Hello all,
I have a question regarding the valve/control valve inputs tab:
When specifying a valve on Aspen HYSYS, you are able to input a Valve Opening [%] and Cv value.
I currently have a metering needle valve, which has a MAX Cv (100% open) of 1.8. There is an existing chart which shows a linear relationship between valve opening and Cv values.
This needle valve is meant to keep constant draining rate out of a separator vessel.
When inputting the Cv value into HYSYS, should I put BOTH the MAX Cv of the valve under the Cv specification, and then the DESIRED valve % opening? Or should I put the DESIRED Cv value AT the DESIRED % opening according to the valve's characteristic curve?
I am running into the issue that I specify the MAX Cv of the valve, then specify the desired % open to achieve the desired Cv (which is lower than the max Cv) based on the characteristic curve, then my valve is open way too far.
In the other case, if I specify the DESIRED Cv, then let a PID determine the % opening based on the liquid level in the pre-filled vessel, it shows a % opening far below what is specified in the characteristic curve.
Which setup will yield the closest results to the real life operation of this system? Please see attached image regarding this question.
Many thanks in advance.
Edit: Attached jpg.
Attached Files
Edited by QuantumEng, 01 April 2024 - 09:54 AM.