Mixtures with Limited and Unlimited Separability

Under unlimited separability, we understand possible separation from the mixture of any component or a component group (fractions) with any purity (i.e., with the preset negligibly small amounts of other impurity components). 

There are two classes of mixtures that are not characterized by unlimited separability the azeotropic mixtures and the thermolabile ones. 

In Section 2.8, we discuss several methods of azeotropic mixtures separation. Thus, the azeotropic mixtures are characterized by a limited separability, while processed in an individual distillation column, and complete separability of these mixtures will be achievable in the case of selection of special schemes consisting of several columns with recycles. 

During the separation of thermolabile mixtures, for example, the petroleum, that is, mixtures to be separated at a high temperature at which detrimental chemical reactions take place, the problem is the maximum possible extraction of light components from these mixtures without the excess of specific temperature level. Vacuum separation in the presence of steam is used to decrease the temperature. 

Moreover, the application of specific separation schemes and stripping columns, in particular, is of primary importance. 

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