(149e) Bed Densities in Cold Flow and Commercial Fluidized Bed Units of FCC Catalyst Particles

Bed density is an important property used in fluidized bed design and operation. Bed density enables estimations of bed heights or solids inventories in fluidized bed units, calculation of standpipe aeration rates, and determination of available pressure driving heads in various components of circulating fluidized bed units. Tests were conducted to measure bed densities in cold flow fluidized bed units of FCC catalyst particles ranging in diameters from 3 in to 5 ft (0.76 to 1.52 m) at gas velocities of up to 3 ft/s (0.9 m/s). The data are compared to literature data obtained from hot commercial FCC fluidized bed units. It was found that fluidized bed densities in cold flow units are significantly higher than in hot units. The roles of temperature and pressure are used to explain this bed density difference.