Page 260 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

236 8 Pre-combustion Air Emission Control

Gas
Solid feedstock
(coal or biomass)
1
Solid
feedstock

Cyclone
Drying
2
Gas
Pyrolysis

Reduction

Oxidation

Oxidant
Oxidant (Steam, Ash
oxygen or air)
Ash

Solid Oxidant
feedstock

1. fixed bed gasifiers,
2. fluidized bed gasifiers
3
3. entrained flow gasifiers.

Gas

Slag

Fig. 8.1 Different gasifiers

bottom, the feedstock is preheated, dried, devolatilized/pyrolysed, gasified, and
combusted. Maximum temperature in the combustion zone can be as high as
1,800 °C, mostly greater than 1,300 °C, depending on the reactor design. Post-
combustion ash leaves at the bottom and the syngas exits at the top to the syngas