Evaluation of effectiveness of highly concentrated alkanolamine solutions for capturing CO2 in a rotating packed bed

Abstract The capture of CO 2 by single and mixed alkanolamine solutions of monoethanolamine (MEA), 2-methyl-amino-ethanol (MMEA) and piperazine (PZ) with total alkanolamine concentrations from 30 to 100 wt% was conducted in a rotating packed bed (RPB). The effects of rotational speed, gas flow rate and composition of the absorbent were investigated. Experimental results showed that increasing the alkanolamine concentration and the rotational speed up to 1800 rpm effectively improved the CO 2 removal efficiency. However, the removal efficiency decreased as the gas flow rate increased. MMEA solutions exhibited a higher removal efficiency than MEA because MMEA reacts faster with CO 2 than MEA. The alkanolamines that were mixed with PZ were more effective in capturing CO 2 than single alkanolamine solutions. The height of transfer unit (HTU) decreased as the alkanolamine concentration and rotational speed increased, but increased with the gas flow rate. A CO 2 removal efficiency of 99.4% and an HTU of 0.74 cm were obtained using absorbent that contained 80 wt% MMEA and 20 wt% PZ at a rotational speed of 600 rpm, a liquid flow rate of 0.1 L/min, a gas flow rate of 30 L/min and a temperature of 313 K. The high removal efficiency and low HTU value reveal that an RPB has great potential for CO 2 capture from a gas stream using an absorbent with a high alkanolamine concentration.