instrumentation

[ashapuramata]

Hello friends

I am working as a comissioning engineer i am seeking the right solution for a pipe 42 " carrying a steam media and i have a 4" control valve to control the pressure on pipe,which type of control i should use P,PD,PID OR PI?

so please guide me about this issue.

 

[JLSeagull]

PI should be just fine.

There are lots of articles on the web about PID control.

P provides a proportional response to the difference between the setpoint and measured value. Proportional only does not bring the measurement back to setpoint.

I applies an integral function that ramps the controller output as long as the error exists.

D provides a derivative spike upon detecting the error. This is useful for slow response such as temperature loops from a heater where you adjust the fuel. The spike helps to get the change moving and is normally applied in addition to the P and I functions.

Tuning the PI loop requires a longer response.

 

[khaoula]

a question for JLSeagull
in case of regulating the level in a scrubber(control valve after the pump) should we use PI or PID?
NB
scrubber--> pumps(export condensate)--> control valve