Intensification of CO₂ Capture by Monoethanolamine Solution in a Rotating Packed Bed Reactor Equipped with High Frequency Ultrasonic Transducers

In this study, a carbon dioxide (CO2) absorption process in a typical rotating packed bed (RPB) reactor equipped with blade packing and under a high frequency ultrasonic field has been studied. The utilized ultrasonic transducers were ultrasonic atomizer humidifiers with a frequency of 1.7 MHz. This reactor takes advantage of both controllable high gravitational force and induced effects of high frequency ultrasound, simultaneously, in a small volume. The overall volumetric gas side mass transfer coefficient (KGa) with and without ultrasound was investigated. The effects of different parameters such as rotational speed (400-1600 rpm), liquid flow rate (20- 120 L/h), monoethanolamine (MEA) concentration (1- 4 mol/L), gas flow rate (2500- 4000 L/h), and CO2 concentration (1- 4 vol%) were investigated in the absence and presence of ultrasound. The obtained results showed that the removal efficiency increased with increasing gas and liquid flow rates, and rotational speed, as well as MEA concentration. With increasing CO2 concentration, absorption efficiency decreased. The average arithmetic value of the relative volumetric gas-side mass transfer coefficient was enhanced 11.4% under the ultrasonic field. Moreover, the average CO2 removal efficiency was enhanced from 27.4 % in the absence of ultrasound to 29.8% in the presence of ultrasound. Therefore, high frequency ultrasound can enhance CO2 absorption, even in high efficiency equipment like RPBs.