AbstractsEngineering

The past two decades have seen the advent of a number of new chemical engineering techniques for the processing of finely-divided solids or liquids. These are in effect contacting techniques, since the solid particles or liquid droplets are invariably dispersed in a continuous gas or vapor phase. Because of the very large surface areas available for heat and mass transfer, which is usually accompanied by reduced internal diffusional resistance, they provide faster rates of treatment - whether evaporation, drying or chemical reaction - than more conventional methods, while generally permitting better control over the operating conditions. They differ from one another in their flow patterns and modes of heat transfer.