Control of operating liquid flow into a liquid ring pump

A method for controlling a system, the system comprising a suction line an exhaust line, an operating liquid line, a liquid ring pump comprising a suction input coupled to the suction line, an exhaust output coupled to the exhaust line, and a liquid input coupled to the operating liquid line, one or more regulating devices configured to control flow of operating liquid into the liquid ring pump, a pressure sensor, a first temperature sensor, and a second temperature sensor, the method comprising:

• measuring, by the pressure sensor, a pressure of an input fluid received by the liquid ring pump via the suction line;
• using a temperature measurement of the exhaust fluid, determining or estimating a vapour pressure of the operating liquid in the liquid ring pump;
• performing a first comparison, the first comparison being a comparison between a function of the measured pressure of the input fluid and a function of the determined or estimated a vapour pressure;
• responsive to the first comparison fulfilling one or more criteria, controlling the one or more regulating devices to increase a flowrate of the operating liquid into the liquid ring pump;
• measuring, by the first temperature sensor, a temperature of an exhaust fluid output by the liquid ring pump via the exhaust line;
• measuring, by the second temperature sensor, a temperature of an operating liquid received by the liquid ring pump via the operating liquid line;
• responsive to the first comparison not fulfilling the one or more criteria, performing a second comparison, the second comparison being a comparison between a function of the temperature measurement of the exhaust fluid and a function of the temperature measurement of the operating liquid;
• and
• controlling the one or more regulating devices based on the second comparison.