C2 Combustion of Biomass

Question 1

combustion process

Answer 1

1. biomass undergoes devotilization
2. it produce votile flame that contain votile gas with help of O2
3. then combustion process occur produce charcoal and CO2 gas released

Question 2

4 stage of biomass combustion

Answer 2

1. drying
2. devotilization
3. combustion of votiles
4. combustion of char

Question 3

votile gas

Answer 3

• CH4
• C2H6
• CO
• CO2
• H2O
• H2

Question 4

drying process

Answer 4

• remove/evaporate moisture content
• important because if moisture >65% heat by combustionn not effision
• take away large amount energy and keep biomass at low temp= called “cooling phenomenon”

Question 5

cooling process

Answer 5

disable the ignition of biomass before sufficient extraction of water

Question 6

devotilization process

Answer 6

• dry biomass turn into tars + votile gases + solid char

Question 7

combustion of votiles process

Answer 7

tars + votile gases + O2(Iin air) ignited&combusted into heat + light + by products (CO,CO2,H2O,soot)
* exothermic reaction

Question 8

combustion of char

Answer 8

char + O2(in air) turn into CO + CO2 + other pollutants
* it occur simultaneously with combustion of votiles
* more exothemic, has lower Ea, much slower reaction speed

Question 9

factors influencing combustion performance

Answer 9

• biomass properties (physical&chemical)
• biomass feeding stock
• combustion air distribution & amount
• operational condition (temp, P, retention time)
• furnace type &design

Question 10

biomass properties

physical structure

Answer 10

• particle size ↑, delay ignition of votiles,tar quantity ↑
• density
• surface area ↑, efficency ↑

Question 11

biomass properties

chemical property

Answer 11

• moisture & ash content ↑, flame temp ↓
• element composition (K, Na, Cl)

Question 12

co-firing biomass with coal process

Answer 12

coal + biomass → reduce consumption coal to generate electricity

Question 13

co-firing biomass with coal benefit

Answer 13

• not require modify existing facility
• lower SO2 emssion
• contribute to lowering CO2 emission - biomass = CO2 neutral free
• ↑ ultize efficency biomass

Question 14

3 basic co-firing technolgy

Answer 14

1. direct co-firing
2. parellel co-firing
3. indirect co-firing

Question 15

direct co-firing

Answer 15

pre-mix biomass + coal →(fed into) combustion with coal

Question 16

parellel co-firing

Answer 16

seperatly combust biomass & coal, steam produce → converge

Question 17

indirect co-firing

Answer 17

1. combust biomass → gas
2. gas combust with coal

Question 18

pollutant type from biomass combustion

Answer 18

1. gases
2. metals
3. particles

Question 19

pollutant type

gases

Answer 19

1. incomplete combustion
   * CO, NH3, VOCs
2. complete combustion
   * CO2,NO,NO2,SO2

Question 20

pollutant type

metals

Answer 20

hazadous metal
Cd & Hg

Question 21

pollutant type

particles

Answer 21

• PM=particle matter emission
• type PM
  1. PM10 = inhalable with particle size <10μm
  2. PM2.5 = inhalable with particle size <2.5μm

Question 22

3 factors affecting PM

measure for pollutant reduction

Answer 22

* biomass properties
-Ash related element (K,Cl,Na,Mg&P)
-high water content - incomplete combustion-emit CO &pollutant

* combustion parameter
-method to reduce pollutant = good mixing biomass with primary air & mixing the produce combustible gases with excess air

* reactor type