Diagrams of Extractive Reversible Distillation for Three-Component Mixtures

Diagrams of Extractive Reversible Distillation for Three-Component Mixtures 

Condition in Tear-Off Points of the Extractive Reversible Distillation Trajectories 

Let s examine a column of sharp reversible distillation with two feedings (Fig. 4.18a) for separation of a three-component mixture (Petlyuk Danilov, 1999). For an intermediate section of such a column, Eq. (4.6) is as follows (F2, upper feeding)  

For the intermediate section, point x plays the same role as the product point XDi for the top section (i.e., at reversible distillation in each cross-section of the intermediate section, the continuation of the liquid-vapor tie-line goes through point x j j). Let s call point the pseudoproduct point. It is seen from Eq. (4.22) that, in contrast to the product point, the pseudoproduct point can lie without the concentration triangle (i.e., the values x can be negative or greater than 1). 

Let s show in the beginning that, for example, for an ideal mixture, for which K2 3, in the intermediate section not the heaviest component as for the top section and not the hghtest component as for the bottom section, but the intermediate component m = 2 can be exhausted. 

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