Question

For equal sized CSTRs in series carrying out 1^st order reactions of constant density, which of the following is true? (ki is the rate constant in a reactor ‘i’ in series)

(a) k1 ≠ k2 ≠ … ≠ kn, τ1 = τ2 = … = τn

(b) k1 = k2 = … = kn, τ1 = τ2 = … = τn

(c) k1 = k2 = … = kn, τ1 ≠ τ2 ≠ … ≠ τn

(d) k1< k2< …<kn, τ1 = τ2 = … = τn

The question was posed to me during an online interview.

Query is from Design of CSTRS in Series in chapter Isothermal Reactor Design of Chemical Reaction Engineering

Answer 1

The correct option is (b) k1 = k2 = … = kn, τ1 = τ2 = … = τn

Easy explanation: All the CSTRs are operated at the same temperature. Hence, k1 = k2 = … = kn. The volume of all the CSTRs is the same, V1 = V2  = … = Vn. τ = \(\frac{V}{v_0},\) hence τ1 = τ2 = … = τn.