ABNORMAL OPENING DEGREE DETECTION DEVICE AND ABNORMAL OPENING DEGREE DETECTION METHOD FOR CONTROL VALVE

The present invention enables highly-accurate detection of an abnormal degree of opening of a control valve, such as a flow control valve or a pressure control valve, without the need to install or construct new instrumentation equipment. The present invention is a method for detecting an abnormal opening degree of a flow control valve on a liquid process line, wherein data is created in advance for a theoretical approximation formula derived from a command opening degree for the control valve and a flow rate of liquid relative to that command opening degree, and a theoretical flow rate value at a predetermined command opening degree found from the theoretical approximation formula is compared to an actually-measured value of the flow rate of the liquid, thereby detecting an abnormal opening degree of the control valve. Also, the present invention is a method for detecting an abnormal opening degree of a pressure control valve on a gas process line, wherein data is created in advance for a theoretical approximation formula derived from an average value of command values for an operating load in one pressure change cycle of a reaction container to which the control valve is connected as well as from a pressure change cycle duration, and a theoretical cycle duration at a command value for a predetermined operating load found from the theoretical approximation formula is compared to an actual cycle duration, thereby detecting an abnormal opening degree of the control valve.