Low-energy-consumption CO2 capture via coupling process of direct organic fluid stripping with biphasic solvents

Amine-based CO2 chemisorption technology has currently gained significant attention in the field of CO2 capture. However, high energy consumption remains one of the key challenges limiting large-scale applications in flue gas CO2 chemisorption. To tackle this, the coupling process of direct organic fluid stripping (DOS) with biphasic solvents was innovatively proposed in this study. Various typical biphasic absorbents were applied in a laboratory-scale continuous flow system. Pentane was identified as the ideal organic fluid for solvents due to its low vaporization heat requirement and outstanding enhancement in CO2 regeneration. Compared to conventional reboiler heating(CRH) process, DOS process effectively mitigated temperature non-uniformity within the stripper and provided extra mass transfer driving force for CO2 desorption of biphasic solvents. Multiple operational parameters were systematically analyzed to establish a comprehensive impact mechanism on the energy-saving efficiency of DOS process. It was revealed that DOS process promoted efficient regeneration of biphasic solvents at temperatures below 100 °C, achieving up to a 46.1 % reduction in regeneration energy compared to CRH process. Moreover, the coupling process demonstrated excellent operational stability in 180-h continuous absorption-desorption cycling tests. While strengthening CO2 regeneration within the stripper, DOS process notably suppressed amine loss in solvents(<6.5 %) compared to CRH process, maintaining high CO2 removal ratio (>90.1 %) and stable phase separation of biphasic solvents. To further enhance energy efficiency and pentane recovery in the system, the pre-compression enhanced recycle process was applied and simulated in Aspen Plus, achieving a maximum recycled energy of 0.65 GJ/t CO2 and a pentane recovery ratio of 99.7 %.