A MODEL FOR PARTICLE COLLECTION IN A TURBULENT BED CONTACTOR - NEW PACKINGS

This work presents an investigation of novel packings for collecting p articles in a turbulent bed contactor. Perforated spheres, oblate sphe roids and the conventional plain spheres, all made of polypropylene ma terial, were tested for collecting particles in a 0.264 m diameter col umn. Alumina (aerodynamic diameter from 1.5 to 5.5 mu-m) and titanium dioxide (aerodynamic diameter = 0.7 mu-m) were used as test powders. T he results show a lower penetration of particles through the fluidized bed of perforated packings in comparison to plain conventional sphere s and oblate spheroids. This indicates that perforated packings are su itable as a contacting medium for particle collection in a turbulent b ed contactor. A semi-empirical model for predicting particle collectio n on the gas-liquid interfacial area formed by the packings is present ed in this work. The model describes particle penetration through the bed as an exponential function of the expanded bed height (H) and a gl obal coefficient of particle transfer (m), similar to the global molec ular mass transfer coefficient. The coefficient (m) was fitted as func tion of dimensionless numbers, which describe the hydrodynamics of pha ses contacting, bed structure and the mechanisms involved in particle collection on a TBC. A statistical analysis of the model predictions h as confirmed it to be satisfactory for all types of packings investiga ted.