Study on Mash Gas Monitoring with Distributed Multipoint Fiber Optic Sensors System in Coal Mine

Fast, accurate, real-time measurement of gas concentration is an important task for preventing the coal mining disaster. Combining tunable diode laser absorption spectroscopy (TDLAS) technique with distributed fiber sensing technique, a multipoint fiber optic sensors system for gas monitoring is designed. The wavelength modulation technique and harmonic detection techniques are used to obtain the necessary sensitivity. Simulating experiment is carried out, and the influence of the laser intensity fluctuation for measurement is eliminated by I_2f/I₀. The detective limit of the system is below 0.05%, the time resolution is 1s. The system offers a simple, intrinsically safe design with fiber optic sensors head, and carries out real-time, fast, continuous and non-intrusive measurement which meets the requirements of coal mining gas monitoring.