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[firefox23]

 IMG_1116.JPG   96.3KB   0 downloadsHi I am struggling with a question on homogeneous reactors where multiple  IMG_1108.JPG   89.5KB   0 downloads  IMG_1107.JPG   85.2KB   0 downloads  IMG_1106.JPG   98.3KB   0 downloads  IMG_1105.JPG   114.44KB   0 downloads  IMG_1110.JPG   82.29KB   0 downloads reactions are taking place i know the question cannot be done just by hand as it is very complex so I am using excel. however i don/t know where to start or ho to set the question up. So far i have done a molar balance on each of the reactants and products in order to find the partial pressures to sb into r1,r2 and r3.  Any ideas where I should go next or if this is even the right first step to take? Any help would be much appreciated! (Please ignore any of my annotations on the questions papers)

Edited by firefox23, 30 January 2017 - 01:37 PM.

[Francisco Angel]

Hi firefox23:

It seems that the information you provided is still incomplete, but I can offer some advice.  You are right in that a mole balance is a path to solution, from what I see, your are not too clear in the mole balance, because you apply 'x' decrements/increments to every component. Because there are three reactions, there must be three reaction terms in the mole balance for every component (some can be zero though), like this for example for ethylbenzene:

EB_outlet = EB_inlet - r_1 - r_2 - r_3 and so on.

 

I didn't see what type of reactor the problem is about. For a plug flow reactor with catalyst for example, you must use a pressure drop equation along the reactor.

Lets suppose the case of a CSTR reactor, you are given the temperature so you can calculate the equilibrium constant and the heat of reaction terms (no needed here, but can be used in a posterior question to determine heating/cooling duties). I assume you know the inlet compositions too?

You need partial pressures for the reaction terms, for that you need to know the total pressure inside the reactor, and the outlet mole fractions, because:
P_i = P_total * y_i 

P_i: Partial pressure.

y_i: Mole fraction.

 

You will have 8 independent mass balances (you listed 8 components) and three reaction rate expressions, that allow to calculate the reaction term as a function of outlet mass fractions. The unknowns will be the 8 outlet mole fractions. You can solve the problem (unknowns = equations) using a nonlinear solver.

Email me if you want: francisco.angel.rod@gmail.com

Best regards.