Bundles and Regions of Sharp Reversible Distillation

Such a set of trajectories for which not more than one trajectory passes through each nonsingular point is convenient for understanding as a distillation trajectory bundle. This notion is different for various modes of distillation because the number of parameters influencing the location of the trajectories is different. 

It is clear from Fig. 4.1 that the location of a reversible distillation section trajectory is determined only by the location of its product point (i.e., it does not depend on any parameter). One component is absent at sharp reversible distillation [i.e., the product point of the section is located at some (n - 1) component edge, face, or hyperface of the concentration simplex]. That is why, in all the points of a section trajectory at sharp reversible distillation, liquid-vapor tie-lines should be directed to this edge, face, or hyperface or from it [i.e., one and the same component should 

Therefore, one or several trajectory bundles, filUng up that region inside the concentration simplex, where one and the same component is the heaviest (for the top section) or the Ughtest (for the bottom section), will correspond to all the product points located at one and the same (n — 1) component edge, face, or hyperface of concentration simplex. We call this region the region of reversible 

As one can see in Fig. 4.2, the trajectory of each section at sharp reversible distillation consists of two parts the part, located inside the (n -1) component boundary element C i of concentration simplex, lying between the product point Xd or xb and the tear-off point of the trajectory from this boundary element x[, and the part located inside concentration simplex C , lying between the tear-off point of the trajectory and the feed point xp. Only the second part should be located inside a region of reversible distillation Reg y orRegJ g, and product point Xd or xb can lie outside this region. 

Unlike trajectories of distillation at infinite reflux, which may come off the boundary elements of the concentration simplex in the saddle points S only, reversible distillation trajectories come off in ordinary points x[.  

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