Thermal decomposition and gasification apparatus of combustible material with particulate and granular material circulating through fluidized bed

PURPOSE:To convert a combustible material, e.g. an agricultural and forestry waste, into a high caloric combustible gas efficiently, by bringing a particulate and granular heating medium of specific void into contact with the combustible material while circulating the particulate and granular heating medium through a cylindrical vessel constituted of a specific structure divided by a small-diameter inner cylinder and partition plates. CONSTITUTION:An inner cylinder 2 is placed in a cylindrical vessel 1 and divided by partition plates 5, 6 and 9 to form anular spaces 7', 10' and 11'. A particulate and granular heating medium having a particle diameter of 0.05-2mm. is contained in the spaces, and a gas, e.g. steam, is continuously fed from feed ports 12, 13 and 14 to transfer the heating medium upward while keeping the void thereof at 0.4-0.85. The heating medium is then introduced into the space 8' in the inner cylinder 2 and transferred upward gradually while kept at a void of 0.4-0.85. A combustible material, e.g. an agricultural and forestry or plastic waste, is fed from a feed port 16, transferred while in contact with the heating medium and decomposed thermally at 500-1,050 deg.C. The formed gas and steam are joined in the upper spaces 7 and 8 and introduced from an outlet 18 into the next step.