short cut distillation column

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short cut distillation column

Postby shoaibjadoon » 17 September 2013, 04:40

is there any way to find out number of stages and minimum reflux ratio in COCO, as it is found by means of DSTWU column-based shortcuts in aspen plus, where by we can calculate the minimum reflux ratio and number of stages through Winn-Gilliand Approximations?
MUHAMMAD SHOAIB
PAKISTAN( UET Peshawar)
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Re: short cut distillation column

Postby jasper » 21 September 2013, 07:40

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: distillation column specs

Postby shoaibjadoon » 25 September 2013, 07:30

thanks Mr. jasper for replying to my question.
i want to ask you a bit more in this regard.
is there any in-built mechanism in the solver of COCO that when a stream whose temperature is 20 degree celcius, is passed through a heater and its temperature approaches 40 degree celcius, after entering into the distillation column chem sepUO, its temperature falls down by about approximately 40kelvins. can you lease tell me why is this so ?
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Re: distillation column specs

Postby shoaibjadoon » 25 September 2013, 07:31

thanks Mr. jasper for replying to my question.
i want to ask you a bit more in this regard.
is there any in-built mechanism in the solver of COCO that when a stream whose temperature is 20 degree celcius, is passed through a heater and its temperature approaches 40 degree celcius, after entering into the distillation column chem sepUO, its temperature falls down by about approximately 40kelvins. can you lease tell me why is this so ?
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Re: short cut distillation column

Postby jasper » 25 September 2013, 07:34

This depends on the specifications of the column. Can you send me the fsd file that demonstrates this?
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Re: short cut distillation column

Postby shoaibjadoon » 25 September 2013, 09:06

this is a simulation of a methanol water separation process. its a case studies in my M.S project.
Attachments
meth-water sep.fsd
(210.75 KiB) Downloaded 806 times
meth-water sep.fsd
(210.75 KiB) Downloaded 863 times
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Re: short cut distillation column

Postby shoaibjadoon » 25 September 2013, 09:08

this is the case problem statement and procedure.
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Task_SimExercise_Methanol_Intro166048_Meunier.doc
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Re: short cut distillation column

Postby jasper » 25 September 2013, 09:12

Your top pressure is too low. Please correct the top pressure specification to use the proper unit of measure.
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Re: short cut distillation column

Postby shoaibjadoon » 25 September 2013, 10:35

i have changed the column top pressure but it only gives an appropriate value of top product's temperature, bottom's remain the same. could you please check it what causes it to be same bottom product(waste's) temperature?
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Re: short cut distillation column

Postby jasper » 25 September 2013, 11:08

Your reboiler duty specification appears inapproprioate. Perhaps try a purity spec on water instead.
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