Page 165 - Distillation theory

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

5.4 Evolution of Section Trajectory Bundles for Three-Component Mixture 139

2
x
D

x a)
F
α 23 x max
B3
x best
B
A
x
B
SN
α 13

1 α 3
23
13
2

b)
α 23 x B

+
1 N
α 13

qS
1
+
N 2
qS 2
1 3
α 23 13
Figure 5.21. (a) The pitchfork region Reg pitch for the acetone(1)-benzene(2)-chloro-
form(3) mixture (shaded), the stripping section trajectories for given x B = x best ; (b)
B
the stripping section trajectories for given x B on the pitchfork region (x B ∈ Reg pitch ).
1 and 2, different values of V/L; qS 1 and qS 2 , quasistationary points; A, tear-off point
for x B = x max on side 2-3; SN, saddle-node point.
B,3
separation x max with the point of azeotrope 13 (line x max − 13), and the line of the
B,3 B,3
saddle-node points SN (line A− 13). Some point at the line of saddle-node points
corresponds to each point at the line of the best product. Reversible distillation
trajectory goes from product point to the point SN and then branches into three
branches – to vertex 1, to vertex 3, and to azeotrope 13. The section’s trajectory
best(3) (3) branch
can be put in brief as follows: x → SN s ≡ x .
B rev
Reg best
B