6 replies to this topic

Hi friends

i am working on dymnamic simulation model, I develop model for it but I am facing problem for tuning of control valves, Can you suggest the method for tuning of valves on hysys.

[Zauberberg]

Refer to HYSYS tutorials, chapter "Dynamic Modeling" for complete information. Everything is already explained there.
Also take a look at http://www.expertune...s.html#BasicPID to see in more details what are you looking for.

Regards,

[Padmakar Katre]

Dear,
Addition the above comments you can vary the controller's tunning parameters and check for the effect on the control by putting the strip-chart for every controller with PV,SP and OP graphs. This merely depends on the operational experience that is what should be the step change, step responce and so many. I had the same problem with the dynamics that there was no stability in the control with the reason of not having the best configuration of the controller tunning parameters so along with the document given by Aspen tech for the dynamics I asked Aspen tech for further assistance in selecting the tunning parameters they gave me the link to download the article and one presentation in which they have shown how to use the IMC design parameters in Hysys to get the right controller tunning parameters. I hope you can even download it from the support website of the Aspen tech.

Thanks for reply
Mk

[Steve McGahey]

Thanks for reply
Mk

You'll find that in simulation land, you can get away with K=0.5, Ti = 0.1 for a lot of your control loops. Some will have to be tuned after this depending on your control objective (e.g. there are optimal tunings), but in terms of getting a stable response for a lot of things like LIC, TIC and PIC, this will do the job.

When dealing with LIC's you may want to dampen out the flow variations into/out of the system by using the capacitance of a vessel. Then, you may want to decrease the K (try K=0.1), and increase the Ti (try Ti=0.5). I know lots of people talk about using K=5, Ti=5, and other such high-Ti&K combinations, but I'm never getting decent results with them.

When dealing with SIC's, you may need to vary the tuning parameters depending on the inertia of your rotating equipment. High inertias and aggressive tunings (eg high Ki, small Ti) may lead to substantial setpoint overshoots.


Oh, and very important to remember - your Ki is dependant on your PV range. Ki=5 and (PVmax-PVmin) = 100 is essentially the same as Ki=1 and (PVmax-PVmin) = 20. So, make sure your controllers have sensible PV ranges.

ABBREVIATIONS
TIC = temperature controller
SIC = speed controller
LIC = level controller
PIC = pressure controller

[linda_pro]

Hi there,
I am a freshman in using Dynamis Hysys, I want to ask you 2 questions:
1. when we use this type simulation and
2. how to analyse the strip charts.

Thanks advance for your help.