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In-Depth Information
TABLE 14.2 Methanol (1)-Water (2) Vapor-Liquid Equilibrium
Temperature (
◦
C)
Pressure (mmHg)
Vapor Mole Fraction,
y
Liquid Mole Fraction,
x
96.4
760
0.02
0.134
93.5
760
0.04
0.23
91.2
760
0.06
0.304
89.3
760
0.08
0.365
87.7
760
0.1
0.418
84.4
760
0.15
0.517
81.7
760
0.2
0.579
78
760
0.3
0.665
75.3
760
0.4
0.729
73.1
760
0.5
0.779
71.2
760
0.6
0.825
69.3
760
0.7
0.87
67.5
760
0.8
0.915
66
760
0.9
0.958
65
760
0.95
0.975
Workshop 14.2f
Make preliminary runs of the column to aid in locating the feed
and sidestream. Experiment with product and sidestream flows to develop appropriate
distillation column specifications.
Workshop 14.2g
Link the column and the decanter and develop a solution with
loose specifications.
Workshop 14.2h
Refine the specification to develop a final conceptual design.
Workshop Notes
Workshop 14.2a
Aspen Plus provides a unique form of binary parameter equation
for almost all activity coefficient equations, which is given in
b
ij
T
+
e
ij
T
2
ln
A
ij
=
a
ij
+
c
ij
ln
T
+
d
ij
T
+
(14.1)
When regressing data, one usually selects
a
i,j
or
b
i,j
or both. The other parameters
are rarely used. For a case where only one data point is available
b
i,j
may be used,
but extrapolation to other temperatures may cause difficulties.
Workshop 14.2b
A plot of vapor - liquid equilibrium for mesityl oxide - water based
on Unifac estimates is shown in Figure 14.11.
Workshop 14.2e
After performing the property analysis, a triangular plot is avail-
able from Aspen Plus's Plot Wizard (see Figure 14.12). Note that a methanol - water
distillation, without mesity oxide, would take place along the left side of the triangle;
however, the presence of a small quantity of mesity oxide places the composition to
