2 replies to this topic

[lee1706]

Hi, I am using ASPEN HYSYS Version 9.0, and got queries as following.

1. When I input control valve into HYSYS model(for dynamic), need to input pressure drop across valve. I am wondering what value is normally used. I know it depends on fluid, valve type etc., however seems I need to use most feasible value. in my case, LNG and globe valve.

2. In HYSYS Dynamic, there are 'valve opening[%]' at valve tab and 'OP' at controller tab. I cannot distinguish these, how it correlate.

I am beginner of HYSYS, therefore please advise me.
thanks.

[villivord]

The determination of the pressure drop across the valve is up to you. This is not something we can tell you without knowing any details of the system for which you design the control valve. Keep in mind that a certain pressure drop across your system is needed to achieve the desired flow. The control valve takes part in this by adjusting the valve opening and so the pressure drop/flow. 

[rish1610]

Hi,

 

1. If you have allowable pressure drop in the valve data sheet, you can assume a value under that to achieve the desired output. However, it is recommended to enter only Valve Cv and Characteristics from the datasheet. Once you run the simulation, you should be able to see the pressure drop across the valve. Make sure it is within the limits.

 

2. OP comes into picture when you are trying to add a controller. When there is no controller associated with the valve or the valve is in OFF mode, valve opening % determines the opening of that valve. When you have assigned a controller to the valve in AUTO mode, controller tries to achieve the set point (SP) and sends an output signal (OP) to the valve, which determines the opening of control valve.

 

Hope this helps.