Extractor

[thubelihle]

Hi. My extractor cannot converge. And also the original document used NRTL with parameters from ASPEN, how do l convert them to the COFE one. attached are both files.

[jasper]

Please verify the units of measure of the Aij NRTL parameters in Aspen Plus from the Aspen manual. It is not clear from the dialog.

[thubelihle]

the other thing is l cant really change the light fraction, l guess that's the reason it does not converge. In this case l used UNIFAC as the model. thanks

[jasper]

Please elaborate on "cannot change the light fraction"?

[thubelihle]

For the bottom feed, l need to put a light fraction of 1 on the chemsep unit for an extractor to let the unit operation know its a bottom feed, but l try to modify this input it does allow me to, hence the flowsheet attached above does not converge. Thanks

[hkooijman]

Indeed you cannot change the light liquid fraction while running the extractor inside COCO. You can when you run ChemSep standalone. Under certain circumstance this indeed may cause the LLX model to not converge. A quick workaround is to load the LL-eXtractor in the ChemSep GUI, press F12 to open the sep-file in text format, and try to locate the [Feeds] section and try to enter the light fraction there by hand. Save the file, use the reload option in the ChemSep GUI, and try to run again. We will address the issue in the next updating of ChemSep LITE.

[thubelihle]

thank you it did work!