Mass loss and gas release during torrefaction of biomass and its constituents

(1)

0 5 10 15 20 25 30 CO 2 CO Met hano l Furfu ral Form alde hyde_Water Acet ic a cid Form ic a cid g / g i n it ia l (% ) 0 5 10 15 20 25 30 CO 2 CO Met hano l Furfu ral Form alde hyde_Water Acetic aci d Form ic a cid g / g i n it ia l (% ) 0 5 10 15 20 25 30 CO 2 CO Met hano l Furfu ral Form alde hyde_Water Ace tic a cid Form ic a cid g / g i n it ia l (% ) 0 10 20 30 40

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0 20 40 60 80 100 220 250 280 300 Temperature (°C) g / g in it ia l ( % )

Mass Loss and Gas Release During Torrefaction

of Biomass and its Constituents

T. NOCQUET

1 _{, C. DUPONT}

1 _{, J.M. COMMANDRE}

2 _{, M. GRATEAU}

1 _{, S. THIERY}

1 _{, M.H. NGUYEN}

1 _{, S. SALVADOR}

3

1

_{CEA Grenoble, DRT/LITEN/DTBH/LTB, France}

2

_{CIRAD, Montpellier, France}

3

_{MINES ALBI, RAPSODEE, Albi, France}

timotee.nocquet@cea.fr

0 20 40 60 80 100 220 250 280 300 Temperature (°C) g / g in it ia l (% ) 0 20 40 60 80 100 220 250 280 300 Temperature (°C) g / g i n it ia l (% ) 0 20 40 60 80 100 220 250 280 300 Temperature (°C) g / g in it ia l (% )

Cellulose - Lignin

Cellulose - Xylan

Xylan - Lignin

→

Is the additive law valid?

Modeling of biomass torrefaction

(200-300°C, N

₂

)

∆

m

biomass

=

∆

m

cellulose

. %

cellulose

+

∆

m

lignin

. %

lignin

+

∆

m

hemicellulose

. %

hemicellulose

?

Torrefaction of beech wood, and its constituents (Cellulose, Hemicellulose and Lignin)

Beech

(composition)

Cellulose

Avicel

Lignin

Extracted from beech

Xylan

Extracted from beech

(Representative of Hemicellulose)

Experiments:

T = 220°C, 250°C,

280°C, 300°C

T = 220°C, 250°C,

280°C, 300°C

Chemical regime

Gas analyser

Cold traps

Reactor

FTIR

(150°C)

1 N2 M P 2 3 5 6 7 4

Samples

Conclusion

Mass balance and volatiles release

Valid at low temperature (T ≤ 250°C)

Not Valid at high temperature (T

≥

280°C)

Interaction between beech constituents?

Modeling approach: additive law

Mix of wood constituents

Further work

Significant interactions between Cellulose

and Lignin/Xylan from 280°C

No significant interaction between

Xylan and Lignin

Blend (Cellulose – Lignin) Additive law

Blend (Cellulose – Xylan) Additive law

Blend (Xylan - Lignin) Additive law

Additive law valid at T ≤ 250°C and not at T ≥ 280°C

To develop a kinetic model predicting:

Interactions origin?

• the mass loss

• the gas composition

Gases Condensable species Torrefied wood

Objective

220°C 250°C 280°C 300°C

Xylan

Lignin

Cellulose

Beech

Drastic

change between 250°C and 280°C

in

cellulose

torrefaction

CO

₂

and CO

mainly

released by Xylan

torrefaction

Main volatile species released:

Steam, Formaldehyde, Acetic Acid, CO

2 Methanol, CO, Formic Acid, Furfural

Samples

Mass balance and volatiles release: TORNADE

Mass loss kinetics: TGA

Extractives (3.0%)

Ash (0.6%)

31.1% 22.0% 43.3%

0

100

200

300

0

100

200

T e m p e ra tu re (° C ) Time (min)

Time: 3h

1 5°C/m in

1: Electrical furnace

2: Crucible (Al)

3: Thermocouples

7: Cold trap (-70°C)

M: Mass flow meter

and controller

P: Pressure gauge

4: Electrical heater (220°C)

5: Electrical heater (180°C)

6: Cold trap (0°C)

Operating conditions

Sample mass: 100-200mg

Gas carrier: N

2

(1NL/min)

P: 1bar

Chemical regime

Sample mass: 5mg

Gas carrier: N

2

(0.03NL/min)

P: 1bar

0 100 200 300 0 100 200 300 T e m p e ra tu re (° C ) Time(min) (Drying) 4 0 °C/m in

Time: 3h

Acetic Acid not produced by Cellulose/Hemicellulose/Xylan

produced from acetyl groups (Hemicellulose)

removed during extraction

280°C

• Interactions between Cellulose and Lignin/Xylan

• No interactions between Lignin and Xylan

Main volatiles species to be modeled are produced

from different constituents

(except Formic Acid)

Operating conditions

Before torrefaction: samples dried at 105°C during 24h

0 20 40 60 80 100 0 25 50 75 100 125 150 175 Time (min) g / g i n it ia l (% ) 250°C 280°C 300°C

Blend (Xylan – Lignine) Additive law 0 20 40 60 80 100 0 25 50 75 100 125 150 175 Time (min) g / g i n it ia l (% ) 250°C 280°C 300°C

Blend (Cellullose – Xylan) Additive law 0 20 40 60 80 100 0 25 50 75 100 125 150 175 Time (min) g / g i n it ia l (% ) 250°C 280°C 300°C

Blend (Cellullose – Lignine) Additive law 220°C 250°C 280°C 300°C 220°C 250°C 280°C 300°C 220°C 250°C 280°C 300°C