Abstract: The HRCS domestic stepless capacity control system has been applied to a catalytic dry gas compressor and a coking dry gas compressor, enabling stepless regulation of discharge capacity within the range of 0~100%. During actual operation, the regulation range is maintained between 30% and 100%. However, when the compressor units operate at loads below 50%, suction valve internal leakage tends to occur, resulting in elevated suction and discharge temperatures, frequent valve failures and significant increase in equipment maintenance frequency. By modifying the control curve of the stepless capacity control system, the control point is adjusted from 30% to 50%. That is, the trigger condition for opening the unit recycle line is changed from a load below 30% to a load below 50%. This measure can effectively reduce the gas-valve failure rate, extend the service life of gas valves, and lower the frequency and cost of equipment maintenance. Meanwhile, countermeasures including tapping tests before startup and gas-bag pressurization are proposed to address sticking of the electro-hydraulic converter and oil-pressure interlock faults. After implementing the above improvements, when Compressor A is put into service for the catalytic dry gas compressor and coking dry gas compressor, the annual electricity cost savings reach approximately 977 000 CNY and 3 688 000 CNY respectively, achieving the goals of energy conservation, power reduction, cost control and efficiency improvement.

Key words: dry airlstepless capacity controllcontrol curvelgas valve failure