碘量法分析天然气中H2S浓度的不确定度评定

Uncertaintyevaluationofmeasuringhydrogensulfidecontentinnaturalgasbyiodometrictitrationmethod

关键词:  碘量法 H2S 天然气 不确定度

Key words:  iodometrictitrationmethod,H2S,naturalgas,uncertainty

摘要:

分析了应用碘量法测定天然气中H2S浓度的不确定度的影响因素,得出测量不确定度的 主要来源为硫代硫酸钠标准溶液标定、H2S采样吸收、吸收液滴定以及重复测定4个部分。分析得出 硫代硫酸钠标准溶液引入的相对不确定度为0.082%,H2S采样吸收引入的相对不确定度为0.16%,吸 收液滴定引入的不确定度为0.17%,重复测量引入的不确定度范围为0.71%~7.07%。当被测样品中 的H2S质量浓度为12.5mg/m3 时,取置信度为95%,包含因子k=2,则其扩展不确定度U =7.08%。

Abstract:

Abstract:Uncertaintiesoriginatingfrom the measurementof H2Scontentin naturalgasby iodometrictitration method wereevaluated.Theuncertainties were mainly obtainedfrom four sources:thecalibrationofsodiumthiosulfatestandardsolution,bubbleabsorptionmethodforH2S, titratedanalysis ofabsorptionliquid andrepetitive measurement.From results ofuncertainty analyses,theuncertaintyvaluesoffourfactorswere0.082%,0.16%,0.17% and0.71%~7.07% respectively.WhentheconcentrationofH2Sinsamplewas12.5 mg/m3,thedesignedconfidence levelwas95% andconveragefactor(k)was2,therelativeexpandeduncertainty (U )oftheH2S concentrationwas7.08%.