Development and field deployment of a mid-infrared methane sensor without pressure control using interband cascade laser absorption spectroscopy

Abstract

A mid-infrared methane (CH 4 ) sensor without pressure control was developed using a continuous-wave (CW) interband cascade laser (ICL) for targeting a CH 4 absorption line located at 3038.5 cm -1 . A multi-pass gas cell with an absorption path length of 54.6 m was utilized for enhancing gas absorption.The pressure inside the MPGC was measured using direct Lorentzian absorption fitting for the compensation of CH 4 concentration changes resulting from pressure variations. Laboratory pressure calibration was conducted in the range of 25 − 800 Torr using 1.3-, 1.5-, 1.7-and 2.1-ppmv CH 4 samples.A pressure precision of ~ 1.65 Torr with a ~ 2.5-s averaging time was achieved based on the measurement of a 2.1-ppmv CH 4 sample at 700-Torr. Concentration level measurements of a 2.1-ppmv CH 4 sample at a 700-Torr pressure yielded an Allan deviation of 2.25 ppbv for an averaging time of 2.5 s.The sensor functioned normally with CH 4 samples at 1.0, 1.2, 1.4, 1.6 and 2.1 ppmv concentration levels as the pressure changes from 25 to 800 Torr. Indoor/outdoor CH 4 concentration measurements on the Rice University campus and a field campaign in the Greater Houston Area (GHA) were conducted to evaluate the performance of the sensor system.

Recent Developments in Modulation Spectroscopy for Methane Detection Based on Tunable Diode Laser

“…Moreover, an external cavity quantum cascade laser (EC-QCL), covering the absorption lines of four atmospheric greenhouse gases, was applied in a sensor system [86]. Additionally, gallium antimonite (GaSb)-based ICLs have been used for mid-infrared sensing [87,88]. In addition, the commercial availability of ICLs was achieved in 2009.…”

“…The weight of the oil-free vacuum pump and pressure controller and readout in the system was heavy. To address the limitations, new portable sensor systems were developed [88,89], in which competitive performances were revealed compared with other reported portable or handheld sensor devices. Mid-infrared sources based on DFG effects are also employed for methane detection.…”

Double-range near-infrared acetylene detection using a dual spot-ring Herriott cell (DSR-HC)

“…Accurate measurement and monitoring on C 2 H 2 in the industrial field is therefore extremely important for assuring a high quality of raw petrochemical materials and products [1][2][3][4]. Tunable laser absorption spectroscopy (TDLAS) has been widely used in trace gas detection because of its non-intrusive, sensitive and selective sensing characteristics [5][6][7]. For example, based on TDLAS technique, both near-and mid-infrared sensor systems were proposed for C 2 H 2 detection using a 76 m long-path absorption cell (AMAC-76, Aerodyne Research Inc) [8] and a 15 cm gas absorption cell [9].…”

Interband cascade laser based mid-infrared methane sensor system using a novel electrical-domain self-adaptive direct laser absorption spectroscopy (SA-DLAS)

“…Furthermore as an inflammable and explosive gas, CH 4 is a safety hazard in several industries, such as natural gas production/distribution/storage/transportation, coal mining, and the handling of liquefied CH 4 . Different applications in environmental science, public safety and industrial monitoring have become a driving force for the development of sensitive, accurate, robust and in situ CH 4 sensor systems [3][4][5][6][7][8]. Compared with conventional mass spectrometry or gas chromatography, infrared laser spectroscopy offers several key advantages in terms of size, time resolution as well as cost and requires no pretreatment and/or accumulation of the concentration of the targeted gas samples, which makes infrared laser spectroscopy particularly suitable for real-time gas sensing applications [9][10][11][12].…”