Long-term fluidization of titania nanoparticle agglomerates

Abstract

Fluidizing nanopowders in industrial processes for chemical reactions or physical processes typically takes multiple hours. Therefore, we investigated in this study the long-term fluidization behavior of titania nanopowders at time scales of several hours. We analyzed bed properties as well as agglomerate properties in the splash zone of the fluidized bed using a settling tube. The bed expansion as well as the agglomerate size decrease over time while the fractal dimension of the agglomerates stay nearly constant. It seems that at low gas velocities, stratification of the agglomerates in the fluidized bed occurs. Furthermore, our results suggest that at all investigated gas velocities small entities break from the outer part of the agglomerates during fluidization.