Control Valve Modelling and Sizing with Aspen Hysys: NGL Fractionation Modelling (Lecture 2)

This video is a guide on how to model and size control valves in Aspen Hysys. In this tutorial you would learn about:
1) How to fully specify a valve.
2) The different sizing methods.
3) The different valve opening characteristics.
4) How to size valves after making valve specifications.
5) How to change valve symbols.

[@shabrazk5182]

Thanks a lot, just one question, by knowing the actual pressure drop, how to conclude the size of the control valve?

[@shabrazk5182]

suppose from the data sheet i know the max. flow and selected Cv of the control valve plus the operating conditions. With that information , how do i calculate the flowrate for 25% and 50% opening. In the data sheet, the pressure drop was wrongly selected, and i am using the current pressure drop as per conditions.

[@shabrazk5182]

What is the control valve size, like 3 inch or 4 inch

[@GofraGokul]

Why Cv value increases as we decrease valve opening % in Hysys. The Cv should be maximum at 100%.

[@PhilBou-ww4iz]

The value of Cv given by Hysys is the Cv max of the valve. Let's say I choose an opening of 50% with a linear opening. If Aspen says Cv (max) is 100, then the value used by the solver is 50, because the opening is 50% (again, assuming linear opening). When I change the opening % with the same other parameters, the calculated Cv max will be different. For 25% opening, the value of Cv max will be 200, but the value used by the solver will be, again, 50 (200 * 25%). To sum up, Aspen shows Cv max, and the value of Cv used for the calculations is hidden.

[@shabrazk5182]

​@@PhilBou-ww4iz😂