Series Multistage Pump Seal Layout for Pressure Spike Isolation
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Solution Overview
Problem
Existing multistage pump arrangements face challenges with mechanical seals being damaged by pressure spikes and liquid slugs, particularly in subsea applications, leading to increased maintenance and operational inefficiencies.
Innovation Solution
A pumping arrangement with two multistage pumps in series, where the process side of the first mechanical seal of the second pump is in fluid communication with the inlet of the first pump, decoupling it from discharge pressure fluctuations, and incorporating balance drums and throttle bushes to stabilize the rotor and reduce axial thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If two multistage pumps are arranged in series to generate high pressure, then the discharge pressure is improved, but the mechanical seal is exposed to pressure spikes and liquid slugs causing damage
Solution Approach 1:
The pump system is divided into two separate multistage pumps arranged in series, with the mechanical seal of the second pump isolated from the high-pressure discharge side. This segmentation allows the first pump to handle the pressure generation while the second pump's seal is protected through fluid communication with the first pump's inlet, maintaining seal reliability while achieving high discharge pressure.
2Reliability
If the process side of the mechanical seal is connected to the pump inlet to protect from pressure spikes, then the mechanical seal wear is reduced, but the device complexity increases due to additional fluid communication pathways
Solution Approach 1:
The fluid communication pathway between the first pump inlet and the process side of the second pump's mechanical seal is integrated into the existing pump structure. This merging approach uses the natural fluid flow path without requiring additional external piping or complex valve systems, thereby reducing device complexity while maintaining seal protection.
3Reliability
If balance drums and throttle bushes are added to stabilize the rotor and reduce axial thrust, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The balance drums and throttle bushes are designed to perform multiple functions: stabilizing the rotor during operation, reducing axial thrust on the mechanical seal, and maintaining proper fluid communication pathways. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved rotor stability and reliability.
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 minimizes mechanical seal wear, reduces barrier fluid consumption, and enhances the reliability and efficiency of the pumping system, especially in subsea environments.
Implementation Method 1
A multistage pump comprises a plurality of impellers, which are arranged on a common shaft. The common shaft is driven for a rotation about an axial direction so that all impellers are commonly rotated about the axial direction.
Implementation Method 2
the process side of the first mechanical seal of the second multistage pump is in fluid communication with the pump inlet of the first multistage pump, so that the pressure prevailing at the process side of said first mechanical seal is always at least approximately the same as the suction pressure of the first multistage pump
Data Source
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AI summary
A pumping arrangement is proposed, comprising a first multistage pump (10a) and a second multistage pump (10b), wherein each multistage pump (10a, 10b) comprises: a housing (2) with a pump unit (3) arranged in the housing (2), wherein the housing (2) comprises a pump inlet (21) for receiving a fluid with a suction pressure, and a pump outlet (22) for discharging the fluid with a discharge pressure, and wherein the pump unit (3) comprises a plurality of impellers (31, 32, 33) for conveying a fluid from the pump inlet (21) to the pump outlet (22), and a pump shaft (5) for rotating about an axial direction (A), with the pump shaft (5) extending from a drive end (51) to a non-drive end (52), wherein each impeller (31, 32, 33) is mounted to the pump shaft (5) in a torque proof manner. The second multistage pump (10b) comprises at least a first mechanical seal (50) for sealing the pump unit (3) at the pump shaft (5), with the first mechanical seal (50) having a process side (59) facing the pump unit (3). The pump outlet (22) of the first multistage pump (10a) is connected to the pump inlet (21) of the second multistage pump (10b), so that the first multistage pump (10a) and the second multistage pump (10b) are arranged in series. The process side (59) of the first mechanical seal of the second multistage pump (10b) is in fluid communication with the pump inlet (21) of the first multistage pump (10a).