Research on Portable Methane Telemetry System Based on TDLAS

This work studies the key technology of a non-contact and long-distance methane-measuring instrument based on tunable diode laser absorption spectroscopy (TDLAS) due to the difficulties in real-time monitoring of methane leaks over a large area and the challenges of installing sensors. Using Beer–Lambert law as the theoretical basis, the spectral line information of methane gas recorded in the high-resolution transmission (HITRAN) database is compared to select the mature light source technology of the 1653.72 nm absorption line. Through simulation and analysis of the optical path within the detection distance of 0–100 m, the size of the optical system is designed to be minimized, and the sensor can be installed in portable equipment or monitoring probes. A reference gas chamber is specially designed in the optical components to provide a feedback optical signal for the system to eliminate the fluctuation of the light source signal and achieve automatic peak searching. The detection accuracy within ten meters is improved from 200 to 130 ppm, and the dynamic monitoring accuracy is maintained at 0.3–3.6% with a detection speed of one second. After multiple experiments, the system is proven to be stable and reliable with fast response speed, which meets the requirements of real-time methane gas detection applications.