Simultaneous Removal of NO_<i>x</i> and SO_<i>x</i> from Flue Gases Using ClO₂: Process Scaling and Modeling Simulations

Abstract

The concept of coabsorption of NO2 and SO2 from flue gases, in combination with the enhanced oxidation of NO by ClO2(g), is studied on three scales, 0.2, 100, and 400 N m3/h, all with flue gases of different origins. The results obtained from each setup are presented, together with modeling that was applied to assess the scale-up of the concept and to validate the model. The measurements confirm that ClO2 is highly selective toward NO oxidation for temperatures in the range of 70–155 °C. A comparison of the results obtained for each scale reveals that the 0.2 N m3/h setup confers a higher level of NOx absorption than the other setups, although the trends remain similar. Simulations of the results underpredict the level of NO2 absorption in the 0.2 N m3/h setup while capturing the levels of absorption in the 100 N m3/h setup. An important finding is the rapid and complete oxidation of S(IV) in the presence of NO2, which is not represented in the reaction kinetics.