4 replies to this topic

[Monolina M]

Dear All,
I am currently pursuing my Masters and as part of my dissertation I am trying to simulate an extractive distillation column for Butadiene recovery from C4 cut. A brief description of my system:

Feed:
C4 mix

Aim:
To Recover maximum Butadiene from the bottom of the column and remove Butenes at the overhead.

Solvent:
A mixture of Acetonitrile-ethanol-water is being used as solvent in the system.

The data I have on hand is from a running plant. From a search on the internet I have understood that NRTL fluid package is best suited for the system.

The problem I have is that the simulation results come nowhere close to the plant data.

I have tried altering the various degrees of freedom and even tried other fluid packages but to no avail. My supervisor thinks that simulation in Aspen Plus might yield results. Is it possible that Aspen Plus can yield results with the same set of data?? Can you please suggest a solution to my problem...Any help is highly appreciated...

Thanks & Regards,
Monolina

[Padmakar Katre]

Dear,
Just want to know from you that did you model your column as built or the column template in Hysys. If you configure the as built model by making some changes in your solver tab of the column property view tab I hope you will be near to the plant results. Could you just give the details like your feed condition and the column details. So that it would be easy for members to give specific suggestions to make your simulation model perfect. Waiting for your comments.

[Monolina M]

I modelled my column in a new case. My feed is a liquid feed C4 mix at a temp of 25 C and pre 11.5 kg/cm2 ,which is heated to 55C and then fed to the column. The column pressure is 3.9 kg/cm2. The feed stage entry is at 13, solvent entry at 84 stage.Total no. of stage 95. The stages are numbered from bottom. A recycle stream which is the overhead from a downstream column is fed to the 1st stage. The temp of the vap recycle stream is 71C and pre 4.5 kg/cm2. The solvent temp is 50C. The feed composition as follows:
n-butane .0145
1-butene .11
i-butene .23
cis2butene .06
1,3 butadiene .53
vinyle acetylene .02

Solvent consist of 77% acetonitrile, 15% water and 7.5% ethanol.

[Monolina M]

Further the composition of the recycle from the second column to the first column is as follows:

n-Butane 0.039
1-Butene 0.1002
i-Butene 0.156
cis2-Butene 0.071
1,3-Butadiene 0.927
VnylAcetylene 0.006
Acetonitrile 0.171
Ethanol 0.0239
Water 0.004

All values are on a mass fraction basis...Hope you can throw further light on where I am going wrong with my simulation...

Thanks

[Padmakar Katre]

Dear,
Please update the complete Data. Nobody could could model your case in any simulator. Aspen Plus or any simulator will not assume any input for you. So please furnish the complete data so that I could model your system and will send you the file as you are student I should help you. I am attching an excel sheet which I expect you to furnish the inputs required to model your system.

Attached Files

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