A scheme for solving strongly coupled chemical reaction equations appearing in the removal of SO2 and NOx from flue gases

The removal of NOx from mixtures of NO–NO2–N2 and NO–NO2–O2–H2O is discussed theoretically in this study, and the removal of SO2SO2 and NOxNOx is further discussed when a gas system of NOx–N2–O2–H2O contains CO2 and SO2. The involved chemical reaction rate equations in the process of SO2/NOx   removal are solved numerically using Treanor's method, in which a scheme separating chemical reactions into fast and slow groups has been proposed for improving the numerical stability. Numerical results show that the contribution of ion reactions to NOxNOx removal is negligible, and that high temperature is not beneficial for the NO oxidation. However, high concentration of O2O2 is conducive to the NO oxidation. Addition of water facilitates the NOx removal, and increasing water vapor concentration enhances the NOx removal efficiency; inclusion of CO2 and SO2 into the system favors the NO removal.