A Review of Design Considerations of Centrifugal Pump Capability for Handling Inlet Gas-Liquid Two-Phase Flows

Abstract

Most of the pumps working under two phase flows conditions are used in petroleum industry applications, like electrical submersible pumps (ESP) for hydrocarbon fluids, in chemistry, nuclear industries and in agriculture for irrigation purposes as well. Two-phase flows always deteriorate overall pump performances compared with single flow conditions. Several papers have been published aiming to understand flow physics and to model all the main mechanisms that govern gas pocket formation and surging phenomena. These mechanisms depend on the pump type, the impeller geometry, the rotational speed, design and off-design liquid flow rate conditions, the volumetric gas fraction, the fluid properties and the inlet pressure. In the present paper, a review on two phase performances from various centrifugal pumps designs is presented, mainly based on experimental results. The main focus is devoted to detect the significant geometrical parameters that: (1) Modify the pump head degradation level under bubbly flow regime assumption; (2) Allow single stage centrifugal pumps keep working under two-phase flow conditions with high inlet void fraction values before pump shut down, whatever the pump performance degradations and liquid production rates should be. Because most of the published experimental studies are performed on dedicated laboratory centrifugal pump models, most of the present review is based on air-water mixtures as the working fluid with inlet pressures close to atmospheric conditions. The following review supposes that gas phase is considered as a non-condensable perfect gas, while the liquid phase is incompressible. Both phases are isolated from external conditions: neither mass nor heat transfer take place between the phases.

Experimental Investigations on the Inner Flow Behavior of Centrifugal Pumps under Inlet Air-Water Two-Phase Conditions

“…However, most research is based on the assumption of bubbly homogeneous flow regimes, which can be observed up to an inlet void fraction not exceeding 4% to 5% depending on the pump geometry and operating conditions. However, conventional designs of centrifugal pumps could work with a maximum of 12% inlet void fraction under design working conditions, as shown by Jiang et al [6]. The handling ability of centrifugal pumps for gas entraining is still confusing for pump designers, which is related to the two-phase flow behaviors inside the impeller and volute passage.…”

Effects of a Combination Impeller on the Flow Field and External Performance of an Aero-Fuel Centrifugal Pump

“…As for the vital role of an impeller for a centrifugal pump, many investigations on impeller design and performance prediction have been carried out. In [10], two phase performances for different centrifugal pumps are studied, and the experiment and simulation results are close. It is still useful to perform experimental two-phase flow studies.…”

Effects of Combination Impeller on the Flow Field and External Performance of an Aero-fuel Centrifugal Pump

“…As for the vital role of an impeller for a centrifugal pump, many investigations on impeller design and performance prediction have been carried out. In [10], a review on two phase performances from various centrifugal pumps designs is presented, mainly based on experimental results. It is still useful to perform experimental two phase flow studies.…”