Various processes in which reagents in consequence of interaction undergo deep conversions followed by changing of internal structure, substances composition and aggregate state are realized in chemistry and applied chemistry. Chemical-engineering processes use to contain the physical ones also, in particular liquids movement, their mixing, heating and cooling, dispersion, etc. It is worth saying that technology of various chemical products production as a rule comprises chemical and physical processes of the same type characterized by common regularities. But for all that processes of different productions are carried out in apparatus of analogous principles of operation. According to the classification of applying chemistry apparatus there are only two theoretical (limit) models of instruments: apparatus of ideal displacement and of ideal mixing. Real ever-functioning reactors are representing apparatus of intermediate type with some approximation to apparatus of mixing or displacement. It is because particles residence time in them distributes more uniformly than in ideal displacement apparatus but never becomes level as in ideal mixing apparatus.