Gasification process for generating producer gas by updraft, downdraft etc. and advantage and disadvantages of gasifier and application of producer gas for generating electricity or motive power for running the engine.

1. PRESENTATION
ON
PRODUCER GAS
DEPARTMENT OF
RENEWABLE ENERGY
ENGINEERING

2. INDEX
1. Gasification
2. Producer Gas and it’s Constituents
3. Producer gas applications
4. Types of gasifier
5. Gasification reactions
6. Advantages and disadvantages

3. Gasification
• Gasification is basically a thermo chemical
process which converts biomass materials
into gaseous components.
• The results of gasification are the producer
gas, containing carbon monoxide, hydrogen,
methane and carbon dioxide.

4. Producer Gas and it’s Constituents

5. • Producer gas is the mixture of combustible and
non- combustible gases
 Combustible gases
1) 18%–22% carbon monoxide (CO),
2) 8%–12% hydrogen (H2),
3) 2%–4% methane (CH4).
 Non- combustible gases
1) 8%–12% carbon dioxide (CO2),
2) 45%–50% nitrogen (N2).

6. Producer gas applications
• The producer gas obtained can be used either to
produce heat or to generate electricity.

7. • In general, the fuel-to electricity efficiency of
gasification is much higher than that of direct
combustion.
• The conversion efficiency of gasification is 35%–45%
whereas that of combustion is only 10%–20%.
• Generated electricity can be fed into the grid or can
be used for farm operations, irrigation, chilling or
cold storage, and other commercial and industrial
applications.

8. • Producer gas can be used
for generating motive
power to run either
dual-fuel engines
• which run on a mixture
of gas and diesel, with
gas replacement of up to
85% of diesel

9. Types Of Gasifier
1. Downdraft gasifier
2. Updraft gasifier
3. Crossdraft gasifier
4. Fluidized bed gasifier
5. Twin-fire gasifier
 Although updraft, downdraft or crossdraft
gasifier have been the most commonly used
systems

10. Updraft or counter-current
gasifier
• In updraft gasifiers (also known as counter-current), air
enters from below the grate and flows upwards, whereas the
fuel flows downwards.
• The gas produced in the reduction zone leaves the gasifier
reactor together with the products of pyrolysis from the
pyrolysis zone and steam from the drying zone.
• The resulting combustible producer gas is rich in
hydrocarbons (tars).

11. Updraft or counter-current
gasifier

12. Downdraft or co-current
gasifier
• The downdraft (also known as co-current) gasifier is the
most common type of gasifier.
• The term co-current is used because air moves in the
same direction as that of fuel, downwards.
• Downdraft gasifier is so designed that tar, which is
produced in the pyrolysis zone, travels through the
combustion zone, where it is broken down or burnt.
• Its main advantage being that produces gas with low tar
content, which is suitable for gas engines.

13. Downdraft gasifier

14. Gasification reactions

15. 1. Drying:
Biomass fuels usually contain 10%–35%
moisture. When biomass is heated to about 100
°C, the moisture is converted into steam.
2. Pyrolysis:
After drying, as heating continues, the biomass
undergoes pyrolysis.
• Pyrolysis involves burning biomass completely
without supplying any oxygen.
• As a result, the biomass is decomposed or separated
into solids, liquids, and gases.
• Charcoal is the solid part, tar is the liquid part,
and flue gases make up the gaseous part.

16. 3. Oxidation:
Air is introduced into the gasifier
after the decomposition process.
• During oxidation, which takes place at about
900–1200 °C, charcoal, or the solid
carbonized fuel, reacts with the oxygen in the
air to produce carbon dioxide and heat.
• C + O2 → CO2 + heat

17. 4. Reduction:
At higher temperatures and under reducing conditions,
that is when not enough oxygen is available, the following
reactions take place forming carbon dioxide, hydrogen,
carbon monoxide and methane.
• C + CO2 → 2 CO
• C + H2O → CO + H2
• CO + H2O → CO2 + H2
• C + 2H2 → CH4

18. Different pyrolysis process
Pyrolysis
process
Residence
time
Heating rate Final temp. (
⁰c)
Product
Torrification 10-60 min Very low 280 Torified
biomass
Carbonizatio
n
24 hr Very low 400-450 Charcoal
Fast
pyrolysis
< 2 sec. High 500 Bio-oil
Flash
pyrolysis
<1 sec. Very high 650 Bio-oil,
chemical gas
Ultra rapid
pyrolysis
<0.5 sec. Very high 1000 Chemical
gas

19. Advantages and disadvantages
Gasifier type Advantages Disadvantages
Updraft Simple design High amount of tar (500-
600 ppm) and pyrolysis
products
High charcoal burn-out Extensive gas cleaning
required if used for power
application
Accepts fuels with higher
moisture content
Accepts fuels of different
sizes
Downdraft Low tar(150-180 ppm) High amounts of ash and
dust
Best option for usage in
gas engines
Fuel requirements are
strict
At lower loads, fewer
particles in the gas
At low temperatures,
more tar
produced

20. • Let’s have a look at Video Clip for a quick
summary.
• ppt on producer gasvideoplayback (1).mp4

21. Thank you