Comparison of Fixed and Fluidized Beds Adsorber with Economic, Engineering, and Environmental approach

Abstract

Release  Volatile  organic  compounds  (VOCs)  as  environmental  and  occupational  pollutant  cause  macro perspective affect such as climate change, humans and economic consequences. Although fixed bed absorber is widely used as a controlling method because of its economically and availability, but these absorbers are facing some issue like high pressure drop, non-uniform distribution of fluid, channeling and blocking. Fixed and fluidized beds adsorbent was compared from three economic, environmental and engineering perspectives using Multi Criteria Decision Making analysis (MCDA) technique. An annular fluidized bed adsorber was designed and charged with 50-100 µm (100-140 ASTM mesh) activated carbon (AC) particles. Effects of factors like flow rate, particle size, inlet concentration and adsorption capacity of VOCs was investigated under steady state. In the flow rate less than 0.25(Lit.min-1), inlet gas slowly passes through the void spaces of the bed’s particles. By increasing the inlet flow from 0.3(Lit/min-1), bubbles start to form in the bed and the bed pressure drop decrease. The pressure drop of 6 (g) of AC in minimum fluidization velocity was 20(KN.m-2). However, the pressure drop of 10 and 20(g) of AC were 150 and 420(KN.m-2) respectively. “maximin” technique used for comparison of two beds indicated that minimum score of pack bed absorber are 0.37 while the minimum score of fluidized bed adsorber are 0.5. It indicated when the adsorbent particles are smaller, fluidized bed adsorber are more suitable to use. In addition, using MCDA technique indicated that annular fluidized bed adsorber could considered as an alternative of fixed beds adsorber.