One hundred kilogram-moles per hour of a feed containing 30 mole% n-hexane and 70% n- octane is to be distilled in a column consisting of a partial reboiler, a theoretical plate, and a partial condenser, all operating at 1 atm (101.3 kpa). the feed, a bubble-point liquid, is fed to the reboiler, from which a liquid bottoms product is continuously withdrawn. bubble-point reflux is returned to the plate. the vapor distillate contains 80 mole% hexane, and the reflux ratio (lr/d) is 2.
assume the partial reboiler, plate, and partial condenser each function as an equilibrium stage.(a) using the mccabe-thiele method, calculate the bottoms composition and moles of distillate produced per hour.
(b) if the relative volatility α is assumed constant at a value of 5 over the composition range for this example (the relative volatility actually varies from 4.3 at the reboiler to 6.0 at the condenser) calculate the bottoms composition analytically.
(c) solve problem graphically, assuming the feed is introduced on plate 1, rather than into the reboiler.
(d) determine the minimum number of stages required to carry out the calculated separation