SCALE-UP ASPECTS OF THE MECHANICALLY SPOUTED BED DRYER WITH INERT PARTICLES

In the dryer developed at MA MUKKI the inert particle circulation is p rovided with an open screw conveyor installed along the vertical axis of the bed. The conveying rate of the screw has an effect on the circu lation (residence) time of the particles. A steady state drying proces s can be achieved only with equilibrium among the partial processes, w hich are: dispersion of the wet material over the surface of the inert particles,drying of the coating and abrasion of the dried coating. Th e scale-up correlations and experiences applied to the convencional sp outed bed dryers can not really be extended to the mechanically spoute d bed dryer. Laboratory and pilot scale hydrodynamic and drying experi ments have been performed. It has been found that for geometrical and hydrodynamic similarity the following parameters and identities had to be taken into consideration: d(SC)/D-SC; H/D-C; u''; Re-p; v(a); tau( p).