Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, 2500 University Dr NW, Calgary, AB, CanadaT2N 1N4.
Applied Optics and Instrumentation Laboratory, Department of Physics, National Institute of Technology Calicut, Calicut 673601, Kerala, India.
Analyst. 2018 Jul 21;143(14):3284-3291. doi: 10.1039/c8an00819a. Epub 2018 Jun 28.
The principle of near-infrared incoherent broadband cavity enhanced absorption spectroscopy was employed to develop a novel instrument for detecting natural gas leaks as well as for testing the quality of natural gas mixtures. The instrument utilizes the absorption features of methane, butane, ethane, and propane in the wavelength region of 1100 nm to 1250 nm. The absorption cross-section spectrum in this region for methane was adopted from the HITRAN database, and those for the other three gases were measured in the laboratory. A singular-value decomposition (SVD) based analysis scheme was employed for quantifying methane, butane, ethane, and propane by performing a linear least-square fit. The developed instrument achieved a detection limit of 460 ppm, 141 ppm, 175 ppm and 173 ppm for methane, butane, ethane, and propane, respectively, with a measurement time of 1 second and a cavity length of 0.59 m. These detection limits are less than 1% of the Lower Explosive Limit (LEL) for each gas. The sensitivity can be further enhanced by changing the experimental parameters (such as cavity length, lamp power etc.) and using longer averaging intervals. The detection system is a low-cost and portable instrument suitable for performing field monitorings. The results obtained on the gas mixture emphasize the instrument's potential for deployment at industrial facilities dealing with natural gas, where potential leaks pose a threat to public safety.
采用近红外非相干宽带腔增强吸收光谱原理，开发了一种用于检测天然气泄漏和测试天然气混合物质量的新型仪器。该仪器利用甲烷、丁烷、乙烷和丙烷在 1100nm 至 1250nm 波长范围内的吸收特性。该区域内甲烷的吸收截面光谱取自 HITRAN 数据库，其他三种气体的吸收截面光谱在实验室中测量。采用基于奇异值分解（SVD）的分析方案，通过进行线性最小二乘拟合来定量甲烷、丁烷、乙烷和丙烷。开发的仪器对于甲烷、丁烷、乙烷和丙烷的检测极限分别为 460ppm、141ppm、175ppm 和 173ppm，测量时间为 1 秒，腔长为 0.59 米。这些检测极限均小于每种气体的爆炸下限（LEL）的 1%。通过改变实验参数（如腔长、灯功率等）和使用更长的平均间隔，可以进一步提高灵敏度。该检测系统是一种低成本、便携式仪器，适用于进行现场监测。在天然气处理工业设施中，潜在的泄漏会对公共安全构成威胁，因此该仪器在这些设施中的应用潜力巨大。
