Enhanced performance on simultaneous removal of NOx-SO2-CO2 using a high-gravity rotating packed bed and alkaline wastes towards green process intensification

Abstract

In order to intensify the gas-liquid absorption processes in the field of energy and environment, high-gravity rotating packed bed (HiGee RPB) has been successfully applied in the multiple air pollutants abatement and CO2 capture by mineralization. Since the mass transfer and chemical reaction through gas-liquid absorption were found to be the key factors affecting acid gas removal, a mass transfer model based on the two-film theory for simultaneous removal of NOx-SO2-CO2 in an RPB was developed in this study. The mass transfer parameters including overall gas-phase mass transfer coefficient (KGa), height of a transfer unit (HTU), liquid mass transfer rate (kL) and enhancement factor (E) were theoretically determined from the experimental data. The effect of key dimensionless operating factors such as high gravity factor (β), gas-to-liquid ratio (GLR), and liquid-to-solid ratio (LSR) on mass transfer parameters were evaluated. Based on the results obtained in this study, the enhancement of high gravity filed on mass transfer and removal efficiencies of NOx and CO2 were significantly higher than that of SO2. It was inferred that the carbonation reaction could compensate the removal efficiency of acid gaseous pollutants at the lower mass transfer rate. The relationship between mass transfer rate and energy consumption for the multiple air pollutant control via a HiGee process was established. The favorable operating factors for NOx-SO2-CO2 simultaneous removal in an RPB were suggested as β of 233.8, GLR of 69.5 and LSR of 40.