9 replies to this topic

[sunny0]

Greetings,

 

I had simulated crude distillation column using Peng Robinson Fluid Package.

This contains three side strippers & three pump around.
But when i input all the data & try to start it than in worksheet i do not get any data for products.

In left bottom i see warning messages stating:

first message: "Warning! Transition in Fluid Package"

Second warning : "Warning! Transition in Fluid Package Object".

 

I am not sure how to resolve this issue.

Please suggest some solutions.

If this forum allows than i can attach my Hysys file for error detection.

Kind Regards,

Sunny.

 

NOTE:

HYSYS Simulation File is Attached.
Thankyou.

Attached Files

•  CDU Simulation.zip   386.14KB   85 downloads

Edited by sunny0, 05 October 2013 - 12:52 AM.

[thorium90]

You can zip up your file to attach to your post.

[sunny0]

Greetings Thorium90,

 

File is attached.

I will be anticipating for your next reply on my simulation.

 

Thankyou.

[thorium90]

I dont think you have to worry too much about the Transition in Fluid Package message.

You need to "walk" the hysys solver abit on your column as there are many variables on your complex column. What I mean is that any numerical problem if given a good initial guess will tend to converge more easily. If given a poor initial guess, especially one that is outside the feasible region, it may never find a solution in the feasible region.

 

The way to get hysys to converge in your case would be to run the column for a couple of iterations, see what is the new current values, input those new values as your guess, run again for a few iterations and repeat until it converges. Now your column would have converged but not at the values you want, so make small adjustments to the guesses and run again, ensuring that each small change you make still converges to ensure the solver is still in the feasible region, until you reach the original values that you want.

 

If at any time upon changing a certain guess and it no longer converges but returning to the previous guess converges, you might have reached a point where your input is not a feasible solution.

 

I understand what I have mentioned above might be sort of hard to understand in words, so perhaps you might want to read it a few times...

 

I have attached the converged file for you. No changes made except to "walk" the solver to the solution.

 

Reuploaded as .xml file

Attached Files

•  CDU SIMULATION_rev1.zip   241.16KB   76 downloads
•  walking the solver.jpg   186.05KB   17 downloads
•  CDU SIMULATION_REV1_XML.zip   245.88KB   49 downloads

Edited by thorium90, 16 October 2013 - 10:55 PM.

[sunny0]

Thankyou Sir for your reply,

 

There is Eid Festival in my country.

I will do on weekend & will share my experiance here :-)

Edited by sunny0, 17 October 2013 - 12:08 PM.

[sunny0]

Sir,

 

I tried to understand what you said.

I also made little changes in iteration's numbers but no results.

The file you attached is created in HYSYS 8 version but i have 2006 version so cant open it.

Please tell me more specificly what i have to do to converge the column?

When i change the reflux ration from 1 to any othe value than still nothing resolves.

Current values are not changing.

I have attached the screenshot of my values.

Sunny.

Attached Files

•  Unconverged.png   379.93KB   15 downloads

Edited by sunny0, 15 October 2013 - 03:07 AM.

[thorium90]

When you first press Run, let it run for a few seconds to get a couple iterations, (no need to wait for 2000+iterations.... You have to use the Stop button to stop the solver midway. When the current values are no longer changing, you can press Stop) Look at the column called Current value, that will be your next guess. The one with the greatest difference is likely the one that the solver is stuck at. In your case, it would seem Reflux Ratio and Naptha Prod Rate are good choices to change. From your screenshot, perhaps you can try a ratio of 18 and a rate of 40. Run it for a few seconds to get a couple iterations, (no need to wait for 2000+iterations....) Change your specified value again to something close to your new Current value and repeat the previous steps until it converges. When it has converged, make minor changes in the direction of your original specified value and Run it each time to ensure it still converges.

Edited by thorium90, 15 October 2013 - 04:13 PM.

[sunny0]

Sir i did it once again but still not happening.

Is it possible for you to let it solve for me through Teamviewer by controlling my PC virtually ?

You can have the access to my PC, where you can let it solve & i can watch ...

I reaaly appreciate you for your presious time sir.

 

If you are available than please let me know the timings so i can get in touch with you to solve this.

[thorium90]

Hi,

 

I've created a video for your viewing and attached the xml file. Hope it is better for your understanding.

Attached Files

•  CDU SIMULATION_REV1_XML.zip   245.88KB   96 downloads
•  CDU Simulation video.zip   1.98MB   167 downloads

Edited by thorium90, 17 October 2013 - 10:11 AM.

[sunny0]

Greetings,

 

Sir, its converged.

I am highly thnkful.

I appreciate your corespondence.

 

I am feeling happy now, because of you.

Thankyou sir.

Kind Regards,

Sunny.