煤自燃影响因素的实验研究

发布时间：2018-05-06 18:55

本文选题：煤自燃 + 高温区域　；参考：《重庆大学》2016年硕士论文

【摘要】：煤炭自燃是常见的煤矿灾害之一,在特定环境下,一旦某一区域的煤体氧化放出的热量不能及时被漏风产生的对流换热和表面导热作用带走,温度就会不断升高导致火灾,甚至引发爆炸。煤体自燃是由于煤体表面活性分子与氧气接触发生物理吸附、化学吸附和化学反应三个阶段,且放热大于吸热导致煤体温度上升所引起的。煤体与氧气接触的过程中,将会伴随着气态产物的增加而氧含量减少的现象,并且同时会有吸热与发热效应。热量的产生导致煤与空隙内气体内能改变及煤体内部产生温差,从而造成热对流、热传导以及热量的积聚。煤体内部气体成分、含量和内能的变化将对气体的运移过程产生影响,而气体运移又与空气渗流息息相关,进而引起氧气含量的变化,又进一步影响到热传导、热对流、热积聚、煤氧复合等一系列过程。影响煤自燃的因素有很多,不同地区煤体所处环境的不同导致引起煤自燃的因素有所差异。针对这一现状,本文运用绝热氧化实验装置、自然发火实验炉及热分析仪等技术,探讨影响煤自燃过程的多种因素,为防灭火工作的开展提供一定的理论支撑。(1)供风量对煤自燃全过程高温区域时空变化规律影响的实验研究。利用绝热氧化实验炉模拟煤自燃的全过程,深入分析不同阶段煤体高温区域的运移机理,并且阐述指标气体的时空变化情况。(2)灰分对煤自燃影响的实验研究。采用绝热氧化法探索不同含量灰分与煤自燃特性的相关关系,分析灰分的作用机理,并讨论R70、CPT、B-M指标受灰分影响的变化情况。(3)初始温度对煤自然发火期的影响研究。本文运用Boddington自然发火模型计算得自然发火期,将此模型所得值与实际测量值进行验证,并且比较不同初始温度下的自然发火期,建立了起始温度与自然发火期关系模型,此模型为y=aexp(-x/b)+c。(4)煤自燃特性影响的热重实验研究。运用差热热重分析仪探索不同影响因素下煤样各个特征温度的变化规律,研究粒径、升温速率、煤质对煤自燃反应速率及放热强度的影响。
[Abstract]:Spontaneous combustion of coal is one of the common coal mine disasters. In a specific environment, once the heat released by oxidation of coal body in a certain area cannot be taken away by convection heat transfer and surface heat conduction caused by air leakage in time, the temperature will keep rising and lead to fire. It even triggered an explosion. Spontaneous combustion of coal is caused by the three stages of physical adsorption, chemical adsorption and chemical reaction when the surface active molecules of coal are in contact with oxygen, and the exothermic is larger than the endothermic heat, which leads to the rise of coal temperature. In the process of contact between coal and oxygen, the increase of gaseous products will lead to the decrease of oxygen content, and there will be endothermic and heating effects at the same time. The heat production results in the change of gas energy in coal and air gap and the temperature difference in coal body, which results in heat convection, heat conduction and heat accumulation. The change of gas composition, content and internal energy in coal body will affect the gas migration process, and the gas migration is closely related to the air percolation, which causes the change of oxygen content, and further affects the heat conduction and thermal convection. A series of processes, such as thermal accumulation, coal and oxygen recombination, etc. There are many factors influencing coal spontaneous combustion. In view of this situation, this paper uses adiabatic oxidation experimental device, natural combustion furnace and thermal analyzer to discuss the factors that affect the process of coal spontaneous combustion. An experimental study on the effect of air supply on the space-time variation of coal spontaneous combustion in high temperature region is carried out in order to provide a theoretical support for the development of fire prevention and extinguishing. By using adiabatic oxidation furnace to simulate the whole process of coal spontaneous combustion, the migration mechanism of high temperature region of coal body in different stages is analyzed in depth, and the influence of ash content on coal spontaneous combustion is described. The relationship between ash content and spontaneous combustion characteristics of coal was investigated by adiabatic oxidation method, the mechanism of ash action was analyzed, and the effect of initial temperature on coal spontaneous combustion period was discussed. In this paper, the natural ignition period is calculated by using the Boddington spontaneous ignition model. The model is verified with the actual measured value, and the relation model between the starting temperature and the natural ignition period is established by comparing the natural ignition period at different initial temperatures. This model is a thermogravimetric experimental study on the effect of coal spontaneous combustion characteristics. By using differential thermogravimetric analyzer (DTA), the variation law of characteristic temperature of coal samples under different influence factors was explored, and the effects of particle size, heating rate and coal quality on coal spontaneous combustion reaction rate and exothermic intensity were studied.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD752.2

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