6 replies to this topic

[Achso]

Hi,
I need your help about how to use the regress Bips in ChemCad. I have the experimental data of VLE of ethanol-water-ethylene glycol system.
I compared the VLE experimental data from the ChemCad and were different, so i need to to do this regression in order to obtain the new bips.
Therefore, I did the regression but i obtained almost the same values of bips that ChemCad has. Attach you can find the comparasion between experimental data and ChemCad.
The other possibility is to edit the bips, i got some bips from the literature but these bips are from the hysys. I used the same bips for
ChemCad 6.2 but my simulation gave me wrong results.

I appreciate your recommendations and your help,

Achso...

Attached Files

•  validating vle.xlsx   13.02KB   36 downloads

[milenkom]

Hi,
I need your help about how to use the regress Bips in ChemCad. I have the experimental data of VLE of ethanol-water-ethylene glycol system.
I compared the VLE experimental data from the ChemCad and were different, so i need to to do this regression in order to obtain the new bips.
Therefore, I did the regression but i obtained almost the same values of bips that ChemCad has. Attach you can find the comparasion between experimental data and ChemCad.
The other possibility is to edit the bips, i got some bips from the literature but these bips are from the hysys. I used the same bips for
ChemCad 6.2 but my simulation gave me wrong results.

I appreciate your recommendations and your help,

Achso...

Mate, I had a look into your excel spreadsheet. I'm not sure why doesn't your chemcad and experimental curves match. Because I did regression in Chemcad myself and I got perfect fit. In fact it was so good that for a minute I wasn't sure If I actually got two curves on the graph. Also please don't just enter BIPs from Hysys into Chemcad without checking first how BIP equation is defined in both simulators. It could be that signs of BIPS are opposite - instead of + and vice versa.

Edited by milenkom, 26 April 2010 - 05:33 PM.

[Achso]

Hi,
I need your help about how to use the regress Bips in ChemCad. I have the experimental data of VLE of ethanol-water-ethylene glycol system.
I compared the VLE experimental data from the ChemCad and were different, so i need to to do this regression in order to obtain the new bips.
Therefore, I did the regression but i obtained almost the same values of bips that ChemCad has. Attach you can find the comparasion between experimental data and ChemCad.
The other possibility is to edit the bips, i got some bips from the literature but these bips are from the hysys. I used the same bips for
ChemCad 6.2 but my simulation gave me wrong results.

I appreciate your recommendations and your help,

Achso...

Mate, I had a look into your excel spreadsheet. I'm not sure why doesn't your chemcad and experimental curves match. Because I did regression in Chemcad myself and I got perfect fit. In fact it was so good that for a minute I wasn't sure If I actually got two curves on the graph. Also please don't just enter BIPs from Hysys into Chemcad without checking first how BIP equation is defined in both simulators. It could be that signs of BIPS are opposite - instead of + and vice versa.

Hi, that is good news that both curves match. Please can you tell me the procedure that you follow to do the regression in ChemCad because i supposed that i did some mistakes when i did my regression.
Thanks for your reply.

[milenkom]

Hi,
I need your help about how to use the regress Bips in ChemCad. I have the experimental data of VLE of ethanol-water-ethylene glycol system.
I compared the VLE experimental data from the ChemCad and were different, so i need to to do this regression in order to obtain the new bips.
Therefore, I did the regression but i obtained almost the same values of bips that ChemCad has. Attach you can find the comparasion between experimental data and ChemCad.
The other possibility is to edit the bips, i got some bips from the literature but these bips are from the hysys. I used the same bips for
ChemCad 6.2 but my simulation gave me wrong results.

I appreciate your recommendations and your help,

Achso...

Mate, I had a look into your excel spreadsheet. I'm not sure why doesn't your chemcad and experimental curves match. Because I did regression in Chemcad myself and I got perfect fit. In fact it was so good that for a minute I wasn't sure If I actually got two curves on the graph. Also please don't just enter BIPs from Hysys into Chemcad without checking first how BIP equation is defined in both simulators. It could be that signs of BIPS are opposite - instead of + and vice versa.

Hi, that is good news that both curves match. Please can you tell me the procedure that you follow to do the regression in ChemCad because i supposed that i did some mistakes when i did my regression.
Thanks for your reply.

Sorry mate, It seems I have made a mistake. Which thermophysical package did you use to regress the data?

[Achso]

Hi,
I need your help about how to use the regress Bips in ChemCad. I have the experimental data of VLE of ethanol-water-ethylene glycol system.
I compared the VLE experimental data from the ChemCad and were different, so i need to to do this regression in order to obtain the new bips.
Therefore, I did the regression but i obtained almost the same values of bips that ChemCad has. Attach you can find the comparasion between experimental data and ChemCad.
The other possibility is to edit the bips, i got some bips from the literature but these bips are from the hysys. I used the same bips for
ChemCad 6.2 but my simulation gave me wrong results.

I appreciate your recommendations and your help,

Achso...

Mate, I had a look into your excel spreadsheet. I'm not sure why doesn't your chemcad and experimental curves match. Because I did regression in Chemcad myself and I got perfect fit. In fact it was so good that for a minute I wasn't sure If I actually got two curves on the graph. Also please don't just enter BIPs from Hysys into Chemcad without checking first how BIP equation is defined in both simulators. It could be that signs of BIPS are opposite - instead of + and vice versa.

Hi, that is good news that both curves match. Please can you tell me the procedure that you follow to do the regression in ChemCad because i supposed that i did some mistakes when i did my regression.
Thanks for your reply.

Sorry mate, It seems I have made a mistake. Which thermophysical package did you use to regress the data?

Hi, the thermophysical package that i used was NRTL (Regress TPxy VLE data), please tell me if i did some mistakes.

[Zauberberg]

See if this is of some help - I'm not an expert on the subject: http://www.cheresour...idatingzz.shtml

[Aaron Herrick]

Hi, the thermophysical package that i used was NRTL (Regress TPxy VLE data), please tell me if i did some mistakes.

That thermo should do fine, If you attach your data I'll see what I can do.