Adsorption and diffusion of moisture and wet flue gas on silica gel

Abstract

Moisture equilibrium and kinetics on silica gel, a potential adsorbent for drying wet flue gas, are measured using static volumetric and dynamic column breakthrough (DCB) methods. Isotherm models are identified that adequately describe the adsorption branch and hysteresis of the desorption branch. The transport mechanism and transport coefficient of moisture in silica gel pores are also presented. DCB experiments in the silica gel bed pre-equilibrated with wet helium are used to quantify N2 and CO2 adsorption reduction in the presence of moisture. Combining present results with those reported recently for equilibrium and transport models for N2 and CO2 (Goyal et al., 2019), a ternary simulation model is finally proposed in this study that sufficiently predicts complete adsorption and desorption breakthrough of wet flue gas (N2, CO2 and H2O mixture) in an initially clean silica gel bed. Two mixture equilibrium calculation methods are compared while retaining the independently established transport mechanism.