Method and device for coal gasification in combined type fluidized bed

The invention discloses a method for coal gasification in a combined type fluidized bed, which comprises coal preparation, gas supply, gasification, slag discharge, dedusting, waste heat recovery and fine powder conveying. An ash agglomeration fluidized bed realizes gasification of large-particle coal; the non-completely converted carryover fine powder enters an entrained flow bed gasifier in a dense phase pneumatic conveying manner; secondary gasification is carried out by using a short retention time high temperature gasification manner; the produced ash slag is carried into an intersection segment of the fluidized bed and the entrained flow bed with high temperature coal gas, and rapidly mixed with ''low temperature'' large-particle partially carbonized coal in the fluidized bed and the produced ''low temperature'' coal gas; and partial ash slag is selectively discharged out of the gasifier in the form of solid. The method and the device of the invention have the advantage of being suitable for various coal types and high in carbon conversion rate.