Single-Shaft Multi-Stage Centrifugal Compressor Inlet Pre-Rotation Control
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Solution Overview
Problem
Single-shaft multi-stage centrifugal compressors face challenges in maintaining stable operation over a wide range of flow rates from the rated flow rate to significantly small flow rates while ensuring uniform flow rate distribution and maintaining discharge pressure, particularly due to non-uniform flow rate distribution caused by pre-rotation application in the first-stage centrifugal impeller.
Innovation Solution
The compressor design incorporates multiple intake nozzles, including a first intake nozzle aligned with the rotary shaft and a second intake nozzle deviated from the shaft, along with a rotation prevention plate and inflow control devices, to manage pre-rotation and enhance uniformity of flow rate distribution across the centrifugal impeller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pre-rotation is applied to the first-stage centrifugal impeller to expand stable operation range to small flow rates, then the stable operation range is improved, but the discharge pressure is reduced
Solution Approach 1:
The patent implements adjustable pre-rotation control through inlet guide vanes that can change their mounting angle dynamically. This allows the system to adapt the degree of pre-rotation based on operating conditions, enabling stable operation across a wide flow rate range while maintaining discharge pressure by optimizing pre-rotation application at different operating points
Solution Approach 2:
The patent changes the mounting angle parameter of the inlet guide vanes to control the amount of pre-rotation applied to the impeller. By adjusting this parameter according to flow rate conditions, the system achieves both expanded stable operation range and maintained discharge pressure performance
2Adaptability or versatility
If an inlet guide vane with vane drive mechanism is installed to control pre-rotation amount, then pre-rotation control capability is improved, but the reliability of moving parts is deteriorated due to high frequency angle changes
Solution Approach 1:
The patent implements adjustable pre-rotation control through inlet guide vanes that can change their mounting angle dynamically. This allows the system to adapt the degree of pre-rotation based on operating conditions, enabling stable operation across a wide flow rate range while maintaining discharge pressure by optimizing pre-rotation application at different operating points
Solution Approach 2:
The patent changes the mounting angle parameter of the inlet guide vanes to control the amount of pre-rotation applied to the impeller. By adjusting this parameter according to flow rate conditions, the system achieves both expanded stable operation range and maintained discharge pressure performance
3Adaptability or versatility
If the mounting angle of the inlet guide vane is changed to apply pre-rotation, then pre-rotation is improved, but the flow rate distribution uniformity in the circumferential direction is worsened
Solution Approach 1:
The patent divides the single inlet flow path into multiple segmented flow paths by providing multiple intake nozzles (first intake nozzle and second intake nozzle) that introduce fluid at different positions and angles. This segmentation allows each nozzle to contribute to uniformizing the circumferential flow distribution while collectively achieving the desired pre-rotation effect
Solution Approach 2:
The patent employs asymmetric positioning and orientation of multiple intake nozzles relative to the rotary shaft. The first intake nozzle is arranged toward the rotary shaft direction while the second intake nozzle is arranged at a deviated direction, creating asymmetric flow patterns that complement each other to achieve both pre-rotation and uniform distribution
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 allows for adjustable pre-rotation application, improving flow rate distribution uniformity and enabling stable operation across a broader flow rate range, from rated to small flow rates, without compromising discharge pressure.
Implementation Method 1
an L-shaped bend part which is provided between the annular flow path part and an inlet of the centrifugal impeller and redirects a flow of the working fluid in an axial direction of the rotary shaft
Implementation Method 2
compress and boost the gas sequentially by means of the centrifugal impellers provided in multiple stages on the rotary shaft
Data Source
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AI summary
A centrifugal fluid machine includes: a rotary shaft; a plurality of centrifugal impellers; a bearing; and a casing. The centrifugal fluid machine includes an intake flow path which is provided in the casing, and the intake flow path includes: a first intake nozzle; an annular flow path part provided around the rotary shaft; an L-shaped bend part which redirects a flow of a working fluid in an axial direction of the rotary shaft; a second intake nozzle provided in the casing on the side opposite to the first intake nozzle and connected to the annular flow path part; and a rotation prevention plate provided on the side opposite to the first intake nozzle in the annular flow path part. The first intake nozzle is arranged toward a direction of the rotary shaft, and the second intake nozzle is arranged in a direction deviated from the direction of the rotary shaft, and the first intake nozzle and the second intake nozzle are each equipped with an inflow control device which controls an inflow of the working fluid. Accordingly, it is possible to apply pre-rotation to the working fluid from the intake nozzle and also suppress a flow rate distribution from becoming non-uniform.