Study of dead zone and spout diameter in shallow spouted beds of cylindrical geometry

The geometry of the dead zone (stagnant solid) and of the spout zone in shallow cylindrical spouted beds of flat base has been studied using an optical fibre probe in a pilot plant unit. The angle formed by the dead zone-moving zone interface surface with the base of the contactor increases as the stagnant bed height and the particle diameter increase. The angle decreases as the ratio of the air velocity to the minimum spouting velocity increases and the ratio of the contactor inlet diameter to the column diameter increase. The influence of the geometric factors of the contactor, of the particle diameter and of the air velocity on the spout geometry have been analysed. The spout presents a neck whose position and magnitude depend on the geometric factors of the contactor and of the operating conditions. A correlation has been proposed for calculation of the mean spout diameter.