Identifying the multi-ion effects on the phase flow, mass and heat transfer in amine absorption of CO2

Carbon dioxide mitigation strongly supports the greenhouse gas control. Amine absorption of CO2, as a method to mitigate the CO2, is a typical multi-ion system with obvious multi-ion effects. However, there is little information about the multi-ion effects on the phase flow, mass and heat transfer in amine absorption of CO2. The multi-ion effects have previously to be neglected to simplify the absorption process description, which produces unknown deviations from the realistic absorption process. According to experiment data, a multi-ion mass transfer, heat transfer and phase flow model is here developed to describe the realistic amine absorption of CO2. The turbulent diffusivity, turbulent thermal diffusivity, turbulent viscosity, CO2 concentration, liquid temperature and velocity are analyzed under the multi-ion conditions. It was found that there is 6-22% CO2 concentration difference between the multi-ion effects case and the neglect of the multi-ion effects (NME) case. The positive ions show the better synergy effects compared with the negative ions. Under the ion concentration of 0.001 kmol/m3 to 0.02 kmol/m3, 0.2 kmol/m3 to 2 kmol/m3 and 4 kmol/m3 to 7 kmol/m3, the multi-ion mass transfer, heat transfer and phase flow model provides an accurate description of the realistic CO2 absorption against the NME case. Finally, Nusselt number and mass transfer coefficient models revised by synergy angles are developed to include the multi-ion effects for engineering application. Adding the amine salt and Na2CO3 respectively reduce the liquid film thickness and liquid film depth, which increases the Nusselt number by 9.5% and 9.3%, respectively. Adding the metal Cu increases the Nusselt number by 11.57%, which helps to reduce the energy consumption by 7.8%.