6 Prins slides2005-09-29_AIOmeeting

8/3/2019 6 Prins slides2005-09-29_AIOmeeting

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2/24

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


3/24

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


4/24

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


5/24

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


6/24

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


7/24

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

,,

,,,,, )(

+=


8/24

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


9/24

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!!


10/24

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


11/24

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


12/24

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


13/24

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


14/24

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


15/24

Composition

Composition hemicelluloses

4-O methyl glucuronoxylan (wt%) 80-90 5-15

4-O methyl glucuronoarabinoxylan (wt%)


16/24

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


17/24

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


18/24

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


19/24

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


20/24

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


21/24

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


22/24

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


23/24

Tor re f ied w ood as a gas i f ie r fue l

1. F-T fuels frombiomass


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


24/24

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


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?

6 Prins slides2005-09-29_AIOmeeting

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