reactive distillation

Discusses use of COCO, the process simulation and modelling software suite from AmsterCHEM, downloadable from www.cocosimulator.org

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reactive distillation

Postby aken » 27 December 2019, 23:45

Hi. I am trying to explore reactive distillation but when l try to solve l get the message as attached in the picture. Thanks for your help!
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Re: reactive distillation

Postby jasper » 30 December 2019, 16:48

Quoting Prof. Ross Taylor:

There may be many things wrong here. (Actually, there are many things wrong.)

I ran this in ChemSep both standalone and in COCO with the ChemSep window open. Both worked after making some changes:

1. Turn off CO properties.

2. Stop it writing all the iteration details. Too much output.

3. Set the number of iterations to a sensible number. Not sure if it was 1 or * when it got to me but it stopped after 1.

Then it runs and converges in about 7 iterations.

There are, however, other issues. The reactions are not set up properly. I do not have any idea where the parameters come from but they don't look right. Also the reaction orders are wrong.
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Re: reactive distillation

Postby aken » 01 January 2020, 00:47

Thanks for the response and it finally converged with unconvincing results after changing errors suggested by Prof. Ross Taylor. My question is, in the form where we input the reaction kinetics data, it does not have where we can input the pre-exponential factor and activation energy unlike in the COCO interface. Is the k in the input window for rate constant or reaction rate? I obtained the reaction kinetics data from the following document:
https://lms.nchu.edu.tw/sysdata/doc/5/5 ... cb/pdf.pdf
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Re: reactive distillation

Postby jasper » 03 January 2020, 09:02

Again quoting Prof. Taylor:

Annotation 2020-01-03 092334.png
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Re: reactive distillation

Postby aken » 16 January 2020, 09:17

Hi,
I used the exact figures as those given by Professor Taylor in the last comment for the methanol esterification and the figures as obtained from Luyben. But still the conversion of methanol is negligible. Does the feed temperature has to be same as the temperature which the specific rate constant was determined? Please see attached documents.
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Re: reactive distillation

Postby jasper » 21 January 2020, 08:02

Quoting Prof. Taylor again:
The reaction model is pseudo-homogeneous, not homogeneous as selected. Stage volume 10 m3 and catalyst activity 1.

The kinetics basis should be concentrations.

Most important, perhaps, the column configuration is wrong. There are too few stages and the reactants should be fed to different stages far apart. And the bottom product rate needs to be more sensibly chosen.
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