Stepped Balance Ring Axial Clearance for Submersible Pump Wear
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Solution Overview
Problem
Electrical submersible pumps face wear issues due to severe thrust forces, particularly in abrasive well fluids, as existing designs lack effective mechanisms to manage thrust-induced stress variations between impellers and diffusers, leading to increased maintenance costs.
Innovation Solution
The design incorporates axially movable impellers with adjustable annular clearances between balance rings and diffuser ribs, which change in response to thrust direction, optimizing fluid pressure dynamics to reduce wear by varying the fluid communication and pressure distribution within the pump stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the clearance between the balance ring and diffuser wall surface is kept constant, then the structure is simple, but wear occurs on thrust surfaces due to severe thrust forces
Solution Approach 1:
The clearance between the balance ring and diffuser wall surface is made variable rather than constant. The balance ring is designed to move axially relative to the diffuser, allowing the clearance to dynamically adjust based on thrust conditions. This dynamic adjustment reduces wear on thrust surfaces by optimizing the fluid pressure distribution and communication paths during both downthrust and upthrust operations.
2Productivity
If abrasive sand particles are present in well fluid, then pump operation continues, but wear is exacerbated on thrust surfaces
Solution Approach 1:
The invention converts the harmful effect of abrasive sand particles into a beneficial outcome by using the thrust forces generated during operation to drive the balance ring movement. The thrust forces, which would normally cause wear, are instead utilized to dynamically adjust the clearance and optimize fluid pressure distribution, thereby reducing overall wear on thrust surfaces even in the presence of abrasive particles.
3Reliability
If thrust surfaces are formed of abrasion resistant material such as tungsten carbide, then wear resistance improves, but pump cost increases
Solution Approach 1:
The invention changes the operational parameters of the pump by introducing dynamic clearance adjustment through balance ring movement. This parameter change allows the system to optimize fluid pressure distribution and communication paths during operation, reducing wear on thrust surfaces. As a result, the use of expensive abrasion resistant materials like tungsten carbide can be minimized or eliminated, reducing pump cost while maintaining reliability.
Data Source
AI summary
An electrical submersible pump assembly includes a centrifugal pump having stages. Each of the stages has an impeller in cooperative engagement with a downstream diffuser. The impeller is axially movable relative to the downstream diffuser between a downthrust and an upthrust position. The downstream diffuser has an annular downstream wall surface, relative to the impeller, defining a downstream cavity. The impeller has a downstream balance ring that locates alongside the downstream wall surface. An annular clearance between the downstream balance ring and the downstream wall surface increases in response to the impeller moving from the downthrust to the upthrust position.