Experimental evaluation of affinity law of pumps by using multistage electric submersible pump at various speeds of operation

Abstract

Electric Submersible Pumps (ESP) are widely used in agriculture and petroleum industries. These pumps are designed to work under wide range of flowrates and heads. To achieve the desired flow rate, various methods are employed. One of the methods widely used in industries to control the flow rate is varying the operating speed of the pump. Speed regulation of the pump with variable duty requirements leads to reliable operation of the pump. To access the performance characteristics of the pump at speeds other than the designed speed the affinity law of pumps is used. This paper investigates the application of the affinity law when a multistage electric submersible pump is operated at variable speeds. A five stage ESP was selected to conduct the performance test at various speeds. A Variable Frequency Drive (VFD) was employed to operate the ESP at five different speed settings from 40 to 60 Hz. Results have shown that there is a deviation between the performance characteristics obtained from the test and the one which was calculated using affinity law when the pump was operated at various speeds, which indicated the necessity of conducting experiments when a VFD is to be employed to vary the flow rate.