Kinetics and mass transfer of carbon dioxide absorption into aqueous ammonia

Aqueous ammonia can be used to capture CO2 from flue gas of coal - fired power plant with acceptable CO2 removal efficiency, high loading capacity of CO2, low corrosion, low cost, and less degradation, and it could remove other acid gas pollutants at the same time. However, the CO2 absorption rate and mass transfer in aqueous ammonia still need to study more deeply. The mass transfer characteristics of CO2 in aqueous ammonia were investigated in this paper. A small wetted wall column (WWC) was used to study the kinetics of CO2 absorbed in aqueous ammonia. The correlation of gas - side mass transfer coefficient k(g) was fitted as Sh = 3.79(RexScxd/h)(0.486) based on the experimental data of CO2 absorption in 30%wt MEA solution for this WWC reactor. The reaction rates of CO2 in 1 wt%, 2.5 wt%, 5 wt% to 7.5 wt% aqueous ammonia were measured at the temperatures of 10 degrees C, 20 degrees C, 30 degrees C to 40 degrees C, and the second-order reaction rate constant k(2) was calculated. The termolecular mechanism model was used and discussed according to the experimental results. The kinetics constants of k(NH3)(T) and k(H2O)(T) in termolecular mechanism were also fitted in this paper. (C) 2011 Published by Elsevier Ltd.