Centrifugal Compressor Intermediate Suction Flow Path Design

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Solution Overview

Problem

In multistage centrifugal compressors, the axial width of the introduction flow path needs to be increased for impellers with large flow coefficients, leading to decreased gas flow velocity and increased separation, especially during intermediate suction, which can promote gas separation on the downstream side.

Innovation Solution

A centrifugal compressor design that includes an intermediate suction flow path adjacent to the introduction flow path, introducing a second fluid to the second impeller, with a side surface on the upstream side of the introduction flow path inclined at an angle between 0° and 15° relative to an orthogonal axis, minimizing separation by guiding fluids effectively through a curved flow path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If the axial width of the introduction flow path is increased to match the suction shape of impellers with large flow coefficients, then the impeller can be properly supplied with gas, but the flow velocity of the gas decreases and separation is likely to occur

Engineering Contradiction:

Improveflow path cross-sectional areaVSAvoidgas flow velocity

Core Design Contradiction:

Area of moving objectVSSpeed

Solution Approach 1:

The invention changes the geometric parameters of the introduction flow path by positioning the upstream side surface on the downstream side from the return position of the return flow path in the axial direction. This parameter adjustment allows the flow path to accommodate larger cross-sectional areas while maintaining adequate flow velocity by optimizing the flow path length and geometry.

Inventive Principle:

Principle #35Parameter changes

2Length of moving object

If the side surface of the introduction flow path on the upstream side is inclined upstream toward the radially inner side to shorten the length of the centrifugal compressor in the axial direction, then the compressor becomes more compact, but separation is more likely to occur

Engineering Contradiction:

Improvecompressor axial lengthVSAvoidgas separation

Core Design Contradiction:

Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

Instead of inclining the upstream side surface upstream toward the radially inner side (conventional approach), the invention inverts this approach by positioning the upstream side surface on the downstream side from the return position. This inverted configuration reduces the inclination angle, thereby minimizing gas separation while still achieving a compact axial length through optimized flow path geometry.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If intermediate suction is performed to meet refrigerator operating condition restrictions, then the compressor can operate under restricted conditions, but the compressor axial length increases and gas separation on the downstream side of the introduction flow path is promoted

Engineering Contradiction:

Improveoperating condition adaptabilityVSAvoidgas separation

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The invention introduces an intermediate suction flow path as a mediator that is adjacent to the introduction flow path. This intermediate flow path allows additional gas to be supplied to the second impeller without significantly increasing the axial length of the compressor. The positioning of the upstream side surface on the downstream side from the return position helps maintain favorable flow conditions that reduce separation in both the introduction and intermediate suction paths.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 minimizes gas separation in the introduction flow path, enhancing the efficiency of the centrifugal compressor by optimizing fluid flow and reducing turbulence.

Implementation Method 1

a curved flow path which is connected to a downstream side of the introduction flow path and the intermediate suction flow path, extends to be bent toward the downstream side in the axial direction and guides the first fluid and the second fluid to the second impeller

Methodology Applied

Scientific EffectFluid flow guidance through curved path:

Data Source

PatentUS10989201B2Centrifugal compressor

Publication Date: 2021.04.27 MITSUBISHI HEAVY INDUSTIES COMPRESSOR CORP

AI summary

A centrifugal compressor includes: a rotating shaft; a first impeller; a second impeller which is disposed on a downstream side of the first impeller; a return flow path which guides a first fluid flowing to a radially outer side from the first impeller toward a radially inner side; an introduction flow path which introduces the fluid guided to the radially inner side to the second impeller; an intermediate suction flow path which additionally supplies a second fluid to the second impeller; and a curved flow path which is connected to a downstream side of the introduction flow path and the intermediate suction flow path, and guides the first fluid and the second fluid to the second impeller, wherein a side surface on an upstream side of the introduction flow path is disposed on the downstream side from a return position of the return flow path.