无烟煤燃烧过程的热分析动力学研究

摘要

The effect of heating rate on anthracite pyrolysis and combustion process was investigated by thermal analysis curves（TG-DSC）,the isoconversional method and Malek method were applied to determine the most probable mechanism function of each stage,and the anthracite kinetics model was also established.The results indicate that the higher heating rate,the lower weight loss rate at the same temperature,the burnout temperature is also higher.With increasing heating rate,the ignition characteristic changes from hetero-homogeneous ignition to heterogeneous ignition.At the lower heating rates,a part of carbon is oxidated accompanied with pyrolysis before the carbon ignition temperature,the oxidation reaction is the controlling step,and the mechanism obeys the retraction balls model function.When the heating rate increases,before the carbon ignition temperature it follows the SB（m,n） mode function with coal pyrolysis rate controlling.The combustion in carbon surface and a part of internal area follows the cylindrical symmetry three-dimensional diffusion model and the stable phase of combustion followed the RO（n） mode function.%采用同步热分析（TG-DSC）法,分析了升温速率对无烟煤热分解和燃烧过程的影响,利用等转化率法和Malek法确定了各个阶段的最概然机理函数,得到了无烟煤燃烧过程热分析动力学模型。结果表明：升温速率越快,相同温度下煤的失重率越低,燃烬温度升高,着火特征由均相-非均相着火方式向非均相着火方式转变。在较低升温速率下,在碳着火温度之前不但发生了有机物的热分解,还发生部分碳的氧化过程,且氧化反应是限制性环节,遵循的机理为收缩球模型;当升温速率较快时,碳着火点之前遵循SB（m,n）模型,挥发分的热解成为限制性环节。在燃烧阶段,碳表面和内部部分燃烧遵循圆柱形对称三维扩散模型,而稳定燃烧阶段遵循反应级数机理。