Centrifugal Compressor Intermediate Scroll Axial Positioning
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Solution Overview
Problem
The existing multi-stage centrifugal compressor designs face challenges in miniaturization due to increased casing diameter and elevated pressure loss caused by the placement of the intermediate scroll, which affects the flow direction and efficiency of the working fluid.
Innovation Solution
The design incorporates a tubular-shaped casing with diaphragms and an external casing that guides the working fluid's flow direction inwardly, featuring an intermediate scroll with a scroll flow path connected to the intermediate discharge port, utilizing an introduction portion to direct fluid from the return flow path into the scroll flow path, with the outer flow path formed by the casing's inner peripheral surface, reducing the need for increased diaphragm size and minimizing pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the intermediate scroll is disposed on the outer side of the curved portion in the radial direction, then the intermediate scroll can be positioned to guide extracted gas, but the diameter of the casing increases which hinders miniaturization
Solution Approach 1:
The intermediate scroll is repositioned from the radial outer side to the axial downstream side of the return flow path, utilizing the axial dimension instead of radial expansion. This dimensional shift allows the scroll to function without increasing casing diameter, enabling miniaturization while maintaining extraction capability
2Length of stationary object
If the intermediate scroll is disposed on the inner side of the curved portion in the radial direction, then the casing diameter can be reduced, but the flow direction change of discharged working fluid increases leading to higher pressure loss
Solution Approach 1:
The scroll flow path is positioned in the axial direction downstream of the return flow path rather than radially inward. This allows the working fluid to be introduced into the scroll flow path with minimal flow direction change, reducing pressure loss while keeping the casing compact
Solution Approach 2:
The introduction portion acts as an intermediary component that smoothly connects the return flow path to the scroll flow path. It facilitates gradual flow transition and reduces abrupt direction changes, thereby minimizing pressure loss in the intermediate scroll assembly
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 a reduction in casing diameter while maintaining performance and reducing pressure loss in the intermediate scroll, enabling efficient miniaturization and pressure-resistant performance.
Implementation Method 1
a plurality of impellers (3) that are disposed in the casing (10) at a distance in the axial direction Da, that are configured to compress a working fluid G supplied from the first side Da1 in the axial direction Da with respect to each of the plurality of impellers (3), and that are configured to discharge the working fluid G to an outer side Dro in a radial direction Dr
Implementation Method 2
a return flow path (35C) that is configured to guide the working fluid G, which is discharged from each of the plurality of impellers (3) and is flowing toward the outer side Dro in the radial direction Dr, so that a flow direction of the working fluid G is directed to an inner side Dri in the radial direction Dr
Implementation Method 3
an intermediate scroll (50) that is configured to guide part of the working fluid G discharged from one of the plurality of impellers (3) in an intermediate stage which is disposed midway in the axial direction Da among the plurality of impellers (3) to the intermediate discharge port (14)
Implementation Method 4
an introduction portion (52) connecting the return flow path (35C) and the scroll flow path (51), the introduction portion (52) being configured to introduce part of the working fluid G flowing in the return flow path (35C) into the scroll flow path (51)
Data Source
AI summary
A centrifugal compressor includes a rotary shaft having a plurality of impellers and a casing having an intermediate discharge port. The casing has a plurality of diaphragms, an external casing, a return flow path that guides a flow direction of a working fluid to an inner side in a radial direction, and an intermediate scroll that guides part of the working fluid discharged from the impeller in an intermediate stage to the intermediate discharge port. The intermediate scroll has a scroll flow path formed on a second side in the axial direction with respect to the return flow path, and an introduction portion connecting the return flow path and the scroll flow path, and an outer flow path forming surface of the scroll flow path is formed by a casing inner peripheral surface facing an inner side of the external casing in the radial direction.