Preheating screw

摘要

A preheating screw for the simultaneous mixing and heating of fine-grained or paste-like substances, in which intensive heat transfer takes place during transport of the substance by use of a rotating hollow screw that is filled with a heat-transfer medium, preferably a fluid, heat being transfered from the heat-transfer medium to the product by way of the heated hollow screw. An electrical heating device is installed in a hollow screw shaft, and is supplied with electrical energy via sliding contacts positioned on the outside of the screw shaft.