Coal gas is a combustible gas processed from coal.
According to the processing method, gas properties and uses, it can be divided into: water gas, semi-water gas and air gas (or producer gas) obtained from coal gasification.
These gases have low calorific value, so they are also collectively called low calorific value gases.
The gases obtained from coking by dry distillation of coal are called coke oven gas and blast furnace gas.