Coal pyrolysis and air gasification coupled combined cycle power generation system

The utility model discloses a coal pyrolysis and air gasification coupled combined cycle power generation system. Coal high-temperature rapid pyrolysis in the downer reactor is coupled with coal pyrolysis semicoke heat exchange and tar cracking in the heat exchange cracking device and coal coke gasification in the gasification furnace; high-temperature low-calorific-value fuel gas obtained throughgasification of the gasification furnace is used for firstly heating semicoke, tar is cracked on the semicoke, and generated medium-temperature low-calorific-value fuel gas preheats raw coal, so thatheat generated by the gasification furnace is fully utilized, and the heat efficiency of converting coal into fuel gas is improved; high-calorific-value fuel gas generated by rapid pyrolysis of a solid heat carrier and low-calorific-value fuel gas obtained by gasification of a gasification furnace respectively enter a gas turbine and a boiler for step-by-step power generation; according to the utility model, raw coal is changed into fuel gas to the greatest extent, even if a small amount of tar is generated, the tar is cracked on the high-temperature semicoke to generate small molecular fuelgas, tar and waste water are not generated, and the fuel gas purification and the environment are facilitated. The utility model has the advantages of carrying out gradient utilization on heat, and being high in energy conversion efficiency and free of pollution emission.