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Gasification of biomass
Lecture no. L3-1
Dr hab. inż. Marek Ściążko
Prof. nadzw.
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Technologies and products of thermo-chemical
biomass conversion
Combustion
Pyrolysis
Gasification
Heat
Gas
Bio-oilstorage
Turbine
Engine
Boiler
Chemicals
Fuels
Hydrogen
Power
Heat
PROCESS MARKETCONVERSIONPRODUCT
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Potential Biomass Gasifier
Feedstocks
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Gasifier Classification
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BIOMASS GASIFICATION TECHNOLOGIES
Pyrolysis
Gasification
Combustion
Ash
Air
Gas
C + CO2 = 2CO
C + H2O = CO + H
2
C + O2 = CO
2
4H + O2 = 2H
2O
Pyrolysis
Combustion
Gasification
Ash
C + O2 = CO2
4H + O2 = 2H2O
C + CO2 = 2CO
C + H2O = CO + H
2
BiomassBiomass
gas
Air
Biomass
Air
Steam
Gas
Ash
Cyclone
CycloneCyclone
Ash
Biomass
Air
Steam
Ash
COUNTER CURRENT/
UPDRAFT
CO-CURRENT/
DOWNDRAFT
BUBBLING FLUIDISED BED (BFB) CIRCULATING FLUIDISED BED (CFB)
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BIOMASA
POPIÓŁ POWIETRZE
GAZ BIOMASA
POPIÓŁ
POWIETRZE
GAZ
A) B)
SUSZENIE
ZGAZOWANIE
PIROLIZA
UTLENIANIE
SUSZENIE
PIROLIZA
ZGAZOWANIE
UTLENIANIE
Fixed bed biomass gasiefiers
Ash Air Ash Gas
Biomass Gas Biomass
Air
Drying
Pyrolysis
Combustion
Gasification
Drying
Pyrolysis
Gasification
Combustion
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Fluid bed reactors features
Ideal radial gas mixing Ideal radial and axial gas mixing
Biomass
Process gas
Oxygen (Air)
Steam
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Gasification steps
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Gasification reactions
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Evaluation of reactors’
characteristics PARAMETERS
Up-draft Down-draft Cross flow Bubbling Circulating
Reaction temperature [C] 1000 1000 900 850 850
Gas temperature [C] 250 800 900 800 850
Throughput [t/h] 10 0.5 1 10 50
Electric power [MWe] 1 - 10 0.1 - 5 0.1 - 2 1 - 20 2 - 100
Tars content v. high v. low v. high medium low
Particulates av. high medium high v. high v. high
Mixing intensity low low low good v. good
Limits for particle size some some some specific specific
Moisture content any limited limited limited limited
Fuel flexibility no effect low effect low effect strong strong
Scaling up limited low low good v. good
Process control medium medium low v. good v. good
Conversion efficiency v. good v. good low good v. good
Thermal efficiency v. good v. good good good v. good
DEVELOPMENT POTENTIAL
EFFECTIVITY
FIXED BED FLUID BED
GAS CHARACTERISTIC
FEEDSTOCK REQUIRAMENTS
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Syngas Contaminants
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GASIFIER CHARACTERISTICS
• P.Quaak, H.Knoef, H.Stassen, ENERGY FROM BIOMASS, A Review of Combustion and Gasification Technologies; World Bank Technical Paper No. 422, Energy Series, 1999
• H.E.M. Stassen, H.A.M. Knoef, SMALL SCALE GASIFICATION SYSTEMS, Biomass Technology Group BV, The Netherlands
• P. Hasler*, Th. Nussbaumer, GAS CLEANING FOR IC ENGINE APPLICATIONS FROM FIXED BED BIOMASS GASIFICATION, Biomass and Bioenergy 16 (1999) 385±395
• A.V. Bridgwater, Fuel 1995, 74 (5), 631.
Parameter Downdraft Updraft CFB
Fuel
-moisture content (%)
-ash content (%, daf)
-size (mm)
< 25
<6
20-100
< 60
<25
5-100
< 25
<25
<20
Gas
- temperature (oC)
- LHV (kJ/mn3)
- tar content (g/ mn3)
- particulates (g/
mn3)
- composition (%
v/v.)
H2
CO
CO2
CH4
800
4-6
0,01-6
0,1-8
15-21
10-22
11-13
1-5
200-400
4-6
10-150
0,1-3
10-14
15-20
8-10
2-3
850
5-6,5
2-30
8-100
15-22
13-15
13-15
2-4
Max commercial capacity
(forecast) (MWth) 1 10 100
Scale-up ability poor good v. good
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Composition of biomass derived
syngas
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Technology: fixed bed, updraft reactor
Power: 2,5-3,5 MWt
Fuel: Waste Biomass granulation: > 300 mm
Gasification agent: Air
1 – gas generator
2 - lock
3 – transport and feeding system
4 – ash removing system
5 – gas pipeline
6 – air installations
7 - burner
Pilot scale tests
EKOD gasification reactor - construction and process description
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Pilot scale tests Stand for gasification tests
Gasifier
Boiler
se
pa
rato
r
Fuel
(biomass)Gas
Aircombustion
gases
AshDust
P - pressure
T - temperature
V - flow
A - composition
Air
Ash
1
V
1
A
3
A
3
P
3
T
3
V
2
P
2
T
2
V 4
P
4
T
4
V
5
V
3
A
6
P
6
T
3
V
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Pilot scale tests Fuel characteristics
Feedstock Form of
the fuel
LHV,
MJ/kg
Volatile
matter
% w/w,
Ash
% w/w
Moisture
% w/w
Ultimate analysis,
% w/w.
C H O N
Waste wood
Irregular
fuel
pieces up
to 30 cm
17,6 79,6 0,4 7,5 48,7 5,9 37,4 0,1
Wood chips
Wood
chips 3-5
cm
16,1 71,9 0,4 15 44,1 5,2 35,3 0,05
Fiber and chipboard
Irregular
fuel
pieces up
to 30 cm
15,6 69,0 0,5 15 42,9 5 35,8 0,8
Tyres / wood mixture
Irregular
fuel
pieces up
to 30 cm
25,6 68,2 2,7 8 63,1 4,8 20,5 0,1
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Pilot scale tests Results: gasification reactor
Feedstock
t, Fuel flow
rate
Air/fuel
ratio
Gas flow
rate (dry)
Gas LHV
(dry)
Cold gas
efficiency
oC kg/h kg/kg mn3/kgfuel kJ/mn
3 %
Waste wood 760 490 2,1 2,5 5660 80
Wood chips 685 580 1,9 2,3 5200 75
Fiber and chipboard 685 680 1,8 2,2 4770 68
Tyres / wood mixture 690 360 2,1 2,4 9250 86
Feedsto
ck
Gaseous compounds, % v/v(dry) Dus
t,
mg/
mn3
Tar,
mg/
mn3 H2
N2 +
O2 CO
CH
4
CO
2
C2
H4
Other
s*
Waste
wood 7,4 59,3
18,
9 4,4 8,6 1,1 0,3
105
5 643
Wood
chips 6,8 59,1
17,
3 3,7
11,
8 0,9 0,4 350 406
Fiber
and
chipboa
rd
6,2 60,9 16,
7 2,8 12 1,0 0,4
197
0
293
4
Tyres /
wood
mixture 3,0 58,0
20,
0 3,5 8,0 6,5 1,0
287
0
121
0
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Gas composition
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Pilot scale tests Results: gasification reactor- boiler
pollutant
Feedstock
Emission
Standard Waste wood
Wood
chips
Fiber and
chipboard
Tyres / wood
mixture
CO, mg/mn3 76 341 338 50 -
SO2, mg/mn3
Bellow
detection
level
39 173 293 400
NO2, mg/mn3 209 212 625 341,3 400
Pył, mg/mn3 54 58 230 284 100
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Pilot scale tests Results: comparison with literature
0
5
10
15
20
25
LHV
(MJ/Nm3)
Tar (g/Nm3) particulates
(g/Nm3)
H2 (% vol.) CO (% vol.) CO2 (% vol.) CH4 (% vol.)
co-current
counter current
Ecod
Ecod (biomass)
150
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Simulation of the process
0
10
20
30
40
50
60
0,5 1,0 1,5 2,0 2,5
Vp/mpal [mn3/kg]
%o
bj.
H2
CH4
CO
CO2
O2
N2
H2O
A)
0
10
20
30
40
50
60
0,5 1,0 1,5 2,0 2,5
Vp/mpal [mn3/kg]
%o
bj
H2
CH4
CO
CO2
O2
N2
B)
Free Gibbs enthalpy minimization.
Composition of generated gas:
CO, CO2, O2, H2, CH4, H20, N2.
Temperature of the process: 750oC
Feedstock properties: waste wood
Chemcad software (Chemstations Inc.)
16,2
3,2
18,5
8,47,4
59,3
53,8
4,4
18,9
8,6
4700
4712
0
10
20
30
40
50
60
70
80
H2 CH4 CO CO2 N2+O2 LHV
compound
% v
ol
0
1000
2000
3000
4000
5000
6000
LH
V,
kJ/m
3
calculation
experiment
LHV, calculation
LHV, experiments
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Raw wood Wood chips
Wood cutter
Start up: 2005
WOOG CHIPS GASIFICATION – 5 MWth
PELLETS
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Wood chips gasification
Current state
Furniture production plant Holzwerk,
Drygały Poland (waste wood)
Lubuski Tannery Plant, Leszno Górne,
Poland (tanning wastes)
Enpal (Słubice, Poland) – wood chips
ICPC, ZAMER, Modern Technologies
and Filtration
drying installation of wood waste for the
pellets production
Parameter Unit value
Gasification agent - air
Thermal output MWth 3 - 5
Gas temperature oC <800
Fuel (wood chips)
Water kontent
LHV
granulation %
GJ/Mg
mm
< 20
> 14
6-40
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Gasifier
Combustion chamber
Process gas
Air
Wood chips Flue
gas
Fuel: Wood chips
Moisture content:
20%
LHV: 14 GJ/Mg
Capacity:
1500 kg/godz
THERMAL CAPACITY 5 MWt
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Process instrumentation and
control template
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Visualization of gasifier
performance
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Gas combustion chamber
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Coal – biomass co-firing systems
Indirect co-firing
High flexibility in arranging and integrating
the main components into existing plants
Now pretreatment of biomass is needed –
low gas quality is sufficient for co-firing
Gas could be fed to the boiler without
cooling and cleaning
No slag formation in the boiler (most
important issue in case of direct co-firing)
Favorable effects on power plant
emissions (CO2 - biomass, NOx -
reburning effect)
No severe modifications of the existing
coal fired boiler
biomass
BOILER
B)
BIOMASS
PULVERIZER
C)
BOILERgas
D)
GASIFICATION REACTOR
BOILER
BOILER
COMBUSTION
CHAMBER
flue gases
A)
BIOMASSbiomass
• T. Nussbaumer, Combustion and co-combustion of biomass, “12th Conference and Technology Exhibition on Biomass for Energy, Industry and
Climate Protection”, Amsterdam, 2002.
• G. Moritz, J. Tauschitz, Mitverbrennung von Biomasse in Kohlekraftwerken. Conference „Bois-Energie, Mulhouse, France, 2001
• Energetische Nutzung biogener (Ersatz-)Brennstoffe durch Vergasung und emissionsoptimierte Einspeisung mittels Gasfeuerung in (Dampf-)
Kesselanlagen und Ofenprozessen. Konzeptpapier, Fraunhofer-Institut für Umwelt-, Sicherheits- und Energietechnik UMSICHT, November 2002.
• A. Mory, J. Tauschitz, Holz Energie 1999, 4, 37.
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Future development
Small scale CHP systems
Contami
nant Examples Problems Cleanup method
Particula
tes Ash
Erosion,
emission
Filtration,
scrubbing
Tars Refractory
aromatics
Clog filters,
deposit
internally,
Tar cracking, tar
removal
Alkali
metals
Sodium and
potassium
compounds
Hot
corrosion
Condensation,
adsorbtion,
filtration
Sulfur,
chlorine H2S, HCl
Corrosion,
emission
Scrubbing,
absorption
biomass
Gasification Gas cleaning Power and heat production
• Tars
• Particulates
• Alkali metals
• Sulfur, chlorine
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Max concentration
of CO for FC – 100 ppm
IMURITIES CONTENT [g/m3]
REQUIRAMENTS
Ash 1.33
Nitrogen (NH3+HCN) 0.47
Sulphur (H2S+COS) 0.01
Alkalis 0.1
Chlorine (HCl) 0.1
Tars 0.15
Heavy metals 0
GAS QUALITY REQU. BOILER ENGINE GT
LHV [MJ/m3] X >4 >4
Particulates [mg/m3] X 5 - 50 5 - 7
Tars [mg/m3] X < 0.5 <0.1
Alkali metals [ppm] X 1 - 2 0.2 - 1
Gas quality required
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CAT
CAT QUE
EXTERNAL
THERMAL
CRACKING
EXTERNAL
CATALYTIC
CRACKING
INTERNAL
CATALYTIC
CRACKING
PHYSICAL TAR
SEPARATION
INTERNAL
THERMAL
CRACKING
ULTRA-HIGH TEMPERATURE
GASIFICATION
Biomass
Process gas
Oxygen (Air)
Steam
Waste water
Gas treatment methods
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ELECTRICAL
POWER
SNG
H2
METHANOL
MOTOR FUELS
TE
CH
NO
LO
GY
OP
TIO
NS
Plant capacity
1 MM t/a
6 MM t/a
700 MM $
2000 MM $
Technology options dilemma
-scale effect
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Indirect biomass gasification –
prospect for efficient hydrogen
production
FLUID BED
COMBUSTION
PYROLYSIS
SHC+CFBR
Air
CONVERSION
GAS CLEANING
Tlen
Ch
ar
+S
HC
Heat
Biomss
BLOCK DIAGRAM - BIOMASS
PYROLYSIS WITH SOLID HEAT
CARRIER FOR SYNTHESIS GAS
DRYING
Process gas
SOLID HEAT
CARRIER
SEPARATION
Heat carrier
Acronym:
PYROSYN
Oxygen
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Summary EKOD fixed bed gasifier is characterized by relatively high conversion
efficiency. Depending on used feedstock, the efficiency was in range
68-86 % (cold gas efficiency).
Produced gas was characterized by relatively high calorific value
(4800 – 9200 kJ/mn3) and low tar content (400 – 3000 mg/mn3).
Operation experiences confirm the flexibility and reliability of the
construction and readiness for commercial applications particularly
for heat generation in stand alone boilers or in existing co-fired units.
Possible further development direction comprises small scale CHP. It
needs to develop tars free gasification systems. This option gives the
opportunity for broad application in heat and power generation
industry.
Biomass gasification and related syngas production for chemical
synthesis or hydrogen production still needs new technology options.
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