Liquid-liquid centrifugal separation - New equipment for optical (photographic) evaluation at laboratory scale

Since liquid-liquid separation techniques are applied in chemical process industry, research and development received a strong level of attention. Thus, liquid-liquid separation behavior in gravity equipment - e.g., in settling tanks - especially sedimentation and coalescence are investigated in detail. However, for liquid-liquid separation in centrifugal equipment - e.g., tube centrifuges - only superficial knowledge and less detailed investigations are given in open literature. This work focuses on the development of a new laboratory equipment for optical (photographic) evaluation of the centrifugal liquid-liquid separation processes. A new stirred centrifugal batch settling cell (SCBSC) utilizing a rotor-rotor/stator concept, experimental setup and method as well as analytical procedures are presented and discussed. Furthermore, results of mixing and separation process within the SCBSC are shown. The centrifugal force field thereby affects the required differential rotation speed for the dispersion process. The evaluation of the separation process is presented and discussed considering sedimentation and coalescence curves exemplary for two liquid-liquid systems. In the course of this, a comparison between gravitational and centrifugal separation was successful. Finally, the separation behavior is described by a dimensionless dispersion number. (C) 2017 Institution of Chemical Engineers. Published by Elsevier By. All rights reserved.