Abstract: In a fluidized bed process for the gasification of coal or similar carbonaceous solids wherein char particles are withdrawn from a fluidized bed reaction vessel, transported to a second vessel, and later returned to the initial vessel, char particles of high ash content are separated from particles to be returned to the fluidized bed reaction vessel by injecting a dense phase stream of char particles including particles of both high and low ash content into a vertically moving gas stream having a velocity sufficient to transport relatively light particles of low ash content upwardly into the fluidized bed reaction vessel but insufficient to suspend relatively dense particles of high ash content, collecting the high ash content particles which are not entrained by the gas stream, and periodically withdrawing the collected particles from the system.

Abstract: Feed coal particles are mixed with fine particles of devolatilized carbonaceous material having an average particle diameter less than about 25% of that of the coal and then injected into a high temperature fluidized bed gasification zone. The devolatilized material adheres to the coal particles as they soften and forms a nonsticky coating which hinders the formation of large coal agglomerates. During the gasification process the adhering particles are retained in the bed and at least partially gasified, resulting in better carbon utilization than might otherwise be obtained.