Near-Burner Flow-Field Characterization and Its Relation to Performance in a Model Industrial, Natural Gas Fired Burner

In-flame NOx control techniques rely on lowering combustion temperatures to reduce thermal NO. These techniques can also lower combustion efficiency by compromising CO and hydrocarbon burnout. To address the "trade-off" between NOx and combustion efficiency, different fuel injector strategies are employed, and flue gas measurements are acquired for a range of excess air and swirl intensities in a natural gas fired, model industrial burner. A performance function is defined to identify conditions suitable for detailed measurements of the flow-field. Non-intrusive, laser anemometry measurements are conducted at three axial locations downstream of the burner exit for seven conditions to quantify the flow-fields and recirculation zones. The results suggest that, in addition to percent recirculated mass, the complex processes of near-field fuel and air mixing have a significant impact on NOx emissions and the maintenance of high combustion efficiency.