To reduce an unburned carbon component in a residual powder which is generated by a heat treatment of coal, waste or the like, and provide a low unburned carbon ash of a high added value, by burning the residual powder of which the average particulate diameter is a specified value or lower, at a specified temperature in a fluidized bed furnace which is filled with a particle having a specified particulate diameter.
A residual powder which is generated in the combustion, gasification, liquefaction or thermally decomposed object, of coal and industrial waste or the like, is an objective. Especially, a fly ash from a combustion boiler of dust coal is preferable. As a residual powder, one of which the average particulate diameter is 20 μm or lower is used. The powder is burned in a fluidized bed furnace while being fluidized, and the unburned carbon component is reduced. In this case, as a fluidized bed furnace for use, one in which a particle having a particulate diameter being 10-100 times of the average particulate diameter of the residual powder is filled. A combustion temperature in the fluidized bed furnace is selected in a range of 700-1,000°C. When the temperature is less than 700°C, the unburned carbon component is not sufficiently reduced, and at 1,000°C or higher, troubles such as the molten residual powder works against fluidization are generated.
FUJIWARA NAOKI
KUROKI HIROAKI
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