Methane gas detection technology and its application in coal mines

Gas disaster is one of the main disaster that restricts coal mine safety production,and methane is the main component of gas. Therefore,accurate detection of methane concentration is of great significance for effective prevention and early warning of gas disasters.Based on the different characteristics of the physical and chemical properties of methane,the principles of methane detection by catalytic combustion,thermal conductivity,optical interference,non-dispersive infrared spectroscopy,and tunable semiconductor laser spectroscopywere summarized,and the development status of methane detection technologies with different principles were discussed.Based on the analysis of the impact of coal mine environment on methane detection technology,the following conclusions are drawn from the comparative study of technology application in underground coal mine:catalytic combustion method uses the flammability characteristics of methane and is suitable for detecting methane with a concentration of less than 4%. It is not suitable for low oxygen concentration,and downhole environment where methane concentration is too high or there are sulfur-containing gases;the thermal conductivity method uses the characteristics of different thermal conductivity of air containing methane concentrations. It is suitable for detecting methane with a concentration of more than 4%,and it is not suitable for underground environments such as low methane concentration and high carbon dioxide concentration;optical interference method uses the different refractive index characteristics of air containing different methane concentrations,which is suitable for most downhole environments,but not suitable for downhole environments with excessive carbon dioxide concentration.Infrared spectroscopy uses the characteristic of methane gas selective absorption and it is suitable for most downhole environments. Among them,non-dispersive infrared spectroscopy is interfered by water vapor and alkane gas,and algorithm optimization is required to reduce errors.Tunable semiconductor laser absorption spectroscopy is less affected by interference of other gases,but both require compensation algorithms to reduce the error caused by the influence of temperature and humidity.Finally,a comprehensive comparative analysis of the technical applicability of different principles of methane gas detection methods is carried out in order to provide reference and guidance for the application of coal mine methane detection technology.