MULTISTAGE PUMP EFFICIENCY GAINS THROUGH THE ELIMINATION OF THE SEAL CHAMBER PRESSURE EQUALIZATION LINE

摘要

The majority of horizontally split multistage pumps were designed when packing was the only cost effective method of sealing the pumpage from atmosphere. As a result, even modern pumps employ a stuffing box pressure equalization line (balance line) to lower stuffing box pressures. This technique of pressure equalization has a major drawback: reduced pump efficiency. The work that is done on the fluid that is throttled back to suction through the balance line is lost and acts to reduce the useful work done by the pump. While this was an acceptable compromise in the 1950s, it is now a true waste of very expensive electrical power. The modern solution to this problem is to eliminate the balance line and apply a correctly specified mechanical seal to the high pressure side of the pump. This paper serves to show that, with careful consideration of the effects of balance line removal, pump life can be maintained and efficiency gains achieved.