Rate of Absorption for CO2 Absorption Systems Using a Wetted Wall Column

Abstract

Knowledge on the absorption rate of CO2 in absorption systems is essential for accurate equipment design. This work is focused on determining the rate of absorption for novel absorption systems using a wetted wall column. This is a widely used method for determining the absorption flux of carbon dioxide in amine solutions. Two absorption systems were investigated, namely aqueous solutions of monoethanolamine (MEA), which is considered a benchmark amine solution, and solutions of 2-amino-2-methyl-1-propanol (AMP) in the organic solvent N-methyl-2-pyrrolidone (NMP). Aqueous solutions of MEA have been widely researched for CO2 capture whereas solutions of AMP in NMP are novel absorption systems that have been reported as promising alternatives for CO2 capture, based on its ability to be regenerated at lower temperatures. Experiments were performed with a wetted wall column in order to investigate the CO2 absorption rate of the previously mentioned amine solutions. Different amine concentrations for the aqueous MEA were investigated, 1.5 and 7 m, as well as for solutions of AMP in NMP, 1.5 and 5 m. From the experiments the overall flux of CO2 could be evaluated and used to calculate the mass transfer coefficients. The results showed a higher flux and higher liquid side mass transfer of CO2 for AMP in NMP compared to aqueous MEA.