Based on the technology of the spectrum absorption and the FBG, the monitoring system realize on line detection of the concentration of methane and oxygen, the temperature and the pressure of the gas in pipeline, and in order to improve the accuracy of the gas detection, we induce the compensation to the gas concentration using the data of the temperature and the pressure. In order to have a effective utilization of the methane in the coal mine gas drainage system, we have to have a accurate measurements of the concentration, the temperature and the pressure of the gas in pipeline. At the same time the dynamic monitoring of the concentration of Oxygen is a sign of the leakage of the pump. This paper gave some data detected in the field of the coal mine gas drainage system.
A 4-element wavelength division multiplexed linear array of asymmetric distributed feedback fiber lasers (DFB-FL), pumped at 1480nm is reported. A very desirable feature of asymmetric DFB-FL is unidirectionality, and relevant principle is presented. Larger output powers are obtained from shorter ends of all the four asymmetric DFB-FLs which are fabricated in our laboratory by phase mask moving method. This obvious advantage has important applications to design sensor array. And furthermore, many experiments are completed to confirm it. Output flatness of the sensor array system presents a good performance with the applications of asymmetric DFB-FLs.
Carbon monoxide is one of the important gases need to be detected in coal mine safety. Detection technology based on signature gas is the primary means of spontaneous combustion forecasting of coal goaf area. Because of the high accuracy requirement of CO concentration in the coal mining applications, we had to introduce more data processig methods to improve the signal-to-noise ratio (SNR), finally to achieve the requirements of coal mining. Therefore, we used three data processing methods to eliminate noises of the CO sensing system which based on the tunable diode laser absorption spectroscopy (TDLAS): Fourier transform, least-squares fitting and Kalman filter. The results show that the combination of three data processing methods had a good inhibitory effect of random noise and interference fringes, etc. and significantly improved the system detection accuracy, the minimum detectable spectral absorption rate could be increased by an order of magnitude. So this high-resolution fiber CO sensing system can better meet the needs of coal mine safety.
Fiber optic methane monitor based tunable diode laser absorption spectroscope technology (TDLAS) is
demonstrated, which is developed for remotely monitoring the concentration of Methane gas at multiple locations. A
DFB LD light source of 1665nm is the key unit in the system.A microprocessor is used to control the driver of DFB LD
and Acquire data.To realize high precision measure of CH4,we use a reference cell. The instrument achived long time
precision of 0.05%(for 0~4% full scale range) and 0.5%(for 0~100% full scale range).The instruments has been used to
monitor the mathane of a VAM Oxidiser unit in methane power generation in a long time .The results of measurement
are shown and discussed in this paper.
We report the development of a comprehensive safety monitoring solution for coal mines. A number of fibre optic
sensors have been developed and deployed for safety monitoring of mine roof integrity and hazardous gases. The
FOS-based mine hazard detection system offers unique advantages of intrinsic safety, multi-location and
multi-parameter monitoring. They can be potentially used to build expert systems for mine hazard early detection and