FORMATION OF EMULSIONS IN A SCREW LOOP REACTOR

The following article concerns emulsification reaction in a continuous screw loop reactor. The influence of hydrodynamics on the emulsificat ion process as well as the influence of some specific substances were examined. We produced oil/water model emulsions under different test c onditions and we determined the correlations between the mixing behavi or of the reactor and the characteristic features of the obtained emul sion. Special consideration was given to the droplet size and its dist ribution. Variable operating conditions of the reactor are the residen ce time and the rotational speed of the screw, both of which have a de cisive influence on the recycle factor and the number of passages thro ugh the rotor/stator system. In addition we determined the dependence of the obtained droplet size distribution on the viscosity of the cont inuous and dispersed phase, on the interfacial surface tension and on the phase proportions. The influence of the specific type of emulsifyi ng agent and its concentration has been examined as well. The positive effect of the mixing and of the recirculation on the emulsification i n the screw loop reactor was particularly evident with low emulsifier concentrations and with emulsifiers with slow adsorption kinetics. The established theories for emulsion formation (Kolmogoroff, Taylor) wer e used for a quantitative description of the experimental results. The screw loop reactor was compared to an agitated tank reactor and a too thed-ring dispersing machine (Ultra Turrax) based on the comminution e nergy which is produced per unit volume of emulsion. The agitated tank reactor produced only coarsely dispersed emulsions through the entire rotational speed range, whereas the screw loop reactor and the Ultra Turrax, particularly at high rotational speeds and, therefore, high po wer densities, showed a similar emulsification and produced much finer dispersed emulsions. the main mechanism for the production of the dis persed phase.