The gas-open FC control valve has opened automatically; experts, please help analyze the reason
Thread Content
Process: 40 kg of steam is reduced to 12 kg of steam. Valves: flow-controlled, FC type, open when there is gas pressure; valves from Leslie brand. The positioner is a Yaskawa AVP300 model, of the double-acting type. Interlocks: 1. The valve closes in case of overtemperature downstream; 2. When the medium-pressure steam compressor stops, the valve opens to 70% capacity. At that time, the valve was in closed position, and it opened on its own without any operations or signals from the control room, resulting in fluctuations in the steam network. Check that both interlocks have not activated.
Was the control mode of this valve automatic or manual at that time?
Checking the historical trends on the DCS shows that the AO output has always been 0
Checking the historical trends on the DCS shows that the AO output has always been 0
Then tell me how the air circuit of this control valve is configured Such as solenoid valves, positioners, and so on
There is a solenoid valve; for interlock 1, the setting is AVP300, with dual outputs
I don’t understand why it’s double-acting; how can the FC function be achieved in this case? The design must be wrong.
I still don’t understand it either: if it’s an air-operated FC, why is it double-acting? I’ve seen double-acting cylinders, and the fault detection is achieved by attaching a small air tank to them.