Optimization of operating parameters for low NO _x emission in high-temperature air combustion

This paper focuses on determining the effects of operating parameters on NO _x emission and parameters optimization to reduce NO _x emission for high-temperature air combustion furnaces. For this purpose, the Taguchi method, based on computational fluid dynamics (CFD) modeling, was implemented. Eight factors were considered, including the velocity of air injection (A), the velocity of fuel injection (B), the oxygen concentration in preheated air (C), the preheated air temperature (D), fuel temperature (E), the interaction between A and B, the interaction between A and C, and the interaction between A and D. An L ₂₇ (3 ¹³) orthogonal array was employed to arrange the CFD modeling tests. By analysis of variance, the degrees of effect of the selected factors are determined, which are as follows, in descending order: E, B, C, A, D, AB, AC, and AD. The major factors are found to be A, B, C, and E, while the other factors are considered to be secondary factors. The optimal operating conditions are determined to be A = 120 m/s, B = 85 m/s, C = 18.5%, D = 1493 K, and E = 298 K. Under the optimal operating condition, the concentration of NO _x emission decreases by 25.45%, compared with the original operating condition.