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.