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Longitudinal mixing in the continuous phase of a vibrating‐plate extractor was examined. Particular attention was focused on the effect of the flow of the dispersed phase, which turned out to be of major importance. Three regimes displaying distinctly different character of longitudinal mixing may be observed. The flow within a stage was studied in detail and it was shown that the stage could split into two regions of different character of the flow. A model was proposed which makes up the total effect of longitudinal mixing from the back flow through the plate plus axial dispersion within the stage. Correlations have been proposed relating the axial dispersion coefficient to the hold‐up and droplet diameter.

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A diffusion model is presented for the course of homogenation. Experimental results show that the relations obtained are suitable for describing the process. Formulas are presented for calculating the homogenation time in the turbulent region for three main types of mixers.Some papers on the homogenation of miscible liquids 1 ,2 show that while for low values of the Reynolds number the product ne depends on Re, a regime is established under intensive mixing which is characterized by the relation ne = const (1) where the value of the constant is dependent only 011 the geometrical arrangement of the system. The region in which ne = f(Re) will be called the viscous, while the region where Eq. (1) applies will be denoted as the turbulent regime. In this paper we shall follow the course of homogenation, the effect of mixer type and of the ratio of the mixer and vessel diameters on the homogenation period in the turbulent region. TheoreticalLet us consider the following process : We add suddenly a small portion of liquid of concentration Xo to a steady turbulent flow of liquid of initial concentration xp in a closed system and allow homogenation of the system to occur. This is a case of unsteady state diffusion in a medium with steady turbulence. In similar cases Fick's law 3 is frequently successfully employed. The turbulent diffusivity4(2) is substituted into it. From experimental results on the study of the structure of turbulent flow after passage through a grid 5 , it is known that for large vortices we have approximately 1", L, u '" UThe characteristic length and velocity of the vortices does not depend on the viscosity