Water Injected Scroll Compressor Control Strategy
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Solution Overview
Problem
Water injected scroll air compressors face issues such as material corrosion, unbalanced operation, potential breakage of the scroll wrap, and failure due to excessive torque and vibration caused by water in the compression chamber, particularly when made of aluminum alloy, which hinders their reliability and efficiency compared to screw-type compressors.
Innovation Solution
Implementing a control system that allows operation without water injection initially, then initiates water injection after a certain time or based on pressure and temperature parameters, and automatically stops water injection before shutting down the compressor to prevent corrosion and ensure dry conditions, using a variable frequency drive to manage energy usage and a check valve for controlled air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If water is continuously injected into the compression chamber, then energy efficiency is improved through heat absorption and sealing, but material corrosion occurs and activation fails due to excessive torque
Solution Approach 1:
The control system implements periodic water injection by alternating between water injection periods and drying periods. During drying periods, the water injection valve is closed and the compression chamber is dried by hot air from the aftercooler, preventing continuous water presence that causes corrosion and activation failure while maintaining energy efficiency during operation.
Solution Approach 2:
The system performs preliminary drying action before each activation cycle. The control unit opens the water injection valve closure to allow dry air to enter and dry the compression chamber before water injection resumes, ensuring the chamber is free of excessive water that would cause activation failure or excessive torque.
2Temperature
If aluminum alloy is used for scroll members, then thermal conductivity and weight are improved, but corrosion resistance deteriorates when water is injected
Solution Approach 1:
The control system implements periodic water injection by alternating between water injection periods and drying periods. During drying periods, the water injection valve is closed and the compression chamber is dried by hot air from the aftercooler, preventing continuous water presence that causes corrosion while maintaining the thermal conductivity benefits of aluminum alloy scroll members.
Solution Approach 2:
The system converts the harmful effect of water presence into a beneficial drying process. The aftercooler, which normally cools compressed air, is used to generate hot air that dries the compression chamber, transforming a potential corrosion hazard into a protective drying mechanism.
3Reliability
If water injection is stopped before shutdown, then corrosion is prevented, but additional control complexity is introduced
Solution Approach 1:
The control unit continuously monitors operating conditions including temperature and pressure, and automatically adjusts water injection based on feedback from sensors. The control unit opens the water injection valve closure when drying is detected and closes it when water injection is needed, implementing intelligent feedback control that prevents corrosion without requiring complex manual intervention.
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 approach stabilizes the operation of water injected scroll air compressors, enhances reliability, and prevents material corrosion, allowing for efficient and reliable operation by managing water injection and drying processes, thus overcoming the limitations of existing technologies.
Implementation Method 1
The oil or the water has effect that inside leakage is reduced because it seals narrow clearance via which compression chamber connects with another space and effect that the heat of compression is absorbed and the thermic deformation of members of the compressor is prevented
Implementation Method 2
The oil or the water has effect that inside leakage is reduced because it seals narrow clearance via which compression chamber connects with another space
Implementation Method 3
using a variable frequency drive to manage energy usage
Implementation Method 4
using a check valve for controlled air flow
Data Source
AI summary
A high reliability water injected scroll air compressor is provided with an orbiting scroll, a fixed scroll corresponding to the orbiting scroll, a motor that generates driving force for making the orbiting scroll orbit the fixed scroll, a compressing path from a suction port to a discharge port, and a portion for injecting water into the compressing path. The operation is controlled by a switching operation in which water is injected into the compressing path and then no water is injected. Corrosion, failure of activation, and concerns about wrap contact when water is injected into an air end are avoided by switching the operation with water injection and the operation without water injection so as to prevent water from remaining in the air end.