Distillation Design
Distillation Design
Distillation Design
Distillation
Column
Process Equipment
Design
Group VI
Himanshu Meena (12CH30015)
Kamble Manish Vijay (12CH30016)
K.S.S.Viswanat
(12CH30017)
Monish Kumar
(12CH30018)
Problem:
A process stream of solution of methanol, acetic acid having zF = 0.5 has to be concentrated by
Distillation. The distillate product stream has to contain methanol of xD = 0.95. The bottom
product stream contain methanol of xB = 0.05. The operating pressure for the operation is 94.13
kPa. Design the distillation column using data supplied.
T [K]
388.95
385.15
383.05
378.15
375.95
370.55
367.95
365.85
364.85
359.95
357.85
354.85
353.05
349.15
346.85
344.75
342.25
340.45
339.05
336.95
336.15
336.05
x1 [mol/mol]
0
0.037
0.058
0.107
0.137
0.208
0.25
0.28
0.306
0.387
0.427
0.492
0.517
0.601
0.657
0.713
0.785
0.839
0.882
0.959
0.995
1
y1 [mol/mol]
0
0.109
0.165
0.303
0.353
0.491
0.556
0.603
0.63
0.735
0.776
0.831
0.853
0.911
0.934
0.951
0.971
0.983
0.989
0.996
0.999
1
First, the equilibrium data was plotted and the 45 feed line was drawn. Then xD point was plotted on
the 45 line and the operating line for enriching section was drawn .From the intercept of this line on y
axis the min reflux ratio was determined on the y-axis. The intercept on y axis was (xD/Rm+1) and
minimum reflux ratio(Rm)= 0.55.
Reflux
ratio
0.5
0.55
0.6
n.o.stages(with
reboiler)
inf
9.8
8.9
Column Diameter
Total
height
0.6
0.6
1.0598
1.0768
16.2
15.3
15
14
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
1.1
1.2
1.3
1.5
8
7.7
7.4
7
6.9
6.8
6.7
6.6
6.3
6
5.9
5.7
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
12
12
11
10
10
10
10
10
9
9
9
8
1.0935
1.1099
1.1261
1.1421
1.1578
1.1734
1.1887
1.2039
1.2336
1.2626
1.291
1.346
13.5
13.5
12.6
11.7
11.7
11.7
11.7
11.7
10.8
10.8
10.8
9.9
But from the table, it is seen that as the reflux ratio is increased; The no of stages hence the tray
installation costs would come down. At the same time, the reboiler and condenser load were found to
be increasing. In order to achieve a balance between the two, we draw a graph between reflux ratio and
the total costs. A sample cost calculation for R=0.75 is shown below:
Sample Cost Calculation
F=10 000kg/h;
M.W of CH3OH=32(distillate);M.W. Of CH3COOH= 60
Mol.Wt of feed=0.5*32+0.5*60
=46
Feed=10000/46=217.39 kmol/h
F=D+B
Fzf=DXd+BXb
and xb=0.05;xd=0.95;zf=0.5
Shell
49000
48000
46000
44000
43000
41000
41700
42000
42500
42800
41000
42000
42500
40500
16875
16380
15320
15410
14753
13988
14123
14248
14300
14500
14850
15221
15592
15120
33408
31320
27144
27144
25056
22968
22968
22968
22968
22968
20880
20880
20880
18792
2622
2622
2622
2622
2622
2622
2622
2622
2622
2622
2622
2622
2622
2622
And a graph between Reflux ratio and total costs is plotted as shown:
steam
Total
cost
18951
19554
20257
20360
21363
21966
22569
23172
23775
24378
25585
26791
27997
30409
189625
188847
184951
184710
184370
182320
185960
189189
192546
195851
197923
204903
211383
218042
and xb=0.05;xd=0.95;zf=0.5
Weight of Head:
Diameter = O.D + (O.D/24) + (2*sf) + (2*icr/3)
Where O.D. = Outer diameter of the shell, inch
icr = inside cover radius, inch
sf = straight flange length, inch
From Table , sf =1.5
icr = 2.31
Also, O.D.= 940 mm = 36.22
II.
III.
Stress due to the weight of the liquid and tray in the column up to a height X
d, liq. = .weight of liquid and tray per unit height X / *Dm* (ts - c)
V.