For the separation of gas and liquid mixtures in absorption, desorption and rectification columns highly effective regular and dumped packings have been developed in the last few years. They have new geometries in comparison to the conventional designs which lead to better fluid flow and mass transfer characteristics. Most equations found in the literature cannot be applied to the design of separation columns with modern packings because they are empirical or semiempirical. New equations were developed and presented subsequently. Besides the static tower internals also fluidized packings can be used to realise the mentioned separation processes. They are especially favoured when the systems tends to block the packing or the gaseous or liquid phase contains solid particles. The operation characteristics of a fluidized packing was investigated. Thin-film evaporators with rotating film distributors has been successfully used for separation in the various processes of the chemical, pharmaceutical, and food industries. Despite the almost unlimited scope that this type of evaporator offers, its performance has not been a subject of active study as compared with other types of evaporators. Therefore, theoretic relationships and results of experimental studies are presented that describe separation by partial distillation from a thin layer. For thin-film evaporators without rotating film distributors, the theory of partial equilibrium distillation must be applied. It can be shown that in technically relevant loading ranges the liquid phase mass transfer resistance must be considered in the preliminary estimate of the separation performance. The deviations from the theoretical limits will be determined by measurements in a cocurrent flow evaporator and expressed in formulae by means of suitable parameters.