Dense phase pump for dry particulate material

Abstract

A dense phase pump for particulate material includes a pump chamber wherein material flows into the pump chamber under negative pressure and flows out of the pump chamber under positive pressure. A plurality of pinch valves are provided to control flow of material into and out of the pump chamber. The pinch valves are operated independent of each other and of the pump cycle rate. A modular design of the pump is provided.

What is claimed is: 
     
         1 . A pump for dry particulate material, comprising:
 a pump chamber defined in part by a gas permeable member disposed in a pressure chamber;   wherein during pump operation material flows into said pump chamber under negative pressure and material flows out of said pump chamber under positive pressure during a pump cycle;   wherein flow rate of material from the pump is adjustable independent of the pump cycle duration.   
     
     
         2 . The pump of  claim 1  comprising a suction pinch valve and a delivery pinch valve that control flow of material in and out of the pump chamber respectively, said pinch valves having open/closed times that are separately controllable from the pump cycle time. 
     
     
         3 . The pump of  claim 1  comprising a control circuit that adjusts duration of time that the negative pressure is applied to the pressure chamber to adjust flow rate. 
     
     
         4 . The pump of  claim 3  comprising a suction valve and a delivery valve that control flow of material in and out of the pump chamber respectively, said valves having open/closed times that are separately controllable with respect to the negative pressure duration time.