Description
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.