A portable laser-based sensor for detecting H2S in domestic natural gas.

• The H 2 S sensor is developed for detecting domestic natural gas based on TDLAS. • A home-made embedded electronics system with an MPC fabricates a compact sensor. • The WMS-2 f /DS-sine technique is employed to reduce external interferences. • The sensor was deployed for real-time and field measurements of H 2 S of natural gas. Hydrogen sulfide (H 2 S) is a highly toxic gaseous component of natural gas that poses a significant hazard during the use of natural gas for domestic purposes; therefore, a high-sensitivity, on-line detection method is extremely important to ensure its safety for domestic use. In this work, a portable sensor was developed based on near-infrared tunable diode laser absorption spectroscopy (TDLAS). A special Herriott multipass cell (MPC) combined with a home-made embedded electronics system allowed for the fabrication of a compact sensor with a size of 50 × 20 × 10 cm3. A rugged movable cell was used for detecting contaminated gas samples. An embedded electronic system with a diameter of 8 cm was implemented to control the laser, acquire and process electronic signal. To reduce external interference, the calibration-free TDLAS (wavelength modulation frequency-2 f /direct sine signal) was employed to suppress common field measurement noise. Based on the results of Allan deviation analysis, the limit of system detection could reach 0.14 ppm using the H 2 S absorption line at 6336.61 cm−1. It is suitable for on-line measurement because of its rapid response time. Its feasibility is validated for monitoring H 2 S in a domestic natural gas of pipeline. This work demonstrates a system for real-time and field measurement of H 2 S, which can be used to address the security risks associated with using natural gas. [ABSTRACT FROM AUTHOR]