摘要
【目的】新疆地区某440 t/h纯燃高碱煤循环流化床(circulating fluidized bed,CFB)锅炉在运行过程中发现其NO_(x)排放不达标,为此,开展了针对该锅炉的低NO_(x)燃烧改造试验研究。【方法】通过改造锅炉部件和调整运行参数来降低NO_(x)排放:为提高分离器效率进而降低锅炉平均床温,在水冷壁上适当扩展受热面和提高分离器的入口速度;为优化二次风,对二次风口高度进行了调整;为创造还原性气氛,增加了烟气再循环系统。【结果】通过综合改造措施,显著降低了锅炉平均床温和炉膛烟温,有效降低了烟气中O_(2)含量,创造了更有利于抑制NO_(x)生成的均匀温度场和还原性气氛,最终降低了NO_(x)的生成和排放。【结论】改造后,在宽负荷条件下,即使不使用选择性非催化还原(selective non-catalytic reduction,SNCR)技术,也实现了NO_(x)的超低排放(低于40 mg/m^(3))。此次改造实践对于现役CFB锅炉低NO_(x)燃烧控制具有积极影响和借鉴意义。
[Objectives]During the operation of a 440 t/h circulating fluidized bed(CFB)boiler burning high-alkali coal in Xinjiang,China,it is found that its NO_(x) emissions do not meet the standard.Consequently,an experimental study for low-NO_(x) combustion retrofit is conducted on this boiler.[Methods]NO_(x) emissions are reduced through boiler component modifications and operational parameter adjustments.To enhance separator efficiency and thereby lower the average bed temperature of the boiler,the heating surface of the water-cooled wall is appropriately extended,and the inlet velocity of the separator is increased.The secondary air is optimized by adjusting the height of the secondary air nozzles.To create a reducing atmosphere,a flue gas recirculation system is added.[Results]Through comprehensive transformation measures,the average bed temperature and furnace flue gas temperature of the boiler are significantly reduced,and the O_(2) content in the flue gas is effectively decreased.A more uniform temperature field and a reducing atmosphere are created,both of which are conducive to suppressing NO_(x) formation,thereby reducing NO_(x) generation and emissions.[Conclusions]Following the retrofit,ultra-low NO_(x) emissions(below 40 mg/m^(3))are achieved under wide-load conditions even without employing selective non-catalytic reduction(SNCR).This retrofit practice holds positive implications and reference value for low-NO_(x) combustion control in existing CFB boilers.
作者
王洪健
黄延凯
喻鑫
于敦喜
WANG Hongjian;HUANG Yankai;YU Xin;YU Dunxi(Xinjiang East Hope Nonferrous Metals Co.,Ltd.,Changji Hui Autonomous Prefecture 831700,Xinjiang Uygur Autonomous Region,China;State Key Laboratory of Coal Combustion(Huazhong University of Science and Technology),Wuhan 430074,Hubei Province,China)
出处
《发电技术》
2025年第5期1005-1013,共9页
Power Generation Technology
基金
国家重点研发计划项目(2023YFB4102703)。
