Carbon dioxide capture by blended alkanolamines in rotating packed bed

Abstract

The capture of CO2 from a 10 vol% CO2 gas by chemical absorption with aqueous solutions containing 30 wt% of single and mixed monoethanolamine (MEA), 2-(2-aminoethylamino)ethanol (AEEA), piperazine (PZ), and 2-amino-2methyl-1-propanol (AMP) in a rotating packed bed (RPB) was studied. The RPB had an inner diameter of 7.6 cm, an outer diameter of 16 cm, and a height of 2 cm. The CO2 capture efficiency was found to increase with increasing temperature in a range of 303 to 333 K. It was also found to be dependent on rotating speed, gas flow rate, and liquid flow rate. The 30 wt% mixed alkanolamine solutions containing MEA or AEEA with at least 10 wt% PZ were the appropriate absorbents compared with the single alkanolamine and the mixed alkanolamine solutions containing AMP. A higher portion of PZ in a mixture was more favourable to CO2 capture. Because of short contact time in a RPB, alkanolamines with high reaction rate with CO2 are suggested to use. For the solutions containing 15 wt% MEA or AEEA and 15 wt% PZ, the highest gas flow rate allowed to achieve a capture efficiency more than 90% were 30 L/min at a solution of 100 mL/min and 50 L/min at a solution of 300 mL/min. The corresponding height transfer units were found to be less than 2.0 cm, significantly lower than those in a conventional packed bed absorber.