Axially Adjustable Impeller for Centrifugal Compressor Surge Control
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Solution Overview
Problem
Conventional centrifugal compressors face instability and performance reduction due to surge phenomena, which can lead to overheating and mechanical damage, and existing surge control methods often require additional components and reduce compressor performance.
Innovation Solution
A centrifugal compressor system that incorporates a magnetic bearing assembly and a controller to adjust the axial position of the impeller, allowing for surge control without the need for additional complex components or performance reduction, by shifting the impeller's position to manage flow rates and velocities effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional surge control methods using adjustable diffuser vanes or inlet guide vanes are employed, then surge can be controlled, but device complexity increases and compressor performance is reduced
Solution Approach 1:
The patent extracts the surge control function from the diffuser vanes and inlet guide vanes, concentrating it instead in the impeller position control system. By removing the need for adjustable diffuser vanes and inlet guide vanes, the system reduces component complexity while maintaining surge control capability through magnetic bearing assembly adjustment of the impeller axial position.
Solution Approach 2:
The magnetic bearing assembly is given a dual function: it not only supports the impeller rotation but also controls the axial position of the impeller for surge control. This multi-functionality eliminates the need for separate surge control mechanisms, reducing overall device complexity while maintaining reliable surge prevention.
2Reliability
If adjustable diffuser vanes or inlet guide vanes are used for surge control, then surge can be managed, but manufacturing costs and system construction complexity increase
Solution Approach 1:
The patent removes the adjustable diffuser vanes and inlet guide vanes from the system, extracting their surge control function and transferring it to the impeller position control mechanism. This simplification reduces manufacturing complexity and system construction requirements while maintaining effective surge control through magnetic bearing adjustment.
3Device complexity
If the impeller axial position is adjusted using magnetic bearing assembly, then surge control is achieved without additional components, but control precision requirements increase
Solution Approach 1:
The patent replaces mechanical adjustment mechanisms with a magnetic bearing assembly that uses electromagnetic fields to control the impeller axial position. This substitution eliminates the need for mechanical linkages and adjustment mechanisms, reducing component complexity while providing precise control through electromagnetic actuation and sensing.
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 effectively controls surge without compromising compressor performance, reduces the risk of overheating and mechanical damage, and simplifies the system construction by eliminating the need for adjustable diffuser vanes and inlet guide vanes, thereby enhancing reliability and reducing costs.
Implementation Method 1
an adjustable magnetic bearing assembly electrically coupled to the controller and arranged and configured to support the shaft
Implementation Method 2
The impeller increases the velocity of refrigerant gas, generally without changing pressure. The diffuser increases the refrigerant pressure without changing the velocity.
Data Source
AI summary
A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a motor and a diffuser. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is rotatable about a rotation axis defining an axial direction, and the impeller is adjustably mounted within the casing along the axial direction between at least a first flow rate position and a second flow rate position. The motor rotates the impeller. The diffuser is disposed in the outlet portion downstream from the impeller with a outlet port of the outlet portion being disposed between the impeller and the diffuser.