Set value of the control valve
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There is a pressure control valve with 2 outputs: when the first outlet is open and the second one is closed, the valve must maintain a pressure of 2.0 MPa (the set value); when the first outlet is closed and the second one is open, the valve must maintain a pressure of 3.0 MPa (the set value). This process repeats automatically every hour. How can this be achieved? Setting the values manually is too time-consuming – could selective control be used? Thank you!
This post was last edited by zxb1990 on 2016-1-17 at 14:48. Is your pressure control valve equipped with a double-acting actuator? A double-acting locator is not purely one path open and the other closed, or the other path open and the first closed
Do you want a control valve to output to two pipelines, with the choice of pipeline made via a shut-off valve? That’s not good; there will be significant pressure fluctuations at the moment of switching, making it unusable
The original poster didn’t explain clearly: do you need to control different pressures in separate pipelines over time, or do you want to use one control valve to regulate the pressure in two pipelines? If it’s the latter case, then as mentioned on floor 4, it can’t be used. What exactly are your process requirements?
This post was last edited by khhby116 on 2016-1-14 at 11:42. This isn’t a problem; there are series flow control valves that allow for gradual pressure release. I just want to know what approach can be used to achieve this? They talk about dual action, but those are two different concepts; I didn’t understand the question clearly
The original poster didn’t explain clearly: do you need to control different pressures in separate pipelines over time, or do you want to use one control valve to regulate the pressure in two pipelines? If it’s the latter case, then as mentioned on floor 4, it can’t be used. What exactly are your process requirements? The first option involves controlling two separate pressure pipelines independently
Contact the regulator manufacturer first to see if a difference of 10 kilograms will still allow for good regulation. It’s actually just a matter of having a control valve; why does the original poster insist on using a single valve to solve it?
My understanding is that it’s a matter of varying given values; two given values are controlled via the opening and closing of two valves, using the DCS to regulate the output of those two values, right?
A control valve regulates two circuits, opening one and closing the other; a three-way valve is the only device that can achieve this function. But while closing one path, it might not be possible to adjust the opening degree of the other path. Even for the same pipeline, it is recommended to use two control valves, one for the main circuit and one for the auxiliary circuit. In the DCS configuration, programming can be used to enable an automatic cycle every hour, with the control valves having their set points automatically adjusted; this can be achieved through PID control using one or two pressure transmitters. Currently, PID diagrams are generally designed with two control valves.
Add a selection block and a timer in front of the setpoint pin of the PID block – it’s simple control logic