Page 202 - Distillation theory

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176 Distillation Trajectories in Infinite Complex Columns and Complexes

Figure 6.3. Reversible distillation trajectories of ideal ternary mixtures
(K 1 > K 2 > K 3 ) for intermediate section of two-feed column: (a) x < 0;
D,1
(b) x < 0. Solid lines with arrows, tie-lines liquid–vapor; x and x ,
D,3 D,1 D,3
concentrations of components 1 and 3, respectively, in pseudoproduct
point.
Reversible distillation trajectories at Fig. 6.3 should connect vertexes 1 and 2
or 2 and 3, and at Fig. 6.4, they should connect vertexes 2 and 4 or 1 and 3.
In this section, we examine only the nonsharp distillation in an intermediate
section, when all flows of the feed contain all the components (in the sections
to follow, we examine sharp extractive distillation in intermediate section, when
entrainer and main feed have different sets of components).
At nonsharp distillation in the intermediate section, as in top and bottom sec-
tions, there is only one reversible distillation trajectory, but in the intermediate
section it has two node points N rev in vertexes of concentration simplex, and in
the top and bottom sections it has one node point in one vertex.