Thermal regeneration of alkanolamine solutions in a rotating packed bed

• Rotating packed bed was successful to regenerate CO2-loaded aqueous solution.
• Volume of RPB could be reduced to one-tenth that of conventional packed bed stripper.
• DETA + PZ mixed solution showed lower regeneration energy required than MEA solution.

In the present study, a 30 wt% monoethanolamine (MEA) aqueous solution that was loaded with CO2 was thermally regenerated in a rotating packed bed (RPB). The effects of rotational speed, liquid flow rate, reboiler temperature, and pressure on the regeneration efficiency and regeneration energy were investigated. The experimental results indicated that the regeneration efficiency of a conventional packed bed could be achieved by an RPB apparatus that was only one-tenth of the volume of the conventional packed bed. Moreover, compared with a conventional packed bed, the RPB apparatus consumed less energy per unit ton of CO2 that was desorbed from an aqueous alkanolamine solution. Virtually the same regeneration efficiencies were found regardless of whether an RPB was present or absent from the regeneration apparatus; however, relative to the process without the RPB, the process with the RPB demonstrated a large advantage of 64% in terms of regeneration energy, indicating the dramatic potential of an RPB for the reduction of energy consumption. A CO2-loaded aqueous solution consisting of a blend of 20 wt% diethylenetriamine + 10 wt% piperazine was also examined in the study. Compared with a 30 wt% MEA aqueous solution, this blended solution demonstrated a more effective CO2 capturing ability, higher regeneration efficiency, and lower consumption of regeneration energy, suggesting that the proper choice of absorbent was an extremely important consideration for the capture of CO2.

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