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Gasification is a thermo-chemical process that convert any carbonaceous material (Solid Fuel) in to combustible gas known as "producer gas or syngas" by partial oxidation process.
PROCESS-STEPS OF GASIFICATION SYSTEM.
| 1. |
Sized fuel is lifted and delivered to the storage hopper above reactor assembly by skip-hoist / Bucket-Elevator / Belt conveyor.
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| 2. |
From the storage hopper, fuel is feed to the reactor through double-bell cone fuel feeding system. |
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| 3. |
Feed coal travels downwards and gets dried and preheated. |
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| 4. |
When the fuel introduced into the reactor, its undergoes through different thermo-chemical processes as follows. |
following reactions take place zonewise from bottom to top:-
1) Combustion (Oxidation) :-
C + O2 » CO2 + Heat (Exothermic Reaction - Rapid)
H2O + C » CO + H2 - Heat (Endothermic Reaction - Slower than oxidation)
2) Reaction (Reduction) :-
CO2 + Heat + C » 2CO - Heat (Endothermic Reaction - Slower than oxidation)
H2O + CO + Heat «» CO2 + H2 + Heat (Slightly Exothermic Reaction - Rapid)
2H2 + C » CH4 + Heat (Exothermic Reaction - Direct Methanation)
CO + 3H2 » CH4 + H2O + Heat (Exothermic Reaction - Methanation)
3) Pyrolysis (Carbonization)
CH0.8 S0.2 O0.1 N0.01 ( Coal Molecule ) » CH4 + H2 + CO + H2O+NH3
+ Heat (hot gases released from the + Tar ( Viscous hydrocarbon
Oxidation and Reduction zone) C6H6, C10H8 )
4) Drying of fuel
The introduced fuel contains moisture which is removed in the Drying Zone.
Besides above reaction zones inside the reactor vessel shell, there is an Ash zone under the Oxidation zone through which calculated quantity of saturated air with steam enters and receives heat from the hot ash.
Producer gas made from coal, under normal operating condition has a composition (Volume %) within range given below:
CO2 |
CO |
H2 |
CH4 |
N2 |
3-5 |
24-28 |
11-18 |
0-3 |
Balance |
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