单煤粉颗粒着火特性的激光辅助高速摄像测量
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摘要
针对煤粉的着火特性,基于平面火焰燃烧器,应用自行开发的连续激光辅助高速摄像的测量方法对煤粉颗粒的着火过程进行了连续捕捉,系统地研究了空气条件下着火过程中的单煤粉颗粒的尺寸、形貌、温度和着火延迟特性.研究发现环境温度1 800 K的空气气氛下,粒径分布为74～98μm的神华烟煤为均相着火;煤粉颗粒析出的挥发分首先氧化燃烧并形成球形的包覆火焰;待挥发分消耗后,继而发生煤焦异相的着火燃烧;煤粉颗粒温度分布进一步证明了煤焦燃烧是非均匀的.
The ignition characteristics of single pulverized coal particles were investigated using a Hencken burner. A laser-assisted high-speed camera was used to image the ignition process,after which the size,shape,temperature,and ignition delay time of the pulverized coal were examined in detail. Shenhua bituminous coal with particle diameter of 74—98 μm underwent homogeneous ignition under an ambient temperature of 1 800 K. The volatiles of the pulverized coal were released and ignited to form a spherical coating flame. When these volatiles were completely consumed,heterogeneous ignition of char began to occur,representing the formation of luminous intensity emitted from the particle surface. The temperature distribution of coal particles demonstrates that combustion on the char surface was non-uniform.
The ignition characteristics of single pulverized coal particles were investigated using a Hencken burner. A laser-assisted high-speed camera was used to image the ignition process,after which the size,shape,temperature,and ignition delay time of the pulverized coal were examined in detail. Shenhua bituminous coal with particle diameter of 74—98 μm underwent homogeneous ignition under an ambient temperature of 1 800 K. The volatiles of the pulverized coal were released and ignited to form a spherical coating flame. When these volatiles were completely consumed,heterogeneous ignition of char began to occur,representing the formation of luminous intensity emitted from the particle surface. The temperature distribution of coal particles demonstrates that combustion on the char surface was non-uniform.
引文
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[2]Yuan Y,Li S,Zhao F,et al.Characterization on hetero-homogeneous ignition of pulverized coal particle streams using CH*chemiluminescence and 3 color pyrometry[J].Fuel,2016,184:1000-1006.
[3]余岳峰,赵铁成,徐伟勇.煤粉燃烧火焰着火判据[J].上海交通大学学报,2000,34(9):1253-1256.Yu Yuefeng,Zhao Tiecheng,Xu Weiyong.Analyzing the judgement of flame in pulverized coal combustion[J].Journal of Shanghai Jiao Tong University,2000,34(9):1253-1256(in Chinese).
[4]邹高鹏.基于光学诊断型携带流反应器的煤粉着火及燃烧特性研究[D].哈尔滨:哈尔滨工业大学能源科学与工程学院,2016.Zou Gaopeng.Ignition and Combustion Characteristics of Pulverized Coal Based on Optical Entrained Flow Rector[D].Harbin:School of Energy Science and Engineering,Harbin Institute of Technology,2016(in Chinese).
[5]Murphy J J,Shaddix C R.Combustion kinetics of coal chars in oxygen-enriched environments[J].Combustion and Flame,2006,144(4):710-729.
[6]Molina A,Shaddix C R.Ignition and devolatilization of pulverized bituminous coal particles during oxygen/carbon dioxide coal combustion[J].Proceedings of the Combustion Institute,2007,31(2):1905-1912.
[7]Shaddix C R,Molina A.Particle imaging of ignition and devolatilization of pulverized coal during oxy-fuel combustion[J].Proceedings of the Combustion Institute,2009,32(2):2091-2098.
[8]Lee H,Choi S.An observation of combustion behavior of a single coal particle entrained into hot gas flow[J].Combustion and Flame,2015,162(6):2610-2620.
[9]栗晶.水平槽道气固两相湍流变动的PIV实验研究和直接数值模拟[D].武汉:华中科技大学能源与动力工程学院,2010.Li Jing.PIV Measurements and Direct Numerical Simulation of Turbulence Modification in a Horizontal Particle-laden Channel Flow[D].Wuhan:School of Energy and Power Engineering,Huazhong University of Science and Technology,2010(in Chinese).