Obtaining stream results at the end of every operating condition for a ASPEN PLUS simulation

[chengg29]

Hi,

Currently I am running a steady state simulation, on ASPEN PLUS (I have only a few years of experience in the usage of ASPEN PLUS), for a Pharmaceutical plant. It's a batch process and I am using a BATCHSEP model in this simulation. The feed comprises Na2co3 along with Dichloromethane, Butyrophenone, 3 Methylpropiophenone and 4 Methylpropiophenone.

The simulation converged but with a warning that Na2Co3 could not be identified properly and hence some of it's properties were not evaluated accurately and some properties were missing (the control panel had messages indicating that the thermodynamic package used viz. initially NRTL and later changed to UNIFAC by the user, was not being accepted by Na2CO3 and hence the properties may not be accurate). The result was that the desired purity of the product i.e. 4 Methylpropiophenone could not be obtained in the distillate stream (product stream).

I wish to know:

a) Since NRTL and UNIFAC do not seem to be able to estimate properties for a product mix of an inorganic compound viz. Na2CO3 and the other organic compounds what would be the appropriate thermodynamic package to be used?

b) There are specific operating steps running in a certain sequence and time duration in this Pharma production process. How would it be possible to get stream results at the end of each operating strep that is being simulated in sequence on ASPEN PLUS?

If needed I can attach a copy of the simulation file for anyone to take a look.

Thanking you in anticipation

 

[jari001]

The file or at the least a screen capture of what your flowsheet looks like would be helpful.

 

[pmoneysh]

In my opinion, you can retrieve parameters from NIST TDE and specify it as user input. NRTL model with UNIFAC to estimate the missing VLE parameters would help in many cases. I did not understand the question (b). However, we can specify the number of cycles in the batch system.

 

[chengg29]

Hi jari001,

Thank you for responding to my query. I have attached a snapshot and a copy of the control panel messages which may also be helpful.

Hi pmoneysh,

Thank you for responding to my query. I did use the NIST Databank for those chemicals which i had to define by drawing their molecular structure viz. 3 Methylpropiophenone and 4 Methylpropiophenone. NRTL with UNIFAC was the property method used for this simulation. What I meant was that I am unable get results for the simulation run at the end of each operating step of the simulation (as you may be aware, for some pharma processes, there may be different operating steps taking place in a certain sequence and of a certain time duration before the final product specification is achieved).

I have attached a snapshot and a copy of the control panel messages which may also be helpful.

Thanks