SOLVED CH3030 Tutorial 5

1. An aqueous solution of ethanol (30 mass% ethanol) is to be enriched into a top product having 88 mass% alcohol. The bottom product must not contain more than 4 mass% ethanol. The feed enters the column at 40°C at a rate of 5000 kg/h. The reflux is at its bubble point and the reflux ratio is 1. Determine a) The number of ideal trays required using the Ponchon-Savarit method b) The heat duty of the condenser and the reboiler. The enthalpy concentration (kJ/kmol; reference states: pure liquids at 0°C) and the vapour liquid equilibrium data at the operating pressure of 1 atm are given below x,y 0 0.0417 0.0891 0.146 0.207 0.281 0.37 0.477 0.61 0.779 1 HL 7540 7125 6880 6915 7097 7397 7750 8105 8471 8945 9523 HV 48150 48250 48300 48328 48436 48450 48450 48631 48694 48950 x 0 0.00 792 0.0 16 0.0 20 2 0.0 41 7 0.0 89 1 0.1 43 6 0. 28 1 0. 37 0. 47 7 0. 61 0. 64 1 0. 70 6 0. 77 9 0. 86 0. 90 4 0.9 5 1 y 0 0.08 50 0.1 58 5 0.1 91 0.3 04 0.4 27 0.4 93 0. 56 8 0. 60 3 0. 64 4 0. 70 3 0. 72 0. 75 6 0. 80 2 0. 86 4 0. 90 2 0.9 45 6 1 Enthalpy of the feed is 4790 kJ/kmol.