Controlling refrigeration compression systems
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Solution Overview
Problem
Conventional control techniques for refrigerant compression systems often fail to provide fully automated stable operation, leading to issues like prime mover overload, compressor surging, and process downtime due to inadequate control of liquid refrigerant quench valves and anti-surge valves, especially during startup.
Innovation Solution
The implementation of suction temperature control circuits and a discharge temperature control circuit in a multi-stage refrigeration compression system, which dynamically adjust quench fluid flow demands based on temperature setpoints, inlet pressures, and recycle fluid flows to maintain optimal valve positions and prevent overheating, allowing for fully automatic and coordinated control of quench valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional control techniques are used for refrigerant compression systems, then the system structure is simple, but the system fails to provide fully automated stable operation leading to prime mover overload, compressor surging, and process downtime
Solution Approach 1:
The patent implements feedback control by using discharge temperature control circuits that continuously monitor discharge temperature and adjust quench valve positions accordingly. The control circuits receive feedback about actual discharge temperature and dynamically adjust the quench fluid flow to maintain temperature within desired ranges, enabling fully automated stable operation without manual intervention.
Solution Approach 2:
The system performs self-service through automated control circuits that independently manage quench valve positioning and cooling requirements. The discharge temperature control circuits automatically determine when cooling is needed and adjust quench fluid flow without external control, allowing the system to self-regulate during transients and prevent compressor trips.
2Reliability
If quench valves are not properly controlled, then the device complexity is reduced, but the system experiences overheating, prime mover overload, and compressor surging
Solution Approach 1:
The patent applies preliminary action by proactively controlling quench valves based on predicted cooling requirements rather than reacting to overheating conditions. The discharge temperature control circuits anticipate when cooling will be needed and adjust quench fluid flow in advance, preventing prime mover overload and compressor surging before they occur.
Solution Approach 2:
The system maintains reliability by dynamically changing operational parameters through automated control. The discharge temperature control circuits continuously adjust quench valve positions and cooling flow rates based on real-time discharge temperature measurements, allowing the system to adapt to varying load conditions and maintain stable operation across different operating points.
3Temperature
If discharge temperature control circuits are implemented, then the discharge temperature can be maintained at or below setpoint, but the control system complexity increases
Solution Approach 1:
The discharge temperature control circuits perform multiple functions simultaneously: they monitor discharge temperature, determine cooling requirements, adjust quench valve positions, and prevent both overheating and over-cooling. This multi-functionality is achieved through integrated control circuits that combine sensing, calculation, and actuation functions, reducing the need for separate dedicated systems for each function.
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 enables improved safety, availability, and efficiency of refrigeration compression systems by minimizing cooling requirements, reducing downtime, and maintaining stable operation during transients, thus avoiding unnecessary compressor trips and optimizing the balance of recycle and quench flows.
Implementation Method 1
The quench fluid flow rate is determined based on a quench heat exchange duty
Implementation Method 2
a quench fluid flow that is injected through the first quench valve into the first compression stage
Data Source
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AI summary
A refrigerant compression system and method for controlling a refrigerant compression system are described. In some aspects, the refrigerant compression system includes a compressor system having a plurality of compression stages, a plurality of quench valves, a first suction temperature control circuit associated with a first quench valve, a second suction temperature control circuit associated a second quench valve, and a discharge temperature control circuit associated with a plurality of the quench valves. Quench valve settings are determined based on evaluation of one or more outputs from the suction temperature control circuits and the discharge temperature control circuit.