Development of Optical Techniques for Multiphase Flows Characterization

Optical methods for investigating multiphase flows are reviewed and discussed in the scope of the development of apparatus convenient for nuclear fuel reprocessing. Indeed, the various processes implemented (e.g. leaching, solvent extraction, filtration, crystallization, etc.) involve either liquid/gas, liquid/liquid and/or liquid/solid flows. Besides the adaptation of classical techniques, such as PIV and image processing, that have been used to quantify velocity fields and particles size distribution in flat-tank reactors, a typical design used in the nuclear industry to mitigate criticality issues, more innovating techniques are currently developed. The latter open the way to the measurement of less usual, although equally important measurements, such as the droplet composition in a liquid-liquid extraction column, and mass transfer rate in multiphase flows.