Photoacoustic Combined Method Research Sensing For Methane And Coal Dust In The Mine

The gas (CH4) explosion and dust explosion often happened with each other in coal mine. The concentration of CH4 and coal dust was detected separately in the past, which were bad for coal mine gas and coal dust explosion accurately forecast. This paper presents a photoacoustic method to meter CH4 and dust concentration simultaneously in the mine gas. The mine gas, including gaseous components and dust particles, were metered in the measuring cell between the light source and the photoacoustic cells. Based on gas filter technology and particle scattering theory, a CH4 gas cell and a reference gas cell (CO gas cell) were used together to meter the light attenuation caused by CH4 absorption and dust particles extinction at two different wavelengths. When the mine gas and coal dust entered the measuring cell, CH4 concentration and dust optical density were obtained by processing the photoacoustic signal attenuation of the two cells.According to the related photoacoustic filtering technology and principle of extinction, designed for use in the experiment of light spoke size. By the microphone and phase-locked amplifier device build the photoacoustic compound methane-coal dust concentration risk judgment device. Using this system to test each performance of the system, experiments show that the system of CH4 and coal dust concentration has very good response. Finally, through the establishment of the acousto-optic scattering light composite detection system of three layers BP neural network model, combined the BP network and fuzzy reasoning properly, alarm time composite algorithm is established. The experimental data show that the photoacoustic combined method can sense for CH4 and dust particles more accurately.