A multi-approach study on CO2 absorption in packed beds: Theoretical, experimental, and CFD perspectives on gas phase pulsation

Abstract

This work seeks to improve CO₂ absorption efficiency in packed bed columns by substituting amine-based solvents with sodium hydroxide and implementing gas phase pulsation to enhance mass transfer coefficients. Experimental analysis and computational fluid dynamics modeling were employed to investigate the impact of pulsation on absorption efficiency under various conditions. Essential parameters comprised superficial liquid velocity (1.2–4.6 cm/s), pulsation frequency (0–10 Hz), amplitude (0–20 mm), and NaOH concentration (0.25 N to 2 N), while maintaining a constant superficial gas velocity of 120 cm/s and a solute gas concentration of 13 %. Three packing materials—glass spheres, ceramic Raschig rings, and ceramic Pall rings—were evaluated. The results demonstrated that ceramic Pall rings exhibited the greatest efficiency. Pulsation, namely at 9.06 Hz and 20 mm amplitude, enhanced the volumetric mass transfer coefficient by as much as 4.53 times for Pall rings. Increased column diameters (from 7.00 cm to 11.5 cm) enhanced performance. The findings show advancement of more efficient CO₂ absorption (by switching from chemical absorption using amine based solvents to classical chemical absorption using aqueous NaOH solution) for industrial applications, aiding climate change mitigation initiatives.