6 replies to this topic

[bluethunder90]

Hi guys,

 

I am trying to simulate a sulfuric acid alkylation reactor unit in HYSYS but the current available reactor model is not robust enough based on the complexity of the sulfuric alkylation reaction it. Thus I wanna give it a shot to simulate this reactor using Aspen Custom Modeler but I have to admit that I don't have any basic knowledge in custom modeling. Doing it as a final year project for my bachelor degree.

 

P/S: I am looking at DuPont's contactor reactor and I appreciate EVERY advice or comments that you guys can give me.

 

Thanks.

 

H.

[Pilesar]

I am wary of your plan. Custom reactor modeling can be very time consuming and it seems too great a task to expect for undergraduate work. To have a shot at using Custom Modeler, you should have advice from your Hysys tech support. If as a student you do not have official access, I would either bend the rules and call them anyway or find an alternate plan.

 

I do not know the parameters you were given by your instructor. Were you given a flowsheet and reaction yields at operating conditions? If the reaction yields are on volume basis, then convert the volumes to mass. You can then normalize the products so that the total product mass matches the feed mass. This will allow you to fix the stoichiometric coefficients for each set of components that react (coefficients do not have to be integers) and you should be able to use a standard equilibrium reactor. In my opinion, for an undergrad project it is most important to document your calculations and assumptions and move on to the next phase of the project. As long as your results are reasonably close, there should not be much emphasis on whether your reactor is inaccurate by 30% or so. 

 

I suggest these References if you can find them (I cannot supply them to you): 

"Refinery Process Modeling" by Gerald Kaes (ISBN-10: 0967927404)

C. R. Cupit, J. E. Gwyn, and E. C. Jernigan, "Special Report Catalytic Alkylation", Petroleum and Chemical Engineering, 33 (12), 203 (Dec. 1961); 34 (1), 207 (Jan. 1962).

[thorium90]

I think the following would be a useful read. Anyway, is it really necessary to use a more complicated model? Is it even necessary to use hysys? If the reaction is so complicated, perhaps Matlab would be more useful in performing the calculations for simulation. Perhaps you can describe your alkylation reactions here, it might help.

http://support.aspen...YSV7_3-Cust.pdf

[bluethunder90]

A BIG thank you to both Pilasar and thorium90 for your kind reply. Well, i do have the material balance sheet with me but i was not given any reaction data, i.e. value of pre-exponential factor k, activation energy Ea etc. I was told that sulfuric acid alkylation is a very complicated process as a slight existance of impurity will decrease acid strength which in turn affects the alkylate production. I will try to summerize my process as simple as possible but it might take some time as I have my hands full with other projects as well.

 

And Pilasar, the reference book (by Gerald Kaes) that you recommended does include sulfuric acid alkylation simulation and i thought of getting one but spending 180 dollars for a single process might be a little bit too expensive isnt it? But if you have read the book and find it helpful for me I will not hesistate to get it on Amazon

[thorium90]

Well, good books are always expensive, provided you can find someone willing to sell on second hand websites. Heard facebook is becoming the next blogshop for stuff, not just clothes, but used books...  Then again, Im guessing most people on this forum dont have facebook, much less a blog or blogshop,,, Although I could be wrong...

Edited by thorium90, 20 March 2013 - 09:58 PM.

[junaid8942]

I done kinetic model of "Light Naphtha isomerization reactors" in my Engineering final year project. Along HYSYS simulation with its basis and catalyst properties and find the optimize size and coking % in reactor.i would be glad, by helping you in Reactor sizing or kinectic modeling in hysys.

[Chellani]

Before you proceed with your model, try answering following questions

• Do you really want to get into this? It will be time consuming activity
• What is your purpose of model and how do you want to do it i.e. how detailed, shortcuts etc. etc. e.g. you can prepare empirical model which would give you RON,MON function of iC4 concentration, mixing parameters, temperature etc. or you can work only bulk properties i.e. density and distillation or you can really get into detailed component modeling. So take a call and decide details before proceeding
• Detailed kinetic model would first require mass transfer model as alkylation is controlled by mass transfer which plays key role in overall reaction.
• If you really want this to be detailed one, you need to write few equations for mass transfer, heat transfer, kinetics and VLE
• How are you going to tune your model? Model will have few tuning parameters for which you’ll require data, are you going to get that for model?

 

Few references which could be helpful

 

Alkylation of isobutane with C₃-C₄ olefins: Identification and chemistry of heavy-end production, Ind. Eng. Chem. Res., 1997, Vol 36(6), 2110

Degradation and isomerization reactions occurring during alkylation of isobutane with light olefins, Ind. Eng. Chem. Proc. Des. Dev., 1976, 15(1), 53.

Degradation and isomerization of isoparaffins while in contact with sulfuric acid in alkylation units: Chemistry and reaction kinetics, Ind. Eng. Chem. Res., 1994, 33, 840.

The reaction of 2,3,4-Trimethylpentane in concentrated sulfuric acid, J. Org. Chem., 1967, Vol 32, 920.

The kinetics of isobutane alkylation in sulfuric acid, Ind. Eng. Chem., 1977, Vol 16(3), 282

Oligomerization of 1-butene in sulfuric acid, I & EC Fundamentals, 1969, Vol 8(3), 397.

Dimethylhexane formation in butene alkylation, I & EC Prod. Res. Dev., 1962, Vol 1(2), 124.

 

Cheers