Chemical Engineering Science, Vol.55, No.8, 1399-1409, 2000
Adsorption dynamics in a stratified convergent tapered bed
Mass transfer characteristics of a novel fixed-bed adsorber configuration with a convergent tapered geometry and reverse layering of adsorbent particles is examined in this paper from both experimental and theoretical standpoint. In the tapered convergent bed, the adsorbent particle diameters and the fluid flow velocity decrease in the direction of flow. Laboratory column studies conducted for the adsorption of trichloroethylene on activated carbon in tapered convergent beds show that the solute front sharpens as it travels along the column depth, resulting in a longer time to breakthrough compared to a conventional stratified fixed-bed adsorber. The experimental results were verified using a modified version of the homogeneous solid diffusion model (HSDM). Model simulations indicate that the mass transfer zone length in this adsorber is sensitive to the angle of taper of the bed, particle size distribution, and influent concentration. With a modest taper angle of 1.5 degrees, this system is shown to provide increase in breakthrough times ranging from 46 to 75% over that for conventional fixed-bed adsorbers operating under same conditions. The improved bed utilization afforded by this arrangement can reduce adsorbent inventory and operating costs relative to a conventional stratified fixed-bed adsorber.
Keywords:GAC