gear pump for pumping high viscosity as well as high viscosity materials, in particular plastics

摘要

A gear pump for the transport of highly viscous materials includes two meshing gear wheels in a casing in which adequate free space is left for the material. A sealed zone near the outlet has a minimum length on both sides of the distance between adjacent teeth across the full axial width. The outlet itself has a cross-sectional area of 0.2 to 2-times the product of gear wheel width and tooth height. In plants for the production of polymers and volatile components, such as low-density polyethylene and ethylene also in mixing and compound installations. The free space around the gear wheels results in an interaction of the pumped material which is caused by the revolving gear wheels and the pump casing above the sealed zone and produces a pressure above the pump intake pressure. The shear surfaces and the power losses caused by shear are on eorder of magnitude lower than with conventional positive displacement pumps. A gear pump is less costly and causes less temp. rise than a screw extruder.