We are separating acetone (MVC) from ethanol in a distillation column that has a partial reboiler and a total condenser. Operation is at \(1.0 \mathrm{~atm}\). CMO can be assumed to be valid. The reflux is returned to the column as a saturated liquid. VLE data are in problem 4.D7. Parts a and \(\mathrm{b}\) are independent (they do not depend on answers to other parts).

a. The column is tested at total reflux. The measured value of mole fraction acetone is 0.08 in the bottoms and 0.88 in the distillate. The column has eight actual stages plus a partial reboiler and a total condenser. What is the value of the overall efficiency, \(\mathrm{E}_{\mathrm{o}}=\mathrm{N}_{\text {equil }} / \mathrm{N}_{\text {actual }}\) ?

b. If the feed is \(40 \mathrm{~mol} \%\) acetone and is a two-phase system that is \(70 \%\) liquid, what is the minimum reflux ratio, \((\mathrm{L} / \mathrm{D})_{\min }\), for \(\mathrm{x}_{\mathrm{B}}=0.08\) and \(\mathrm{x}_{\mathrm{D}}=0.88\) ?

Problem 4.D.7

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D7.* A distillation column with a total condenser is separating a feed that is 30 mol% acetone from ethanol. Distillate xD = 0.90, and bottoms xp = 0.13, both mole fractions acetone. Assume CMO is valid. L/V = 0.8. Boilup ratio is /B = 1.0. . Find the composition of the liquid leaving the fifth stage below the total condenser. . The column has a partial reboiler that acts as an equilibrium contact. Find the vapor composition leaving the second stage above the partial reboiler. Find optimum feed plate location, total number of stages, and required q value of feed. Equilibrium data for acetone (A) and ethanol at 1 atm (Perry et al., 1963, pp. 13-4): XA O 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.50 0.60 0.70 0.80 0.90 1.0 YA O 0.262 0.348 0.417 0.478 0.524 0.566 0.605 0.674 0.739 0.802 0.865 0.929 1.0 TC 78.3 - 67.3 65.9 63.6 - 60.4 59.1 58.0 57.0 56.1