Q3/ An ethanol - water feed holding 20 mol % ethanol, 25% saturated gas, is to be separated into a distilate holding 75 mol % and a bottoms holding 2 mol % ethanol in a distillation column equipped with a partial reboiler and total condenser. The reflux ratio is set to 2.5 and the overall column efficiency can be estimated to 45%. (a) How many physical trays are needed in the column? (b) What is the minimum reflux ratio? (c) How much energy is used in the reboiler and condenser? Equilibrium data for ethanol-water system at 1 atm pressure are in Table given below: XA 0 0.02 0.07 0.09 0.12 0.16 0.23 0.26 0.32 0.39 0.50 0.52 0.57 0.67 0.74 0.9 390.50 0.52 0.5 YA 0 0.17 0.39 0.43 0.47 0.50 0.54 0.56 0.58 0.61 0.65 0.66 0.68 0.74 0.78 0.9 Solution: (H.W) xf = 0.2, Xd = 0.75, 0.02 atb lih R = 2.5