Numerical Study of NOx Abatement Using Ozone Injection Integrated with Wet Absorption

Nitrogen oxides emitted from power plants and the chemical industry are poisonous to humans and animals, contribute to ozone depletion, and cause acid rain. More than 90% of nitrogen oxides (NOx) consist of nitric oxide (NO), which is insoluble in water. Among the various available techniques of NOx abatement, ozone injection is a promising method in which NO is oxidized to higher-order nitrogen oxides (NO3, N2O3, N2O4, and N2O5), which can easily be absorbed in a wet scrubber. In this article, the ozone injection process integrated with an absorber column is numerically modeled and simulated at various operating conditions. The predicted results of NOx oxidation with ozone injection and absorption in water agree with the published experimental results. The ozone injection process is modeled using a plug flow reactor, while the wet absorption is based on a rigorous rate-based RateFrac model. Detailed kinetic mechanisms of O-3-NOx oxidation and absorption of nitrogen oxides in water are incorporated in the model to simultaneously predict the performance efficiency of the ozone reactor and absorber column. Thermodynamic properties of the components are estimated using an Electrolyte NRTL model. The influence of performance parameters (such as feed gas flow rate, inlet gas temperature, reactor configurations, ozone concentration, and NO/NO2 molar ratio) on the oxidation efficiency of NOx in the reactor and absorber column is investigated to predict the optimal operating conditions.This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (No. NRF-2011-0017220