At one point in the production of chloromethanes, the preliminary product purification has produced a scrubbed, dried mixture comprising 35 mol% methylene chloride (A), 45 mol% chloroform (B), and 20 mol% carbon tetrachloride (C), at a total feed rate of 100 kmolh. This mixture is to be fractionated into essentially pure A, B and C. The operation requires two fractional columns operating in series, the second column received as its feed either the overhead or bottom product of the first column. What distillation sequence would you recommend? Screening: Two sequence distillation operations will be necessary to meet the requirements of producing three "essentially pure" products, and two distillation sequences are possible. For the system, A (bp. 40.7C) is more volatile than B (bp. 61.2C), which in turn is more volatile than C (bp. 76.8C). The two possible sequences are shown in Figure 1 below. TAB B A, B, CI A, B, CI II B B, C C -C (a) (b) Figure 1: Distillation Sequence: (a) Alternative 1 and (b) Alternative 2 A preliminary, semi-quantitative comparison of energy requirements for the two competing alternatives can be made if we make three reasonable simplifying assumptions: 1. The separations are all approximately equal difficulty, so that the reflux ratio requirements will be equal for both alternatives. 2. The molar heats of vaporization AHvare equal for the three components A, B, and C. We will take as the basis of our calculations 100 mol of the mixture comprising 35 mol of A, 45 mol of B, and 20 mol of C. 3. Feed is all liquid. Calculate the duty of the reboilers and condensers for the 2 columns in Case 1, in terms of R and . Calculate the duty of the reboilers and condensers of the two columns in Case 2: Which is case is more energy efficient