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Aspen Plus Crystallizer Help


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#1 elito123

elito123

    Brand New Member

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Posted 05 February 2023 - 05:36 PM

Hello all, I am trying to simulate a terephthalic acid (TA) plant and I am learning to use the crystallizer unit. 

 

I have a couple questions concerning the crystallizer (feel free to answer any of them please).

 

The stream inlet for the unit is the product stream of a PBR at high pressure (73bar) and temperature (around 285C). In patents I have found it specifies that the first  crystallizer (the unit I am trying to model) should operate at 237 C and 31bar.

 

My first question when modeling is the following: I try to use the chemistry tab to calculate solubility and I get the following warning:

 

*  WARNING
   UNABLE TO FIND SOLID SOLUBILITY FOR COMPONENT 'TA-SOLID' WITH
   LIQUID MOLE FRACTION =  0.2076E-07 AT T =   453.2      P =  7.2500E+06
   MAXIMUM NUMBER OF ITERATIONS (30) REACHED.

 

Similarly, I have found a correlation of solubility for TA in literature and I get a similar error when using that. Does any one know if this is important or not as it is just a warning. 

 

Moreover, In the crystallizer unit I would like it to calculate the PSD using growth kinetics. However, it only gives me the option to use overall nucleation rate and not growth rate that I have found in literature. 

 

Additionally, it mentionions a error about the PBR being a specified temperature sometimes. 

 

Finally, when playing around with the unit and specifying a random PSD I can get a convergence how ever there is no mass flow through the vapor stream which doesnt make sense. 

 

 

I cannot attach the doc as the files are saved on a virtual machine, but I would really appreciate some help as I have been going in circles for two days.

 

Regards



#2 SilverShaded

SilverShaded

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Posted 07 February 2023 - 03:22 AM

You need to go and hassle Aspentech customer support, as far as i am aware the crystallizer model is not well used and quite buggy.






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