Conveying device for transportation of flowable materials

Claim 1

Device for the transportation of flowable material in powder, particulate, lump, granular or pasty form which comprises a feed pipe having an inner wall, a coaxial feeder screw coated with a substance having good sliding properties within said feedpipe, means for driving said feeder screw and a drive shaft rigidly coupled to said feeder screw, wherein said feeder screw can be moved backwards and forwards in the axial direction (A), and the means for driving produces a rotation-free forward stroke and a return movement with forced, regular rotation of the feeder screw per screw pitch length (s) is situated in line with the feeder screw, and wherein the feeder screw features no bearings within the flowable material in the feed pipe, includes blades thereon which are continuous and the distance of the feeder screw from the inner wall of the feed pipe is on all sides just slightly larger than the average particle or lump size of the flowable material being transported, whereupon in the presence of a pneumatic or hydraulic counter-pressure a compact, homogenous column of material is produced further including means for admitting a conveyance stream of gaseous or fluid propellant downstream to said feeder screw, such that the length of the feed pipe is of such a size that the pressure from the propellant at the entry of the material into the feeder screw is only a small fraction of the value it has in the conveyance stream, whereby said device provides a self-sealing facility wherein said feed pipe has an end wall with an opening therein, a seal is provided outside the opening of the end wall of the feed pipe and including a feeder screw shaft which passes through said end wall opening, said feed pipe having an exit including a spring back flap means provided on the feed pipe at the exit.