Research Of Fiber Optic Sensor With Multi-channel For Coal Mine

It is gas calamity that imperils the safety of mining industry in our country. It has been the most serious matter which restricts the development of the mining industry. In mining exploitation, hidden trouble in safety has increased gradually. It can not be ignored that the ratio of gas accident to whole mining accident has increased gradually. So, detecting the origin, leak and density of methane (the main component of gas) in time is crucial to the safety of mining industry and personal security and safety.This project is the experiment focusing on fiber-optic sensor and the whole system, so that the system can widely be applied into industrial field. We lay emphasis on the detection of CH4 and C₂H₂, and develop the instrument and data analysis system, which continuously detects the concentration of methane in the environment of excavating working face, wind laneway and so on. Besides, the system can display the instant concentration, alarm at the threshold of limitation, and the frequency signal is output which is linear to methane concentration detected. Our design in fact is the safety and explosive avoid one. That is why it can be used in many dangerous coal mines. In the explosive avoid monitoring system, the system can be used with other monitoring systems, which are compatible. Here, the experiment includes several schemes as follows:1) We detail the spectrum absorption theory and the technology of TDLAS. There are 2 methods of measuring, whose precision are compared based on experiments. Then choose the one with higher precision.2) Using HITRUN to choose absorption apex. Then select the source and photo electricity diode, based on the wavelength and measuring method that is selected.3) According to the theoretical analysis, we design the light path, circuit and gas channel. The feeble signal is obtained by phase locked amplifier. The noise will be restrained in maximum degree. Also the signal to noise ratio will be raised.4) The design is safety in essence, and so it can be suitable for coal mine use. 5) Multi-channel online detection reduces the total cost.6) According to method using dual light source, the research is on fiber-optic sensors detecting multi-gas. Method based on dual light source is carried out and the detailed analysis on feasibility stability and precision are about C₂H₂.