Performance enhancement of CO2 capture from flue gas in a bubbling fluidized bed

Abstract

The rise in mean atmospheric temperature resulting from the emissions of greenhouse gases, especially CO2, has become a widespread concern in the recent years. This awareness of increase in greenhouse gas emissions has resulted in the development of new technologies which would lower emissions of CO2 from flue gases. The purpose of this study is to investigate the performance of bubbling fluidized bed for CO2 adsorption to mitigate CO2 from flue gas. Adsorption of CO2 had been carried out onto zeolite 4A, zeolite 5A, zeolite 13X and activated carbon at a pressure up to 4 bars. The effects of adsorbent mass on breakthrough time, gas velocity, adsorption isotherm, thermodynamics and heat transfer characteristics were also investigated during the continuous operation of the bubbling fluidized bed. As flow rate increased, the breakthrough curves become steeper and reached the breakthrough quickly due to the residence time of the adsorbate in the column, which was long enough for adsorption equilibrium to be reached at high flow rate. The experimental data were fitted with isotherm models like Langmuir and Freundlich isotherm model. It was found that the Langmuir model fit well with the zeolites based adsorbent and Freundlich model fit well with activated carbon. The experimental results permitted the determination of adsorption capacities of the adsorbents and showed that there is an improvement in the adsorption capacity using fluidized bed due to a better gas solid contact as compared to conventional fixed bed.