低氮改造对四角切圆锅炉NO_x生成特性的影响
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摘要
对某300 MW四角切圆锅炉低氮改造前后NOx的生成特性进行了数值计算,分析了低氮改造对NOx生成特性的影响.结果表明:原有双通道自稳燃型燃烧器稳燃腔的设计明显加速了热力型NOx的生成;新型水平浓淡燃烧器浓侧和淡侧煤粉均处于偏离化学当量比条件下燃烧,喷口附近火焰温度明显降低,有利于控制热力型NOx的生成,缺氧燃烧降低了煤粉的燃烧效率,冷灰斗区域及三次风以上区域燃料型NOx的生成速率有所增大.
Numerical simulation was conducted to NOxformation characteristics in a 300 MW tangentiallyfired boiler before and after low-NOxretrofit,so as to analyze the effects of low-NOxretrofit on the NOx formation characteristics.Results show that the design of stabilized combustion cavity in the original dualchannel self-stabling burner obviously increases its thermal NOxemission.The combustion of both dense and dilute pulverized coal-air mixture flow in the new horizontal bias burner is under the condition deviating from the chemical equivalent ratio,which lowers the flue gas temperature around burners and compresses the emission of thermal NOx.Rare oxygen combustion also reduces the combustion efficiency,and increases the production of fuel NOxin cold ash hopper and in upper furnace area above tertiary air flow.
Numerical simulation was conducted to NOxformation characteristics in a 300 MW tangentiallyfired boiler before and after low-NOxretrofit,so as to analyze the effects of low-NOxretrofit on the NOx formation characteristics.Results show that the design of stabilized combustion cavity in the original dualchannel self-stabling burner obviously increases its thermal NOxemission.The combustion of both dense and dilute pulverized coal-air mixture flow in the new horizontal bias burner is under the condition deviating from the chemical equivalent ratio,which lowers the flue gas temperature around burners and compresses the emission of thermal NOx.Rare oxygen combustion also reduces the combustion efficiency,and increases the production of fuel NOxin cold ash hopper and in upper furnace area above tertiary air flow.
引文
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[16]FANG Q,MUSA A A B,WEI Y,et al.Numerical simulation of multi fuel combustion in a 200MW tangentially fired utility boiler[J].Energy&Fuels,2012,26(1):313-323.
[2]谢毓麟,陈春元,许传凯,等.大型煤粉锅炉燃烧设备性能设计方法[M].哈尔滨:哈尔滨工业大学出版社,2002:14-15.
[3]陆燕荪,周鹤良,杨锦山,等.火力发电设备技术手册[M].北京:机械工业出版社,1999:14-15.
[4]路春美,王永征.煤燃烧理论与技术[M].北京:地震出版社,2001:167-179.
[5]ZHOU H,MO G,ZHAO J,et al.DEM-CFD simulation of the particle dispersion in a gas-solid two-phase flow for a fuel-rich/lean burner[J].Fuel,2011,90(4):1584-1590.
[6]安恩科,杨震,宋谦.浓淡煤粉燃烧器双通道速度差对NOx排放的影响[J].同济大学学报(自然科学版),2009,37(4):537-539.AN Enke,YANG Zhen,SONG Qian.Effect of velocity difference of two channels in biased pulverized-coal concentration burners on NOx emissions[J].Journal of Tongji University(Natural Science),2009,37(4):537-539.
[7]毕明树,张丛,周一卉.煤粉浓淡空气分级燃烧过程的数值模拟[J].动力工程学报,2010,30(8):612-616.BI Mingshu,ZHANG Cong,ZHOU Yihui.Numerical simulation on processes of pulverized coal bias airstaged combustion[J].Journal of Chinese Society of Power Engineering,2010,30(8):612-616.
[8]孙保民,王顶辉,段二鹏,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,DUAN Erpeng,et al.Investigation on NOxformation characteristics under air-staged combustion[J].Journal of Chinese Society of Power Engineering,2013,33(4):261-266.
[9]ZHOU Hao,MO Guiyuan,SI Dongbo.Numerical simulation of the NOxemissions in a 1 000 MW tangentially fired pulverized coal boiler:influence of the multi group arrangement of the separated over fire air[J].Energy&Fuels,2011,25(5):2004-2012.
[10]ABBAS A,NASER J,HUSSEIN E K.Numerical simulation of brown coal combustion in a 550 MW tangentially fired furnace under different operating conditions[J].Fuel,2013,107:688-698.
[11]CHOENG R C,CHANG N K.Numerical investigation on the flow,combustion and NOxemission characteristics in a 500MWe tangentially fired pulverizedcoal boiler[J].Fuel,2009,88(9):1720-1731.
[12]CHUI E H,GAO H.Estimation of NOxemissions from coal fired utility boilers[J].Fuel,2010,89(10):2977-2984.
[13]CONSTENLA I,FERRN J L,SAAVEDRA L.Numerical study of a 350MWe tangentially fired pulverized coal furnace of the As Pontes Power Plant[J].Fuel Processing Technology,2013,116:179-200.
[14]VUTHALURU H B,VUTHALURU R.Control of ash related problems in a large scale tangentially fired boiler using CFD modeling[J].Applied Energy,2010,87(4):1417-1426.
[15]HABIB M A,BEN M R,ABUALHAMAYEL H I,et al.Thermal and emission characteristics in a tangentially fired boiler model furnace[J].International Journal of Energy Research,2010,34(13):1164-1182.
[16]FANG Q,MUSA A A B,WEI Y,et al.Numerical simulation of multi fuel combustion in a 200MW tangentially fired utility boiler[J].Energy&Fuels,2012,26(1):313-323.
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