Consideration of chemical kinetics on mechanism of NOx reduction by steam addition

In the steam-injected combustion field where the Prompt mechanism controls NOx formation, a decrease in flame temperature physically affects the NOx r eduction. In addition, it is anticipated that the changes of concentrations of active radicals (CHI OH, H, etc.) due to steam addition bring about a c hemical kinetic effect on the NO, reduction. In order to investigate the chemical reaction effect of steam addition on N Ox reduction, we carried out numerical calculations of counterflow diffusio n flame using detailed chemical kinetics, when the maximum flame temperatur e were adjusted to the same value by varying the initial temperatures. Unde r the same maximum flame temperature, the NO emission index decreases with increasing amount of steam addition, and the concentration and mass product ion rate of CH, HCN and N, etc., related to NOx formation also decrease whe n steam is added. Consequently, we clarify chemical kinetic effect of steam addition on NOx reduction.