This device is used as an auxiliary system of rotary atomization semi-dry deaidification. The dry powder bin is set on the ground, and after being measured by a weight loss scale or a pan feeder, the powder is conveyed of the entrance of the reaction tower or bag filter by a Roots blower or compressed air, and it is fully mixed with the fume to remove the acid gases in the fume (SOx, HCI, HF). The disc feeder is composed of mixing distributor and several groups of metering distributors. The conveying air source is fan, and the metering mode is volumetric metering; The weightlessness scale is composed of measuring bucket, measuring screw, weighing table and weighing instrument. The conveying gas source is fan or compressed air, and the measurement method is weightlessness. Commonly used dry deacidification agents: powdery baking soda and hydrated lime.