*Answers to problems with an asterisk are at the back of the book.
D1. A mixture of water and n-butanol is being processed in an enriching column coupled to a total condenser and a liquid-liquid settler. The feed is a saturated vapor that is 28 mol% water. Feed rate is 100 kmol/h. The distillate product is the water phase from the liquid-liquid settler. The butanol phase in the settler is refluxed to the enriching column as a saturated liquid. Operation is at 1.0 atm and CMO is valid. An external reflux ratio of L/D = 4.0 is used. Equilibrium data are in Table 8-2.
a. Find the mole fraction water in the bottoms product.
b. How many equilibrium stages are needed?