Mass transfer and warming during adsorption of high concentrations of VOCson an activated carbon bed: Experimental and theoretical analysis

An experimental and theoretical study was carried out to predict the warmin g and the mass-transfer rate during adsorption of high concentrations of vo latile organic compounds (VOCs) in an activated carbon bed. A linear drivin g force (LDF) model is found to provide an acceptable Tit to the measured d ata. An empirical correlation of the mass transfer rate is proposed as a fu nction of the strength of adsorbent-adsorbate interactions and the gas velo city to design the adsorption process without using any adjustable paramete r. The model was validated for an adsorption unit with high loadings (up to 100 g.m(-3)) of seven kinds of VOC and within the velocity range 0.139-0.5 56 m.s(-1). The prediction of the temperature rise inside the adsorber is i mproved by the use of the differential heat of adsorption instead of the in tegral heat. A theoretical parameter sensitivity test indicates that the te mperature rise is strongly dependent on the molar VOC concentration, the ad sorption heat, and the volumetric heat capacity of the carrier gas. The war ming of the activated carbon bed can be well predicted from these variables . The relation obtained appears to be a practical means for designing the s afety of an adsorber and preventing carbon bed ignition.