Rui Francisco Pessoa (Master of Science in Petroleum Engineering)
Experimental Investigation of Two-Phase Flow Performance of Electrical Submersible Pump Stages
(199 pp. – Chapter VI)
Directed by Dr. Mauricio Prado
(298 words)
Two-phase flow behavior prediction of centrifugal pumps is a hard task due to the complexity involved in modeling multiphase flow inside turbo machines. No models are currently available for this purpose. Some empirical correlations are available in the literature, but they are valid only for the tested pumps in the experimental range used to develop them.
An experimental study has been conducted at TUALP with a 22-stages GC6100 pump to gather data for pump performance under two-phase flow conditions. Air and water were used as working fluids. This study differs from other experimental works because the pressure changes were recorded stage-by-stage. The results of previous works have been reported as an average of the intake and discharge conditions, and depend on the number of stages used.
Phenomena like surging and gas locking were observed during these tests and their boundaries have been mapped. It will provide some insight regarding when they appear, and the way they are revealed.
The pressure increment and total hydraulic horsepower for the average pump and per stage as a function of the liquid flow rate, and each gas flow rate considered are presented. The average brake horsepower and efficiency for the pump are also plotted for the variables mentioned.
The results indicate that the average behavior for the pump is significantly different from that observed per stage. Additionally, it was found a second region after the surging condition, where the slope of the pressure increment vs. flow rate curve changes again. In this region the first stage of the pump develops a positive pressure increment.The first stage showed a performance far below from the manufacturer specification. Some reasons for this behavior could be related with stage wear, fluid pre rotation and/or pressure drop in the pump intake channel. Further investigation is required.
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