Mass and heat transfer characteristic in MEA absorption of CO2 improved by meso-scale method

CO2 capture affords to control the greenhouse gas emissions effectively. Monoethanolamine (MEA) absorption of CO2 shows great potentials to mitigate the industrial CO2 emission. Unfortunately, it is an energy-intensive process. A meso-scale model was developed to characterize coupling effects between micro-scale and phase-scale to intensify the MEA absorption process. Mass transfer coefficient (MC) and Nusselt number (Nu) are used to determine the mechanisms among micro-scale, phase-scale and meso-scale. It is found that meso-scale MC and Nu do not equal to the sum of micro-scale and phase-scale values due to the interaction effects between micro-scale and phase-scale. MEA conformer, O-N distance, temperature and slip velocity significantly affect the meso-scale MC and Nu due to their strong impacts on film structure and interphase area. The liquid film thickness and length decrease by 40% and 32% as slip velocity increased from 0.1 m/s to 0.3 m/s, respectively, while the interphase area increases by 6%. The energy consumption is reduced to 2.65 GJ/t under the gGt MEA conformer, saving 17% energy against the experiment baseline case. The meso-scale model is proved to be a useful method to intensify the amine solutions absorption of CO2. Adjusting pH value, concentrating the amine solution to 9 kmol/m3, extremely increasing the absorption temperature up to 353.15 K and adding nano Fe3O4 are the feasible ways to achieve the meso-scale intensification effects.