Evaluation of thermal effects on carbon dioxide breakthrough curve for biogas upgrading using pressure swing adsorption

Abstract

Selective carbon dioxide capture using pressure swing adsorption can transform raw biogas into high energy content biomethane and subsequently sequestration of CO2. In this work, the PSA technology for biogas upgrading is modelled and evaluated using one-dimensional binary mixture adsorption, heat and mass transfer model using Aspen Adsorption™ version 10. This model is validated using experimental data reported previously on zeolite NaUSY, since the CO2 breakthrough curve depicts reasonable agreement. This work considers two heat transfer conditions (gas and gas/solid conductions) to compare their effects on CO2 breakthrough and temperature responses at different positions along the adsorption bed. Three different biogas mixtures are charged over zeolite NaUSY bed to evaluate CO2 concentration on breakthrough curve and bed temperature profile. The influence of axial mass dispersion coefficient on breakthrough characteristics and temperature distribution along adsorption bed is examined. In addition, the effects of cooling outside column wall on CO2 breakthrough curve and bed temperature distribution is also explored. The findings indicate that the heat generated during adsorption possesses influences the adsorption performance rather significantly. Reducing this heat restrains the thermal effects on the breakthrough curves, thereby improving the methane purity and recovery.