Cryogenic Helium Compressor Speed Control to Prevent Surge and Choke
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Solution Overview
Problem
Controlling compressors in series for cryogenic helium compression is challenging due to temperature and pressure variations, leading to inefficiencies and instability, particularly at low cryogenic temperatures where compressor efficiency drops and volatility increases, and existing control methods struggle to maintain stable operation across the compressor series.
Innovation Solution
A method that sets desired inlet pressures, records actual pressures, calculates a proportional integral value, determines a capacity factor, and adjusts compressor speeds using a control function based on the capacity factor and model total pressure ratio to maintain stable operation, dampening fluctuations and ensuring constant temperature cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compressor speed is increased to handle higher evaporation rates, then cooling capacity is improved, but compressor efficiency drops dramatically due to choke operation
Solution Approach 1:
The patent implements dynamic speed control for each compressor stage based on real-time operating conditions. The control system continuously adjusts compressor speeds to maintain optimal operation within the performance map, preventing choke operation even when evaporation rates increase. This dynamic adaptation allows the system to handle variable cooling demands while maintaining high efficiency.
Solution Approach 2:
The patent changes the operating parameters of compressors by adjusting speeds individually for each stage. By modifying speed parameters dynamically rather than operating at fixed speeds, the system can adapt to varying evaporation rates and maintain optimal efficiency across different operating conditions, avoiding the dramatic efficiency drop associated with choke operation.
2Stability of the object's composition
If compressor speed is decreased to avoid surge, then stability is improved, but cooling capacity is reduced
Solution Approach 1:
The control system dynamically adjusts compressor speeds based on real-time monitoring of operating conditions. By continuously adapting speeds rather than using fixed conservative settings, the system maintains stability while maximizing cooling capacity. The dynamic control allows operation close to but not into the surge region, optimizing both stability and productivity.
Solution Approach 2:
The patent implements a feedback control system that monitors compressor operation and adjusts speeds to prevent surge while maintaining cooling capacity. The control system uses feedback from pressure and temperature sensors to continuously optimize compressor speeds, ensuring stable operation without unnecessarily reducing cooling capacity.
3Device complexity
If traditional control methods are used for compressor series, then device complexity is low, but the system cannot maintain stable operation at low cryogenic temperatures
Solution Approach 1:
The patent implements a sophisticated feedback control system that monitors and adjusts compressor speeds based on real-time operating conditions. This feedback mechanism enables stable operation at low cryogenic temperatures by continuously adapting to temperature and pressure variations that occur in the compressor series, something traditional control methods cannot achieve.
Solution Approach 2:
The control system dynamically changes operating parameters (compressor speeds) to maintain stable operation at cryogenic temperatures. By adjusting speeds based on actual operating conditions rather than using fixed parameters, the system achieves reliability at low temperatures despite increased complexity.
4Adaptability or versatility
If compressors operate away from design points to handle varying loads, then adaptability is improved, but efficiency and profitability deteriorate
Solution Approach 1:
The patent implements dynamic speed control for each compressor stage, allowing the system to adapt to varying loads while maintaining optimal efficiency. By continuously adjusting speeds rather than operating at fixed settings, the system can handle different load conditions while staying close to optimal operating points, preventing the efficiency losses that would otherwise occur when operating away from design points.
Solution Approach 2:
The control system dynamically changes compressor speed parameters to maintain efficient operation across varying load conditions. By adjusting speeds rather than changing physical configurations or operating modes, the system achieves adaptability while minimizing efficiency losses and maintaining profitability.
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 method effectively stabilizes and optimizes the operation of compressors in series by controlling compressor speeds, preventing surge and choke states, and maintaining efficient operation across the compressor series, ensuring stable and economical operation even at low cryogenic temperatures.
Implementation Method 1
compressors arranged in series for compressing a fluid, in particular cryogenic helium
Implementation Method 2
controlling compressor speeds, preventing surge and choke states, and maintaining efficient operation
Data Source
AI summary
A method for controlling speeds of compressors arranged in series for compressing a fluid. The desired inlet pressure is predefined and the actual inlet pressure is detected. The actual discharge pressure of the fluid is recorded and the actual total pressure ratio is recorded. A proportional integral value is determined from the deviation of the actual inlet pressure from the desired inlet pressure and a capacity factor is determined from the proportional integral value and the actual total pressure ratio. A model total pressure ratio is determined from the actual total pressure ratio and the capacity factor. A reduced desired speed for each compressor is determined as a function value of the control function associated with the respective compressor. The control function assigns a reduced desired speed to each value pair of capacity factor and model total pressure ratio and is used to adjust the speed of each compressor.