【作者】 李林；

【导师】 姜德义；

【作者基本信息】 重庆大学 ， 安全技术及工程， 2008， 博士

【摘要】 建立了煤自燃过程数学模型。依据模型确定出煤自燃过程数值模拟所需的关键参数为煤的耗氧速度和放热强度及松散煤体内的氧气扩散系数和渗透系数。并建立了一维状态下的煤自燃全过程数学模型。对具有代表性的9个煤样进行了绝热氧化模拟实验,获得了煤在理想状态条件下的温升曲线。通过数据分析得到了在煤低温氧化过程中,随着温度的上升,煤的低温氧化表观活化能逐渐下降规律。这说明随着温度的升高,煤中活性结构需要激活的能量不断减小,温度越高,煤中的活性结构越容易激活。在上述研究的基础上,提出煤自然活化机理,即:煤自燃过程是因为煤结构中不同官能团（活性结构）先后被激活,既而发生氧化反应的结果,先被激活而发生氧化反应的官能团释放能量使煤温度升高。在煤体温度升高后,煤中的活性结构更容易被活化,需要较小的能量便能被激活,因此煤随着温度的升高变的越来越容易被活化,氧化反应越来越剧烈,热量释放越来越多,温度上升速度也越来越快,直至加速升温而导致自然发火。基于在对不同煤样不同温度段的活化能进行分析研究后,提出了零活化能理论,即:活化能为零。零活化能是煤活化能由正值向负值转变的过渡值,零活化能意味着煤开始从被动氧化进入自发氧化。煤的零活化能与其R70值成一定的数值关系,因此可以利用零活化能来鉴定煤的自燃倾向性。在零活化能理论的基础上提出了零活化能温度值,即煤活化能为零时刻的温度值。零活化能温度意味着煤从此温度开始,煤进入自发反应阶段。零活化能温度同样与煤的R70存在一个数值关系。利用煤自然活化机理能对煤自燃现象、一般规律和其特征进行充分合理的解释。通过两组实验煤样的自燃发火全过程实验,得出了煤自然发火过程中温度变化规律以及高温点移动规律。在实验开始阶段,低温下煤氧化反应速度和温度升高都处于缓慢状态。随着实验的进行,由于空气将水蒸气和热量从下带到上部,导致上部温度升高,第2天时的高温点出现在145cm处。之后,高温点开始向下移动,这是由于下部煤样完全干燥,温度上升迅速,最后高温点出现在60cm处并发火自燃。总结了指标气体的产生规律。在煤自燃发火全过程中,CO₂、CO、H₂、乙烯和乙烷含量随着时间的推移,煤体温度逐渐升高。而氧气的产生变化则刚好相反,随着时间的推移而减低。而且这些气体的产生与煤自燃过程的温度呈现一定的关系,因此,这些气体能称为预防预测煤自燃发火的指标气体。同时在煤最终发火前期,煤样的温度升高速率达到120℃/天,对于煤矿而言,没有足够的时间去采取措施来避免发火。因此,防治煤自燃发火需防范于未然,需要长时间的测量监控。更多还原

【Abstract】 Based on mechanics of fluids in porous media and theory of heat and mass transfer, the mathematical model is set up. According to the model, oxygen consumption rate and heat liberation intensity of coal, diffusion coefficient and osmotic coefficient of oxygen is confirmed for key parameter to numerical simulation of coal self-ignition process, and these parameters are researched and test by experiment. And set up the mathematical model of whole process of self-heating of coal in one-dimensional.Furthermore, based on dynamic equation of coal’s adiabatic oxidation, the simulation system for the process of spontaneous combustion of coal is worked out. And the spontaneous combustion simulation using small coal sample was carried out, which is the first successful case nationwide. And coal’s ideal (under the condition of thermal insulation) temperature-rise curve is obtained by doing simulation experiments on nine coal samples in different moisture content, rank and ash content. And obtained some rule about those factors effecting in orientation on self-heating of coal.Based on analyzing data from adiabatic testing, the rule that activation energy descend gradually with temperature rise was obtained, which shown that energy that activate active structures in coal is getting low as the temperature rises. It is easier to activate it at more high temperature.And based on theory of activation reaction, the simulated experiments and the characters in process of spontaneous combustion of coal, such as index gases, generation heat rate and coal structures changes, the Self-activation Theory of Spontaneous Combustion of Coal is put forward: The process of self-heating of coal is that the different function group (active structures) in coal is activated early or late, and reactive with oxygen and release energy to make the temperature raise. With the higher temperature, active structures are easier to active with lower activation energy. So, active structures are easier to active more and more with temperature rise, and oxidize respond more and more violent, heat releases more and more, the temperature rises also more and more quick, keep accelerating to ignition.According to analyses changing rule of activation energy in different temperature range at different coal, the Zero-Activation Energy Theory was put forward: Activation energy amount zero. Zero-Activation Energy is a transition value from positive to negative; it means oxidize with coal turning to self-oxidize.更多还原