14 replies to this topic

[flangecoupling]

Dear All,

 

I am in process of simulating a reactor for metathesis reaction (olefins combining to form propylene). There are 5 main reactions which are governed by equilibrium and 10 side reactions. I am modeling the main reactions as equilibrium reactions and side reactions as conversion reactions to match the inlet and outlet of the reactor.

 

The problem is that I am not sure that in which direction the side reactions will proceed, either in backward or the forward direction.

 

The simulation process is becoming a bit complex. Any advise or help would be very helpful. For details about the reactions please see the attached excel file.

 

Regards,

 

Attached Files

•  Multiple Reactions.xlsx   8.41KB   37 downloads

[thorium90]

Heterogeneous catalysis and using metal catalysts. Might I ask what is the purpose of the simulation? For academic research or for a real plant? Is it just simply to estimate plant production from certain inlet flows?

Edited by thorium90, 03 October 2013 - 10:21 AM.

[Bobby Strain]

I would simply input the reactor outlet composition, presuming you only want to use your licensor information. That makes it simple.

 

Bobby

[flangecoupling]

Dear Thorium,

 

I have to match the licensor data. 

 

Regards

[curious_cat]

Dear All,

 

I am in process of simulating a reactor for metathesis reaction (olefins combining to form propylene). There are 5 main reactions which are governed by equilibrium and 10 side reactions. I am modeling the main reactions as equilibrium reactions and side reactions as conversion reactions to match the inlet and outlet of the reactor.

 

The problem is that I am not sure that in which direction the side reactions will proceed, either in backward or the forward direction.

 

The simulation process is becoming a bit complex. Any advise or help would be very helpful. For details about the reactions please see the attached excel file.

 

What are you simulating in?

 

What kind of reactor is it? Plug flow? Isothermal? 

[thorium90]

Might I ask, what is the information provided to you in this licensor information? In the absence of any kinetic data, the easiest way would be to calculate reactor outlet compositions using gibbs free energy minimization.

[flangecoupling]

Dear Bobby,

 

Thanks for your reply. But I am not clear what you meant. I mean my simulated reactor should give same composition at outlet as the licensor data, but how can I directly input the licensor data, I have to simulate a reactor which should do this.

 

Regards

[flangecoupling]

Dear Curious Cat,

 

I am simulating in isothermal fixed bed reactor.

 

Regards

[flangecoupling]

Dear Thorium,

 

I do not have any kinetic data. But I cannot also use gibbs energy reactor, there are two issues.

 

1. I do not have the gibbs energy reactor in the provided simulator.

2. The side reactions are not going to equilibrium but are rather in kinetic range.

 

Although I agree that the main reactions are governed by equilibrium.

[curious_cat]

Dear Thorium,

 

I do not have any kinetic data. But I cannot also use gibbs energy reactor, there are two issues.

 

 

2. The side reactions are not going to equilibrium but are rather in kinetic range.

 

I'm rather confused if it is even possible fundamentally to simulate a kinetic regime reaction without any access to kinetic data.

 

My impression is you are trying to do the impossible. 

[thorium90]

The cat has stated the most important thing. If you have no kinetic data, you cant simulate kinetic reactions. You can either send a sample of catalysts for test runs or simulate equilibrium conditions. Catalysts change kinetics but do not change the equilibrium. You do not need to use your assigned simulator to minimize gibbs free energy. An excel spreadsheet can also do the job. I understand what you mean by your equilibrium and kinetically controlled reactions and how they will affect the numerical integration. However, you should note that the kinetics will tell you if any reactions are modelled as reversible or irreversible. It does not matter what we say about the reaction but what the researcher who did the kinetic studies decided in his model.
Another alternative is to get the vendor to provide you with the model...

Edited by thorium90, 06 October 2013 - 09:51 PM.

[flangecoupling]

Dear All, 

 

Thank you very much for your valuable replies. These will help me a lot.

 

Dear Thorium,

Can you share an excel spreadsheet which will minimize gibbs energy for a certain reaction as an example. It will help me and get me running on runway a bit fast.

 

I believe you are referring to chapter 13 in Introduction to Chemical Engineering Thermodynamics by Smith and Van Nes.

 

Regards

[curious_cat]

Can you share an excel spreadsheet which will minimize gibbs energy for a certain reaction as an example. It will help me and get me running on runway a bit fast.

 

If you have Gibbs free energies for each reaction or every species you can try a GoalSeek I think. 

 

Though be careful with local minima. 

[thorium90]

I dont have a spreadsheet, but yes, I was implying chapter 13 of the book.

I would say that your task to get the standard values could have been easier if NIST was up and running though.

Attached Files

•  equilibrium equations.png   229.02KB   5 downloads

Edited by thorium90, 07 October 2013 - 11:10 AM.

[flangecoupling]

Dear All, Thank you for your valuable inputs and time. Regards