No signal is being sent from the second anti-surge valve chamber of the centrifuge – is it operating in surge mode on its own? The reason for seeking guidance from all the teachers
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The signal output is stable, the locator is functioning properly, there is no sticking in the valve, and no air leakage is present. What could be the reason for it to operate intermittently once set to automatic mode? Dear experts, please help analyze the reasons
What actuator does your valve use?
Contact the process engineers to switch to manual operation; the control valve still exhibits fluctuation issues. It is possible to try replacing the positioner and see the effect after its installation. If the same fluctuations persist, it is likely that the output signal from the safety barrier is unstable intermittently; in such cases, replacing the safety barrier is likely to resolve the problem. I encountered the same issue with temperature safety gates (P+F): the DCS temperature readings fluctuated (intermittently, without any discernible pattern). After checking the thermal resistors and wiring on site and finding no problems, the safety gate was replaced and the issue was resolved. The poster might want to try replacing the safety barrier!
The inlet flow rate and speed of the centrifuge are generally controlled in a cascade manner, with the anti-surge controller of the CCS sending out signals to adjust the anti-surge valve. Since the system experiences surge when operated in automatic mode, try operating it in manual mode first; if surge still occurs, check whether the configuration of the anti-surge controller is appropriate.