2 replies to this topic

[mg34]

Dear All,
I would like to modelling a petlyuk and/or divided wall column in Chemcad (Chemstation).
Would anybody share an example job or give details about the settings?
Many thanks,
Gabor

[aransari85]

Hi MG34,

Devided wall technology was developed long back in 1940's but due to non availability of powerful simulation software and construction technology its not implemented for long time.. But after 1980's it's implementing..

You can refer to hydrocarbon procesessing for one of the case study provided for 1,3 butadien..

or you can see http://www.chim.upb....v_040822_01.pdf

http://www.segovia-h...0(FER%20GA).pdf

I suggest you do google and collect maximum information about its functioning and principles.

For your referance i give you one example overview please find attached sketch showing the scheme without DWC at left and with DWC at right..

First understanding the problem without DWC is important so that we dont miss out objective for the the separation and implement it DWC..

Here, Crude 1,3 butadien is the feed, which having some heaviers and some ligthers and 1,3butadien..

in traditional distillation this is possible in 2 distillation columns, where in first column lighters are removed and in second column pure 1,3 butadien and heaviers are saperated.

In second attachments shows the section of DWC as (1,2), 3, 4, and (5,6)...

You have to simulate the 2 column of traditional distillation into 4 columns as:

(1,2) simple mass transfer section where you will add the feed to section above 2. No. of stages for section 1 and 2 has to desided.
Parallel to this (5,6) section have to be simulated here the location of sidedraw is to desided. ie. stages for 5 and 6..
section 3 the top section with condenser.. where vapors from above 2 sections will go to this section and liquid from section 3 will be devided to section (1,2) and (5,6).. flow distribution for these 2 section from section 2 has to be decided..
and last section section 4 with a reboiler at bottom of (1,2) and (5,6), where liquid from these 2 section will go to section 4 and vapor from section 4 will go to section(1,2) and (5,6), again portion of vapor from section 4 going to these 2 section to be desided..

All these variables to be adjusted in such a way that we dont deviate from the purity.. of the products..

this case of simulation will be having many recycle streams, which need to be converged...

Good hand on recycle and distillation column simulation, it is possible to solve the problem..

There are many benifits mentioned in literature about DWC, it saves intial cost, operating cost..

You can choose any of 3 componets sytem and can work on it.. first i suggest you simulate the traditional column and then DWC..

Best luck,

Regards,
ARA

Attached Files

•  DWC.pdf   139.65K   37 downloads
•  DWC1.pdf   46.95K   20 downloads

[mg34]

Dear ARA,
many thanks for information.
I have found several articles about the Petlyuk and DWC columns. I have found a very good example (Ramirez-Corona et al ChemEngResDes 88 2010 1405-1418) which one I would like to put in Chemcad. The columns alone are working but when I try to connect them it does not work. Convergence problem.
Again thanks for your help.
Regards,
Gabor