(20c) Centrifugal Fields and Process Intensification – the Role of High Gravity Technologies in PI and Microprocessing

It is often quoted that a large part of process intensification is about the control of fluid mechanics and perhaps there is no area where this is more the case than in systems which exploit centrifugal fields. The criteria of reduction in residence time, control of mixing and shear, energy efficiency, operating and capital cost, temperature control are all strongly influenced by the fluid mechanics. With this in view, the paper will place the application of centrifugal field based technologies in their historical context with a brief overview. The application of centrifugal fields for the enhancement of separation and contacting processes in multiphase systems has a long history with developments including various designs of rotary contactors developed for enhanced liquid-liquid extraction such as the Podbielnak Centrifuge and the Wesfalia Decantor extractor. Other examples of the application of high gravity fields include the development of cyclone technology for gas cleaning and for solid liquid separations. These are well established and mature technologies with many well proven applications. In the last several years however the concept of process intensification has been strongly driven by a desire to achieve miniaturization in equipment design, which in turn is driven by the resetting of economic, safety, and environmental goals. Another factor is the closer integration of new green chemistry with equipment innovation to achieve viable manufacturing routes for conversion and separations based on new science.  The paper will summarize some case studies where high gravity and other centrifugal field based techniques have shown promise in this regard.  Secondly some key developments in equipment design with a particular focus on spinning disk technology and related techniques will be reviewed. Finally the importance of simulation techniques in aiding improvements in design and furthering the understanding of the fluid mechanics in rotating equipment will be discussed.