Fixed bed-fluidized bed serially connected gasification method and apparatus

The invention relates to a method and a device for gasification, in particular to the method and the device for serial gasification of a fixed bed and a fluidized bed, wherein the method comprises the following steps: 1) feeding a gasification raw material with the particle size of between 13 and 50 millimeters and a gasification agent to a fixed bed gasifier to perform gasification reaction so as to generate coal gas and ash content, discharging the ash content from an ash discharging opening of the fixed bed, and introducing the coal gas to the lower part of a dense phase zone of a fluidized bed gasifier; 2) feeding a thin particle shapeed coal gasification raw material with the particle size of between 0.5 and 8 millimeters and the gasification agent into a fluidized bed gasifier to perform gasification reaction with the vertically raising coal gas so as to generate the coal and the ash content, discharging the ash content from the ash discharging opening of the fluidized bed, and introducing the coal gas