煤粉工业锅炉预燃式低氮燃烧器试验研究与开发

The increasingly strict emission standards on NO_x put forward higher requirements for the performances of the coal-fired industrial boilers. It is hard for the existing burners in industrial boilers to meet the emission restrictions by operation optimization. In this study, a new type of coal-fired low-NO_x swirling burner for industry boilers was developed. Through the experiments in a 25 t/h industry boiler, the effects of primary air ratio, secondary air distribution, swirling angle, recirculated flue gas (FGR) and over fire air(OFA) ratio on NO_x emission and combustion efficiency were studied. The results show that the NO_x emission increases when the primary air ratio increases from 7.8% to 8.5% and the inner/outer secondary air ratio increases from 0.67 to 1.32. As the angel of swirl vane increases from 30° to 60°, the NO_x emission decreases first and then increases. With the increase of FGR ratio from zero to 13.3%, the NO_x emission first decreases and then tends to be stable. The effect from OFA ratio on NO_x emission is slight, and with the increase of OFA ratio, the NO_x emission first decreases, and then increases. During the test process, the coal stream flame is stable and the unburned carbon content in fly ash (UBC) is always lower than 25%. The lowest NO_x emission is obtained as 171-178 mg/m³(9% O₂), with a UBC value of 14.9% and a boiler efficiency of 91.7%.