Fluidized bed furnace and waste treatment method

A fluidized bed furnace for heating waste to extract a combustible gas from the waste, comprising:

• fluidizable particles making up a fluidized bed to heat the waste;
• a furnace body having a bottom wall supporting the fluidizable particles from therebelow, and a sidewall standing upwardly from the bottom wall, wherein the bottom wall has a mixture discharge port provided at a position offset from a center position of the bottom wall in a specific direction to discharge non-combustible substances in the waste and carbides produced by heating of the waste, together with a part of the fluidizable particles, and an upper surface of the bottom wall is inclined to become lower toward the mixture discharge port so as to cause the fluidizable particles to fall on the upper surface of the bottom wall toward the mixture discharge port;
• a gas supply section for blowing a fluidizing gas from the bottom wall of the furnace body toward the fluidizable particles to fluidize the fluidizable particles;
• a waste supply section for supplying waste from a supply-side portion of the sidewall located on the same side as the mixture discharge port with respect to the center position of the bottom wall, to a region on the fluidized bed adjacent to the supply-side sidewall portion, thereby causing the waste on the fluidized bed to be moved toward an opposite-side portion of the sidewall on a side opposite to the mixture discharge port across the center position of the bottom wall,
• wherein:
• the gas supply section is adapted to blow the fluidizing gas from around the mixture discharge port to form a first fluidization region having a degree of fluidization of the fluidizable particles which is set to an extent allowing waste to be accumulated on the fluidizable particles, while blowing the fluidizing gas between the first fluidization region and the opposite-side sidewall portion at a flow velocity greater than that of the fluidizing gas to be blown in the first fluidization region, to form a second fluidization region having a degree of fluidization of the fluidizable particles greater than that in the first fluidization region, whereby the fluidizable particles are moved in a convection-like pattern and mixed with the waste to gasify the waste;
• and
• the waste supply section is adapted to supply waste from the supply-side sidewall portion to the fluidized bed to cause the waste to be accumulated on the first fluidization region while causing the accumulated waste to be moved into the second fluidization region step-by-step.