Take a look at the changes in this compressor shutdown automatic control system
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The compressor outlet flow is very low, less than 100 tons; the actual rotation speed has decreased. The anti-surge system is fully activated, and the instantaneous speed sensor has failed – will this lead to an automatic shutdown? Why does the speed sensor fail, while the rotation speed probe is fine?
To be more specific, first check if there are any SOE alarm records.
Check whether there is any change in the output of the electro-hydraulic converter
3# limohan: Could you please explain what you mean by the variation in the output of the electro-hydraulic converter? How exactly does the working principle lead to this result?
The speed signal measured by the speed sensor is sent to the DCS, which then processes it and outputs a signal to the electro-hydraulic converter in order to control the opening degree of the steam turbine valves, thereby regulating the speed of the steam turbine and consequently the speed of the compressor. This is basic control, but compressors generally come equipped with surge control; therefore, once surge occurs, the speed also drops. If the flow rate cannot be maintained, it is necessary to shut down the machine in order to avoid damaging it. Looking forward to experts' explanations regarding the sudden loss of signal from the speed sensor.
Speed sensors come in eddy current and magnetic induction types; for turbines with high rotational speeds, the magnetic induction type is generally used. At low speeds, the speed probe does not display any readings, and it usually starts to show values only when the speed exceeds 500 revolutions per minute. You might want to check whether this is the issue.
Have all the speed sensors failed?
How does it fail? Does it suddenly drop from normal speed to 0, or what happens?
Please provide more detailed technical parameters. How is the process system configured? A steam-driven fan or an electric-driven fan? Based on the information you have provided, my personal judgment is that it is surge, which has caused backflow.
It’s likely surge is occurring; stall can’t be the primary cause of trip, check the SOE