Research Of Distributed Methane Detecting System Based On TDLAS

The rapid economic development of China drive the growth of all walks of life, including mining industry. And it is also making a growing demand for energy of coal. Along with the increasing of the mine, the accident number is also growing up, which make people pay more attention to mine safety problem. In these coal mine accidents, the gas-explosion occupies the most and makes the biggest damage. As methane gas is the main ingredient, methane gas monitoring becomes one of the effective ways to solve this problem.The harmonics of Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology is a new way of gas detection based on spectral absorption. It has a high measurement accuracy, and it can effectively decrease laser intensity shake and other common system noise. As there are some disadvantages in practical application in second harmonic detecting method, such as complex structure and low stability, which is based on TDLAS. The first harmonic is chosen to instead to detect the concentration of methane in this paper.At the same time, some optical devices in the system make the multipoint monitoring cost more if using single detector in a large place. In this paper, a multipoint methane sensing system is built based on this technology. It divides the emergent light by optical splitter, using the time division multiplexing to merge the signals, and then processing the signals to get the harmonic amplitudes, thus we can realize the multipoint monitoring. In this paper, I made a simulation of this system based on TDLAS. And the result basically verifies the feasibility of distributed monitoring system based on time division multiplexing theoretically.This system,which using time division multiplexing system, inherits the advantages of TDLAS. And it can make it easier to lay the optical cable and do the remote monitoring. It can be used in the mine and some other places.