Rapid Response Concentration-Controlled Desorption of Activated Carbon to Dampen Concentration Fluctuations

Abstract

Fluctuations in concentration of organic vapors in gas streams that are treated by devices such as biofilters or oxidizers make it challenging to remove the vapors from the gas streams in an efficient and economic manner. Combining adsorption with concentration-controlled desorption provides an active buffer between the source of vapors and the control device for better control of concentration and flow rate of the gas stream that is treated by the secondary control device, hence further enhancing the performance or reducing the size of the devices. Activated carbon fiber cloth is used with microwave swing adsorption to remove methyl ethyl ketone (MEK) from air streams and then provide a readily controllable feed stream of that vapor in air at a specified concentration and gas flow rate with steady-state tracking desorption. MEK was captured with >99.8% efficiency during the adsorption cycle. The MEK concentration during the regeneration cycle was readily controlled at concentration set-points between 170 and 5000 ppmv, within relative standard deviations of 1.8 and 4.9%, respectively, and at 20% of the gas flow rate that was treated during the adsorption cycle. Such capability of the system allows the secondary control device to be optimized for select constant concentrations and low gas flow rates that is not possible without such pretreatment.

Water adsorption with hysteresis effect onto microporous activated carbon fabrics

“…Resistance heating has been shown to be a more rapid and energy-efficient method of regenerating activated carbon than desorbing with steam or inert gas (Petkovska and Mitrovic 1994). Because of this, ACFCs have been studied recently in an effort to develop next-generation energy-efficient cyclic adsorption systems (Subrenat and Le Cloirec 2006;Vidal et al 2006;Hashisho et al 2007).…”

Adsorption of volatile organic compounds on peanut shell activated carbon

“…A variety of separation methods such as condensation, adsorption, catalytic oxidation, and biofiltration have been employed to remove a number of pollutants from the air stream . Adsorption processes constitute an important class of separation processes that are typically low in energy consumption .…”

Using Microwave Heating To Improve the Desorption Efficiency of High Molecular Weight VOC from Beaded Activated Carbon

“…Because phenol oligomerization necessitates the use of high regeneration temperatures, the authors consistently experienced pore blockage and corresponding decreases in adsorption capacity during subsequent use, attributed to phenol decomposition during regeneration. For gas-phase studies, nondestructive regeneration using microwave heating has been shown, but only for low molecular weight, low boiling point adsorbates (e.g., methane, ethane, ethylene, methyl ethyl ketone, water). − For many industrial applications, however, heavy compounds (e.g., n -dodecane, ethylbenzene, and 1,2,4-trimethylbenzene) are present in the gaseous VOC mixtures and often have high affinity for the adsorbent, requiring more intense regeneration conditions (i.e., higher temperature, longer times) for complete regeneration . It would be beneficial to evaluate whether microwave regeneration can be similarly efficient and nondestructive when desorbing high molecular weight, high boiling point contaminants.…”