Hydrodynamics and mass transfer of a static mixer at high pressure conditions

The use of static mixers as alternative contacting devices for supercritical fluid separation processes has been proposed recently. Here, we present new data that addresses the hydrodynamic behavior and mass transfer kinetics of a Kenics-type static mixer under high pressure conditions. The gas pressure drop and the mass transfer coefficient for the fractionation of an oil mixture by supercritical carbon dioxide were measured for several operating conditions of pressure, temperature, feed composition and gas to liquid mass flowratio. Based on the experimental data, a correlation was developed for the pressure drop and the mass transfer coefficient as a function of dimensionless numbers. The extraction efficiency of the static mixer was compared with the extraction yield obtained with a countercurrent packed column, for the same system. The oil loading in carbon dioxide was the same for both contacting devices. Whereas the yield of extraction was higher for the packed column, the static mixer presented the higher extraction efficiency per transfer unit.