
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20 Years later….always the same process developed in the
RENET Biomass Power Station, Güssing, Austria (Schematic layout)
Photos of the RENET Pilot
which start in Austria in 2001
Circulating Fluidized Bed with CO2 Absorber
Complete Syngas Process
Flue Gas
Fly Ash
removal
Wet
scrubber
Shift
Reactor
Heat
Exchangers
Combustor
Catalyst
heat
carrier
Gas
compression
Gasifier
Water treatment &
steam production unit
Bottom Ash
Extraction
Air
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CO2
elimination
Steam
Synthesis
Gas
Dried
Biomass
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Optimum Capacity of Gasification Processes
1 kW
10 kW
100 kW
1 MW
10 MW
100 MW
1000 MW
Updraft
Downdraft
Fluidised Bed
Circulating Fluidised
Bed
Pressurised fluidised
Bed
0,2 kg/h
2 kg/h
20 kg/h
200 kg/h
2 t/h
20 t/h
200 t/h
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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1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
6. Conclusion
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rapport H/C
pétroles
cellulose
1,5
asphaltes
bitumes
200 °C (91,8 %)
lignine
230 °C
1
charbons
bois
300 °C (51,4 %)
400 °C (37,8 %)
charbons
0,5
(rendement de production
en % de la masse anhydre)
500 °C (33 %)
600 °C ( 31 %)
800 °C (26,7 %)
1000 °C (26,5 %)
0
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Van KREVELEN Diagram
giving the elementary
Composition and yield
of Charcoal vs
carbonization temperature
0,2
0,4
0,6
It is possible to select
which kind of Char
you want:
high Carbon content
high Yield
………………..
Porosity depends on the
heating Rate
0,8
rapport O/C
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Low temperature Pyrolysis for Wood Residues
“The Chartherm Process”
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1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
6. Conclusion
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1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
Liquid fuels from Syngas
Liquid fuels from Pyrolysis
6. Conclusion
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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:
CO+2H2 = CH3OH
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Biomass-derived Fischer-Tropsch diesel production
energy efficiency from tree-to-barrel: 44%
light products: 11%, power: 14%
overall energetic efficiency: about 69%
Stepwise gasification to bio-diesel production
1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
Liquid fuels from Syngas
Liquid fuels from Pyrolysis
6. Conclusion
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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
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Circulating fluid bed reactor
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Wood Liquefaction via Fast Pyrolysis
Product 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,
CO+H2O = CO2+H2) in water at elevated temperatures (300350°C) 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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1.
Introduction
2. Pyrolysis
3. Gasification
4. Carbonisation
5. Liquefaction
6. 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 ?
Treated Wood wastes
Untreated Wood Wastes
Primary Processing
SNG
Charcoal
Methanol
Charcoal
Gasification
Recovered wood from
Forest Operations
Thinnings….
Dry urban Wastes
Paper, cardboard
Charcoal
CO + H2
Charcoal
Bio-diesel (FT)
Hydrocarbons
(FT)
Pyrolysis
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Questions?
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