W火焰锅炉氮氧化物排放特性数值模拟研究

Numerical Simulation Study of Nitrogen Oxide Emission Characteristics of W Flame Boiler

W火焰锅炉将面临NO_(x)超低排放改造的要求,需要在现有的SCR脱硝系统上增加炉膛SNCR脱硝技术,而炉内NO_(x)浓度分布对SNCR脱硝效率有影响。炉膛NO_(x)浓度分布无法通过实际测量获得,为了优化设计SNCR脱硝技术方案,采用数值模拟计算分析不同负荷、磨煤机组合方式下炉内NO_(x)质量浓度分布。以某660 MW燃煤机组W火焰燃烧方式锅炉为研究对象,研究结果显示,100%BRL、75%BRL和50%BRL磨煤机运行台数分别为6台、5台和4台,燃烧器喷口生成NO_(x)质量浓度较高区域的值分别为950 mg/m^(3)~1000 mg/m^(3)、800 mg/m^(3)~900 mg/m^(3)和600 mg/m^(3)~800 mg/m^(3),NO_(x)质量浓度与锅炉负荷呈正相关变化关系。磨煤机组合方式影响炉膛NO_(x)质量浓度分布均匀性。100%BRL负荷采用ABCDEF 6台磨煤机运行、75%BRL负荷采用BCDEF和ABCDF磨煤机组合、50%BRL采用BCDE磨煤机组合较合理。W火焰锅炉超低排放改造采用SCR组合SNCR的脱硝技术时要重点关注炉膛水平折焰角截面上NO_(x)浓度分布,优化设计NH3喷口数量、位置和各喷口喷NH3量,使得SNCR脱硝处于最佳运行水平。

W flame boiler will face the requirements of NO_(x)ultra-low emission transformation,and it is neces⁃sary to add furnace SNCR denitrification technology on the existing SCR denitrification system.NO_(x)concentra⁃tion distribution has an impact on SNCR denitrification efficiency.The NO_(x)concentration distribution in the fur⁃nace can not be obtained through actual measurement.In order to optimize the design and study the SNCR denitration technology scheme,numerical simulation is used to calculate and analyze the NO_(x)mass concentration distribution in the furnace under different loads and coal mill combination methods.Taking the W flame combus⁃tion boiler of a 660 MW coal-fired unit as the research object,the results show that the operating number of 100%BRL,75%BRL and 50%BRL is 6,5 and 4,respectively,and the value of NO_(x)generation mass con⁃centration is 950 mg/m^(3)~1000 mg/m^(3),800 mg/m^(3)~900 mg/m^(3)and 600 mg/m^(3)~800 mg/m^(3),respectively,and the NO_(x)emission mass concentration is positively correlated with the boiler load.The combined mode of coal mill affects the uniformity of NO_(x)concentration in furnace.It is reasonable to use ABCDEF 6 mill opera⁃tion for 100%BRL load,BCDEF and ABCDF mill for 75%BRL load,and BCDE mill for 50%BRL.W flame boiler ultra-low emission transformation using SCR combination SNCR denitration technology should fo⁃cus on the NO_(x)mass concentration distribution on the furnace horizontal folding flame Angle section,optimize the design of NH3 nozzle number,position and each nozzle injection NH3 amount,so that SNCR denitration in the best operating level.