Comparative study of removal of volatile organic compounds by cryogenic condensation and adsorption by activated carbon fiber

This paper describes studies on two abatement techniques, namely: adsorption by activated carbon fiber (ACF) and condensation at cryogenic temperatures for controlling emissions of volatile organic compounds (VOCs). The breakthrough analysis was carried out on commercially ACF packed in a tubular reactor under dynamic adsorption conditions. The breakthrough time was found to significantly decrease with increase in VOC concentration from 5000 to 50,000 ppm. The regeneration of ACF was carried out by electrical (dc similar to50 V) heating. A temperature range of 120-150degreesC and regeneration time of 45-60 min were typically required for the complete regeneration of ACF pre-equilibrated with 8000 ppm of VOC. The VOC removal by condensation was carried out in a vertical tubular condenser using liquid nitrogen (LN) as a coolant medium. The studies showed that adsorption was effective if VOCs concentrations in the pollutants laden gas were in parts per million (ppm) levels, whereas the removal by cryogenic condensation was found to be effective at the relatively higher VOCs concentrations levels (>1%). The simulation results from the mathematical models developed to understand the separation process in each of two methods studied were found to be in good agreement with the experimental data. (C) 2004 Elsevier B.V. All rights reserved.