Experimental study of the mass transfer behavior of carbon dioxide absorption into ternary phase change solution in a packed tower

Phase change absorbents for CO2 are of great interest because they are expected to greatly reduce the heat energy consumption during the regeneration process. Compared with other phase change absorbents, monoethanolamine (MEA)-sulfolane-water is inexpensive and has a fast absorption rate. It is one of the most promising solvents for large-scale industrial applications. Therefore, this study investigates the mass transfer performance of this phase change system in the process of CO2 absorption in a packed tower. By comparing the phase change absorbent and the ordinary absorbent, it is concluded that the use of MEA/sulfolane phase change absorbent has significantly improved mass transfer efficiency compared to a single MEA absorbent at the same concentration. In the 4 mol⋅L−1 MEA/5 mol⋅L−1 sulfolane system, the CO2 loading of the upper liquid phase after phase separation is almost zero, while the volume of the lower liquid phase sent to the desorption operation is about half of the total volume of the absorbent, which greatly reduces the energy consumption. This study also investigates the influence of operating parameters such as lean CO2 loading, gas and liquid flow rates, CO2 partial pressure, and temperature on the volumetric mass transfer coefficient (KGaV). The research shows that KGaV increases with increasing liquid flow rate and decreases with the increase of lean CO2 loading and CO2 partial pressure, while the inert gas flow rate and temperature have little effect on KGaV. In addition, based on the principle of phase change absorption, a predictive equation for the KGaV of MEA-sulfolane in the packed tower was established. The KGaV obtained from the experiment is consistent with the model prediction, and the absolute average deviation (AAD) is 7.8%.