Effects of inorganic salts on absorption of CO2 and O2 for absorbents containing diethylenetriamine and piperazine

Abstract

In this study, inorganic salts potassium chloride (KCl), sodium chloride (NaCl), lithium chloride (LiCl), or lithium bromide (LiBr) were added, respectively, at 1.5m (molality) into an absorbent containing 15wt% diethylenetriamine (DETA) and 15wt% piperazine (PZ) to capture CO2 from a gas stream containing 10% CO2 in a rotating packed bed (RPB). The experimental results revealed that although the CO2 capture efficiency of each absorbent decreased upon adding the inorganic salt, the CO2 capture efficiency of the absorbent containing KCl was only slightly lower than that of the absorbent in the absence of any inorganic salt. And the height of the transfer unit in the RPB was much lower than that in a packed bed. In addition, the dissolved oxygen (DO) in the absorbent containing KCl was significantly lower than that of the absorbent in the absence of any inorganic salt. A central composite design was applied not only to analyze the effects of the gas flow rate, temperature, and KCl concentration on the CO2 capture efficiency and DO in the absorbent but also to optimize the process to ensure high CO2 capture efficiency and low DO in the absorbent.