In power stations, adjusting operating parameters to control NOx emissions has attracted more and more attention. In this study, a three-dimensional CFD model was established to simulate a 600 MW tangentially coal-fired boiler. The orthogonal tests were employed to analyze the effect of operating load, primary air rate, air staging, burner swing, and SOFA air swing on NOx emissions. Results show that at 35% BMCR, primary air ratio of 0.24, air staging of 0.75, burner swing of 15°, and SOFA air swing of 0°, the NOx emission is 208.8 mg/Nm3, which is 27.8% lower than the basic case. Increasing the operating load has the opposite effect to the primary air ratio, so does the burner swing and SOFA air swing. Orthogonal analysis shows that the air staging is the most significant factor in NOx emissions. Appropriate reduction of air staging is beneficial to reduce NOx emissions.
Keywords orthogonal analysis, NOx emission, numerical simulation