Analysis of gas dehydration in TSA system with multi-layered bed of solid adsorbents

The paper presents theoretical analysis of adsorptive drying of gaseous mixtures, containing water vapor and volatile organic compound (VOC), in a cyclic thermal swing adsorption (TSA) system. The system consists of two fixed bed adsorption columns each containing three layers of different adsorbents. The first two layers consist of silica gel and zeolite 13X, as adsorbents of water vapor. The third layer consists of activated carbon, as an adsorbent of the organic component (benzene). A non-equilibrium, non-isothermal, and non-adiabatic mathematical model is developed in order to simulate the performance of a TSA gas drying unit employing the layered bed. The results of the computer simulation show that the layered bed, containing silica gel and zeolite 13X, reveals a longer water vapor breakthrough time compared with those for single bed with silica gel and zeolite 13X, and that desorption behavior of the layered bed is significantly enhanced compared with single bed. The quantity of adsorbed benzene on silica gel and zeolite 13X is considerably smaller than that on activated carbon. The validation of the modeling results showed fairly good agreement between experimental and theoretical data for both the zeolite 13X and layered bed containing silica gel and zeolite 13X.