Centrifugal Compressor Liquid Injection Modification

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Solution Overview

Problem

Existing centrifugal compressors face difficulties in precision and quality when modifying the casing to accommodate a liquid injection device, particularly in securing size precision for the supply pipe and ensuring proper welding and straightness of support members.

Innovation Solution

A multistage centrifugal compressor design that includes a liquid injection device with a liquid injection path penetrating through the casing at a return bend, an internal path in the diaphragm, and a support system for the liquid supply pipe, allowing for liquid injection without requiring drill processing or welding on the casing, enabling modification of existing compressors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a liquid injection device is installed in an existing centrifugal compressor by drilling holes and welding support members, then the liquid injection function is achieved, but the manufacturing precision and welding quality cannot be ensured

Engineering Contradiction:
Improveliquid injection functionVSAvoidhole size precision and welding quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The liquid injection path is pre-formed in the casing during manufacturing, and the support member position is pre-prepared. This allows the supply pipe to be simply inserted and fixed without requiring on-site drilling or welding operations, thereby ensuring manufacturing precision while achieving the liquid injection function.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If drill processing and welding are performed on the casing to install the liquid injection device, then the liquid supply pipe can be connected, but the on-site processing becomes extremely difficult

Engineering Contradiction:
Improveliquid injection device installationVSAvoidon-site drill processing and welding
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The casing is pre-equipped with a liquid injection path and a support member position during manufacturing. This preliminary preparation eliminates the need for difficult on-site drilling and welding operations, making the installation process simple and easy to perform at the installation location.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the supply pipe is inserted through the casing with pre-formed liquid injection path, then easy installation is achieved, but the supply pipe must be precisely guided to the injection path

Engineering Contradiction:
Improvesupply pipe installationVSAvoidsupply pipe positioning precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

A guide member is introduced as an intermediary component to guide the supply pipe into the liquid injection path. The guide member ensures precise positioning of the supply pipe without requiring high precision in the insertion operation itself, thereby facilitating easy installation while maintaining positioning accuracy.

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

Enables effective liquid injection for cooling and cleaning without the need for on-site drill processing or welding, ensuring precise installation and maintaining compressor performance.

Implementation Method 1

cleaning liquid or cooling liquid is injected into the flow path from nozzles that are provided in a pipe inserted from an outside into an inside of a casing of the centrifugal compressor

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 2

cleaning liquid or cooling liquid is injected into the flow path from nozzles that are provided in a pipe inserted from an outside into an inside of a casing of the centrifugal compressor

Methodology Applied
Scientific EffectFluid spray cleaning: Fluid Spray

Data Source

PatentEP3505767B1Centrifugal compressor and method of modifying centrifugal compressor
Publication Date: 2021.06.23 MITSUBISHI HEAVY INDUSTIES COMPRESSOR CORP
  • EP3505767B1 patent drawingFigure 1
  • EP3505767B1 patent drawingFigure 2
  • EP3505767B1 patent drawingFigure 3

AI summary

A multistage centrifugal compressor includes a casing, a rotor including a plurality of impellers, a diaphragm defining a gas flow path that includes a return flow path, and at least one liquid injection device configured to inject liquid into the gas flow path. The liquid injection device includes a liquid injection path, an internal path, a chamber, and a plurality of nozzles. The liquid injection path penetrates through the casing at a position corresponding to a return bend. The internal path receives a liquid supply pipe inserted from the liquid injection path through the return bend. The chamber is provided in the diaphragm along a circumferential direction and the liquid is introduced into the chamber through the internal path. The plurality of nozzles inject the liquid introduced into the chamber, to the gas flow path from different positions of the chamber in the circumferential direction.