Coal elevator is used for conveying coal into coal bin, then the coal is transported into hearth by stoker. In pyrolysis section of the furnace, the coal is dried and carbonized. The Coal will move downwards slowly with temperature increasing and come to gasifying section after 8 to 10 hours. All the water in coal is released, tar and most sulphide are carbonized out and hydrocarbons produced, which forms up gas; While down gas is produced by gasification reaction of semi-caking coal which is gasified.
Discharge up gas comes into electrostatic tar separator from tar preremover, where tar carried by the gas is removed, then the gas comes into electrostatic precipitator after mixing with the gas in the lower zone.
The gas in the lower zone comes into heat exchanger after being removed most dust by cyclone separator, it mixes with up gas and fine dust and part light oil in gas are is removed by electrostatic dust separator again. Then the gas comes into indirect cooler to be cooled to normal temperature. Finally the gas is transported to its consumption place after pressurized with gas compressor.