【作者】 杨永良；

【导师】 李增华；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2009， 博士

【摘要】 煤自燃火灾严重威胁着煤炭生产和储运的安全,给煤炭产业带来极大的安全隐患。为有效的防治煤炭自燃,研究煤炭自燃特性,确定煤最短自然发火期,并提出合理的煤自燃防治技术是非常有必要的。准确测定煤自燃过程中的基本参数是进行自然发火规律研究的前提。本文依据传热学、传质学及渗流力学理论,建立了一整套煤低温氧化过程中主要参数测试的理论方法及相关实验系统,包括煤体氧化放热强度、导热系数、氧气扩散系数、渗透系数、耗氧速率及活化能等参数。其中,自行设计组建的煤氧化放热强度测试实验系统,实现了快速准确测定的目标。利用实验系统准确测定了各参数,分析了粒度、温度、煤变质程度等因素对上述参数的影响,并给出了影响函数,为不同条件下煤自燃特性研究提供了基础。以绝热圆柱形煤柱为物理模型,建立了煤实验条件下最短自然发火期计算模型。利用实测的煤自燃基本参数,通过解算分析各影响因素与自然发火期的正交关系,准确测定了煤最短自然发火期。结果基本与煤体自然发火实际情况一致,验证了测试结果的准确性。该方法耗时短,适用于大批量煤样测试的要求。建立了煤堆二维空间自热升温数学模型,采用FLUENT软件进行了数值解算,研究了煤堆的自热氧化规律,模拟所需参数均为实验测得;结果揭示在自热过程中气流均从煤堆下部流入,上部流出,并掌握了煤堆内部高温点分布规律;在模拟结果的基础上提出了合理的抑制煤堆自燃新方法——煤堆下部表面覆盖细煤预防自燃。为考察细煤覆盖煤堆下部表面抑制自燃效果,对细煤覆盖煤堆进行了数值模拟。模拟分析了细煤覆盖煤堆内部的气体渗流及氧气分布规律,通过与原煤堆比较分析,综合考察了细煤覆盖对煤堆自热规律的影响。同时建立了煤堆升温实验台,对覆盖不同厚度细煤煤堆沿水平方向的空气扩散和沿竖直方向的空气热对流的二维空间传热、传质规律进行了实验研究。实验与数值分析结果表明覆盖细煤阻碍了煤堆内部的氧气补充,从而有效的抑制了煤堆自燃。最后,将细煤覆盖煤堆自燃抑制方法应用到现场进行了大型煤堆试验,成功抑制了神华最易自燃煤堆的发火。没有覆盖细煤的煤堆在很短的时间内(18 d)即发生了自燃,而覆盖1 m厚细煤的煤堆历时123 d最高温度仅为59.9℃。并得出了煤堆高温区域移动规律,分析了环境温度及大气风速对煤堆自燃的影响。该论文有图79幅,表23个,参考文献137篇。更多还原

【Abstract】 Spontaneous combustion exists in the process of production and transportation commonly. It is a great hidden danger in coal industry. In order to control coal spontaneous combustion effectively, it is necessary to study the characteristics, forecast the shortest period and develop appropriate control technology of coal spontaneous combustion.Accurately measuring basic parameters of coal spontaneous combustion is the precondition to study the regulation of coal spontaneous combustion. According to the theories of heat transfer, mass transfer and seepage mechanics, a set of method and test system of main parameters measurement in the process of coal oxidation at low temperature was developed. The parameters include coal oxidative heat release intensity, heat conductivity, oxygen diffusion coefficient, and filtration coefficient. Moreover, we established the experimental system to measure heat release intensity of coal spontaneous combustion. The system can measure fastly and accurately. Using the measured parameters, the effect of size, temperature and metamorphic grade of coal on those parameters is analyzed. Moreover, the effect functions are also established and it is the base of studying the characteristics of coal spontaneous combustion at different conditions.Based on accurately measured basic parameters of coal spontaneous combustion, a 2D mathematical model of adiabatic coal column to calculate the shortest experimental spontaneous combustion period of coal is developed. Through analyzing the orthogonality relationship of spontaneous combustion period and effect factors, the shortest experimental spontaneous combustion period of coal can be accurately measured. The result is fit for the real performance and the accuracy of the result can be indicadited. The method cosumes less time and is capable of measuring mass coal samples.A 2D numerical model of auto thermal of coal stockpile is developed. The model is calculated by FLUENT to study the regulation of auto thermal of coal stockpile. The data of numerical simulation is measured by experiments. The result shows that air flows into the stockpile from the bottom and out of from the top. Moreover, the distribution of high temperature dot also can be found out. Based on the simulation result, a new appropriate spontaneous combustion control method of coal stockpile, paving fine coal on the surface of the bottom part of stockpile, is developed.In order to study the effect of above method, we make a numerical simulation of coal stockpile covered with fine coal. The numerical simulation analyzes the gas seepage and oxygen distributive regulation inside the coal stockpile covered with fine coal. Compared with coal stockpile without fine coal, the effect of the method can be analyzed comprehensively. At the same time, a coal stockpile temperature rising experimental table is developed. Experimental study of 2D heat and mass transfer regulation of horizontal air diffusion and vertical heat convection of coal stockpile covered with different fine coal in thickness. The experimental and numerical analysis result shows that fine coal covered can prevent oxygen supply to the coal stockpile, so spontaneous combustion can be controlled.Finally, using the control method of covering fine coal on coal stockpile in the field test, the spontaneous combustion of Shenhua coal is controlled. The coal stockpile without fine coal covered can ignite in 18 days. However, the temperature of coal stockpile can only reach 59.9℃during 123 days if it covered with 1 m fine coal. In addition, analyzing the effect of environmental temperature, air flow and sunshine irradiation, the moving regulation of high temperature section of coal stockpile can be found by the field test.79figs., 23tabs., 137refs.更多还原