Information Technology Reference
In-Depth Information
1
0.9
0.8
0.7
0.6
0.5
ratio of aniline to cyclohexan + benzene
0.4
0 a/(c+b)
0.5 a/(c+b)
1 a/(c+b)
2 a/(c+b)
4 a/(c+b)
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
x - liquid mole fraction cyclohexane
Figure 14.6
Effect
of
aniline
addition
on
relative
volatility
in
a
benzene - cyclohexane
system.
incorporated in a sensitivity study to develop the effect of solvent flow rate on prod-
uct compositions. This study is given at Examples/ExampleThreeS. The results of the
study are shown in Figure 14.7. An optimum occurs at a solvent flow rate of 300
lbmol/hr.
The design of the complete system to produce products that are at least 95% pure
products is given at Examples/ExampleThree2. It is important to note that the amount
of makeup solvent is difficult to determine in advance; therefore, a series of runs
ExampleThree1, ExampleThree2, and ExampleThree3 were executed to determine the
effect of solvent makeup on the composition of the products. These were transferred to
a spreadsheet, with the results shown in Figure 14.8. An approximate optimum appears
at a solvent makeup of 0.4 mol/hr per 100 mol of feed.
14.4 HETEROGENEOUS OPERATIONS
These types of separations usually involve a decanter in the process. A system such as
that shown in Figure 14.9, production of purified ethanol at a concentration higher than
the ethanol - water azeotrope composition, involves the inclusion of a third component,
some times called an
entrainer
, which when combined with the azeotrope forms two
liquid phases, one rich in ethanol and the other rich in water. The water-rich product
of the decanter is fed to the azeotropic column, Dist1, and the entrainer-rich product
to the alcohol-producing column, Dist2. The aqueous product issues from the bottom
of Dist1 and ethanol is the bottom product of Dist2.
