摘要
采用数值模拟方法,研究了超低负荷、不同运行氧量工况下某300 MW切圆燃烧锅炉炉膛温度、氧量、CO和NO_(x)的分布规律,分析其对燃烧稳定性和NO_(x)排放特性的影响。结果表明:与中、高负荷相比,90 MW和60 MW超低负荷工况下,高运行氧量时假想切圆难以形成,稳燃能力降低,深度空气分级燃烧系统的脱硝效果变差;当辅助风全关后,炉膛整体温度升高,着火距离缩短,假想切圆更易形成,燃尽距离增加,燃烧稳定性提升,截面平均NO_(x)质量浓度分别降低29%和24%;继续减少燃尽风风量使得运行氧量达到3.5%时,燃尽风区温度略有升高,NO_(x)排放量分别继续降低9%和10%;超低负荷下绝大部分NO_(x)为燃料型NO_(x),初期运行氧量的降低对修正后NO_(x)排放量的降低效果显著。因此,超低负荷下建议减少主燃区的辅助风,保持燃尽风不变,90 MW和60 MW负荷工况下运行氧量推荐值分别为6.5%和8.5%。
Numerical simulation was used to investigate the distribution rules of temperature,oxygen,CO and NO_(x)in a 300 MW tangential combustion boiler under ultra-low load and different oxygen operating conditions,to analyze the effect on combustion stability and NO_(x)emission characteristics.Results show that compared with medium and high load,under 90 MW and 60 MW ultra-low load conditions with high boiler operation oxygen,the imaginary tangent circle is difficult to form and the combustion stability is weakened.The de-NO_(x)effectiveness of the deep-air-staging combustion system gets worse.When the auxiliary air is completely turned off,the overall temperature of the furnace increases,the ignition distance is shorter.Meanwhile the imaginary tangent circle is easier to form,the burning-out distance increases,and the combustion stability is improved,and the average mass concentration of NO_(x)is reduced by 29% and 24% respectively.Continuing to reduce the exhaust air volume until the operating oxygen volume reaches 3.5%,temperature of the separated over-fire air(SOFA) zone increases slightly,and the NO_(x)emission decreases by 9% and 10% respectively.In addition,most of the total NO_(x)at ultra-low load is fuel-NO_(x),and the reduction of oxygen has a significant effect on the reduction of NO_(x)emission.Therefore,it is recommended to reduce the auxiliary air in the main combustion area under ultra-low load and keep the burnout air constant.The recommended oxygen values under 90 MW and 60 MW load are 6.5% and 8.5% respectively.
作者
马达夫
刘平元
张守玉
何翔
吴玉新
MA Dafu;LIU Pingyuan;ZHANG Shouyu;HE Xiang;WU Yuxin(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Shanghai Power Equipment Research Institute Co.,Ltd.,Shanghai 200240,China;Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)
出处
《动力工程学报》
CAS
CSCD
北大核心
2023年第2期174-184,共11页
Journal of Chinese Society of Power Engineering
基金
国家自然科学基金重点国际(地区)合作研究资助项目(51761125011)。
关键词
超低负荷
切圆锅炉
运行氧量
燃烧稳定性
NO_(x)排放
ultra-low load
tangentially fired boiler
operation oxygen
combustion stability
NO_(x)emission
