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Bed behaviour in rotary cylinders with applications to rotary kilns Henein, Hani

Abstract

Two modes of transverse solids motion, slumping and rolling, in rotary kiln operation have been experimentally characterized and mathematically modelled in this study. Other modes of bed behaviour encountered in rotary cylinders; slipping, cascading, cataracting and centrifuging have been formulated mathematically. The models have been verified using experimental observations reported in the literature. An experimental study of those conditions under which the bed changed from slumping to rolling was undertaken and the characteristics of these modes of motion quantified using different types of solids in three horizontal rotary cylinders and a small pilot kiln. A Bed-Behaviour Diagram which is a plot of bed depth versus rotational speed was developed to delineate the various areas of dominance of slumping and rolling and it was shown using this Diagram that bed behaviour observations made on batch cylinders were representative of solids motion in a continuous kiln operation, the effects of bed depth, particle size, particle shape and cylinder diameter on the position of the slumping-rolling boundary were also experimentally investigated. The quantitative characterization of slumping and rolling indicated that a new interpretation of the change in bed motion from slumping to rolling was required.

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