Water Injected Scroll Compressor Cooling and Corrosion Control
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Solution Overview
Problem
Water injected scroll air compressors face issues such as corrosion of aluminum alloy materials, unbalance and increased vibration due to water injection, potential damage to the wrap under high pressure and temperature, and rapid pressure rise from evaporated water, leading to unstable operation and potential damage to piping systems.
Innovation Solution
A water injected scroll air compressor design with a control system that switches between water injection and non-injection modes, using a cooler to separate air and water, and a separator tank to manage water, along with a variable frequency drive to optimize operation and prevent corrosion, unbalance, and pressure issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is injected into the compression chamber, then heat absorption and sealing effects are improved, but corrosion of aluminum alloy materials occurs
Solution Approach 1:
A water injection valve is introduced as an intermediary device to control water injection into the compression chamber. The valve system allows precise control of water injection timing and quantity, enabling heat absorption benefits while minimizing corrosion through controlled injection rates and proper water management.
2Stability of the object's composition
If water is injected into the compression chamber, then sealing and heat absorption are enhanced, but unbalance and vibration increase
Solution Approach 1:
Water injection is implemented as a periodic action controlled by a water injection valve that operates in synchronization with the compressor's rotation cycle. The valve opens and closes at specific angular positions to inject water only during appropriate compression phases, maintaining sealing benefits while minimizing vibration through rhythmic, controlled injection rather than continuous injection.
Solution Approach 2:
The injection parameters (quantity, timing, pressure) are dynamically changed based on compressor operating conditions. The control system adjusts water injection parameters to optimize sealing effects while minimizing vibration and unbalance, adapting to different load and speed conditions.
3Temperature
If water is compressed in the wrap, then compression cooling is achieved, but wrap damage may occur due to insufficient strength tolerance
Solution Approach 1:
Instead of compressing water to full pressure, the system uses partial compression cooling where water is injected and allowed to evaporate partially during compression, providing sufficient cooling effect without subjecting the wrap to excessive liquid compression forces that could cause damage.
Solution Approach 2:
The system exploits phase transition of water from liquid to vapor during compression. Water is injected as liquid and evaporates during the compression process, absorbing heat and providing cooling effect without requiring full liquid compression, thereby protecting the wrap from excessive mechanical stress.
4Temperature
If water remains in the compression chamber during activation, then compression cooling is maintained, but excessive torque and activation failure occur
Solution Approach 1:
The control system performs preliminary action by controlling water injection to cease before the compression stroke reaches maximum pressure. This ensures compression cooling benefits are achieved while preventing excessive liquid water from remaining in the chamber during activation, avoiding excessive torque and activation failure.
Solution Approach 2:
The control system uses feedback from pressure and temperature sensors to monitor compression chamber conditions and dynamically adjust water injection timing and quantity, ensuring optimal cooling while preventing excessive torque by reducing injection when pressure thresholds are approached.
5Temperature
If water remains in the compression chamber during stop, then cooling is maintained, but corrosion of aluminum alloy scrolls occurs
Solution Approach 1:
The system extracts or removes water from the compression chamber before stopping operation. The control system stops water injection prior to shutdown and may activate drainage or drying mechanisms to remove residual water, preventing corrosion during idle periods while maintaining cooling benefits during active operation.
Solution Approach 2:
The system implements periodic operation cycles with active cooling phases followed by idle phases where water injection is stopped and chamber drying is performed. This periodic action maintains cooling during operation while preventing corrosion during stop periods.
6Temperature
If water evaporates due to high temperature, then cooling effect is achieved, but rapid pressure rise damages piping and tank
Solution Approach 1:
The system allows rapid evaporation of water during the compression stroke to achieve cooling effect, but the control system has already prepared discharge pathways and pressure relief mechanisms to handle the rapid pressure rise from evaporation, skipping the dangerous pressure buildup phase by directing evaporated water vapor through controlled discharge routes.
Solution Approach 2:
A controlled discharge system acts as an intermediary between the compression chamber and the piping network. When water evaporates and pressure rises rapidly, this intermediary system safely manages the pressure release, preventing damage to downstream piping and storage tank while maintaining the beneficial cooling effect from evaporation.
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
The solution effectively prevents material corrosion, reduces vibration, ensures stable operation by removing moisture, and prevents rapid pressure rises, enabling efficient and reliable operation of the compressor.
Implementation Method 1
a cooler which is provided on the path of the discharge piping between the tank and the air end and which cools the compressed air discharged from the air end
Implementation Method 2
a tank which is provided on a path of the discharge piping and which stores water separated from compressed air
Implementation Method 3
a tank which is provided on a path of the discharge piping and which stores water separated from compressed air
Data Source
AI summary
As pressure in a water tank rapidly rises when water inside a compressor is evaporated by the high temperature of compressed air and this situation makes the operation unstable, an object of the present subject matter is to address this problem. A water injected scroll air compressor is provided with: an air end of the scroll air compressor; a driving unit that generates driving force for the air end; a compressing path from a suction port to a discharge port; a portion to inject water into the compressing path; a discharge piping of air discharged from the air end; a tank provided on a path of the discharge piping for storing water separated from the compressed air; and a cooler that is provided on the path of the discharge piping between the tank and the air end and cools the compressed air discharged from the air end.