Characteristics of Powder Flow and Interstitial Air Pressure in Dual Structure Hopper Using Air Vibration

Abstract

A dual structure hopper which consists of a cone hard container and a flexible container of soft material can avoid the blockage phenomenon of cohesive powder near the orifice using the periodic vibration by the air pressure which changes on the opening and shutting times of the solenoid-controlled valve. This study experimentally investigated the characteristics of powder flow structure and interstitial air pressure during the discharge of flyash powder of 22.4μm from an orifice of this hopper when the air pressure and the opening time were changed. Then, the discharge mass of powder, the interstitial air pressure and the flow pattern in powder bed were measured. It is found that the cavity is generated by the collapse of powder bed due to the air vibration, and that it has risen toward the top of powder bed inside the hopper. And, the continuous discharge of powder and the periodic interstitial air pressure by the change of flow structure of powder bed can be confirmed. In addition, we made a schematic diagram of powder flow in the dual structure hopper using air vibration, and discussed powder flow state inside the hopper.