Soot formation characteristics in a lab-scale turbulent pulverized coal flame with simultaneous planar measurements of laser induced incandescence of soot and Mie scattering of pulverized coal
Soot formation characteristics in a lab-scale turbulent pulverized coal flame with simultaneous planar measurements of laser induced incandescence of soot and Mie scattering of pulverized coal
复制标题
DOI：
10.1016/j.proci.2012.10.002
复制
发表时间：
2013-01-01
影响因子：
3.4
通讯作者：
Akamatsu, Fumiteru
中科院分区：
文献类型：
--
作者：
Hayashi, Jun;Hashimoto, Nozomu;Akamatsu, Fumiteru
采用精细控制的激光诊断方法研究了实验室煤粉火焰的煤烟形成特性。采用激光诱导白炽灯（LII）和米氏散射成像（Mie scattering imaging）同时测量了煤烟体积分数和煤粉颗粒的空间分布。此外，我们还将烟尘体积分数的径向分布与我们之前研究中得到的OH自由基荧光、气体温度和氧气浓度进行了比较[1,2]。结果表明，在测量煤粉火焰中煤烟体积分数时，应严格控制激光脉冲通量。为了使用LII精确测量煤粉火焰中的煤烟体积分数，需要调整激光脉冲的能量，使其足够高，以将所有的煤烟颗粒加热到升华温度，同时又足够低，以避免煤粉颗粒的形貌变化过大，以及来自煤粉颗粒的LII信号与来自煤烟颗粒的LII信号叠加。LII信号强度峰值的径向位置位于Mie散射信号强度峰值和OH自由基信号强度峰值之间。LII信号、OH自由基荧光和Mie散射共存的区域随着燃烧器口上方高度的增加而扩大。同时满足高温、低氧浓度和煤粉颗粒存在的条件时，煤粉火焰中煤烟的形成加快。(C) 2012燃烧研究所。Elsevier Inc.出版。版权所有。
Soot formation characteristics of a lab-scale pulverized coal flame were investigated by performing carefully controlled laser diagnostics. The spatial distributions of soot volume fraction and the pulverized coal particles were measured simultaneously by laser induced incandescence (LII) and Mie scattering imaging, respectively. In addition, the radial distributions of the soot volume fraction were compared with the OH radical fluorescence, gas temperature and oxygen concentration obtained in our previous studies [1,2]. The results indicated that the laser pulse fluence used for LII measurement should be carefully controlled to measure the soot volume fraction in pulverized coal flames. To precisely measure the soot volume fraction in pulverized coal flames using LII, it is necessary to adjust the laser pulse fluence so that it is sufficiently high to heat up all the soot particles to the sublimation temperature but also sufficiently low to avoid including a too large of a change in the morphology of the soot particles and the superposition of the LII signal from the pulverized coal particles on that from the soot particles. It was also found that the radial position of the peak LII signal intensity was located between the positions of the peak Mie scattering signal intensity and peak OH radical signal intensity. The region, in which LII signal, OH radical fluorescence and Mie scattering coexisted, expanded with increasing height above the burner port. It was also found that the soot formation in pulverized coal flames was enhanced at locations where the conditions of high temperature, low oxygen concentration and the existence of pulverized coal particles were satisfied simultaneously. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.