Process intensification of CO₂ capture by low-aqueous solvent

Low-energy solvent-based CO₂ absorption processes have drawn attention as a next-generation post-combustion CO₂ capture technology to reduce CO₂ emissions from fossil fuel– or biomass-fired power generation and industrial flue gas streams. A low-aqueous (or water-lean) solvent process may substantially reduce the thermal energy consumption for solvent regeneration. Low-aqueous solvent–based processes are thermally sensitive, requiring a delicate temperature control within the absorber because of the fast exothermic amine-CO₂ reaction and low heat capacity organic diluent. This reaction may result in heat accumulation in a packed absorption column and undesirable CO₂ desorption occurring as the solvent moves through the column, reducing the solvent's CO₂ capture efficiency if its temperature is not controlled. Using a 3D printed intensified packing device, enhanced heat and mass transfer were demonstrated in an amine-CO₂ scrubbing process using low-aqueous solvent. The multifunctional intensified device facilitates contact of the reactive solvent and gas phases in a single stage and heat removal by a cooling fluid flowing through channels in the interior of the corrugated plates of the device. These functionalities led to effective thermal management along the column via intrastage cooling and significant improvement in CO₂ uptake under a wide range of operating conditions. Intrastage cooling effectively reduced the solvent average temperature along the column by ~10 °C and, as a result, the solvent's capture efficiency improved by up to 25%.