Coal gasification reaction control method of circulating fluidized bed gas furnace

The invention provides a coal gasification reaction control method of a circulating fluidized bed gas furnace. The coal gasification reaction control method comprises the following steps that (A) a coal raw material is charged into a gasification furnace, air is supplied to make coal combusted, furnace box temperature is controlled to reach 900-920 DEG C; (B) water vapor is led to the gasification furnace, the pressure at the bottom of the furnace is 14-15 KPa, the furnace box temperature is continuously kept to 900-920 DEG C for reaction; (C) mixed gas produced through reaction passes through a separating device to obtain coal gas and fine coal particles, the coal gas is guided out of the coal gas furnace, and the fine coal particles enter a material returning device; (D) compressed air is not adopted in the material returning device and is replaced by input water vapor, the fine coal particles are re-guided into the bottom of the coal gas furnace through wind power of the water vapor, and reaction continues