To attain high combustion efficiency of multi-waste fuel by making the temperature in a fluidized layer lower than a conventional temperature under stable fluidity to completely burn char produced in the fluidized layer and scattered in back wash, particularly fuel with low specific gravity.
An air ratio in the fluidized layer is set into a range of 0.2-0.6. Exhaust gas recirculation is performed, and the ratio of exhaust gas recirculation flow to total air flow is set into a range of 50-80%. A fluidized layer temperature is controlled to 600-800°C. Secondary air with the air ratio set into a range of 0.3-0.4 is supplied from a freeboard at an angle of 30-60° to a perpendicular direction to a furnace wall, and tertiary air with the air ratio set into a range of 0.4-0.9 is supplied from the freeboard in back wash behind the secondary air at the same angle as the secondary air. Char produced in the fluidized layer and scattered in back wash, particulaly fuel of low specific gravity, is gasified in a reducing atmosphere and completely burnt in an oxidizing atmosphere.
OMURA YOSHITAKA
IKEDA KIYOTO
TANIGUCHI KOJI
