CO₂ capture by membrane absorption coupling process: Experiments and coupling process evaluation

An experiment system composed of a membrane absorption unit and three regeneration units was set up. The membrane absorption unit could be equipped with single and multiple modules in single cycle absorption mode. The three regeneration units included a hot regeneration, a vacuum desorption and an inert gas sweep. An efficient blended absorbent comprised of potassium glycinate (PG) and 2-amino-2-methyl-1-propanol (AMP) was developed in this work. Coupling process of membrane module-blended absorbent was evaluated by various operation modes such as single and multiple modules, single cycle absorption and regeneration, and continuous circulation of absorption and regeneration. Results show that performance of the blended absorbent (PG+AMP) was better than that of single ones (PG or AMP). The hot regeneration could give a high circular absorption capacity and a high regeneration efficiency while the vacuum desorption and the inert gas sweep gave a poor circular absorption capacity and a poor regeneration efficiency. Membrane flux of the coupling process increased as the gas and liquid flowrates increased. The absorption and regeneration time would greatly reduce by the assembly of multiple modules in consecutive and parallel modes. The circular absorption capacity and the regeneration efficiency by the hot regeneration were far larger than that by the membrane regeneration in the continuous circulation of absorption and regeneration. The membrane absorption process by coupling membrane and absorbent could be scale-up linearly. The parallel assembly mode of multiple modules was more effective than the consecutive assembly mode for CO₂ capture.