基于激光诱导击穿光谱的燃煤热值定量分析

煤的热值是影响燃煤锅炉运行最重要的煤质特性之一。燃煤热值在线分析能够为实时优化调整锅炉运行提供重要依据。采用激光诱导击穿光谱技术对烟煤样品热值进行了定量分析。实验用Nd:YAG固体激光器1 064 nm激光脉冲在空气环境下烧蚀烟煤样品表面而形成等离子体。采用偏最小二乘法和基于主导因素的偏最小二乘法提高煤热值定量分析的准确性。对于基于主导因素的偏最小二乘法，利用碳双原子分子（C2）和碳氮双原子分子（CN）的谱线强度建立主导因素模型。采用偏最小二乘法建立的定标曲线拟合优度和预测均方根误差分别为0.94和1.46 MJ/kg；采用基于主导因素的偏最小二乘法建立的定标曲线拟合优度和预测均方根误差分别为0.99和1.18 MJ/kg。结果表明:激光诱导击穿光谱技术对燃煤热值在线分析具有很大的应用潜力。

Quantitative analysis of heat value of coal by laser-induced breakdown spectroscopy

The heat value of coal is one of the most important coal properties that affects the operation of coal -fired boilers. The on -line analysis of heat value of coal can provide important reference for optimizing and adjusting the boiler operation in real time. The heat values of bituminous coal samples were quantitatively analyzed by laser -induced breakdown spectroscopy (LIBS). The 1 064 nm laser radiation emitted by a Q-switched Nd:YAG laser was utilized for laser ablation and plasma generation in air. The partial least square (PLS) method and the dominant factor based PLS method were used to improve the measurement accuracy of heat value of coal. In the dominant factor based PLS model, the molecular emissions of C2 and CN were utilized to build the dominant factor model. The coefficient of determination and the root-mean-square error of prediction of the PLS model were 0.94 and 1.46 MJ/kg, respectively; and those values for the dominant factor based PLS model were 0.99 and 1.18 MJ/kg, respectively. The results show that LIBS has great potential for the on-line analysis of heat value of coal.