Characteristics of fixed beds packed with anisotropic particles - Use of image analysis

Fixed beds of anisotropic particles are commonly involved in chemical engin eering processes: beds of cylindrical catalyst pellets or beds of wood shav ings in paper industry. The characterization of the spatial variations of t heir structural properties is of great importance for flow modelling purpos es. In this work, we intend to produce new data concerning a bed of long cy linder (h/ d = 5.29) and a bed of flat plates (e/a = 0.209). This study foc uses on the characterization of top and bottom effects, as well as wall eff ects. The experimental procedure is based on the study of sections of packe d beds consolidated with a resin. The captured images of successive transve rse and longitudinal sections of the beds are treated and analysed, thanks to an image analysis software. The local variation of the voidage is determ ined in both the transverse and the longitudinal directions of the beds. Fu rthermore, mean intercept lengths and mean numbers of particles are measure d and discussed. Concerning flat plates, an anisotropic ratio calculated fr om intercept measurements is compared to that previously obtained from pres sure drop measurements. The main results of this work concern the enlighten ing of wall effects and end effects importance for the two studied beds com pared to beds of spheres studied in the literature. (C) 2001 Elsevier Scien ce B.V. All rights reserved.