Modelling a custom PFR model using DAEs

[abhi24x7]

Dear IDAES community,

I just started using the framework a week ago and I would like to thank all the concerned developers for working on the tutorials and examples, they really gave me insights about how the platform works. It was a really good guide.

Now, through this thread, I am seeking your help to make a custom packed bed PFR model with my own Mass & Energy balance equations and rate equations (which are not simple Arrhenius model), I just want to know how can I declare the same?

Thank you very much!

[andrewlee94]

Hi @abhi24x7, welcome to IDAES. It seems there are two parts to your question, and it sounds like you are trying to do a fairly custom model.

Firstly, on the topic of the reactor itself. It is possible to use the core PFR model and turn off the mass, energy and/or pressure balances if you desire, but at that point you might be better off asking if it is better to use a completely custom model. Depending on how you want to write the reaction model, you might also need to change how the extent of reaction is defined - the PFR uses extent = area*rate (i.e. a volumetric definition of reaction rate). To turn off the material balances, you can do m.fs.pfr = PFR(material_balance_type=MaterialBalanceType.useDefault) (and similar for the energy and momentum balances). However, before you start working on this, it might be a good idea to discuss what it is you want to do in more detail so we can give some more detailed suggestions on how to go about it (specifically, what is it you want to customize about the mass and energy balances).

On the topic of the reactions, you can write your own custom reaction package. A simple example can be found here: https://github.com/IDAES/idaes-pse/blob/main/idaes/models/properties/examples/saponification_reactions.py. This uses a simple Arrhenius power law model, but you can replace those equations with those of your choice. As long as the final rate is on a volumetric basis (e.g. mol/m^3), it will fit into the core models.

[abhi24x7]

Dear @andrewlee94,

Thank you very much for all your previous help. Is there any method through which I can generate a stream summary of simulation table to a .csv file? Could you please refer me to an example which does a similar thing?

Thank you in advance! Looking forward to your reply.

[andrewlee94]

@abhi24x7 For a flowsheet, you should be able to call flowsheet.stream_table(time_point) to get the stream table as a Pandas dataframe. You can then send this to a csv file using the Pandas to_csv method: https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.to_csv.html

[abhi24x7]

Dear @andrewlee94,

Could could you please guide me on how to use flowsheet.stream_table(time_point)? I can't figure it out.

Thank you in advance! Looking forward to your reply.

[andrewlee94]

stream_table is a method which exists on all FlowsheetBlocks - one you have built your flowsheet you can just call this method to get the stream table. time_point is primarily for dynamic simulations and lets you pick a point in the time set to show the stream table for.

E.g.

m = ConcreteModel()
m.fs = FlowsheetBlock()

# Add properties, unit models and Arcs
# Initialize and solve

m.fs.stream_table()

[abhi24x7]

Dear @andrewlee94,

Thank you so much for the previous reply! This was a really really helpful command.