Energy Balance for Multiple Reactions in a CSTR

Anatvst The reactant is virtually consumed by the time it reaches a reactor volume V = 0.4S dm- and beyond this point Q, and the reactor temperature begins to drt. In addition, the selectivity 5a/c == Fg/Ff - 55/22.5 = 2.44 remains constant ter this point. If a hi selectivity is letjuiied. then the reactor should be shortened to V = 0.3 dm, at which point the selectivity is Sb, C = 20/2 lO. 

Recall that for the steady-state mole balance in a CSTR with a single reaction [-FfjnX = /aK] and that -h ACp(7- Tg), so that for Tq = 

we must account for the heat generated by all the reactions in the reactor. For q multiple reactions and ni species, the CSTR energy balance becomes 

Substituting Equation (12-20) for Q, neglecting the work term, and assuming constant heat capacities. Equation (12-39) becomes 

For the two parallel reactions described in Example 12-5, the CSTR energy balance is 

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