Experimental approaches for understanding mixing performance of a minireactor

Three experimental approaches are presented to determine the mixing characteristics of a new kind of high-efficiency membrane dispersion minireactor in which microfiltration membranes are applied as the dispersion media. Residence time distribution (RTD) curves were measured for determining the macromixing characteristics. A typical Dushman reaction (iodide-iodate) coupled with a neutralization and precipitation reaction of BaSO4 were introduced to characterize the micromixing performance of a single-phase mixing process. A dye extraction method was also applied to study the micromixing performance of a two-liquid phase-mixing system. The RTD result showed that the flow performance in the minireactor was almost in the plug flow condition. The micromixing performance was expressed with a segregation index, which could be < 0.002. The single-phase micromixing performance reached the desired level. The result of precipitation of BaSO4 showed that the mixing performance had a substantial influence on the particle size and size distribution. It was found that in the single-phase mixing process the mixing performance was mainly influenced by the phase flux and the membrane pore size. With decreasing dispersed fluid flux or the membrane pore size, or with increasing continuous fluid flux, the micromixing performance was enhanced. The dye extraction method can correctly determine the mixing performance of a two-liquid phase-mixing system. Unlike the single-phase mixing process, in the two-liquid phase-mixing process there was a minimum value for the mixing efficiency with the change of the continuous or dispersed-phase flux, when the membrane pore size was > 0.9 mu m. (c) 2005 American Institute of Chemical Engineers.