PURPOSE: To incinerate completely a burning material having a wide variety of particle size distributions by a method wherein the particles of the material are transferred into the middle of the fluidized bed type incinerator.

CONSTITUTION: Primary combustion air is introduced into the fluidized bed type incinerator 1 through an air inlet chamber 3 and a porous plate 2 by use of a blower 4 and the burning material is transferred into the incinerator 1 from a hopper 6 through a feed pipe 5 together with the secondary combustion air supplied from the blower 4. In this case, the feed pipe 5 is connected tangentially to the side wall of the incinerator so that a whirlpool generates within the incinerator 1. Accordingly, a stream of air at the upper part of the porous plate 2 becomes an ascending air current which, when moves upward, forms itself a whirlpool and therefore, large sized particles of the material are fluidized and burned on the porous plate 2 while fine particles thereof are burned as they turn within the incinerator. Thus, even a material having a wide variety of particle size distributions can be burned completely.