Page 158 - Distillation theory

P1: JPJ/FFX P2: FCH/FFX QC: FCH/FFX T1: FCH
0521820928c05 CB644-Petlyuk-v1 June 11, 2004 20:15

132 Distillation Trajectories and Conditions of Mixture Separability

K
a) 4 i
3.5 K
1
3
2.5
2
1.5 K 3 α 13
1
K
0.5 2
0 0.2 0.4 0.6 0.8 1
x
3
x B3
b) max 0.3
x
B 3
0.25
0.2
x
B3
0.15
0.1
0.05
x t
3
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
x rev 1 t A x rev 2 t α 13

1
t
Figure 5.15. The determination of tear-off segment Reg and possible
s
2,3
1
bottomproductsegmentReg forbottompoint x B ontheside2-3ofthe
B
2,3
concentration triangle for the acetone(1)-benzene(2)-chloroform(3)
t
mixture: (a) functions K i (x 3 ) on the side 2-3, (b) the function x B3 (x rev )
on the side 2-3. x t1 and x t2 , concentration of component 3 at first and
rev
rev
second reversible trajectory tear-off points from the side 2-3 for given
bottom point x B3 ; A, tear-off point for end of possible bottom segment
1
Reg on the side 2-3 (x max ).
B
B3
2,3
It is expedient to discuss the influence of these peculiarities on the evolution
of distillation trajectories at the concrete example of azeotropic mixture, such as
acetone(1)-benzene(2)-chloroform(3). At side 2-3, there is reversible distillation
trajectory tear-off segment Reg t(2) of the bottom section from vertex 2 to α 13 -point
rev,s
(Fig. 4.18a). Possible bottom segment Reg rev,B , adjacent to vertex 2, corresponds
j
(2)
to this segment. Possible bottom segment Reg at adiabatic distillation of three-
B
i
component mixtures (Petlyuk, Vinogradova, & Serafimov 1984) coincides with
possible bottom segment at reversible distillation. To determine the end of this
segment, it is necessary to scan the values of phase equilibrium coefficient of