EFFECTIVENESS OF A FLUIDIZED BED IN REMOVING SUBMICRON PARTICULATE FROM AN AIR STREAM

Submicron particulate (mean size 0.52 micron) was filtered from air at substantially atmospheric temperature and pressure by passing air up through a bed of fluidized glass shot in a 2-inch column. Removal efficiency (percentage removal of particulate from the air stream) was essentially constant during the life of the bed and independent of the entering concentration over the range of 0.03 to 8.3 mg. per cu. meter. Varying superficial gas velocity from 8.75 to 25 feet per minute and bed heights from 5 to 12 inches, resulted in filtration efficiencies ranging from about 50 to 90%. Removal efficiency of the fluidized bed improved with increased bed height and decreasing superficial gas flow velocities. Analysis of filtration mechanisms indicated that inertial impaction forces may be considered negligible and that the predominant effects are Brownian diffusion, direct interception, and induced electrostatic attraction. An equation describes effective filtration efficiency as a function of mean sizes of challenging aerosol and bed material, air viscosity and density, bed height-to-diameter ratio, and superficial gas velocity. © 1969, American Chemical Society. All rights reserved.