Centrifugal Turbo-compressor Inter-stage Sealing and Clearance Control
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Solution Overview
Problem
Conventional double-stage centrifugal turbo-compressors face high manufacturing costs and complex assembly due to the need for precise machining accuracy to maintain axial and radial clearances, and suffer from fluid leakage issues caused by the inter-stage sealing device configuration.
Innovation Solution
The design includes a hermetic casing with a main casing portion that houses the compression stages and inter-stage sealing device, featuring annular disc-shaped aerodynamic members and a securing mechanism with elastic elements to maintain clearance and flexibility, reducing machining requirements and enhancing assembly ease, while the inter-stage sealing device is simplified to minimize leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high level of machining accuracy is used for manufacturing the hermetic casing and internal parts, then axial and radial functional clearances are maintained, but manufacturing cost substantially increases
Solution Approach 1:
The hermetic casing is divided into a first casing portion and a second casing portion that can be assembled together. The first aerodynamic member is positioned between these casing portions, allowing the clearance control function to be distributed. This segmentation enables the use of less precise machining on individual casing portions while maintaining overall functional clearances through the modular assembly structure.
Solution Approach 2:
The first aerodynamic member acts as an intermediary element between the first and second casing portions. It provides a reference surface for positioning and helps maintain the axial clearance between compression stages without requiring high-precision machining of the casing portions themselves. The elastic element further mediates by providing flexible compensation for clearance variations.
2Reliability
If high level of machining accuracy is used for the inter-stage sealing device, then fluid leakage is limited, but manufacturing cost and assembly difficulty increase
Solution Approach 1:
The inter-stage sealing device uses the first aerodynamic member as an intermediary reference surface for positioning the sealing members. This approach transfers the positioning function from requiring high-precision casing machining to using the aerodynamic member as a datum, thereby reducing overall manufacturing complexity while maintaining sealing effectiveness.
Solution Approach 2:
The sealing structure incorporates an elastic element that allows for parameter changes in the form of flexible deformation. This elasticity compensates for minor variations in manufacturing tolerances and assembly positions, maintaining reliable sealing performance without requiring extremely tight machining tolerances on all components.
3Manufacturing precision
If re-machining and adjustments are performed to guarantee appropriate clearances, then functional clearances are maintained, but assembly time and complexity increase
Solution Approach 1:
The design incorporates features that establish clearances during the initial assembly process rather than requiring subsequent re-machining. The first aerodynamic member is pre-positioned between the casing portions with built-in positioning features, and the elastic element is pre-installed to provide automatic clearance compensation, eliminating the need for post-assembly adjustments.
Solution Approach 2:
The elastic element introduces a dynamic component to the clearance control system. Instead of relying on rigid, fixed clearances that require precise machining, the elastic element allows the assembly to adapt its clearance parameters dynamically during operation, compensating for thermal expansion and manufacturing variations without requiring complex assembly procedures.
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 reduces manufacturing costs, simplifies assembly, and ensures reliable operation by maintaining axial clearances and flexibility, thereby extending the lifespan of the centrifugal turbo-compressor.
Implementation Method 1
an elastic element arranged between the main casing portion and the second aerodynamic member, the elastic element axially biasing the first and second aerodynamic members, the inter-stage sealing device and the inlet distributor with a predetermined force
Implementation Method 2
a first and a second compression stage configured to compress a refrigerant, the first and second compression stages respectively including a first and a second impeller
Data Source
AI summary
The centrifugal turbo-compressor (2) includes a hermetic casing; a drive shaft (6); a first and a second compression stage (12, 13) configured to compress a refrigerant and respectively including a first and a second impeller (18, 19) connected to the drive shaft (6) and being arranged in a back-to-back configuration; an interstage sealing device provided between the first and second impellers (18, 19). The hermetic casing includes a main casing portion (4) in which are arranged the first and second compression stages (12, 13) and the inter-stage sealing device. The first and second compression stage (12, 13) respectively includes a first and a second aerodynamic member (29, 31) each having an annular disc shape and respectively facing front-sides (21, 22) of the first and second impellers (18, 19).