It is proposed to distil a solution mixture containing 40 mol % methanol and 60 mol % water using a continuous distillation column. An overhead product is to be obtained containing 90 mol % methanol and bottom product will contain 95 mol % water. The feed is introduced at a rate of 100 kmol/hr with 30% vapourised, and a side stream is withdrawn from the column at a rate of 20 kmol/hr containing 70 mol % methanol. If the reflux ratio used is 3 times the minimum, evaluate: a) The minimum reflux b) The optimum stage for the feed c) The composition of the liquid on the third stage from the top

Use the vapour-liquid equilibrium data provided below: 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Y 0.43 0.58 0.67 0.73 0.78 0.83 0.87 0.8 0.92 0.9 0.96