FLUIDIZATION OF SINGLE AND BINARY SIZE PARTICLES

Over the past 8 years a hydrodynamic model for gas-solid fluidization has been developed for fluidized beds of single size and multi-size particles at the Illinois Institute of Technology (IIT). In this thesis the experimental validation of the hydrodynamic model has been performed by comparing experimental and theoretical time-averaged porosities, bubble sizes, porosity and pressure fluctuations.; Bubble sizes were determined photographically in a two-dimensional plastic fluidized bed with a jet using a high speed movie camera. The measured bubble sizes validated well those predicted by the hydrodynamic model. They increase with the height of the bed and with the jet velocity and decrease with increase in the particle size. The model produces bubble splitting which agrees with observations.; The effect of pressure on fluidized beds with a jet was also examined. The results of the measurements of time-averaged porosities in a steel bed at elevated pressures were compared with the hydrodynamic model predictions. The computed lengths of jet were close to those reported by Knowlton and Hirsan (1980) in their high pressure fluidized bed. The fluidization becomes smoother at higher pressures in agreement with the claims of Knowlton and Hirsan.; Pressure and porosity fluctuations were measured with the aid of a sensitive pressure transducer and with a (gamma)-ray densitometer, respectively, in cylindrical beds and in a two-dimensional fluidized bed with a jet. The results were analysed using a spectrum analyzer. The variations of frequencies and amplitudes of pressure and porosity oscillations have been obtained as functions of static bed height, particle size, location in a bed and gas velocity.; A new experimental technique has been developed to measure time-averaged volume fractions of particles and of the gas in fluidized beds involving particles of two sizes (glass beads and leaded glass beads) using two radiation densitometers (X-ray and (gamma)-ray). In such binary fluidized beds the coarse and fine particles were found to segregate. The boundary line of segregation was found as a function of jet velocity and grid flow rate. The novel experimental technique was applied to desulfurization of a coal-pyrite mixture in a fluidized bed with a jet.