This paper is a continuation of research concerning gas-solid flow modelling using the Euler-Lagrange approach in a spout-fluid bed apparatus. The major challenge in this case was to determine the friction coefficient for particles hitting against the walls of the apparatus. On the basis of the properties of similar materials the value of this quantity was estimated at 0.2. Therefore, it proved useful to check the model’s sensitivity to the value of this parameter. The study investigated the effect of friction coefficient on calculated values of particles velocity in the draft tube and the annular zone of the device for various volumes of the circulating bed. In the course of calculations, a relatively small influence of friction coefficient on particles velocity was observed in the tested zones of the apparatus. The changes were most visible for large volumes of the bed, which was connected with an increase in the number of collisions of particles with the walls.
The purpose of this paper was presentation of the value of cores electrification during their flow in the modified Wurster apparatus, applied for dry encapsulation of pharmaceutical materials. Previous works of the authors dealt with vulnerability of the particles of different diameter, produced by SYNTAPHARM (Cellets 1000, 700 and 100) on electrification in laboratory conditions. The presented work gives the results of examination on particles electrification in real conditions of their stable circulation in a column. The measurement system, that was applied, allowed determination of electrification potential and electrification current. Those quantities, which are the measures of charge accumulation on cores were determined for several particles (Cellets 1000, 700 and 500) with the different humidity, for different mass of the bed and spouting gas velocities.
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