VOC Adsorption in Circulating Gas Fluidized Bed

Abstract

International audienceThe purpose of the work is to show that CFB adsorption process is technically feasible to obtain an interesting pollution abatement, and to set the bases of a process design. Experimental results are presented, obtained with toluene being adsorbed from an air stream on polymeric adsorbent in a batch operation circulating fluidized bed. This results in a breakthrough behavior at the top of the riser, analogous to a fixed-bed experiment. The existence of breakthrough curves that are astonishingly sharp in spite of the strong mixing of the solid phase implies that efficient toluene abatement can be achieved. The breakthrough curves can be used to predict the behavior of the process in a continuous mode where the adsorbent would be partially regenerated, and which would lead to an less than total toluene abatement. The shape of the breakthrough curves clearly depends on the operating parameters, in particular the gas flow rate and the solids circulation rate. The EMMS model was adapted and implemented to describe the flow pattern of gas and solid. The model predicts the relative volume fractions of these phases, the volume fractions inside each, the superficial velocities of gas and solid in each phase, and the average cluster size. From this description, an estimation of the apparent gas/solid mass transfer coefficients may be done, and their dependence on operating conditions investigated

Effect of Beaded Activated Carbon Fluidization on Adsorption of Volatile Organic Compounds

“…These results are consistent with the literature. Previous literature also found sharper breakthrough curves using fluidized bed configurations when adsorbing methanol and isobutane on ZSM-5 (zeolite) and toluene on a polymeric adsorbent, respectively. , A similar trend was obtained for multicomponent tests (Figure -c and Figure -d). For multicomponent tests, the average first cycle TPR for triplicate experiments was 0.73 ± 0.03 and 0.79 ± 0.01 for fixed and fluidized bed configurations, respectively, based on breakthrough curves determined with the FID.…”

“…The choice of an adsorber configuration depends on several factors such as the adsorbent attrition resistance, cost, flow rate, and system complexity. The engineering advantages of fluidized bed adsorbers are well-established and include lower pressure drops, sharper breakthrough curves, and less formation of localized hotspots compared to fixed bed adsorption systems. − Fluidized beds are especially applicable for treating large flow rates, consuming less energy, and improving mass and heat transfer. ,− However, there is a knowledge gap about the impact of a fluidized adsorbent bed on heel buildup of organic contaminants. For fixed bed adsorbers, competitive adsorption has been described as a contributor to heel development due to nonuniform distribution of heavy adsorbates .…”

Photocatalytic removal of xylene as a pollutant in the air using ZnO-activated carbon, TiO2 -activated carbon, and TiO2 /ZnOactivated carbon nanocomposites

“…Due to the effect of VOCs on humans and the environment, developing strategies for reducing organic vapors is a very important issue (10). One of the most important and common methods used to control VOCs is photocatalytic degradation (11,12). In the photocatalytic degradation of VOCs, semiconductors such as zinc oxide are used for carrying the photon of oxidation process in order to convert VOCs to water and carbon dioxide (13)(14)(15).…”

Inside Cover Picture: Rapid Trifluoromethylation and Perfluoroalkylation of Five‐Membered Heterocycles by Photoredox Catalysis in Continuous Flow (ChemSusChem 6/2014)

“…Kohlenstoffhaltige Adsorbenzien aus Polymeren zeichnen sich durch ihre sehr hohe Materialstabilität und Hydrophobie aus. Aufgrund dessen werden polymerbasierte sphärische Aktivkohlen u. a. auch in Adsorberfließbetten eingesetzt 24. Diese bestehen hauptsächlich aus hyperverzweigten Copolymeren 21, 22 und werden vorwiegend zu Granulaten verarbeitet.…”