Seal-Less Process Fluid Pump With Reduced Radial Bearings
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Solution Overview
Problem
Existing process fluid lubricated pumps for subsea applications are complex, costly, and prone to maintenance issues due to the need for multiple radial bearings, which complicates their design and increases the risk of failure, especially when operating in deep-sea environments with high pressure requirements.
Innovation Solution
A process fluid lubricated pump design featuring a common housing with a reduced number of radial bearings, utilizing hydrostatic support devices like throttle bushes to center the pump shaft and eliminate the need for direct contact bearings, and operating as a seal-less pump to simplify the design and reduce maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple radial bearings are used to support the pump shaft, then the pump shaft is adequately supported, but the device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates unnecessary radial bearings from the pump design. By analyzing the actual support needs of the pump shaft, the invention removes redundant bearings while maintaining adequate support through the essential ones, thereby reducing device complexity and cost without compromising shaft stability.
Solution Approach 2:
The patent replaces traditional mechanical radial bearings with a magnetic bearing system. This substitution uses magnetic fields to provide the necessary radial support for the pump shaft, eliminating the need for multiple physical bearings and their associated complexity while maintaining reliable support.
2Reliability
If traditional contact bearings are used, then the pump shaft is supported, but wear and maintenance requirements increase
Solution Approach 1:
The patent replaces mechanical contact bearings with magnetic bearings that use magnetic fields for support. This eliminates direct mechanical contact between moving parts, thereby eliminating wear entirely and significantly reducing maintenance requirements while maintaining reliable shaft support.
Solution Approach 2:
The patent employs a hydrostatic support system using fluid pressure to maintain the pump shaft in position. This non-contact support method eliminates mechanical wear by using fluid pressure rather than solid contact, thereby reducing maintenance needs while providing reliable shaft support.
3Reliability
If seals are included to prevent leakage, then process fluid containment is improved, but the design complexity and maintenance needs increase
Solution Approach 1:
The patent extracts and eliminates traditional seal systems from the pump design. By using magnetic bearings and a sealed rotor construction, the invention prevents process fluid leakage without requiring separate seal components, thereby reducing design complexity while maintaining containment reliability.
Solution Approach 2:
The patent merges the sealing function into the rotor structure itself. The rotor is designed as a sealed unit where the process fluid is contained within the rotor cavity, eliminating the need for separate seal components between the rotor and stator, thus reducing complexity while maintaining containment.
4Stress or pressure
If multiple components are used to achieve high pressure, then the pressure requirement is met, but the cost and complexity increase
Solution Approach 1:
The patent replaces traditional multi-stage mechanical compression with a magnetic bearing-supported single-stage or reduced-stage compressor design. The magnetic bearings enable more efficient energy transfer and reduced losses, allowing high discharge pressure to be achieved with fewer stages and components, thereby reducing complexity and cost.
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
The reduced complexity and cost of the pump design enhance reliability and minimize maintenance, while the hydrostatic support and seal-less operation improve rotordynamic performance and reduce the risk of failure in high-pressure subsea environments.
Implementation Method 1
the pump shaft is radially supported in a non-contacting manner during operation of the pump, wherein the pump unit comprises at most one hydrodynamic radial pump bearing
Implementation Method 2
a first throttle bush, which is fixedly connected to the pump shaft between the first stage impeller and the non-drive end of the pump shaft or at the non-drive end, the first throttle bush defining a first throttle front side facing the first stage impeller and a first throttle back side
Implementation Method 3
a relief passage is provided between the balance drum and a first stationary part configured to be stationary with respect to the common housing, the relief passage extending from the drum front side to the drum back side
Implementation Method 4
the pump unit further comprising at least a first stage impeller fixedly mounted on the pump shaft, and a last stage impeller fixedly mounted on the pump shaft
Data Source
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AI summary
A process fluid lubricated pump is proposed, for conveying a process fluid, having a common housing (2), a pump unit (3) arranged in the common housing, and a drive unit (4) arranged in the common housing (2), wherein the common housing (2) comprises an inlet (21) and an outlet (22) for the process fluid, wherein the pump unit (3) comprises a pump shaft (5) extending from a drive end (51) to a non-drive end (52) of the pump shaft (5) and configured for rotating about an axial direction (A), the pump unit (3) further comprising at least a first stage impeller (31) fixedly mounted on the pump shaft (5), and a last stage impeller (33) fixedly mounted on the pump shaft (5), and optionally at least one intermediate stage impeller (32) fixedly mounted on the pump shaft (5) between the first stage impeller (31) and the last stage impeller (33) wherein the drive unit (4) is configured to exert a torque on the drive end (51) of the pump shaft (5) for driving the rotation of the pump shaft (5), wherein a balance drum (7) is fixedly connected to the pump shaft (5) between the pump unit (3) and the drive end (51) of the pump shaft (5), the balance drum (7) defining a drum front side (71) facing the pump unit (3) and a drum back side (72), wherein a relief passage (73) is provided between the balance drum (7) and a first stationary part (26) configured to be stationary with respect to the common housing (2), the relief passage (73) extending from the drum front side (71) to the drum back side (72), wherein the pump shaft (5) is radially supported in a non-contacting manner during operation of the pump, wherein the pump unit (3) comprises at most one hydrodynamic radial pump bearing (54) for supporting the pump shaft (5), wherein the at most one radial pump bearing (54) is arranged at the non-drive end (52) or at the drive end (51) of the pump shaft (5).