Ethylene Oxide Separation Column In Chemcad 2

[processendbd]

Respected forum Members,
I am trying to simulate a separation column in ChemCad,
I have taken the exact specs given in the literature and used in the ChemCad simulations. But the simulation does not provide any results in the outlet stream (all zeros) or any warning.
ChemCad file attached, 

https://filebin.net/g08tsn89d87vjtco

Any input is appreciated. 

Column Specs
Property Package Ideal (Raults law)

https://ibb.co/GP2JPpg

 

[pmoneysh]

this should have run smoothly if you are used to the simulator (chemcad). I don't have chemcad now but using PRO/II solves it easily and chemcad is no less than PRO/II.

 

[processendbd]

Thank you so much for taking the time and doing the simulation. would it be possible for you to share the simulation file with me? If not possible can you please tell me how much EO was removed from the outlet Gas streams? I can share CHemCAD which is installed in the virtual machine. Thank you again.

 

[pmoneysh]

It's not a problem sharing the file. I use version 10 PRO/II. I tried to attach the file here but am not sure if you can access it. Do let me know if you cannot open the file.

 

[pierreick]

Hi,
Based on literature EO is very soluble in water .

https://www3.epa.gov/ttnchie1/old/ap42/ch07/s01/reference/bref17_c07s01_ch3_1997.pdf

Good luck
Pierre

 

[processendbd]

Thank you for your comments.

Yes, I agree that EO is very soluble in water. I also tried with NRTL but failed to converge this specific column in Aspen Plus and ChemCad. I realized that this unit operation predominately separates gases (methane, ethylene (unreacted), Carbon dioxide) and liquids (water and Ethylene Oxide) so currently using UNIFAC. My initial assumption was it would be easier to converge this unit operation with most of the property packages. But I was wrong.


In the downstream column that actually separates water and Ethylene Oxide, we have used experimental regression data.

 

[processendbd]

Unfortunately, I have Pro II version 9.1 will try to simulate it. Thank you.

 

[pmoneysh]

If you want to proceed to really build the scrubber on the basis of simulation, the appropriate thermodynamic model should be elecNRTL (you can change the vapor phase to RK model). You are not supposed to use UNIFAC model (it is my recommendation). you can estimate missing interaction parameters using UNIFAC model using NRTL (the best approach is ofcourse VLE experimental data regression....). Further, for such scrubbers rather than using equilibrium model, in my experience, rate-based model would be more efficient. Also, make sure your Henry's components are selected appropriately to predict the solubility of gas correctly.

 

[processendbd]

Thank you again. Can you please direct me to any documentation? where we have used different property models for different phases.