The quick-shut oil pressure is normal, but the quick-shut valve closes suddenly; please analyze the cause
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The oil pressure for rapid shutdown is normal, but the rapid shutdown valve closed suddenly, causing the turbine to stop. Has anyone encountered a similar situation? Please analyze the reasons
Is there any historical trend for the quick-shut oil pressure? Otherwise, how can you determine that the quick-shut valve closed suddenly while the quick-shut oil pressure was normal? It is likely that a sequential project action (although false values may be collected) caused the turbine to stop
Did you change the pump outlet filter or oil cooler before the quick-shut-off oil pressure dropped? Some trends cannot be displayed on the DCS. Here, during a maintenance task involving the switching of filters, there was a temporary drop in pressure, but it couldn’t be detected by checking the trends. It is recommended to temporarily bypass the interlock before performing such operations in the future. This is just one possibility; however, since the quick-close valve closes automatically, it must be due to some kind of interlocking mechanism, and you can rule out each possible factor one by one.
1. Short-term fluctuations; no trend detected； 2. The oil pressure reading is incorrect ； 3. Mechanical failure: the steam turbine valve has broken (related to the turbine’s structure). If there are no other interlock commands to close the quick-shut valve, it must be that the actual oil pressure has dropped, causing the quick-shut valve to close. We have encountered this situation before; it was quite strange at the time – there were no interlocks, no SOE records, yet the turbine stopped running.
Check the solenoid valve; if possible, replace it with a new one! I think it's this problem.