Separability in Extractive Distillation Columns

Conditions of Separability in Extractive Distillation Columns and Minimum Reflux Mode 

Let s examine the conditions of sharp separation in each of the three sections 

Conditions 1 3 are necessary for the fact that at big enough values of param- 

For the mixture acetone(l)-water(2)-methanol(3) (the entrainer is water, see Fig. 6.8) these four conditions are valid (1) at side 1-2 there is intermediate section 

We now examine the conditions of joining of sections trajectories at a set flow rate of entrainer (i.e., at set value of the parameter E/D) for a three-component mixture in the mode of minimum reflux. Each of two feeds can be the control one, and the intermediate section trajectory in the mode of minimum reflux in both cases should pass through the saddle point Sm because this trajectory passes through the node point not only in the mode of minimum reflux, but also at reflux bigger than minimum (point arises at the boundary element of the concentration simplex because the extractive distillation under consideration is sharp). 

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