Energy-Saving Operation Modes of Natural Gas Cooling Units

The article addresses improvement of the energy efficiency of gas-air units for cooling main compressor stations by replacing discrete fan speed control with continuous control. The problems of electromagnetic compatibility of compressor station electrical equipment components when using a large number of frequency-controlled fan drives are noted. The possibility of using a combined fan speed control in which only a part of the cooling system’s air-cooling devices is controlled is considered. The combined control optimization problem and criterion are formulated taking into account the constraints on control actions and the technological process requirements. Using the method of indeterminate Lagrange multipliers, the problem of optimizing the control modes has been solved. Versions of the algorithm for optimal control of the discretely- and frequency-controlled drives of air-cooling devices are considered taking into account the nonlinear distribution of gas temperature along the heat exchanger length, and their efficiencies are analyzed. A procedure for estimating the energy savings when using the frequency and combined control of fan rotation speed is proposed.