For the distillation problem outlined in Section 21. 3.2,

a. Determine the values of \(F, B\), and \(x_{B}\) required when the concentration of the feed becomes \(z_{F}\) \(=0.25\). Assume that the values of \(D\) and \(x_{D}\) are to remain the same \(\left(D=30 \mathrm{kmol} / \mathrm{h}ight.\) and \(x_{D}=\) 0. 885 ) and that the recovery is to remain \(90 \%\).

b. Report any risks associated with the solution.

c. What are the values of \(L_{0}\) and \(V_{N+1}\) for this case?

Data from section 21.32

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For distillation, there is no universal set of performance curves as for multistage equilibrium separations involving mass separating agents. However, for a given situation, performance curves can be generated. This section demonstrates how this is done. Figure 21.16 illustrates a multistage distillation system for separating benzene from a mixture of benzene and toluene. Figure 21.17 is a sketch of a typical distillation column. This problem is modified from Bailie and Shaeiwitz [1].