燃气-蒸汽联合循环机组烟气氮氧化物的排放规律

Emission characteristics of nitrogen oxides from gas steam combined cycle unit

针对燃气-蒸汽联合循环机组运行过程中排放黄烟的现象,开展了烟气污染物(NO和NO_2)浓度的现场测试,研究了联合机组运行工况和生产负荷对其排放特性及变化规律的影响。结果表明:烟气中NO浓度和氮氧化物(NOx)浓度随机组生产负荷的增大而增大,NO_2浓度以及NO_2与NOx的浓度比值(NOx构成)则随生产负荷增加而逐渐降低。联合机组在单循环和低负荷工况运行时,黄色烟羽成因是烟气中NO_2含量高造成的,与烟气中NOx浓度和NO浓度没有明确的对应关系;提高联合机组生产负荷,会减少NO_2在氮氧化物中所占的比例,有助于缓解烟气黄色烟羽的生成。此外,初步分析了燃气轮机燃烧器的运行模式,认为值班燃烧区形成的高温富氧条件是造成排放高浓度NO_2烟气的重要原因。

Pollutant concentrations(NO and NO2) were monitored and measured for the phenomenon of the yellow smoke emissions in a gas steam combined cycle unit. Effect of the unit operation condition and production load on the pollutant emission characteristics and change rules was studied based on the monitoring results. The results show that the concentration of NO and that of nitrogen oxides(NOx)increase, the concentration of NO2 and the concentration ratio of NO2 to NOx(nitrogen oxides composition)gradually decrease with the increase of production load. The yellow smoke plume is caused by a high concentration of nitrogen dioxide in the flue gas, and is no direct relation with the concentration of NO and NOx, when the combined cycle unit is in the stage of the single cycle and low-load operation. The proportion of NO2 in nitrogen oxides can be decreased by increasing the production load, which is helpful to reduce the generation of the yellow smoke plume. In addition, the operating mode of burner is preliminarily analyzed, and the high-temperature and oxygen-rich condition formed in the on-duty combustion area is considered to be an important cause of high NO2 emission.