Multistage Compressor Labyrinth Sealing Against CO2 Corrosion
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Solution Overview
Problem
Centrifugal multistage compressors face corrosion issues in the intermediate stage labyrinth, particularly with carbon dioxide, leading to performance degradation and potential damage due to liquid condensation and contact with carbonic acid.
Innovation Solution
Incorporating an intermediate diaphragm with a bypass flow path that supplies high-pressure, high-temperature CO2 to the intermediate stage labyrinth, reducing leakage and inhibiting corrosion by preventing liquid condensation and contact between carbonic acid and metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intermediate stage labyrinth is used to seal between ejection and suction flow paths, then sealing effectiveness is improved, but corrosion damage occurs due to liquid condensation and carbonic acid contact
Solution Approach 1:
The bypass flow path introduces high-temperature fluid from the ejection flow path to the intermediate stage labyrinth before the fluid reaches conditions where condensation and corrosion occur. This preliminary heating action prevents the harmful condensation and carbonic acid formation that would otherwise damage the labyrinth sealing structure.
Solution Approach 2:
The bypass flow path acts as an intermediary mechanism that delivers protective high-temperature fluid to the intermediate stage labyrinth. This intermediary flow path enables the introduction of protective fluid without disrupting the main compression and sealing functions of the compressor stages.
2Ease of repair
If aluminum is used for labyrinth fins to enhance maintainability, then ease of repair is improved, but corrosion resistance deteriorates due to aluminum's reactivity with carbonic acid
Solution Approach 1:
The bypass flow path applies preliminary anti-action by introducing high-temperature fluid that prevents condensation and carbonic acid formation on the aluminum labyrinth fins. This protective thermal action counteracts the corrosive environment before corrosion can occur, enabling the use of easily maintainable aluminum materials.
Solution Approach 2:
The bypass flow path changes the temperature parameter of the fluid environment around the intermediate stage labyrinth. By maintaining elevated temperatures through the bypass flow, the system prevents the temperature and pressure conditions that would otherwise lead to condensation and corrosion of aluminum components.
3Productivity
If the compressor operates with CO2 fluid, then productivity is improved, but harmful factors increase due to carbon dioxide corrosion
Solution Approach 1:
The bypass flow path converts the potentially harmful CO2 fluid into a beneficial protective medium. By routing CO2 fluid through the bypass flow path to the intermediate stage labyrinth, the system uses the same CO2 that causes corrosion elsewhere as a protective heating medium that prevents condensation and corrosion at the sealing interface.
Solution Approach 2:
The bypass flow path serves as an intermediary system that redirects CO2 fluid to where it provides protection rather than harm. This intermediary flow path enables the CO2 to serve dual purposes: maintaining compression efficiency while simultaneously protecting the intermediate stage labyrinth from corrosion.
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
Effectively inhibits carbon dioxide corrosion of the intermediate stage labyrinth, maintaining compressor performance and preventing damage, while allowing the use of aluminum for the labyrinth fins to enhance maintainability.
Implementation Method 1
supplying the intermediate stage labyrinth with some of the fluid flowing to the ejection flow path
Implementation Method 2
high-pressure, high-temperature CO2 to the intermediate stage labyrinth, reducing leakage and inhibiting corrosion by preventing liquid condensation
Data Source
AI summary
The present invention provides a centrifugal multistage compressor adapted to inhibit corrosion of an intermediate stage labyrinth. More particularly, the present invention provides a centrifugal multistage compressor adapted to inhibit carbon dioxide corrosion of the intermediate stage labyrinth. The centrifugal multistage compressor of the present invention includes: a rotary shaft equipped with a plurality of impellers; an ejection flow path extended between a first stage of the impellers and a last stage of the impellers and serving to discharge a fluid once from the compressor; a suction flow path extended between the first stage of the impellers and the last stage of the impellers and serving to inject the discharged fluid once again into the compressor; an intermediate diaphragm disposed between the ejection flow path and the suction flow path; and an intermediate stage labyrinth for sealing between the ejection flow path and the suction flow path, and has a configuration where the intermediate diaphragm includes a bypass flow path for supplying the intermediate stage labyrinth with some of the fluid flowing to the ejection flow path.