Mass-Transfer Characteristics of CO2 Absorption into Aqueous Solutions of N-Methyldiethanolamine plus Diethanolamine in a T-Junction Microchannel

摘要

The mass-transfer process of CO, absorption into aqueous solution of N-methyldiethanolamine (MDEA) + diethanolamine (DEA) in a T-shaped microchannel was studied using a high-speed camera. The effects of two-phase flow rates and diethanolamine concentration on CO2 absorption efficiency, liquid mass-transfer coefficient k(L), specific surface area a, and volumetric mass-transfer coefficient k(L)a were investigated under slug flow. Results showed that the CO2 absorption efficiency increased with the increase of DEA concentration and liquid flow rate, and decreased with increasing gas flow rate. The k(L) increased with the increase of liquid flow rate and DEA concentration, while it was insensitive to gas flow rate. For a given liquid flow rate, both k(L)a and a increased rapidly with gas flow rate and then the trend was slowing down. The increase of liquid flow rate and DEA concentration led to the decrease of the a, whereas the k(L)a was improved. The enhancement of the liquid flow rate on k(L) and k(L)a was more obvious under low DEA concentration. An empirical correlation for predicting the volumetric mass-transfer coefficients k(L)a was proposed by taking the Hatta number Ha into account for characterizing the effect of chemical reaction.