Seal Reliability And Performance Improvements In A Large, High Pressure, High Temperature Barrel Pump

Abstract

Modifications to a high-pressure, high-temperature barrel pump to increase seal reliability and throughout are discussed. The pump is in unspared hydrodewaxer (HDW) feed service. The original seal design included nonpressurized dual seals to provide an additional level of reliability. However, due to the heavy-oil/high-temperature nature of the service, the dual seals produced less than desirable run times. Substantial modifications to the dual seals were made to improve their reliability, but this also proved to be disappointing. Finally, the dual seals were replaced with single seals of a different design resulting in much more favorable results. The paper provides a detailed description of both seal modifications and their results. After approximately two years of service the capacity of the pump become the unit limit. The throughput of the pump was increased by approximately 25 percent without substantial capital outlays. This performance increase was accomplished by modifying the impeller diameter, the impeller vane tip widths, and reducing the internal circulation through the use of high temperature abraidable materials and reduced internal clearances. These modifications were preceded by a rotordynamic analysis of the pump before and after the internal clearances were reduced. Performance and vibration data before and after the modifications are presented.