Multi-stage Pump Casing Openings for Axial Thrust Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-stage pumps experience excessive axial thrust loads due to pressure differences across impellers, which often exceed the load ratings of available thrust bearings, and existing thrust balancing technologies provide limited reduction and are compromised by hydraulic friction losses.
Innovation Solution
The new thrust balancing technology reduces axial thrust loads by leaking liquid through large openings in the pump casings instead of drilled holes in rotating impellers, allowing for increased pressure reductions across multiple stages and optimizing pressure balances across impellers to minimize thrust loads on the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If drilled holes are used in impellers to reduce axial thrust loads, then some thrust reduction is achieved, but hydraulic friction losses increase and thrust reduction is limited to about 60%
Solution Approach 1:
The patent introduces an intermediary chamber between stages that mediates the pressure balance. Instead of direct leakage through impeller holes, liquid is routed through a designated chamber space, reducing friction losses while achieving thrust balance across multiple stages simultaneously.
Solution Approach 2:
The invention transitions from two-dimensional impeller hole leakage to three-dimensional chamber-based pressure equalization. By creating a volumetric chamber space between stages, the system achieves more effective thrust reduction across multiple stages rather than being limited to single-stage pressure differential.
2Force
If existing thrust balancing technology with drilled holes is used, then some pressure differential reduction is achieved, but the thrust reduction is limited to the pressure differential potential of just one pump stage
Solution Approach 1:
The patent segments the pump into distinct stages with intermediate chambers between them. Each chamber independently balances pressure for its adjacent impellers, allowing multi-stage thrust reduction rather than being limited to single-stage pressure differential potential.
Solution Approach 2:
The invention merges multiple pressure balancing functions into a unified chamber system. The intermediate chamber simultaneously balances pressure across multiple impeller stages, combining what would otherwise require separate balancing mechanisms for each stage.
3Power
If larger pumps with larger exposed areas are used, then higher head capacity is achieved, but axial thrust loads increase and exceed thrust bearing load ratings
Solution Approach 1:
The intermediate chamber acts as a mediator that distributes and balances the pressure loads across larger pump configurations. This allows larger pumps to achieve thrust balance proportional to their size, preventing thrust bearing overload in high-capacity applications.
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 approach effectively reduces axial thrust loads by multiple stages of head, enabling the selection of suitable thrust bearings for large, high-head multi-stage pumps and minimizing hydraulic friction losses, thus addressing the limitations of existing technologies.
Implementation Method 1
axial thrust loads are the product of pressure difference across the impeller (from hub-side to eye-side) times the area to which that differential pressure is exposed
Implementation Method 2
The thrust reduction of this existing thrust balancing technology is further compromised by high hydraulic friction losses as leakage passes through drilled holes moving at high speeds on the rotating impellers
Data Source
Figure 1
Figure 1B
Figure 1C
AI summary
A multi-stage pump featuring first and second stages, each stage having an impeller arranged on a rotor of the pump, each impeller having a hub-side and an eye-side, and each impeller configured to pump a liquid through the pump that applies an axial thrust load caused by a pressure difference in an axial direction from the hub-side to the eye-side of each impeller; and a first and second stage pump casing, each casing configured to form a casing enclosure to contain components of the first stage and the second stage, including each impeller, and configured with one or more pump casing openings formed therein and passing thru the pump casing to leak at least some liquid being pumped from inside to outside the casing enclosure to reduce substantially the axial thrust load caused by the pressure difference in the axial direction from the hub-side to the eye-side of each impeller.