某电厂燃煤锅炉SOFA率对燃烧特性影响分析
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摘要
空气分级燃烧技术已经成为燃煤电站低氮燃烧主要手段之一。为探究不同燃尽风率对锅炉燃烧及NO_X排放的影响,应用数值模拟的方法研究不同燃尽风率下,炉膛温度、烟气组分、炉膛出口NO_X排放浓度以及飞灰含碳量的变化。结果表明,燃尽风率不断提高,燃烧过程被推迟,主燃区的温度会随之降低;同时,随燃尽风率的提高,NO_X排放浓度不断降低,但炉膛出口飞灰含碳量不断升高,且变化速率越来越大。燃煤电站在应用空气分级技术时,要综合考虑NO_X排放浓度与飞灰含碳量,将燃尽风率控制在合理的范围内。
Air staged combustion technology has become one of the main means of low-nitrogen combustion in coalfired power plants. In order to explore the effects of different separated over fire air( SOFA) rates on boiler combustion and NO_X emissions,the changes offurnace temperature,flue gas composition,NO_X emission concentration at furnace outlet and carbon content of fly ashunder different SOFA rates arestudied by numerical simulations. The results showed that with the increase of SOFA rate,the combustion process isdelayed,and the temperature of main combustion zone decreases accordingly. At the same time,with the increase of SOFA rate,the concentration of NO_X emission decreasescontinuously,but the carbon contentof fly ash at the furnace outlet keeps increasing,and the rate of change is increasing. In the application of air-stagingtechnologyin coal-fired power plants,the concentration of NO_X emission and carbon content of fly ash should be considered comprehensivelyto control the SOFA ratewithin a reasonable range.
Air staged combustion technology has become one of the main means of low-nitrogen combustion in coalfired power plants. In order to explore the effects of different separated over fire air( SOFA) rates on boiler combustion and NO_X emissions,the changes offurnace temperature,flue gas composition,NO_X emission concentration at furnace outlet and carbon content of fly ashunder different SOFA rates arestudied by numerical simulations. The results showed that with the increase of SOFA rate,the combustion process isdelayed,and the temperature of main combustion zone decreases accordingly. At the same time,with the increase of SOFA rate,the concentration of NO_X emission decreasescontinuously,but the carbon contentof fly ash at the furnace outlet keeps increasing,and the rate of change is increasing. In the application of air-stagingtechnologyin coal-fired power plants,the concentration of NO_X emission and carbon content of fly ash should be considered comprehensivelyto control the SOFA ratewithin a reasonable range.
引文
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[3]蒋信,范卫东,赵达,等.大同烟煤空气分级燃烧NOX生成特性的试验研究[J].锅炉技术,2016,47(1):54-58.JIAN GXin,FAN Weidong,ZHAO Da,et al. Experimental research on NOXemission of Datong bituminous coal in air-staged combustion[J]. Boiler Technology,2016,47(1):54-58.
[4]王科,王贲,于洁,等. SOFA参数对W锅炉燃烧及NOX排放影响的数值模拟[J].煤炭学报,2018,43(3):839-845.WANG Ke,WANG Ben,YU Jie,et al. Influence of separated overfire-air parameters on combustion and NOXemission characteristics for ababcock&wilcox(B&W)down-fired boiler[J]. Journal of China Coal Society,2018,43(3):839-845.
[5]孙保民,王顶辉,段二朋,等.空气分级燃烧下NOX生成特性的研究[J].动力工程学报,2013,33(4):261-266.SUN Baomin,WANG Dinghui,DUANErpeng,et al. Investigation on NOXFormation Characteristics Under air-staged combustion[J]. Chinese Journal of Society Power Engineering,2013,33(4):261-266.
[6]刘敦禹,秦明,刘辉,等.深度空气分级条件下炉内氮氧化物生成的数值模拟[J].燃烧科学与技术,2011,17(5):469-475.LIU Dunyu,QIN Ming,LIU Hui,et al. Numerical simulation of NOXproduction under deep air staged combustion in furnace[J].Journal of Combustion Science and Technology,2011,17(5):469-475.
[7]刘帅,孙路石,李楠,等. 300 MW四角切圆锅炉燃尽风布置方式对低氮燃烧特性的影响[J].工程热物理学报,2015,36(10):2293-2297.LIU Shuai,SUN Lushi,LI Nan,etal. Influence of arrangement form of SOFA on low NOXcombustioncharacteristics of a 300 MW tangential boiler[J]. Journal of Engineering Thermophysics,2015,36(10):2293-2297.
[8] HU L,LIU Y,YI G,et al. Effects ofair staging conditions on the combustion and NOXemission characteristics in a 600 MW wall fired utility boiler using lean coal[J]. Energy&Fuels,2013,27(10):5831-5840.
[9] CHEN H,LIANG Z. Damper opening optimization and performance of a co-firing boiler in a 300 MW eplant[J]. Applied Thermal Engineering,2017,123.
[10]王顶辉.煤粉锅炉燃烧特性及降低氮氧化物生成的技术研究[D].北京:华北电力大学,2014.WANG Dinghui. Study on combustion characteristics andlowerNOXtechnology for pulverized coal boiler[D]. Beijing:North China Electric Power University,2014.
[11]张宏伟,王波,袁益超,等. 900MW超临界锅炉混煤燃烧的数值模拟[J].锅炉技术,2014,45(6):47-52.ZHANG Hongwei,WANG Bo,YUAN Yichao,et al. Numerical simulation of co-combustion of blended coal in a 900MW supercritical boiler[J]. Boiler Technology,2014,45(6):47-52.