Study On Particles' Coating In Forced Rotating Fluidized Bed With Spraying

Particles' growth kinetics in the spraying rotating fluidized bed is analyzed and investigated on the basis of mass transfer and heat transfer in this paper. According to the theory of drying of liquid drop, Mathematical model of the total variation velocity of liquid film and increasing of coating thickness is gained by heat accounting. A liner model of mass increasing is created by mass accounting. Moreover, the models are modified. The theoretical values are consistent with the experimental values after modified, and the errors are less than 20%.Influencing factors, e.g. air flow, air temperature, coating solution feed rate, tangential air, on granulation are studied detailedly. The results prove that these factors have many-sided influence on particle's coating. Increasing rate of relative coated mass can be regarded as a criterion of the mode of particles' growth. If the increasing rate is greater than normal value the particles agglomerate; On the contrary, if it is less than the normal the coating liquid drops are dried ahead. Through the simulating of flow field and the comparisons among the curves of growth of relative coated mass the analyze is done that tangential air influence the flow field in the chamber, coated mass and the modes of particle' growth. Tangential air makes the particles rotating and intensifies particles' turbulent motion, so the liquid drops are easier to collide with particles and wet them. The experiments show that the tangential air changes the critical point between glomeration and layer growth, and expand the operating area of layer growth.