Performance of CO2 absorption in a spray tower using blended ammonia and piperazine solution: Experimental studies and comparisons

Abstract

Slow CO2 absorption rate is one of the major drawbacks of the ammonia-based CO2 capture. To overcome the drawback, piperazine (PZ) is widely recommended to add into the aqueous NH3 solution as a promoter. In this work, we experimentally studied the performance of CO2 absorption in a spray tower using the blended NH3/PZ solution. The effects of varying operating parameters on the CO2 removal efficiency, outlet gaseous NH3 concentration, ammonia loss mass ratio, and volumetric overall mass transfer coefficients Kg,CO2aV have been revealed. Considering that the volumetric overall mass transfer coefficient Kg,CO2aV is an important parameter for CO2 capture application, we further shed some light on the underlying relationships between the coefficients Kg,CO2aV and the operating parameters. Additionally, to examine the feasibility of the blended solution in a spray tower, we compared the absorption characteristics identified in this work with those reported in the literature using NH3 or the blended NH3/PZ solution as absorbents. The comparisons demonstrate CO2 absorption in a spray tower using the blended NH3/PZ solution can be a great potential alternative for the CO2 capture and storage technologies.