Environmental Engineering Reference
In-Depth Information
=
.
x N
0
05
y N + 1 =
0 [note that the solvent stream doesn't always have to be pure solvent].
Equilibrium line:
From the given K d , the equilibrium relationship is y
1.6 x . The equilibrium line was
plotted (Figure 5.25) as Y vs X , using the relationship between weight fractions ( x , y )
and weight ratios ( X , Y )given in Equation (5.17).
=
Operating line:
Since points on the operating line are passing streams, we can plot the operating line
using the given information about the passing streams above Stage 1 and below Stage N .
These points are ( X D ,
Y N + 1 ); remember to convert to ratios.
Stepping off stages (see Figure 5.25):
(a) Two equilibrium stages are required.
(b) The ratio of water to 1-butanol is:
Y 1
Y 1 ) and ( X N ,
Y N + 1
X 0
0
.
106
0
X N =
005 =
0
.
85;
0
.
13
0
.
this is the slope of the operating line: F D /
F S .
0.45
Equilibrium line
0.4
0.35
0.3
0.25
0.2
0.15
1
Y 1
0.1
Operating line
2
0.05
3
4
0
0
0 .0 5
0 .1
0. 15
0.2
0 .2 5
X D
Y N +1
X N
X (kg acetic acid kg water)
Figure 5.25 Countercurrent immiscible extraction, Example 5.5.
 
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