Study On The Distinguishing Criterion Of Coal Seam Smoldering Dying Out, Stable Propagation And Transition From Smoldering To Flaming In Natural Diffusing Roadway

Smoldering combustion is a special way, is one of the forefront of combustion. This combustion way widely exists in the environment which oxygen is insufficient, such as coal storage factory, the power plant coal pile, coal docks, underground coal seams and so on. In recent years, China's coal fires smoldering facing increasingly serious, this paper for this phenomenon, under the conditions for the spread of smoldering coal roadway development of a theoretical analysis and experimental research.This paper through extensive access to other fuels smoldering Chinese and foreign literature and systematic summary of previous research, using the similar related criterion, experimental device with their own design made of smoldering lignite oxidation simulation experiments, and collected the smoldering of the temperature and gas concentration data, combined with mine ventilation theory, theory of coal-oxygen compound, heat transfer, mass transfer, Fick diffusion law, etc. knowledge, have a theoretical analysis and experimental research, the last major results are as follows.(1)Analyzed the characteristics of smoldering combustion of lignite, the results show that①lignite ignition time interval from 150℃to 300℃the mean value is 33.3min;②smoldering lignite temperature above 300℃, the average time was 923min, analysis shows that the smoldering lignite at the high temperature to maintain a long time and strong ability to save the fire.③Slow propagation speed of smoldering lignite brown coal, the average rate of smoldering propagation is 1.4×10-7m / s;④lignite smoldering velocity and oxygen concentration gradient is linear relationship, the higher the oxygen content, the faster the smoldering lignite.(2)Infer that the diffusion Roadway stable propagation of smoldering coal, off, into a fireworks equation of the oxygen concentration during combustion, CO concentration equation and temperature field equations, and experimental validation.(3)Obtained the proliferation of coal under the roadway in the stable propagation of smoldering criterion is smoldering roadway surface oxygen concentration gradientηnot less than the absolute value; Coal tunnel under diffusion smoldering of criterion is smoldering roadway surface oxygen concentration gradientηless than the absolute value; Diffusion into the smoldering under the criteria of fireworks are burning in the smoldering roadway surface oxygen concentration gradient absolute value is not less than the minimum value ofδfireworks burning, smoldering surface temperature at or above the ignition point of coalλ, smoldering surface oxygen concentration not less than the minimum concentration of coal burningβ, CO concentration is not less than the lowest concentration of burning fireworksθ. For lignite, experimentally derivedηis 158.33% / m,δis 316.67% / m,λis 270℃,βwas 4.44% andθis the 28351.29ppm.This paper, through the mechanism of smoldering coal more in-depth experimental study, not only help us to deepen the understanding of coal mine caused fire, but also for the comprehensive process of research in fire lay a certain foundation.