To extremely reduce an amount of powder fluid discharged out of a fluidized-bed furnace together with gas in the furnace by providing a plurality of exhaust gas outlets between a top center of the furnace and a straight shell of an upper part side of a furnace body.
A predetermined amount of gas in the furnace is exhausted from a free board 16 of an upper art of a fluidized bed 13 via an exhaust gas duct 5 in a reaction process. Then, a position of the duct 5 is not formed at a center of a mirror plate 2 for forming a furnace top, not a straight shell 3 of an upper part side of a furnace body but disposed therebetween. Thus, there is small possibility of exhausting powder fluid out of the furnace accompanied with the gas in the furnace to be exhausted from the duct 5. And, since a retention time in the furnace of powder fluid-like material, i.e., reducing time and carbonizing time can be sufficiently ensured long, a transfer ratio of iron oxide to an iron carbide is extremely high. Accordingly, such a fluidized- bed furnace 1 can be particularly suitably used as a large-sized fluidized-bed furnace.
TSUTSUMI KAZUO
KAZARI MASAHIDE
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