200 MW锅炉低NOx燃烧系统改造与试验研究

针对某燃用烟煤的200 MW机组采用四角切圆布置方式燃烧器的670 t/h锅炉，在主燃烧区域采用水平浓淡燃烧器、加装燃尽风喷口，采取燃料水平分级与空气垂直分级结合的方式进行改造，降低氮氧化物(NOx)排放水平。研究了该低NOx燃烧系统对锅炉NOx/CO排放和飞灰可燃物的影响规律。试验结果表明，当采用合理的燃尽风布置合理的二次风配风调节方式，燃尽风份额控制在30%时，机组NOx排放量可降低到300 mg/m3以下；在任一工况下都不高于400 mg/m3，其中最低NOx排放浓度为250.84 mg/m3。同时，对飞灰含碳量影响较小，保持在1.5% ~ 3%之间。

Experimental Study on a 200 MW Boiler Retrofitted With Low NOx Combustion System

An experimental investigation to reduce the NOx emission during burning bituminous coal was carried out on a 670 t/h tangential pulverized coal firing furnace, with a technique combining horizontal bias combustion (HBC) burners in the primary combustion zone and separated over firing air (SOFA) nozzles above the highest secondary air nozzles. The influence mechanisms of this low NOx combustion system on NOx /CO emission and unburned carbon in fly ash have been measured and studied in situ. The tests indicate the amount of NOx emission can be decreased to less than 300 mg/m3 after adopting the reasonable distribution of secondary air, of which the OFA ratio is 30%. The concentration of NOx is lower than 400 mg/m3 in any case, and the lowest concentration can reach 250.84 mg/m3. Meanwhile, there is little effect on the unburned carbon content in fly ash which varies between 1.5 % and 3 %.