Double Stage Gas Station

As the name suggests…. in this type of gasification technology there are two levels of gasification taking place. The first is the lower level gasification, which is that of Carbon in the coal, and the second or the Upper is that of the Volatile Matter present in the coal.

The coal is transported to the coal bin by coal elevating system then sent into the hearth in batches by the assistance of a Triple Seal Mechanism which comprises of a Rotary Valve, a Flash Board and then finally a Bell Jar. All these are hydraulically operated with complete auto controls. Firstly, the coal comes to the pyrolysis section of the gasifier and moves downwards slowly. Then the coal is dried and carbonized. All the water in the form of moisture in coal is released. Tar and most sulphides are carbonizedout. Then hydrocarbons and light tar are produced and carried out by the upper gas.

With coal moving downwards continuously and temperature increasing, it normally takes 8-10 hours for the coal to come down to the level of gasification to gasifying section. The semi-caking coal is gasified and lower gas is produced.

The upper gas comes into tar removerto remove the tar and then it mixes with lower gas in the electrostatic tar collector.

The lower gas comes into heat exchanger after removal of most dust by cyclone separator. Then it mixes with upper gas in the electrostatic tar collectorto remove the fine tar and dust. In order to ensure the gas cleanliness and meet long-distance utility, the gas comes into indirect cooler to be cooled and electrostatic precipitator removes the tar and dust again. Finally the gas is transported to the user by gas compressor.