Active clearance management in screw compressor
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Solution Overview
Problem
Screw compressors face challenges in managing rotor clearances effectively across different operational conditions, leading to compromised mechanical stability at start-up and compression efficiency during regular operation due to fixed clearance settings.
Innovation Solution
The implementation of a controllable bearing, such as a magnetic bearing, which actively manages rotor clearances by moving rotors in three-dimensional directions to adjust clearance distances based on operational conditions, using controllers and sensors to optimize clearance settings for mechanical stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed clearance settings are used in screw compressors, then mechanical stability is maintained at start-up, but compression efficiency is compromised during regular operation
Solution Approach 1:
The patent applies the dynamics principle by replacing fixed clearance settings with actively controllable clearances. The controllable bearing allows the rotor clearance to be dynamically adjusted based on operational conditions - maintaining larger clearances during start-up for mechanical stability, and reducing clearances during regular operation for optimal compression efficiency. This transforms a static system into a dynamic one that adapts to different operating phases.
2Reliability
If larger rotor clearances are used, then mechanical stability is improved at start-up, but compression efficiency decreases during regular operation
Solution Approach 1:
The patent implements parameter changes by actively modifying the rotor clearance parameter based on operational conditions. During start-up, larger clearances are maintained to ensure mechanical stability. During regular operation, the clearance parameter is reduced to optimize compression efficiency and minimize energy losses. The controllable bearing enables precise adjustment of this critical parameter throughout the operational cycle.
3Productivity
If controllable bearings are implemented to actively manage clearances, then compression efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies mechanics substitution by replacing traditional mechanical bearings with controllable magnetic bearings. This substitution eliminates mechanical contact and friction while enabling active control of rotor clearance through magnetic fields. The magnetic bearing system provides both support functionality and clearance control capability, reducing the need for additional mechanical components and simplifying the overall system architecture despite the added control electronics.
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 enables dynamic adjustment of rotor clearances to enhance mechanical stability during start-up and increase compression efficiency during regular operation, improving the overall performance and reliability of screw compressors.
Implementation Method 1
A magnetic bearing is defined as a bearing that supports a load, e.g., a rotor, using magnetic levitation. A magnetic bearing may move a supported load in any one, two, or three dimensional directions by changing a force, e.g., magnetic field, of the magnetic levitation.
Data Source
AI summary
A compressor includes a housing defining a working chamber. The housing further includes a bore and an endplate disposed toward a discharge end. The compressor further includes a rotor having helical threads, the rotor being configured to be housed in the bore, a rotor clearance, a controllable bearing supporting the rotor, and a controller configured to control the controllable bearing such that the controllable bearing moves the rotor in a manner to reduce and/or enlarge the rotor clearance.