Solve number 11.4.3

11.4-1. Distillation Using McCabe-Thiele Method. A rectification column is fed 100 kg mol/h of a mixture of 50 mol % benzene and 50 mol % toluene at 101.32 kPa abs pressure. The feed is liquid at the boiling point. The distillate is to contain 90 mol % benzene and the bottoms 10 mol % benzene. The reflux ratio is 4.52 :1. Calculate the kg mol/h distillate, kg mol/h bottoms, and the number of theor- etical trays needed using the McCabe-Thiele method. Ans. D = 50 kg mol/h, W 50 kg mol/h, 4.9 theoretical trays plus reboiler 11.4-3. Graphical Solution for Minimum Reflux Ratio and Total Reflur. For the rec- tification given in Problem 11.4-1, where an equimolar liquid feed of benzene and toluene is being distilled to give a distillate of composition to 0.90 and a bottoms of composition xw = 0.10, calculate the following using graphical methods. (a) Minimum reflux ratio Rm. (b) Minimum number of theoretical plates at total reflux. Ans. (a) R = 0.91; (b) 4.0 theoretical trays plus a reboiler