元素分析仪测定煤中碳氢氮含量的不确定度评定  

Evaluation of uncertainty in determination of carbon,hydrogen and nitrogen content in coal by using elemental analyzer

作　　者：龚婉莉 GONG Wanli(China Coal Research Institute Corporation Ltd.,Beijing 100013,China;National Coal Quality Inspection and Testing Center,Beijing 100013,China)

机构地区：[1]煤炭科学技术研究院有限公司,北京100013 [2]国家煤炭质量检验检测中心,北京100013

出　　处：《煤质技术》2023年第2期85-89,96,共6页Coal Quality Technology

基　　金：煤炭科学技术研究院有限公司技术创新II类基金资助项目(2022CX-II-14)。

摘　　要：针对煤中碳氢氮含量的测量不确定度进行评定,可提高实验室检测碳氢氮含量数据的准确性以及提升实验室检测的相应技术水平。采用vario MACRO cube型全自动元素分析仪测定煤中碳、氢、氮元素含量,分析不确定度的来源以建立整个测定过程中不确定度分量的数学模型,并讨论测定过程中测量重复性引入的不确定度、曲线标定时试剂纯度引入的不确定度、用标准煤样确定仪器日校正因子时引入的不确定度、样品称量时引入的不确定度以及仪器示值误差引入的不确定度,计算测定煤中碳、氢、氮含量的合成标准不确定度及扩展不确定度。煤中碳、氢、氮含量及其置信区间分别为50.88%±0.61%、6.04%±0.22%、0.15%±0.03%,其中k=2。各不确定度来源中,使用标准煤样确定仪器校正因子对测定结果的不确定度起主导作用,应严格控制校正过程,选择合适的标准煤样,可有效控制不确定度在较低水平,提高样品检验检测的准确度。Evaluating the uncertainty of measurement of carbon,hydrogen and nitrogen content in coal could improve the accuracy of data of carbon,hydrogen and nitrogen content determined by laboratory and improve the corresponding technical level of laboratory testing.Vario MACRO cube automatic elemental analyzer was used to determine carbon,hydrogen and nitrogen content in coal.The sources of uncertainty were analyzed.The mathematical model of the uncertainty component were established.The uncertainty components such as repetition of determination,reagent purity at curve calibration,determination of daily calibration factor of instrument by using standard coal samples,sample weighing and instrument indication error were discussed.The combined standard uncertainty and extended uncertainty of the carbon,hydrogen and nitrogen content in coal sample were calculated.The content of carbon,hydrogen and nitrogen in coal sample and their confidence intervals were:50.88%±0.61%,6.04%±0.22%,0.15%±0.03%,among which k=2.Among these sources of uncertainty,daily calibration factor of instrument by using standard coal samples played a leading role in the uncertainty of the measurement results.The correction process should be strictly controlled,and the appropriate standard coal samples should be selected to effectively control the uncertainty at a low level,so that the accuracy of measurement could be improved.

关 键 词：元素分析仪 碳氢氮含量 不确定度评定 示值误差 准确度 置信区间 数学模型 

分 类 号：TQ533.1[化学工程—煤化学工程]