Accident: Release valve of the main fan in the catalysis workshop opened
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At around 8:11 a.m., the main operator in charge of the reaction process detected an alarm indicating that the differential pressure between the two reactors had exceeded the allowable limits; he immediately stopped the feed, and the control system switched to safety mode. At around 8:14, the instruments showed a rapid increase in pressure, prompting an on-site inspection of the main fan, where it was found that the vent valve had been opened. A thorough inspection of the instruments afterward revealed no abnormalities. To prevent similar situations from occurring again, it was decided to remove the valve positioner and replace it with the positioner for the standby fan’s vent valve. After investigation, 1. The operational trends in terms of process are stable and normal, so operational factors can be ruled out ； 2. The dynamic wind pressure is normal, and the power supply is normal ； 3. The historical trend signal of the valve position opening degree has not been lost ； 4. The locator has stable performance ； 5. No human factors occurred. It is worth noting that the vent valve was opened, while the inlet valve was not closed. To date, the exact cause of this accident has not been determined. I would appreciate any insights from those who are more knowledgeable; thank you! ! !
Check what the pressure in the regenerator is when the differential pressure alarm for the two instruments is triggered; it’s possible that the regenerator pressure exceeds the main air pressure, causing the vent valve of the main fan to open.
Reply to 2# sun-rock: Thank you, I’ll take a look!
A sudden increase in pressure in the regenerator generates shock pressure, which is also one of the reasons.
I think, based on what the original poster said about the procedures to be followed, there should be no problems; the issue lies likely with the surge valve. It is recommended to check the positioner of the surge valve, as well as the solenoid valve and the air duct system. I have encountered situations where aging solenoid valves caused the control valve to exhaust air slowly (the relief solenoid valve). When the pressure reached a certain level, the surge valve would open suddenly, resulting in fluctuations in the reactor pressure.
Is the control valve equipped with a solenoid valve? Check whether all the accessories of the control valve are in good condition; also inspect the control circuit to see if the shielding is properly connected.