Multi-stage Centrifugal Compressor Drain Flow Path Design
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Solution Overview
Problem
In multi-stage centrifugal compressors, the alignment of drain pipes, suction nozzles, and ejection nozzles can cause interference, leading to increased vibration due to the need for a longer rotor shaft and reduced natural frequency, which may result in resonance during operation.
Innovation Solution
A multi-stage centrifugal compressor design that includes a rotor with impellers in multiple stages, diaphragms with guide flow paths and communication holes, and an axial flow path connecting these holes to form a drain flow path between the suction and ejection nozzles, allowing for fluid discharge without extending the rotor main body, thus avoiding interference between the nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If drain pipes, suction nozzle, and ejection nozzle are aligned in the axial direction below the casing, then the structure is compact, but interference occurs between these components
Solution Approach 1:
The patent introduces a radial dimension for the drain flow path by forming communication holes through the diaphragm in the radial direction, rather than aligning all components in the axial direction. This dimensional change allows the drain pipe to exit radially from the casing, avoiding interference with the axially-aligned suction and ejection nozzles while maintaining structural compactness
2Object-generated harmful factors
If the rotation shaft is lengthened in the axial direction to avoid interference, then component interference is avoided, but the natural frequency of the rotation shaft decreases
Solution Approach 1:
Instead of extending the rotation shaft axially to avoid interference, the patent uses a radial drain flow path that exits through the casing wall. This approach avoids the need for axial extension entirely, thereby maintaining the rotation shaft's natural frequency away from operational resonant frequencies while still achieving component separation
3Object-generated harmful factors
If the rotation shaft is lengthened to increase the interval among drain pipes and nozzles, then interference is avoided, but resonation is likely to occur
Solution Approach 1:
The patent resolves the interference problem by changing the drain pipe's exit direction from axial to radial. This allows sufficient spacing between all components without extending the rotation shaft axially, thereby avoiding the reduction of natural frequency and preventing resonation and vibration during operation
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 design enables the formation of a drain flow path that does not interfere with the suction and ejection nozzles, preventing vibration and resonance by maintaining the rotor's natural frequency away from the rotational frequency, while allowing for efficient fluid discharge without lengthening the rotor main body.
Implementation Method 1
the centrifugal compressor compresses the working fluid in a gas state by utilizing a centrifugal force generated when the impeller rotates
Data Source
AI summary
A multi-stage centrifugal compressor includes: a rotor including a plurality of impellers disposed in a plurality of stages in an axial direction; a plurality of diaphragms each including a guide flow path that guides a fluid discharged radially outward from one of the impellers to an adjacent impeller on the following stage, and a communication hole extended from a bottom portion of the guide flow path; a casing that accommodates the plurality of diaphragms therein; and an axial flow path that connects the plurality of communication holes to each other. The casing includes a drain flow path disposed only between the communication hole that is the closest to a suction nozzle and the communication hole that is the closest to an ejection nozzle.