short cut distillation column

Discusses use of CAPE-OPEN compliant Process Modelling Components

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Re: short cut distillation column

Postby shoaibjadoon » 25 September 2013, 15:14

thanks a lot Mr. Jasper,
its really been so cooperative and helpful discussion with you, throughout for me.
my problem's been solved. bottom's temperature has also come within a real matchable range now. the only warning now that coco issues me is temperature range of liquid viscosity correlation is out of range. but its quite satifactory for me to have top and bottom product temperatures within a very suitable range and up to mark.
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Re: short cut distillation column

Postby jasper » 25 September 2013, 15:25

You can turn these warnings off in the configuration of the TEA property package, but typically it is handy to have these warnings to remind you that the results are reasonable. Temperature correlations are all kinds of functions, and extrapolation may lead to very unrealistic values.

Viscosity is not actually used by the ChemSep Unit Operation when using an equilibrium model. So in this case it is safe to ignore.

After the unit operation has been solved, you can also accept the warnings that are issued for that particular unit operation (double click the unit, go to the status tab). This will remove the little triangle overlay on the unit operation's icon (until next time it is solved).
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Re: short cut distillation column

Postby colancto » 26 September 2013, 11:46

The AixCAPE ShortCut unit is not available to organizations outside the AixCAPE membership. CO-LaN has access to it because it was tested in various PMEs. Anyhow it does not work exactly as the shortcut unit you find in most libraries of unit operations. It functions mostly in verification rather than in design mode.

The Fenske-Underwood-Gilliland methods usually implemented in a shortcut calculation are not that complicated. They rely on the kvalues which are often available from a Property Package or which can be inferred from other properties. You may want to have a look implementing these methods in Excel or Scilab. That way you may make the Unit Operation a CAPE-OPEN Unit Operation. Input parameters for such a Unit Operation are just a few, like a light compound, a heavy compound for which you are stating the splitting you want to achieve. Pressure needs to be also a parameter since the column may operate at a different pressure than the feed pressure.

Mind that you may want to have a look at the source code of the shortcut unit available in DWSIM which is open source. The unit is not CAPE-OPEN compliant.

jasper wrote:There is no CAPE-OPEN based shortcut method that comes with COCO. However, as COCO can use any CAPE-OPEN compliant unit operations, third party shortcut methods that are CAPE-OPEN compliant can be used.

AIXCape presented such a method back in 2006: http://www.colan.org/News/Y06/AixCAPE_ACHEMA06.pdf; I am not sure whether or not this is publicly available.

There is also of course the possibility of implementing the shortcut method yourself as a CAPE-OPEN unit operation. In this way you cannot use it only in COCO, but also in many other simulation environments (including Aspen Plus).
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Re: short cut distillation column

Postby shoaibjadoon » 03 November 2013, 10:13

dear sir,
once again i have to seek help from your side that whether there is any procedure for process parameters sensitivity analysis in coco, as do we have in aspen plus???
if not, then whether is it appropriate to export our data from coco to excel and draw graphs showing sensitivity of variation of one variable with the other???
regards!!!
muhammad shoaib
from
pakistan
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Re: short cut distillation column

Postby jasper » 03 November 2013, 12:01

Please try whether the parametric study gives you the information you are after. Solve the flowsheet, then select Parametric Study from the Flowsheet menu. Select which input parameters you are interested in, and the range that they should be varied in as well as the number of intervals. Each variation will run one simulation, so be careful to select all output parameters you are interested in before running the study, as depending on your selections this may take a while. If you have multiple cores, COFE will divide simulations over cores, but will use the nearest solution as a starting point, which may limit the number of cores in use.
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