Hopper system and clamping arrangement for a permeable membrane

Abstract

A hopper system comprising a hopper having a side wall sloping downwardly and radially inwardly from the inlet at the top of the hopper to the outlet at the bottom of the hopper. Secured to the inside of the hopper is a membrane having a shape generally conforming to the inside of the hopper and closely overlying the conical side wall of the hopper. The membrane is permeable to air but generally impermeable to fluent material in the hopper and has a plurality of pockets for receiving stay bars. The upper and lower cylindric ends of the membrane are clamped to clamping assemblies mounted on the inside of the hopper adjacent its upper and lower ends, respectively, without the use of fasteners extending through holes in the ends of the membrane or other means of attachment to the hopper. The clamping assemblies are removable from the hopper without first unclamping the membrane whereby the clamping assemblies and membrane may be readily installed in and removed from the hopper. Pressurized air is introduced into the hopper through the hopper walls and passes inwardly through the membrane with the stay bars in the membrane preventing substantial inward billowing. After passing through the membrane, the air enters into fluent material contained within the hopper thereby to fluidize the material for efficient unloading from the hopper.