6 prins slides2005-09-29_aiomeeting
TRANSCRIPT
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Gasi f ier fue ls
0.40 0.2 0.80.6
0.2
0.4
1.0
1.2
1.4
1.8
0.8
0.6
1.6
Atomic O/C ratio
Biomass
Peat
Lignite
Coal
Anthracite
Increased Heating Value
Atomic H/C ratio
Lignin
Wood
Cellulose
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Whic h fuel c an be c onver t ed t o
gas w i t h t he h ighest ef f ic ienc y?
A. Solid Carbon, because it has thehighest calorific value
B. Cellulose, because it requires lessoxygen
C. It does not matter
D. I dont know
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Reac t ion Gibss func t ion Gr
C6(H2O)5 + H2O = 6 CO + 6 H2
-400
-350
-300
-250
-200
-150
-100
-50
0
50
100
150
0 50 100 150 200 250 300 350
Temperature (C)
Gr(kJ/mol)
Scientist dream:kinetic pathwayto synthesis gas
BUT: catalyst doesnot exist!
CO2, CH4 and C (s)
more stable at lowtemperature
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Gasi f ic at ion in a CHO-diagram
0.00 0.25 0.50 0.75 1.00
0.0
0.2
0.4
0.6
0.8
1.0 0.0
0.2
0.4
0.6
0.8
1.0
1500 K1100 K
1000 K900 K
700 K
Mol % C
CH4
H2O
CO
CO2
Mol % H
Mol % O
coal
peatbiomass
lignite
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Gasi f ic a t ion at c arbon boundary
0.0 0.2 0.4 0.6 0.8
500
1000
1500
2000
2500
0.0 0.2 0.4 0.6 0.8
500
1000
1500
2000
2500
0.0 0.2 0.4 0.6 0.8
500
1000
1500
2000
2500
Gasificationtemp
erature(C
)
lowH/C
ratio
highH/C
ratio
927C
1227C
carbon boundary
temperature
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Steam, ch = 527 kJ/kg
ph = 92 kJ/kg
Fuel, ch = 18000-39000 kJ/kg Product gas
Oxygen, ch = 124 kJ/kgGasifier
Therm odynam ic ef f ic ienc y
of gasi f iers
fuelchfuelm
oxygenchoxygenmgasphgaschgasm
total
,,
,,,,, )(
+=
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Gasif i c a t ion ef f ic ienc y
0.0 0.2 0.4 0.6 0.860
62
64
6668
70
72
74
76
78
80
82
84
86
8890
lowH
/Cratiohig
hH/C
ratio
highH/Cratio
highH/Cratio
Therm
odynamicefficiency(%
)
Atomic O/C ratio of fuel
0.0 0.2 0.4 0.6 0.860
62
64
6668
70
72
74
76
78
80
82
84
86
8890
0.0 0.2 0.4 0.6 0.860
62
64
6668
70
72
74
76
78
80
82
84
86
8890
0.0 0.2 0.4 0.6 0.860
62
64
6668
70
72
74
76
78
80
82
84
86
8890
0.0 0.2 0.4 0.6 0.860
62
64
6668
70
72
74
76
78
80
82
84
86
8890
0.0 0.2 0.4 0.6 0.860
62
64
6668
70
72
74
76
78
80
82
84
86
8890
lowH/Cratio
lowH/Cratio
lowH/CratiohighH/Cratio
1227C
927C
carbon boundary
temperature
1227C927C
carbon boundary
temperature
overall
efficiency
chemical
efficiency
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In t erm ediat e c onc lus ions
fuelLHV
fuelch
Fuels with high O/C ratio have relatively highchemical exergy ( = 1.12-1.14 for biomass,
1.05 for solid carbon)
and therefore lower gasification efficiency
= ,
Fuels with high O/C ratio are over-oxidized atpractical gasification temperatures (1200-1500 K)
Biomass needs to be upgraded!!
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Biom ass t o rrefac t ion
0.40 0.2 0.80.6
0.2
0.4
1.0
1.2
1.4
1.8
0.8
0.6
1.6
Atomic O/C ratio
Biomass
Peat
Lignite
Coal
Anthracite
Increased Heating Value
Torrefied Wood
Atomic H/C ratio
Lignin
Cellulose
Wood
Torrefaction
(at 250-300C)
1. Thermo ofgasification
2. Biomasstorrefaction
3. TW as agasifier fuel
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Volatilessteamacetic acidmethanolCO2, COother organics
Torrefac t ion ex per im ent s
Thermo balance (TGA):
reaction kinetics
Small scale oven: product recovery product analysis
mass and energy balances
Feed
Product 1
Product 2
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Weight loss k inet ic s (250C)
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500
Time (s)
Relativew
eight(-)
150
170
190
210
230
250
270
290
Temperature(C)
cellulose
xylan
straw
willowbeech
larch
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Weight loss k inet ic s (270C)
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500Time (s)
Relative
weight(-)
150
170
190
210
230
250
270
290
Temperature(C)
cellulose
xylan
straw
willowbeech
larch
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Tor re fac t ion Reac t iv i t y (a t 250-300C)
OH
O
O O
OH
O-Ac
O
O
O-Ac
OH
O
O
O O
O
OH
OH
O
O
OH
OH
H2CO
COOH
OH
O-AcHemi-cellulose Highly
reactive
Hardlyreactive
Cellulose
LigninOnly side-
chains
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Composition
Composition hemicelluloses
4-O methyl glucuronoxylan (wt%) 80-90 5-15
4-O methyl glucuronoarabinoxylan (wt%)
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K ine t i c m odel (for w i l l ow )
Di Blasi &
Lanzetta, 1997 A B C
V1 V2
KB KC
KV1KV2
Hemi-cellulose
decomposition
(Ea = 76 kJ/mol)
Cellulose
decomposition
(Ea = 152 kJ/mol)
Relative rates250C 1 0.025
300C 5.5 0.52
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Requi red res idenc e t im e
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
230 240 250 260 270 280 290 300
Torrefaction temperature [C]
Relativew
eight[-]
0
20
40
60
80
100
120
140
160
180
200
Reactiontime[min]
C
B
A
time
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Set -up for produc t analys is
Cooling
Cooling
h
eater
h
eater
Mass flow
controller
Reactor
Pressure
controller
Cold
trap
Gasbag
Argon
Temp
controller
120 CTracing inlet
180 CTracing outlet
230-300 CTemp
AtmosphericPressure
10-50 ml/minFlow
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Condensable vo lat i les
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
12.0%
14.0%
230C (50 min.) 250C (30 min.) 270C (15 min.) 280C (10 min.) 300C (10 min.)
Condensablevolatileyield(wt%)
acetic acid water formic acid methanol
lactic acid furfural hydroxy acetone phenol
willow
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Non-c ondensable vo lat i les
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
230C (50 min.) 250C (30 min.) 270C (15 min.) 280C (10 min.) 300C (10 min.)
Non-condensablevo
latileyield(wt%
)
carbon dioxide carbon monoxide
willow
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LHV of so l id produc t
18000
18500
19000
19500
20000
20500
21000
21500
220 230 240 250 260 270 280 290 300
Temperature (C)
Lowerheatingvalueofso
lidproduct[kJ
/kgdry]
brown larch
green willow
10 minutes
15 minutes 30 minutes
50 minutes
60 minutes
brown larch
green willow
10 minutes
15 minutes 30 minutes
50 minutes
60 minutes
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Energy y ie ld
70%
75%
80%
85%
90%
95%
100%
105%
220 230 240 250 260 270 280 290 300
Temperature (C)
Lowerheatingvalueretain
edinsolidproduct[%] larch
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Tor re f ied w ood as a gas i f ie r fue l
1. F-T fuels frombiomass
2. Biomasstorrefaction
3. TW as a
gasifier fuel
Attractive Gasification Properties
Low ash, sulphur and nitrogen content
Increased energy density: 18 to 21 MJ/kg
Reduced moisture content: 10 % to < 2 %
Ratio of volatiles/FC: 80/20 to 60/40
Reduced hemi-cellulose: 20-30% < 5 %
Friable
Cheaper to transport
storage
Densification from 400 kg/m3
topellets > 800 kg/m3 possible
50-85% lesselectricity forsize reduction
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Ac t ions fo r fu t u re developm ent
Construction & demonstration ofcontinuous torrefaction reactors
Demonstration of TW (co-) gasification inentrained flow gasifiers
1. F-T fuels frombiomass
2. Biomasstorrefaction
3. TW as a
gasifier fuel
For stand-alone torrefaction:
Catalytic combustion of volatiles
Techno-economic analysis of torrefaction-aided gasification (stand-alone, integrated)
versus direct wood gasification
airlessdrying unitin Sneek
EF pilot plantat ECN;Buggenum?