Fluidization behaviors of nanoparticle agglomerates with high initial bed heights.

The fluidization behaviors of SiO 2 nanoparticles with high initial bed heights of 8–24 cm are investigated experimentally. The effects of the initial bed height and the superficial gas velocity on the minimum fluidization velocity, bed heights, axial solid distributions and the agglomerate diameter are discussed. The results show that the minimum fluidization velocity decreases significantly with the increase of the initial bed height. Over 80% of nanoparticles are fluidized at the bottom dense region of the bed under all fluidization conditions. The high bed expansion arises from a significant increase of the upper dilute region of the bed. The mean diameter of agglomerates measured in the dilute region increases with the initial bed height and the superficial gas velocity. There exists a low-frequency mass transfer between the dense and dilute regions of the bed. [Display omitted] • The fluidization behaviors at high initial bed heights are investigated. • The minimum fluidization velocity decreases with increasing initial bed height. • The high bed expansion arises from a significant increase of the dilute region. • The mean agglomerate diameter increases with the initial bed height. [ABSTRACT FROM AUTHOR]