CO2 absorption with polyethyleneimine solution intensified by a rotating packed bed with liquid detention

Abstract

This study explored the absorption of CO₂ by the polyethyleneimine (PEI) solution in a rotating packed bed (RPB). In order to boost the CO₂ absorption effect, the liquid detention phenomenon in the RPB was utilized to overcome the short residence time of liquid. The effects of different operating parameters on CO₂ absorption efficiency (η) and gas-phase volumetric mass transfer coefficient (K_Ga_v) in the RPB were investigated. The experimental results indicated that the RPB can greatly intensify the absorption of CO₂. η and K_Ga_v increased from 3.3 % and 0.041 kmol·m⁻³·h⁻¹·kPa⁻¹ to 76.0 % and 1.634 kmol·m⁻³·h⁻¹·kPa⁻¹, respectively, as the rotational speed of the RPB rose from zero to 700 rpm with 250 mL detained liquid. It was also found that the liquid detention phenomenon can significantly elevate η and K_Ga_v as a result of extended liquid residence time and increased liquid holdup in the RPB. When the detained liquid volume increased from zero to 250 mL, η and K_Ga_v increased by 55.6 % and 113.1 %, respetively. In addition, it was observed that CO₂ load in the rich PEI solution increased from 9.650 to 11.189 molCO₂/kg PEI while η remained around 85 % after five cycles of absorption–desorption, suggesting an excellent cyclic stability of PEI. This work contributes to the development of viable CO₂ capture technologies by intensifying the CO₂ absorption process in the RPB with an efficient absorbent.