Advanced Electric Submersible Pump Design Tool for Geothermal Applications Page: 2 of 17
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effectively boost 80kg/s of working fluid (water, with a gas fraction of 2% or less) by 300bar in a
well that is nominally 10-5/8" in diameter. The operating temperature is up to 300"C.
Compared to the traditional lifting mechanisms, such as Line Shaft Pump, Gas Lift, Progressing
Cavity Pump, and Jet Pump, Electrical Submersible Pumps (ESPs) have better performance in
terms of effectively handling larger production rate in deeper wells. ESPs incorporate a
submerged electric motor unit driving a multistage centrifugal pump to produce flow back to
the surface. The design aims to lift large volumes of high temperature water against a pressure
difference within the production well in which the system is installed.
The multistage radial- or mixed-flow centrifugal pump is a key component to the ESP system in
which flow and pressure are generated dynamically. Generally, lift or head developed by a
single stage centrifugal pump is relatively low, due to the limited well casing diameter . Thus,
a multistage pump must consist of many stages stacked together in series to provide the
desired lifting capability. Each stage consists of two basic components: a rotating set of
impellers and a stationary diffuser, shown as Figure 1. The geothermal fluid (water) from the
previous stage enters the impeller in an axial direction at a relatively low velocity and attains a
higher velocity through the impeller due to the centrifugal force. The fluid then leaves the
impeller with high kinetic energy that is converted into potential energy at the discharge of the
diffuser, at higher pressure level than it was at the inlet of the impeller. Since the diffuser
redirects the flow into the next stage, the process repeats and the rotary action is finally
converted to an increase of the fluid pressure. However, the theoretical design of such rotating
machinery remains very empirical because it is hard to predict three-dimensional unsteady flow
in varying locations, and one must rely on numerous experimental and statistical rules [2-4].
In this investigation, an advanced ESP design tool was developed by combining a one-
dimensional theoretical model with a three-dimensional Computational Fluid Dynamics (CFD)
analysis. The numerical simulation of both single phase flow and water/air mixture multiphase
flow are presented. The results of the simulation include streamlines, velocity and pressure
distributions and Gas Volume Fraction (GVF) within the ESP flow channels. The designed
mixed-flow multistage centrifugal pump is seen to be able to produce 80kg/s geothermal fluid
(at 300"C) with high efficiency and meet Department of Energy's design criteria. In order to
validate the design tool and methodology, the same design practice was carried out for an
existing ESP product. The performance curves such as efficiency, head and power consumption
agree with the test data very well. It is shown that the advanced design tool presented in this
study can help understand and predict 3D flow behavior in an ESP with sufficient accuracy. It
also helps to significantly shorten the development cycle of ESP for geothermal applications.
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Qi, Xuele; Turnquist, Norman & Ghasripoor, Farshad. Advanced Electric Submersible Pump Design Tool for Geothermal Applications, article, May 31, 2012; United States. (digital.library.unt.edu/ark:/67531/metadc843079/m1/2/: accessed December 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.