Pump with seal purge heater

Abstract

A pump assembly which overcomes a shaft and cover cracking problem comprising a means for heating the seal purge water flowing along the shaft before it exits into an annulus (mixing region) thus reducing the temperature difference between the cooler seal purge water and the hotter product water prior to the mixing of the two waters. Three embodiments of the invention include 1) a cover sleeve surrounding the pump shaft which extends into the hydrostatic bearing (mixing region) so as to be heated by the product water and thereby heating the seal purge water before mixing with the product water, 2) a rotating shaft sleeve surrounding the pump shaft which extends into the hydrostatic bearing (mixing region) to heat the seal purge water by circulating product water before mixing with the product water and 3) a rotating baffle type heat exchanger extending into the hydrostatic bearing (mixing region) to heat the seal purge water flowing in a bi-directional path by product water also flowing in a bi-directional path before mixing with the product water.