Abstract: A plurality of dispersive air pipes for combustion (11) containing a plurality of dispersive air holes and projecting in a cantilever fashion from the side walls (1b, 1c) in an oblique downward direction are provided in the lower portion of a combustion zone (2b) of a furnace main unit (1) which includes an ash discharge outlet (6) formed in the base portion of the furnace main unit, and an incombustible material discharge space (12) is formed between the ends of the dispersive air pipes for combustion (11). As a result, incombustible material accumulating on the dispersive air pipes for combustion (11) is guided to the incombustible material discharge space (12) and then discharged.

Abstract: The oblique bed wall (6) of the furnace main unit (1) is inclined in downward direction towards the ash discharge outlet (5). Oblique side walls (24R, 24L) are formed in the right and left side walls (1c, 1d) on the inlet (4) side of the furnace main unit (1), and fluidized bed material (S) blown up from the side fluid layers (RS, LS) is guided into the central fluid layer (CS). The fluidized bed material (S) is caused to circulate in succession from the central fluid layer (CS) at the inlet (4) side towards the central fluid layer (CS) at the ash discharge outlet (5) side towards side fluid layers (RS, LS) at the ash discharge outlet (5) side towards side fluid layers (RS, LS) at the inlet (4) side towards central fluid layer (CS) at the inlet (4) side, by dispersive air emitted from dispersive air pipes (21A, 21B, 25). In this way, the fluidized bed material (S) is caused to circulate in virtually a horizontal plane without partitioning walls.