Gas is a gas containing combustible components processed from coal as raw material.

　　Mixed gas is widely used as a heating fuel for various industrial furnaces. In addition, the use of steam and air together with the "half water gas". It can be used as fuel, or as feedstock for synthesis of ammonia, synthetic petroleum, organic synthesis, hydrogen production, etc. Natural gas is an important energy source, widely used as urban gas and industrial fuel; In the 70 's world energy consumption, natural gas accounted for 18%~19%. Natural gas is also an important chemical material.