Spout geometry of fine particle conical spouted beds equipped with internal devices

Abstract

The size and geometry of the spout are crucial parameters for the design and scaling-up of spouted beds because they condition heat and mass transfer rates. It is well-established in the literature that spouted beds without draft tube show axisymmetric spout shape, but this does not occur with open-sided draft tubes. Particle velocity has been measured at several bed heights and angular coordinates, under different geometric parameters and operating conditions, to determine the location of the spout-annulus interface in beds provided with open-sided draft tubes. Narrow draft tube wall slits and low air velocities lead to spouts of small size and triangular shape. The greatest spout expansion (high air velocities and wide draft tube wall slits) leads to a Reuleaux triangle shape, in which the spout swallows the tube. The results allow a better understanding of fine particle hydrodynamics in conical spouted beds, which is essential information for their scaling-up.