Multistage Pump Seal Configuration for Recirculation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multistage submersible pumps face efficiency losses and reduced lifespan due to recirculation of water and abrasive particles, which decreases pressure and can cause damage from debris accumulation.
Innovation Solution
The implementation of a seal configuration comprising a diffuser assembly with a hub seal and retainer ring, a disc assembly with a wear ring and retainer ring, and a thrust washer to minimize fluid recirculation and absorb thrust loads, allowing for limited lateral and axial movement of impeller components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the number of stages in a multistage pump is increased to increase total output pressure, then the pump's total output pressure increases, but efficiency is lost due to water recirculation within stages
Solution Approach 1:
The pump stage is segmented into multiple functional components: impeller assembly, disc assembly with wear ring, and diffuser assembly with hub seal. This segmentation allows each component to perform a specific function in controlling fluid flow, preventing recirculation while maintaining pressure buildup across stages
Solution Approach 2:
The hub seal and wear ring act as intermediary elements between the impeller and diffuser assemblies. These intermediary components create sealing interfaces that prevent fluid recirculation pathways while allowing the pressure buildup function to continue across multiple stages
2Productivity
If abrasive particles are passed into the pump, then pumping function is maintained, but pump life is severely decreased due to debris dwelling in the stage
Solution Approach 1:
The wear ring and hub seal are designed as extractable, replaceable components that can be removed and replaced when worn by abrasive particles. This allows the main pump structure to remain intact while the sacrificial sealing components are periodically maintained, extending overall pump life
Solution Approach 2:
The wear ring and hub seal function as sacrificial components that are intentionally designed to wear and be replaced rather than protecting the entire pump. These relatively simple, low-cost components absorb the wear from abrasive particles, protecting the more expensive impeller and diffuser assemblies
3Loss of energy
If a seal configuration is added to prevent recirculation, then recirculation is minimized, but device complexity increases
Solution Approach 1:
The hub seal and wear ring serve multiple functions simultaneously: they seal to prevent recirculation, support radial and axial thrust loads, and provide wear surfaces for abrasive particle management. This multi-functionality reduces the need for separate components, managing complexity while achieving recirculation prevention
Solution Approach 2:
The sealing function is merged with the thrust bearing function in the hub seal and wear ring assembly. Rather than having separate seals and thrust bearings, these components combine both functions, reducing the number of parts and simplifying the overall stage configuration while preventing recirculation
4Force
If thrust bearing and wear member configuration is improved to manage thrust forces, then impeller thrust loads are managed, but manufacturing complexity increases
Solution Approach 1:
The wear ring and hub seal are designed as simple annular components with uniform cross-sections and standard geometries. This homogeneous, simple geometry makes them easy to manufacture using standard machining or forming processes, despite their important thrust-bearing function
Solution Approach 2:
The thrust bearing capability is achieved through controlled clearance parameters between the wear ring and impeller, and between the hub seal and diffuser. By optimizing these dimensional parameters, the design achieves effective thrust load management without requiring complex structural features, maintaining ease of manufacture
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces fluid recirculation, maintains sealing efficiency throughout the pump's life, and extends the pump's operational life by preventing debris accumulation and managing thrust forces effectively.
Implementation Method 1
The diffuser assembly preferably incorporates a diffuser, a hub seal and a retainer ring to secure the hub seal to the diffuser
Implementation Method 2
The disc assembly preferably incorporates a disc, a wear ring and a retainer ring securing the wear ring to the disc
Implementation Method 3
A thrust washer is disposed in a planar relation to the diffuser hub seal
Implementation Method 4
a thrust washer and a diffuser assembly, all disposed about the impeller shaft
Data Source
AI summary
A centrifugal pump includes plural pump stages, each comprising an impeller assembly, a stationary disc assembly and a diffuser assembly, all disposed about an impeller shaft. A floating impeller hub seal is supported by a diffuser assembly to minimize fluid recirculation. A thrust washer is disposed around the impeller shaft and is engageable with an impeller hub and the hub seal. A wear ring is secured to a disc assembly and engageable with a wear surface on the impeller.