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. Thiscombustion way widely exists in the environment which oxygen is insufficient, such as coalstorage factory, the power plant coal pile, coal docks, underground coal seams and so on. Inrecent years, China’s coal fires smoldering facing increasingly serious, this paper for thisphenomenon, under the conditions for the spread of smoldering coal roadway development of atheoretical analysis and experimental research.This paper through extensive access to other fuels smoldering Chinese and foreignliterature and systematic summary of previous research, using the similar related criterion,experimental device with their own design made of smoldering lignite oxidation simulationexperiments, and collected the smoldering of the temperature and gas concentration data,combined with mine ventilation theory, theory of coal-oxygen compound, heat transfer, masstransfer, Fick diffusion law, etc. knowledge, have a theoretical analysis and experimentalresearch, the last major results are as follows.(1)Analyzed the characteristics of smoldering combustion of lignite, the results showthat①lignite ignition time interval from150℃to300℃the mean value is33.3min;②smoldering lignite temperature above300℃, the average time was923min, analysis showsthat the smoldering lignite at the high temperature to maintain a long time and strong ability tosave the fire.③Slow propagation speed of smoldering lignite brown coal, the average rate ofsmoldering propagation is1.4×10-7m/s;④lignite smoldering velocity and oxygenconcentration gradient is linear relationship, the higher the oxygen content, the faster thesmoldering lignite.(2)Infer that the diffusion Roadway stable propagation of smoldering coal, off, into afireworks equation of the oxygen concentration during combustion, CO concentration equationand temperature field equations, and experimental validation.(3)Obtained the proliferation of coal under the roadway in the stable propagation ofsmoldering criterion is smoldering roadway surface oxygen concentration gradient η not lessthan the absolute value; Coal tunnel under diffusion smoldering of criterion is smolderingroadway surface oxygen concentration gradient η less than the absolute value; Diffusion intothe smoldering under the criteria of fireworks are burning in the smoldering roadway surfaceoxygen concentration gradient absolute value is not less than the minimum value of δ fireworks burning, smoldering surface temperature at or above the ignition point of coal λ, smolderingsurface oxygen concentration not less than the minimum concentration of coal burning β, COconcentration is not less than the lowest concentration of burning fireworks θ. For lignite,experimentally derived η is158.33%/m, δ is316.67%/m, λ is270℃,β was4.44%and θ isthe28351.29ppm.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 thecomprehensive process of research in fire lay a certain foundation.