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大型煤自燃试验的火源演化特征模拟

Simulation on ignition source evolution features of large scale coal spontaneous combustion experiment

  • 摘要: 为弥补大型自然发火试验可重复性差的不足和掌握不同外部环境下煤自燃过程火源的演化特征,利用数值模拟的方法,通过设定与试验环境一致的边界条件,得到了自然发火过程炉内火源演化的主要特征。通过改变模型参数,研究了散热环境和漏风对火源分布及温度的影响,结果表明:在火源位置逐渐向空气表面发展的过程中,漏风量增大不仅显著扩大了高温范围,而且相同温度下火源位于距表面更深的位置;降低环境散热量,会导致火源区域径向扩散,并使整个区域内煤的温度梯度减小;漏风条件主要影响高温阶段煤的升温速率,而散热量增多则会显著延长煤的低温氧化过程。

     

    Abstract: In order to make up the shortage that the repeatability poor of the large spontaneous combustion experiment and to master the fire source evolution feat ures of the coal spontaneous combustion process under different external environment,with the application of the numerical simulation method and the establishment of the boundary condition same to the experiment environment,the major features of the fire source evolution in the furnace during the spontaneous combustion process W ere obtained.With the variation of the model parameters,the paper had a study on the heat radiation environment and the air leakage affected to the fire source distribut ion and temperature. The results showed that during the development process of the fire source location steadily forward to the air surface,the air leakage volume increa sed would not only obviously expand the high temperature scope,but the fire source location would be in a deep depth of the air surface under the same temperature.Th e environment heat radiation volume reduced would cause the fire source area to be expanded radially and would cause the coal temperature gradient reduced in the w hole area.The air leakage condition would be mainly affect the coal temperature rising speed at the high temperature stage and the heat radiation volume increased wo uld obviously expand the low temperature oxidation process of coal.

     

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