一种天然气组成分析结果的不确定度评定方法

Uncertainty Evaluation on Composition Analysis Results of Natural Gas by Gas Chromatography

关键词:  气相色谱  不确定度  单点外标  校正因子

Key words:  gas chromatography  uncertainty  singlepoint external standard calibration  correction factor

摘要:

针对用外标法和比例校正归一法定量的天然气组成气相色谱常规分析,研究了其结果的不确定度来源及评定方法,以实例说明了评定步骤,并分析了各因素对评定结果的影响程度。结果 表明,浓度越高的组分重复性引入的不确定度值也越大;单点外标定量时校正因子变动性引入的不确定度不应忽略;仅规定标准气的浓度范围可能得不到准确的外标定量结果;组分含量较小时,使用推荐的FID相对校正因子有可能满足定量准确度要求。

Abstract:

The uncertainty of the composition analysis results of natural gas by gas chromatography was evaluated,which were quantified by external reference method and modified normalization method. The sources of uncertainty and their influence factors on analysis results were analyzed as well. It was found that one component of higher concentration accompanied with a larger value of uncertainty brought by repeatability. The uncertainty brought by calibration factor should not be neglected when a single point external standard calibration was conducted. Accurate quantitative results may not be acquired only reference gas in accordance with one certain concentration range was applied.Acceptable results may be acquired quantified by recommendatory FID relative correction factors when low concentration components were analyzed.