Near-infrared incoherent broadband cavity enhanced absorption spectroscopy (NIR-IBBCEAS) for detection and quantification of natural gas components

Abstract

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.

Dual-cavity spectrometer for monitoring broadband light extinction by atmospheric aerosols

“…The estimation of measurement uncertainty in the retrieved extinction coefficients of aerosols from Equation (1), was carried out using a standard propagation of errors (Varma et al 2009;Prakash et al 2018). The uncertainty in the extinction coefficient DE was calculated from…”

“…This simple, cost effective method does not require mode matching, which makes it suitable for field measurements. IBBCEAS has been effectively used to quantify trace gases like NO 2 (Ball, Langridge, and Jones 2004), NO 3 (Suhail et al 2019;Ball, Langridge, and Jones 2004;Venables et al 2006), I 2 (Dixneuf et al 2009;Ball, Langridge, and Jones 2004), HONO (Gherman et al 2008), glyoxal (Washenfelder et al 2008), natural gases (Prakash et al 2018), 1,4-dioxane (Chandran and Varma 2016), etc. in both laboratory and in-situ field measurements.…”

Accurate analysis of HCl in biomethane using laser absorption spectroscopy and ion-exchange chromatography

“…Laser absorption spectroscopy has been demonstrated for accurate HCl and other gas species amount fraction measurements in a variety of applications. [7][8][9][10][11][12][13][14] So far, reports on laser spectroscopic measurements of HCl in biomethane, addressing traceability of the results to the international system of units (SI), are lacking. Direct tunable diode laser absorption spectroscopy (dTDLAS) and wavelength modulation spectroscopy ((WMS) with comparably higher sensitivity 2,9 ) specifically as demonstrated in other applications 2,8,9,11 are good candidates for the development of test methods for HCl concentration measurements in biomethane.…”

Near-Infrared Broadband Cavity-Enhanced Spectroscopic Multigas Sensor Using a 1650 nm Light Emitting Diode

“…In 2015, Chandran et al reported a SC-based NIR-IBBCEAS setup to record the absorption of 1,4-dioxane using a 644-cm-long cavity consisting of two highly reflective mirrors (99.9%), leading to a detection limit of 8 × 10 –8 cm –1 in a 120 min averaging time . In 2018, Prakash et al developed a NIR-IBBCEAS sensor for the detection of natural gas mixtures, and a detection limit (3σ) of 460 ppmv, 141 ppmv, 175 ppmv, and 173 ppmv for methane (CH 4 ), butane (C 4 H 10 ), ethane (C 2 H 6 ), and propane (C 3 H 8 ), respectively, was achieved . In our previous work, an NIR-IBBCEAS sensor system in combination with a Fourier-transform spectrometer was developed for high-resolution CH 4 detection.…”