Multistage Pump Axial Thrust Optimization via Bypass Flow
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Solution Overview
Problem
Multistage pumps face high residual axial thrust at part load conditions, limiting the use of antifriction bearings and resulting in excessive heat generation and high costs associated with tilting pad bearings and their lubrication systems.
Innovation Solution
A bypass system is introduced that includes a throttle valve and bypass line to increase pressure in the clearance gap, reducing unbalanced axial thrust by redirecting balancing flow through the bypass line, thereby optimizing axial thrust compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If balancing flow is increased to reduce axial thrust at part load, then axial thrust compensation improves, but pump efficiency deteriorates due to excessive recirculation
Solution Approach 1:
The balancing flow path is segmented into two separate paths: one through the clearance gap (for axial thrust balance) and another through the bypass line with throttle bush (for flow control). This segmentation allows independent optimization of each function, enabling axial thrust compensation without excessive recirculation that would reduce pump efficiency.
Solution Approach 2:
The throttle bush defines a bypass line with controllable flow resistance, allowing the balancing flow rate to be adjusted as a parameter. By changing the flow resistance in the bypass line, the system can maintain optimal balancing flow at part load conditions without causing excessive recirculation through the clearance gap, thus preserving pump efficiency while compensating axial thrust.
2Reliability
If tilting pad bearings are used to handle high axial thrust, then bearing reliability improves, but system cost and complexity increase due to forced oil lubrication requirements
Solution Approach 1:
The bypass system with throttle bush enables the clearance gap to maintain optimal pressure and axial thrust balance automatically across varying operating conditions. This self-regulating mechanism reduces residual axial thrust to levels that allow use of simpler antifriction bearings with basic lubrication, eliminating the need for complex forced oil lubrication systems required by tilting pad bearings.
3Device complexity
If antifriction bearings are used without axial thrust optimization, then system simplicity improves, but bearing temperature increases excessively at part load due to high residual thrust
Solution Approach 1:
The bypass system with throttle bush performs preliminary axial thrust balancing by controlling the balancing flow before it reaches the clearance gap. This preliminary action reduces residual axial thrust to acceptable levels, preventing excessive bearing temperature rise and enabling the use of simple antifriction bearings even at part load conditions without requiring complex cooling or lubrication systems.
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 solution allows the use of antifriction bearings, reduces the size and cost of tilting pad thrust bearings, and minimizes lube oil requirements, effectively managing axial thrust at part load conditions while maintaining efficiency and reducing bearing temperatures.
Implementation Method 1
the clearance gap (Se) is configured to receive a balancing flow through the bypass line (506)
Implementation Method 2
for increasing a pressure in the clearance gap (Se) for axial thrust optimization
Data Source
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AI summary
A multistage pump (100) with axial thrust optimization is disclosed. The multistage pump (100) includes a pump discharge nozzle (101); and a bypass system (102) coupled to the pump discharge nozzle (101). The bypass system (102) includes a throttle valve (104) operatively coupled to the pump discharge nozzle (101), and a bypass line (106) provided within the multistage pump (100), the bypass line (106) being coupled to the throttle valve (104) and a clearance gap ("Se"), wherein the clearance gap ("Se") is configured to receive a balancing flow through the bypass line (106) for increasing a pressure in the clearance gap ("Se") for axial thrust optimization.