Impeller Bearing Configuration for Liquid Ring Compressor Stability
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Solution Overview
Problem
Current liquid-ring pump designs with overhung impellers suffer from premature thrust bearing failure due to radial loads, wobble during startup and shutdown, and require external lubrication and maintenance, limiting their placement and efficiency.
Innovation Solution
A bearing arrangement with a radial bearing on the shaft side and a forward thrust bearing between the impeller and inlet gas head, using a poly-crystalline diamond bearing that eliminates external lubrication needs and provides continuous support through the impeller's revolution, reducing vibrations and wobble.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an overhung impeller design is used, then the compressor can operate with the impeller offset from the bearing, but the radial bearing is located outside the casing at a distance from the impeller, causing the impeller weight to be cantilevered far from its support point, which produces a moment in the shaft that creates radial load on the thrust bearings, leading to premature failure
Solution Approach 1:
The patent moves the radial bearing from an external position to an internal position on the impeller itself, changing the spatial dimension of bearing placement. This eliminates the cantilevered moment arm by positioning the bearing directly at the impeller center, resolving the contradiction between operational flexibility and bearing reliability.
Solution Approach 2:
The radial bearing is nested within the impeller structure, with the bearing housing integrated into the impeller body. This nesting eliminates the need for external bearing housings and reduces the moment arm to zero, preventing radial loads on thrust bearings while maintaining impeller positioning flexibility.
2Ease of manufacture
If the radial bearing is located outside the compressor casing at a distance from the impeller, then the bearing can support the impeller, but this configuration requires external lubrication and maintenance, limiting placement options and increasing complexity
Solution Approach 1:
The radial bearing is designed to be self-lubricating using the process liquid (water or gas) that naturally flows through the bearing. This eliminates external lubrication systems and maintenance requirements, reducing device complexity while maintaining ease of manufacture through integrated bearing housing.
Solution Approach 2:
The bearing housing serves multiple functions: it houses the radial bearing, provides structural support for the impeller, and channels process liquid for self-lubrication. This multi-functionality eliminates external lubrication systems while simplifying manufacturing through integrated design.
3Speed
If the impeller is started from an inactive state, then the impeller must turn through water at the bottom of the compressor casing, but this water creates significant drag on the impeller, combined with less drag from gas at the top, causing the impeller to wobble inside the casing until sufficient speed is reached
Solution Approach 1:
The radial bearing provides continuous rotational support and stabilization to the impeller during startup and operation. By supporting the impeller at its center, the bearing counteracts the wobbling motion caused by asymmetric drag forces from water and gas, maintaining rotational stability throughout the speed range.
4Productivity
If the impeller is significantly larger in diameter than the shaft, then the impeller can effectively move gas and liquid, but the bearing arrangement requires external bearing housing and lubrication monitoring
Solution Approach 1:
The bearing housing is merged with the impeller body, creating an integrated structure where the radial bearing is housed within the impeller itself. This eliminates separate bearing housings and external lubrication systems, reducing device complexity while maintaining impeller productivity through direct bearing support.
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 enhances the reliability and maintenance-friendliness of liquid ring compressors by reducing bearing failure, eliminating wobble, and allowing for more flexible placement without external lubrication, thus improving operational efficiency and reducing costs.
Implementation Method 1
A radial bearing may be disposed on the shaft side of the impeller and a forward thrust bearing may be disposed between the impeller and an inlet gas head
Implementation Method 2
The forward thrust bearing rotor may be mounted to a forward face of the overhung impeller and the forward thrust bearing stator may be mounted to at least one of an inlet gas head surface or compressor casing
Implementation Method 3
using a poly-crystalline diamond bearing that eliminates external lubrication needs
Implementation Method 4
provides continuous support through the impeller's revolution, reducing vibrations and wobble
Data Source
AI summary
An impeller-type liquid ring compressor having a particular bearing configuration. Such a bearing arrangement may completely support the impeller as it rotates, eliminating many of the problems inherent in the prior art designs without changing the general overhung impeller design. This may allow the impeller-type liquid ring compressor to be easily retrofitted in existing use environments, such as, for example, oil and gas processing facilities, oil refineries, and petrochemical processing facilities. In some exemplary embodiments, a thrust bearing may be located on the front face of the impeller, or radial bearings may be disposed between the vanes of the impeller. A radial bearing and thrust bearing may further be disposed on the shaft side of the impeller close to the impeller itself. The compressor may be configured so that the process fluid carries heat away from each of these bearings.