Краткое описание

NO_x emissions have been measured from a low NO_x Swirl Burner concept at various geometrical sizes (400 kW, 200 kW, and 10 kW) in different boilers using propane as fuel. The measured emissions of NO_x expressed as the emission index of NO_x (EL_NOx) multiplied by ρ₀u₀/d₀ have been found to be proportional to Fr for confinement ratios (boiler to burner diameter ratio) below 8. This result implies that the flame volume is the leading-order parameter for NO_x formation in these burners. It has further been found that heat extraction from the Swirl Burner is enhanced by high confinement ratios (>8) and by low combustion chamber wall temperatures. Measurements of flame heights using laser-induced fluorescence (Spangelo, 2004) have indicated that the flame volume is reduced with increased thermal load when the confinement ratio is higher than 8. This is due to enhanced heat extraction, especially from the postflame region, at high confinement ratios.