33.1 Introduction
Coal or hydrogenation of coal involves raising the atomic hydrogen to carbon ratio. Coal can be converted to liquid and gaseous fuels by direct and indirect processing. Hydrogenation of coal is also called liquefaction of coal. The source of coal is from various coal mines.
33.2 Hydrogenation reaction:
4(C3 H4 )n + nH2→ nC6 H6 + 5nC + nCH4
Powdered coal Aromatic liquid Hydrocarbon
This is highly exothermic reaction.
Process flow sheet: Illustrated in Figure.
Figure 33.1 Flow sheet of hydrogenation of coal
33.3 Functional role of each unit (Figure 33.1):
.(a) Coal storage vessel:
- • Here pulverized coal is stored.
• Produced coal is fed to the preheater by a screw conveyor.
• Hydrogen gas stream is added to the fed.
• Hydrogen is obtained from any dehydrogenation process or any other hydrogen synthesis ...process.
• Pressure equalizing line is used to maintain pressure of reaction mixture stream with the help ...of valve.
(b) Preheater:
- • Powdered coal and hydrogen are the raw material fed to the preheater.
• Optimum temperature is required for reaction so reaction mixture is preheated instead of ....feeding it in reactor directly.
• Heat required for preheating is supplied by furnace.
• In furnace, combustion of fuel gases is occurring and all hot gases from furnace are passed ....from preheater.