Indirect heating screw conveyor

摘要

Single or multi-screw indirect-heating screw conveyor desorbers having a heating gas guide enclosed by the screw shaft wall (single-wall screw shafts) or located between a screw shaft wall and an internal chamber wall (double-walled screw shafts). Predetermined amounts of cooling and diluting fluid may be added to a heating gas stream to control the maximum temperature thereof. Screw shaft support bearings and rotary drive components may be cooled, and conveyor wall and/or screw shaft surfaces (e.g.. screw flights and interflight surfaces) may be automatically cleaned during screw shaft rotation by hardened bits and/or breaker devices. Cleaning operations may also involve the interaction of two counter-rotating conveyor screw shafts having mutually interleaved and opposite-handed external flights. Sizing and placement of breaker devices and/or hardened bits is determined empirically to be that necessary to effect substantial removal of material accumulations which would otherwise significantly interfere with efficient conveyor operation. Application of the invention allows design and production of desorbers having decreased weight and size and increased efficiency and reliability compared with currently available indirect-heating screw conveyor desorbers having external screw flights.