DISPERSION AND TRANSPORT OF COHESIVE LACTOSE POWDER USING TRAVELING-WAVE FIELD TECHNIQUE

The main objective of this research was to study transport phenomena o f cohesive powders using the travelling wave field technique. In the l iterature only limited attention has been paid to the transport of coh esive powder materials using this technique, although it has been succ essfully used with non-cohesive powders. Cohesive powders are generall y much more difficult to transport due to short range molecular forces as well as electrostatic forces. Such forces usually cause agglomerat ion and adhesion of particles which may significantly impede the flow. In this study, an optimisation process is presented for selecting an appropriate electrode arrangement for levitation and transportation of a given powder. Computer modeling was used to establish how the shape and geometry of the electrodes influence the transport of a particle having a given size and charge-to-mass ratio. Based on the modelling r esults a flat-bed travelling wave panel with optimised strip electrode s arrangement was constructed and used in the experimental study. Cohe sive lactose powder (150 mesh, D-4,D-3 = 80 mu m) was successfully dis persed and transported using this panel arrangement. Particle trajecto ries were examined using a CCD camera with telemicroscopic lenses inte rfaced with a computer controlled image grabbing system. (C) 1998 Else vier Science S.A. All rights reserved.