A feed at 100F and 480 psia is to be separated by two ordinary distillation columns into the indicated products.

Two distillation sequences (see §1.7.3) are to be examined. In the first, CH₄ is the LK in the first column. In the second, toluene is the HK in the first column. Compute the two sequences by estimating the actual reflux ratio and stage requirements for both sequences.
Specify a reflux ratio 1.3 times the minimum. Adjust isobaric column pressures to obtain distillate temperatures of about 130^οF; however, no column pressure should be less than 20 psia. Specify total condensers, except that a partial condenser should be used when methane is taken overhead.

Species H 1.5 CH4 19.3 C6H6 (benzene) 262.8 C7Hg (toluene) 84.7 C12H10 (biphenyl) 5.1 Feed Product 1 1.5 19.2 1.3 Ibmol/h Product 2 0.1 258.1 0.1 Product 3 3.4 84.6 5.1