Two liquids, A and B, which have nearly identical boiling points, are to be separated by liquid-liquid extraction with solvent C. The following data represent the equilibrium between the two liquid phases at 95°C.

Determine the minimum amount of reflux that must be returned from the extract product to produce an extract containing 83% A and 17% B (on a solvent-free basis) and a raffinate product containing 10% A and 90% B (solvent-free basis). The feed contains 35% A and 65% B on a solvent-free basis and is a saturated raffinate. The raffinate is the heavy liquid. Determine the number of ideal stages on both sides of the feed required to produce the same end products from the same feed when the reflux ratio of the extract, expressed as pounds of extract reflux per pound of extract product (including solvent), is twice the minimum. Calculate the masses of the various streams per 1,000 lb of feed, all on a solvent-free basis. Solve the problem using equilateral-triangle coordinates, right-triangle coordinates, and solvent-free coordinates. Which method is best for thisexercise?

EQUILIBRIUM DATA, WT% Raffinate Layer Extract Layer C, % A, % C, % B, % B, % A, % 7.0 93.0 92.0 8.0 1.0 1.8 6.1 5.5 4.4 92.9 9.0 81.7 9.3 75.0 63.0 92.7 14.9 10.1 3.7 91.9 25.3 11.7 35.0 42.0 48.1 52.0 90.5 6.2 3.3 51.5 13.5 9.2 13.0 2.4 41.0 17.0 88.4 1.8 85.2 29.3 22.6 18.3 1.8 79.9 20.0 28.0 24.5 31.2 3.0 72.5 47.1 12.9 40.0 Plait point 63.2 5.6