FLUIDIZATION OF FCC POWDERS IN THE BUBBLE-FREE REGIME - EFFECT OF TYPES OF GASES AND TEMPERATURE

A 0.152 m diameter stainless steel fluidization column was constructed which can operate at closely regulated temperatures up to 500 degrees C. A wide range of experiments was performed at different temperatures using specially-prepared size fractions of FCC powders in various gases: air, argon, neon, carbon dioxide and Freon-12. Measurements of the incipient fluidization and bubbling velocities, and the voidage at the bubbling point, are compared with existing correlations and new improved correlations have been developed. Published theoretical equations, which are based entirely on hydrodynamic considerations, predict that the voidage at minimum bubbling should increase as temperature increases, but our experimental results show virtually no change. Although these equations predict the voidage well for the coarser fractions at room temperature, they become increasingly inaccurate as particle size is decreased, and this is believed to be the result of ignoring the interparticle forces.