Verfahren zur Steigerung der Wärmeübergangszahl bei dem Wärmeaustausch in Schneckenapparaten

1,155,368. Screw pumps. FARBEN FABRIKEN BAYER A. G. June 20, 1966 [June 22, 1965], No.27499/66. Heading F1C. Also in Division F4] A method of operating a screw pump as a heat exchanger consists in rotating the pump at a speed outside its normal working range and modifying the flow thus achieved through the pump, either by a change in pressure at the supply conduit to the pump, or, by the use of an additional pump, whereby the heat exchange between a fluid flowing through the pump, and the pump cylinder, is improved. In the only example specifically described for pumping a highly viscous fluid, a screw pump designed to run 240 r.p. m. is operated at 60 r. p. m. at which latter speed the heat transfer factor (α) is shown by a graph (Fig. 1) to be higher than at the normal speed range of the pump. Shown is a multiple screw pump for carrying out the method, the output of single screw pumps b being modified either by the use of a meshing screw pump a or by a change in pressure in the inlet pipe d. Recirculation of fluid through the pump a is controlled by an adjustable check valve f. Jackets c for a heating or cooling fluid surround the cylinders of pumps b. Fluid output is through a throttle valve at e.