Page 323 - Distillation theory

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8.4 Multicomponent Azeotropic Mixtures: Presynthesis 297

1

Figure 8.17. The edge 1-3 of the concentration pen-
t
x t
1−3−2
x tahedron is segment of possible bottom product
1−3−5
2,4,5 2 4 5
t (2) (2) (2) (2)
x Reg B = Reg B = Reg B = Reg B for the distillation
1−3−4
1,3 1,3 1,3 1,3
15 of five-component mixture and of all ternary con-
x B stituents of five-component mixture. Lines with ar-
rows, section trajectories on three-component faces
of the concentration pentahedron.
5
3
2
4
(2)
possible product segments Reg at the sides of two-dimensional faces of
bound,D,B
the concentration simplex (according to Fig. 8.8). For the example under consid-
eration, these segments are shown in Fig. 8.16.
For example, faces 1-2-3, 1-3-4, and 1-3-5 are adjacent two-dimensional faces
for edge 1-3 (Fig. 8.17). For each face, all points of edge 1-3 are possible bottom
2 4 5
product points Reg, Reg, and Reg. Therefore, they are also possible bottom prod-
1,3 1,3 1,3
uct points at distillation of five-component mixture under consideration ([1-3] ≡
2,4,5
Reg B ).
1,3
We now for example examine face 1-2-3 and its edges 1-2, 1-3, and 2-3 (Fig.
8.18). Components 4,5 are absent in this face. Therefore, it is necessary to examine
4 5
the segments of possible bottom product Reg B , Reg B at edge 1-2 at distillation of
1,2 1,2
three-component mixtures 1,2,4 and 1,2,5. The segment joining vertex 1 is common
4,5 4,5
segment of possible bottom product for these two mixtures − Reg B ∈ Reg bound,B .
1,2 1,2,3
Similarly, we have to examine the segments of possible bottom product
4 5
Reg B , Reg B at edge 1-3 at distillation of mixtures 1,3,4 and 1-3-5 (the whole edge
1,3 1,3
4,5 4,5 4 5
[1-3] ≡ Reg B ∈ Reg bound,B ) and segments Reg B , Reg B at edge 2-3 at distillation of
1,3 1,2,3 2,3 2,3
mixtures 2,3,4 and 2,3,5 (the segments are absent). Hence, it follows that the region
(3)
of possible bottom product Reg in face 1-2-3 looks like Fig. 8.18d shows it.
B
3,5
The contour of the region of possible top product Reg bound,B at face 1-2-4 (Fig.
8.19) is determined in a similar way. 1,2,4
For example, in conclusion, we discuss the determination of the region of pos-
3
sible top product Reg D in one of the three-dimensional hyperfaces – in hyperface
1,2,4,5
1-2-4-5, where component 3 is absent. For this purpose, it is necessary to determine