Vertical Pump Wear-Ring Bearings Eliminate Suction Bearing Obstruction
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Solution Overview
Problem
Vertical turbine pumps face issues such as increased ambient pressure requirements due to suction bearing obstructions, material strength and weight, vibration due to equidistant bearing supports, hydraulic thrust, and hydraulic efficiency losses from wear ring galling, which affect efficiency and operational life.
Innovation Solution
The use of non-galling wear-ring bearings made of materials like Vesconite® that eliminate the need for suction bearings and their retainers, allowing impellers to rotate directly against wear rings, reducing running clearances and guiding flow without obstructing the impeller eye, and using non-metallic suction bells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If suction bearing and suction bearing retainer are included in the suction bell, then the power transmission shaft alignment is maintained, but the impeller eye is obscured requiring increased ambient pressure and submergence
Solution Approach 1:
The suction bearing retainer is completely removed from the suction bell assembly. Instead, the suction bearing is mounted directly to the suction bell housing, eliminating the retainer structure that was obstructing the impeller eye and increasing required ambient pressure.
Solution Approach 2:
The bearing support function is segmented from the suction bell structure. The suction bell is designed to guide flow without structural bearing supports, while bearing mounting is handled separately through direct mounting to the suction bell housing, separating flow guidance from mechanical support functions.
2Reliability
If suction bearing retainer is included in the suction bell, then shaft alignment is maintained, but product weight and cost increase due to required material strength
Solution Approach 1:
The suction bearing retainer is completely removed from the design. The suction bell is redesigned without this additional structural component, reducing material requirements and overall product weight while maintaining shaft alignment through alternative bearing mounting arrangements.
3Reliability
If bearing supports are positioned above and below the rotating impeller, then shaft support is provided, but shaft deflection is maximized due to equidistant bearing configuration
Solution Approach 1:
The bearing support configuration transitions from symmetric (above and below impeller) to asymmetric arrangement. The suction bearing is repositioned to provide non-equidistant support, with the bowl bearing positioned to create optimal shaft support geometry that minimizes deflection during operation.
4Reliability
If wear rings are used between impeller and bowl, then relative motion wear is managed, but clearances must be increased for galling materials causing recirculation and efficiency loss
Solution Approach 1:
The wear ring design utilizes composite or non-galling materials that combine wear resistance with non-galling properties. This allows the use of corrosion-resistant materials without requiring increased clearances, as the non-galling material properties prevent adhesion and sticking issues that would otherwise necessitate larger tolerances.
Data Source
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AI summary
A vertical pump features stationary bowl assembly, a rotating power transmission shaft, impellers and bottom wear-ring bearings. The stationary bowl assembly includes bowls, each bowl having a respective bowl bottom inside surface. The rotating power transmission shaft is configured to extend through the stationary bowl assembly. The impellers are arranged on the rotating power transmission shaft to rotate and draw material through the stationary bowl assembly, each impeller having a respective impeller bottom outside surface. Each bottom wear-ring bearing is arranged between the respective impeller bottom outside surface of each impeller and the respective bowl bottom inside surface of each bowl, made from a non-galling bearing material, and configured to maintain the alignment of the rotating power transmission shaft in relation to the stationary bowl assembly.