Study On Fiber Methane Sensing System Using FBG Filters

Methane is a flammable and explosive gas. It is the main component of mine gas and many liquid fuels. In recent years, the explosion of mine gas happened from time to time, which resulted in the number of people died from mine gas explosion was half of total number of people died from accidents. These have caused great threats to the miners’ lives and State property. It is significant to measuring and monitoring the concentration of methane real-time, for when the concentration of methane reach between4.9%and5%, it is easily to cause mine gas explosion with enough oxygen and flames.This article is designed gas detection program (FBG) and EFPI sensors based on fiber Bragg grating, the establishment of a broadband light source SLD methane gas detection system, measuring gas. This paper introduces the background and significance of the present situation of gas sensing fiber and this research. And describes the absorption line spectrum of a typical absorbance detector, and the general principles of selective absorption of gas molecules theory, the general gas molecules to determine the feasibility of detection of the absorption spectrum. Using detection methods have a variety of general interference and influence, so we chose FBG filter to reduce the interference source of instability and background absorption. Through the introduction of fiber gratings, we know that only light in order to satisfy the Bragg condition is reflected back into the fiber grating fiber, fiber grating that can be seen as narrow-band filter. In addition to the EFPI sensors were introduced and the principle of derivation formula will be applied to detect methane gas. The experiment uses a software platform LasIRView, the software enables two-way synchronous communication, which can meet the requirements of real-time online monitoring. The software also incorporates a user interface with a graphical interface, and can clearly facilitate observation and testing.Finally, the calculation of the sensitivity of the detection system analysis conducted a comparison test, measurement repeatability and stability of the experiment including fiber link loss experiments, real-time monitoring of the experiment, methane gas absorption experiments, cross-sensitivity experiments, experiments, showing the value of the gas detection system the overall experiment. Experimental results show that the designed...