Determination of char combustion kinetics parameters: comparison of point detector and imaging-based particle-sizing pyrometry.
Determination of char combustion kinetics parameters: comparison of point detector and imaging-based particle-sizing pyrometry.
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DOI：
10.1063/1.4890438
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发表时间：
2014-07
期刊：
影响因子：
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通讯作者：
M. Schiemann;M. Geier;C. Shaddix;N. Vorobiev;V. Scherer
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文献类型：
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作者：
M. Schiemann;M. Geier;C. Shaddix;N. Vorobiev;V. Scherer
在这项研究中，两种德国煤(一种褐煤和一种高挥发分烟煤)在两个不同的实验室中用两种不同的实验构型和光学技术研究了焦炭的燃尽特性，以测量燃烧颗粒的温度和尺寸。这两个系统的光学诊断硬件有很大的不同，但都对在高温层流中相互隔离燃烧的单个颗粒进行双色测温和光学尺寸测量，以表征焦炭消耗动力学。比较了两种不同的燃烧气氛(氧气体积分数分别为6.6%和12%)和1700~1800K的燃气温度下专用系统的性能。在颗粒燃尽过程中，测量的颗粒温度和直径被转换为几个停留时间的煤焦燃速参数。结果证实，尽管在基于成像的高温计设置中观察到测量数据的更高水平的可变性，但两种配置获得的结果具有可比性。相应的动力学参数的不确定度较大，当实验中使用较低的氧含量时，动力学参数对系统测量误差似乎更敏感。因此，在氧气含量足够高的环境中进行燃尽实验可以用来测量可靠的煤焦燃烧动力学速率。根据对两种煤的模拟结果，对于100μm颗粒的动力学速率测量，O2浓度建议在10%-30%的范围内。
In this study, the char burnout characteristics of two German coals (a lignite and a high-volatile bituminous coal) were investigated using two different experimental configurations and optical techniques in two distinct laboratories for measurement of temperature and size of burning particles. The optical diagnostic hardware is quite different in the two systems, but both perform two-color pyrometry and optical sizing measurements on individual particles burning in isolation from each other in high-temperature laminar flows to characterize the char consumption kinetics. The performance of the specialized systems is compared for two different combustion atmospheres (with 6.6 and 12 vol.% O2) and gas temperatures between 1700 and 1800 K. The measured particle temperatures and diameters are converted to char burning rate parameters for several residence times during the course of the particles' burnout. The results confirm that comparable results are obtained with the two configurations, although higher levels of variability in the measured data were observed in the imaging-based pyrometer setup. Corresponding uncertainties in kinetics parameters were larger, and appear to be more sensitive to systematic measurement errors when lower oxygen contents are used in the experiments. Consequently, burnout experiments in environments with sufficiently high O2 contents may be used to measure reliable char burning kinetics rates. Based on simulation results for the two coals, O2 concentrations in the range 10%-30% are recommended for kinetic rate measurements on 100 μm particles.