Page 203 - Distillation theory

P1: FCH/FFX P2: FCH/FFX QC: FCH/FFX T1: FCH
0521820928c06 CB644-Petlyuk-v1 June 11, 2004 20:17

6.3 Distillation Trajectories and Minimum Reflux Mode 177

Figure 6.4. Reversible distillation trajectories of ideal four-
component mixtures (K 1 > K 2 > K 3 > K 4 ) for intermediate
section of two-feed column: (a) x < 0; (b) x < 0. Solid
D,1 D,4
lines with arrows, tie lines liquid−vapor.

6.3.2. The Structure of Trajectory Bundles of Intermediate Sections
We examine the structure of trajectory bundles of intermediate sections (i.e.,
location and character of the stationary points of these bundles).
In Chapter 5, we saw that the distillation process in a column section is feasible
only if there are reversible distillation trajectories inside concentration simplex
and/or at several of its boundary elements, because only in this case a section
trajectory bundle with stationary points lying at these trajectories of reversible
distillation arises in concentration simplex. This condition of feasibility of the
process in the section has general nature and refers not only to the top and the

bottom, but also to intermediate sections. Therefore, pseudoproduct points x can
D
be located only the way it is shown in Figs. 6.3 and 6.4, (it is result of direction of