Modeling and simulation of the combined removal of SO 2 and CO 2 by aqueous ammonia

The combined removal of SO 2 and CO 2 using aqueous ammonia has many advantages over the conventional processes, such as the ability to capture multiple pollutants, the low cost of absorbent, high CO 2 loading capacity, and the capacity to regenerate solvent at low temperature. In this paper, a closed‐loop CO 2 absorption‐desorption process integrated with packed column flue gas desulfurization system was investigated. The CO 2 absorption was modeled using the rigorous rate‐based RateFrac model in Aspen Plus, whereas the SO 2 column and CO 2 stripper were modeled based on the RadFrac equilibrium model. The thermodynamic properties of the components were estimated with the Electrolyte NRTL model. The model was coupled with chemical equilibrium and kinetic reactions of the NH 3 ‐CO 2 ‐H 2 O and NH 3 ‐SO 2 ‐H 2 O system. The predicted results of temperature profile, variation in CO 2 concentration along the column, SO 2 removal efficiency, and CO 2 separation rates agreed with published experimental results. To optimize the operating conditions, the impacts of performance parameters are investigated including flue gas temperature, concentration of CO 2 and SO 2 in flue gases, and the temperatures of the lean solution and ammoniated water. Furthermore, the performance efficiency of the stripper column is analyzed in terms of reboiler heat duty and CO 2 regeneration rate, for the stripper operating pressure range of 2–20 bar and the stripper inlet temperature range of 60–105 °C. The results show that the suggested model is an adequate approach for the combined removal of CO 2 and SO 2 from the stack gases.