Mechanism Of Spectral Thermo-radiation Properties Of Mine Dust-polluted Atmosphere Under Disaster Conditions

Coal resources have been the most important fossil energy and will remain so in the foreseeable future in China,where coal,as the primary energy source,has reached 70% contribution rate.Presently in China,over 90% of coal resources are extracted from underground coal mines.With the improvement of mine mechanization level and the increase of mining depth,large number of toxic gases which is released from coal seam/coal spontaneous combustion and coal dust particles which are generated by coal mining/tunneling disperse and pollute the whole atmosphere under the effect of mine ventilation.The dust-polluted atmosphere under disaster condition poses grave threat to the safety production of coal mine as well as the occupational health of coal workers.In this study,from the perspective of optical monitoring and identifying mine atmospheric pollutants during disaster period,we conducted modeling,experimental and numerical analysis on the infrared radiation properties of dust-polluted atmosphere which can provide theoretical foundation and database support for optical monitoring of mine disasters in underground coalmine atmospheric environment.Firstly,solid pollutants were sampled from underground mining face which were then tested by FT-IR and calculated by dispersion theory to obtain the complex refractive index of mine dust particles.The infrared scattering properties of mine dust particles were calculated by Mie scattering model based on the obtained complex refractive index.The influence of underground working condition and location on the infrared attenuation properties of mine dust particle system was also further analyzed.Focusing on the typical toxic gases generated under disaster conditions(CH4、CO、SO2、NO2),by HITRAN spectral data and Narrow Band Model,the infrared spectral absorption database of typical mine disaster gases were established.The influence of mine atmospheric pressure and temperature on the absorption intensity and absorption peak of mine gases were further investigated and analyzed.Then,based on the basic optical properties of mine atmospheric pollutants and their spatial distribution,by building radiative transfer model of non-gray-absorbing-emitting-scattering participating medium,the infrared radiation properties of mine dust-polluted atmosphere were calculated and obtained by discrete ordinate method.The absorption and extinction characteristics of mine dusty-wet-inert optical background were analyzed first;the thermal radiation properties of dust-polluted atmosphere under disaster conditions of methane gas emission,coal spontaneous combustion,sulfurous gas emission,mine blasting operation were then calculated and investigated,respectively.Finally,aiming at the inverse problem of optical monitoring on mine disasters,taking the thermal radiation properties of dust-polluted atmosphere under methane emission disaster as case study,inverse study on infrared information identification method of mine disaster was conducted.By analyzing the transmission spectrum of mine dust-polluted environment under methane emission condition,four independent spectral bands were selected to establish inverse radiation problem model combined with Stochastic Particle Swarm Optimization(SPSO)algorithm.The result indicates that the inversed methane gas concentration is consistent with its true value by keeping the relative error within 10%.Considering the complex working environment in underground coalmine and the demand of real-time monitoring on disaster gases,the multi-band infrared detection window was optimized and the influence of optical background and signal noise on SPSO inverse precision for this study was further analyzed.