To provide a method for injecting powdery material with which the powdery material is discharged from a feed-tank in high accurate discharging speed and can be inject into a furnace.

This method for injecting powdery material, is performed as the followings, with which in the case of receiving no powdery material into the feed-tank, the proofreading of a powdery material flow-rate meter is performed by using the weight measured value with a load-cell set in the tank, and in the case of receiving the powdery material into the tank, too, the discharging speed of the powdery material is measured and controlled in high accuracy. Further, the powder discharging amount is controlled in the high accuracy, in the case of being the differential pressure between the pressure in the tank and the pressure in a powder transporting piping at lower than a prescribed value by using a differential pressure control, or in the case of being the differential pressure at the prescribed value or higher by using the opening degree control of a powdery material flow-rate adjusting valve. Depending on this control method, even in the case of which either one of the load cell or the powdery material flow-rate meter can not be used, the stable powder injection can be continued by combining the differential pressure control and the useable load cell or the opening degree control of the powdery material flow-rate adjusting valve using the powdery material flow-rate meter.

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