C4 Pyrolysis of Biomass

Question 1

general concept pyrolysis

Answer 1

• thermal process that decompose/break down complex compound to simple molecule(gases,liquid,char)
• process absence/very limited O2

Question 2

final product pyrolysis

Answer 2

1. bio-oil (dark brown liq)
2. char/bio-char (solid product= carbonaceous residue, stable)
3. pyrolytic gases (CO2,CO,H2,CH4,ethylene,propane,SO2,NOx,NH3)

Question 3

pyrolysis vs gasification

Answer 3

pyrolysis
* minimise side reaction due to absence/limited O2
* conducted at temp range 300-650 °C

gasification
* involve several chem reaction in presence of gasification agent
* conducted at temp range 800-1000 °C

Question 4

steps in pyrolysis technolgy

Answer 4

1. pre-drying
2. drying
3. post-drying heating
4. torrefaction zone
5. cooling zone

Question 5

simple layout of tropical pyrolysis plant

step A

Answer 5

• biomass under gas flow is heated in a rector
• generatad condensable & non-condensable gas leave the reactor
• solid char remain in rector
• while, tiny quantity of char particle carried along with gas

Question 6

simple layout of tropical pyrolysis plant

step B

Answer 6

• cyclone create centrifugal force that seperate tiny char particle from gas
• char particle stay on the bottom of the collector

Question 7

simple layout of tropical pyrolysis plant

step C

Answer 7

• gas is cooled
• condensable vapor condenses as bio-oil/pyrolysis oil
• non-condensable gas leave as product gas

Question 8

slow pyrolysis vs fast pyrolysis

Answer 8

slow
* target product: char
* residence time: longer (min)
* heating rate: slow

fast
* target product: bio-oil
* residence time: short (sec)
* heating rate: high

Question 9

factors influencing pyrolysis yeild

4 factors

Answer 9

1. biomass compostion
2. pyrolysis temperature
3. heating rate & residence time
4. particle size

Question 10

biomass compostion

depend on biopolymer constituent

Answer 10

• cellulose= primary source consensable vapor, produce ↑ tar
• hemicellulose= yeild ↑ non-condensable gas, ↓ tar
• lignin= contribute ↑ char yeild

Question 11

pyrolysis temperature

Answer 11

• ↓ temp, ↑ char, ↓ condensible gas
  and vice verca

Question 12

recidence time

Answer 12

amount of time that biomass stay in reactor during pyrolysis process

Question 13

heating rate

Answer 13

• rapid heating rate = ↑ condensible gas, ↑ bio-oil
• slow heating rate = more char

Question 14

particle size

Answer 14

1. finer
* ↑ surface area, ↑ active site
* condensable gas easy escape
* minimise chance condensable gas undergoing 2nd reaction
* ↑ bio-oil produced

2. bigger
* ↓ surface area, ↓ active site
* condensable gas trapped
* high chance condensable gas undergoing 2nd reaction
* ↑ non-condensable gas produced

Question 15

max char product

Answer 15

• ↓ heating rate, ↓ temp, ↑ residence time

Question 16

max bio-oil product

Answer 16

• ↑ heating rate, moderate temp, ↓ residence time

Question 17

max gas product

Answer 17

• moderate to slow heating rate, ↑ temp, ↑ residence time