A settling tube to determine the terminal velocity and size distribution of fluidized nanoparticle agglomerates

Abstract

There are few techniques to measure in situ the size distribution and density of fluidized nanoparticle agglomerates. Visualization techniques, which are the most applied approach, currently have two important limitations: (1) they do not allow a continuous determination of the terminal velocity of the agglomerates, because it is necessary to stop the fluidization and (2) often, the agglomerates are tracked in very dilute zones of the bed, typically in the splash zone, where agglomerates are likely not representatives for the agglomerates in the whole bed. In this communication, we propose a sampling technique that allows to determine the size distribution and terminal velocity of fluidized agglomerates larger than ∼20 μm continuously, in situ, and allows to work with concentrations of agglomerates higher than other reported techniques.