PURPOSE: To enable a stable and economic operation of a calcination apparatus by controlling the flow rate of the fuel so as to maintain the temp. of waste gas discharged from a drying apparatus at a fixed temp.
CONSTITUTION: Slurry of a raw material is dehydrated by a filter 1 to obtain cake, said cake is dried in a drying apparatus 2W5 to obtain dry powder, and said dry powder is calcined after feeding the powder to a rotary kiln 8 provided with a suspension preheater together with a calcination burner 13, while the waste gas from the suspension preheater is fed to the above described drying apparatus to dry by allowing it to contact directly with the waste gas. After separating the waste gas from dry powder, it is sucked by a blower. The flow rate of the fuel to be supplied to a burner 13 is controlled so as to obtain a fixed temp. of said waste gas independently of fluctuation of water content in the cake, on one hand the flow rate of the waste gas discharged from the blower 14 is increased if the concn. of O2 in the waste gas in the suspension preheater is decreased. The suction amt. of the blower is controlled so as to reduce the flow rate of the waste gas to be discharged from the blower if the O2 concn. is increased.
TOMINAGA SATORU
KAWADA TAKASHI
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