One hundred kmol/h of a saturated-liquid mixture of 12 mol% ethyl alcohol in water is distilled continuously using open steam at 1 atm introduced directly to the bottom plate. The distillate required is 85 mol % alcohol, representing 90 % recovery of the alcohol in the feed. The reflux is saturated liquid with L/D = 3. Feed is on the optimal stage.

Calculate:

a) The steam requirement in kmol/h

b) The number of theoretical stages

c) The optimal feed stage

d) The minimum reflux ratio (L/D)min

\begin{tabular}{ccc|ccc} \hlinex & y & T,C & x & y & T,C \\ \hline 0.0190 & 0.1700 & 95.50 & 0.3273 & 0.5826 & 81.50 \\ 0.0721 & 0.3891 & 89.00 & 0.3965 & 0.6122 & 80.70 \\ 0.0966 & 0.4375 & 86.70 & 0.5079 & 0.6564 & 79.80 \\ 0.1238 & 0.4704 & 85.30 & 0.5198 & 0.6599 & 79.70 \\ 0.1661 & 0.5089 & 84.10 & 0.5732 & 0.6841 & 79.30 \\ 0.2337 & 0.5445 & 82.70 & 0.6763 & 0.7385 & 78.74 \\ 0.2608 & 0.5580 & 82.30 & 0.7472 & 0.7815 & 78.41 \\ & & & 0.8943 & 0.8943 & 78.15 \\ \hline \end{tabular}