CO2 absorption into highly concentrated DEA solution flowing over a vertical plate with rectangular windows

A novel element for gas-liquid contact, the plate with rectangular windows was proposed to enhance CO2 absorption into aqueous diethanolamine(DEA) solutions with high concentration. Absorption experiments were performed within the following test range: the mass fraction of DEA from 5% to 63%, viscosity from 1.1 mPa s to 25.3 mPa s, liquid load from 30 m3 m−2 h−1 to 60 m3 m−2 h−1 and volume fraction of CO2 from 15% to 45%. The results show that the normal plate reaches the maximum absorption efficiency when the DEA content is 40 wt% (the corresponding viscosity is 5.8 mPa s), and the liquid-side mass transfer coefficient KL decreases as the viscosity of solution further increases, even increasing liquid load KL is not enhanced obviously. Comparing of the two types of plate, when DEA(wt%) ≤ 40% (μ ≤ 5.8 mPa s), KL of the plate with windows has increased by 30-40% over the normal one, and when DEA(wt%) > 40% (μ > 5.8 mPa s), KL could be increased by 60-70%, even 100%. Furthermore, the mass transfer strengthening mechanism of the plate with windows was also discussed.