Conference Dates

May 22-27, 2016


Spray dried fluidized bed catalysts belong to the Geldart Group A classification and vary between 22 m to 200 m in diameter (1). Binder is either distributed throughout the particle with the active phase or surrounds the active phase as in a core-shell structure (2, 3). We slurried WO3/TiO2 micronized powder (0.2 m to 2 m) with colloidal silica (LUDOX® HS-40) to form a slurry with a mass fraction of 5 % to 20 % solids. The solution entered the top of GB-22 Yamato fluidized bed spray dryer chamber (0.12 m ID) through a two-fluid nozzle and the drying air entered the bottom counter-currently. We varied the feed slurry concentration, binder concentration, slurry and drying air flow rates, two-phase nozzle pressure drop and inlet temperature.

Most conditions only produced a very fine powder (Group C, dpm) (Fig. 1a). (Ideally, the particle size should exceed 80 m for laboratory experimental equipment). The small particles were often fully spherical but we also produced large clusters that reached 150 m (Fig. 1b). The high pressure drop through the nozzle and low slurry concentration produced the fine powder. Particles agglomerated in the fluidized bed when we increased the slurry flow rate to the chamber such that the powder had not yet dried sufficiently.

Please click Additional Files below to see the full abstract.