Control valve interlocking and regulation
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I would like to ask experts in instrument control: For the existing distillation tower, the temperature at the bottom of the tower is controlled by adjusting the opening degree of the heating steam control valve (0%–100%); when the temperature becomes too high, the steam control valve is automatically shut off； At the same time, the steam control valve should be shut off when there is no water pressure (or no flow) in the condensate water, and it should also be shut off when the pressure at the top of the tower exceeds the specified level. Can a single steam control valve meet all the above requirements?
Personally, I think it’s okay. Based on your description, I believe the logic is as follows: 1. High temperature; 2. No pressure (or flow rate) of condensate water; 3. High pressure. I’m not sure if what you mean is that as long as one of these three conditions is met, the valve should shut down automatically If that is the case, all that is needed is to add a solenoid valve to the air supply line of the control valve; the input signal for this solenoid valve will be the output resulting from these three conditions or later
Generally as analyzed in the second floor, the three conditions should be in an OR logical relationship; of course, a RS resetter is also required, along with a reset button. Additionally, bypass switches should be provided for the preceding conditions to facilitate maintenance and operation.
Thank you for the reply from above; it’s fine as long as it can be done
How is the parking set point for low water pressure determined? A flow meter must also be expensive, right? The circulating water pressure (or flow rate) does not need to be included in the interlock system; only the tower pressure needs to be part of it, as the two are directly related. Interlocks ultimately depend on tower pressure; for higher-level interlocks, there are 3 tower pressure transmitters.