A 20-stage column with the overhead condenser as stage 1, the feed stage as stage 10, and the reboiler as stage 20 is used to distil a binary mixture. The relative volatility, α, is 2.5. The feed rate...

A 20-stage column with the overhead condenser as stage 1, the feed stage as stage 10, and the reboiler as stage 20 is used to distil a binary mixture. The relative volatility, α, is 2.5. The feed rate is F = 1 mol/min, the feed composition is zF = 0.5, and the feed condition is q = 1 (bubblepoint liquid). The reflux flow rate is R = 3 mol/min and the distillate leaving the column is 0.5 mol/min. The holdups in the condenser and the reboiler are both 5 mol, and the holdup in each stage is maintained constant as 0.5 mol.At t = 2 min, there is 0.2 mol/min step change in the reflux flow rate. Plot the liquid compositions of the distillate and the bottoms for 0 ≤ t ≤ 30. Also plot the liquid composition profile along the stages at t = 30 min.