【作者】 王聪；

【导师】 李君； 唐振峰；

【作者基本信息】 天津大学 ， 动力工程（专业学位）， 2017， 硕士

【摘要】 由于人类活动和自然因素的影响,地下煤火问题越发严重。地下煤火已经成为涉及煤炭资源、安全生产和生态环境的重大灾害之一,监测和防治地下煤火灾害对我国乃至其他国家能源的安全和社会、经济发展有重要的战略意义和现实意义。地下煤火是复杂的物理、化学、环境等多过程相互耦合的结果,地下煤火演化规律中一个重要问题是地表热异常与煤氧化进程的关系,目前实验室尺度的地下煤火的实验系统大多过于简化而无法有效模拟地下煤火的核心物理、化学过程,对地表热异常也未做深入研究。本文针对现有研究中的不足,以地下煤火发生、发展的热动力学演化过程为基础,根据其传热、传质和渗流的特性,设计搭建了研究地下煤火的实验模拟装置。采用点状裂隙和线状裂隙泡沫陶瓷模拟煤火火区的上覆盖层,通过在煤体下端外加热源的方式对煤层加热,研究了不同裂隙条件下地下煤火低温氧化阶段地表温度热异常及气体释放特性。实验结果表明:不同裂隙和盖层厚度条件下,煤样温度随时间的变化规律基本一致;点状裂隙条件下,盖层厚度的增加可以加快煤低温氧化进程,减少到达快速氧化临界温度所需的时间;烟气温度与盖层表面标志点温度随时间的变化规律与煤温随时间的变化规律基本一致,烟气温度和标志点温度可以用来推断煤样温度的变化进程;当煤样温度到达快速氧化阶段的临界温度时,CO浓度和CO/CO₂值会快速上升;CO浓度与煤温近似呈指数式关系。CO浓度与煤温的关系方程可以用来判断煤低温氧化的程度,对地下煤火的早期探测有一定的指导意义。更多还原

【Abstract】 Because of human activities and natural factors,worldwide underground coal fires problem becomes more and more serious.Underground coal fires have become one of the major disasters endangering coal resources,mining safety and environmental protection.Detection and control of underground coal fire disasters are important to energy security,social and economic development of China and many other countries.Identifying the relationship between the surface thermal anomaly and coal oxidation is important in the understanding of the evolution of underground coal fires.However,most lab-scale studies could not simulate the essential physical and chemical processes involved in underground coal fires because of oversimplification,and insufficient attention has been paid to surface thermal anomaly.In view of the problem,focusing on the thermodynamic evolution of underground coal fires,an experimental apparatus was built up to simulate heat transfer,mass transfer and infiltration of oxygen and combustion products occurring in underground coal fires.The overburden of coal seams was simulated using ceramic foams,and by applying external heating to the bottom of the coal layer,the surface temperature of the ceramic foam and gas concentrations were measured.The experimental results indicate:under different conditions,the variations of coal temperature with time are similar,under the condition of the single-point fracture,the increase of ceramic foam thickness accelerates the process of low temperature oxidation of coal,thus reducing the time needed to reach the fast-oxidation critical point.The variation of gas temperature,temperature at typical points and coal temperature with time are consistent,based on which the variation of coal temperature can be inferred.The gas temperature and the temperature at typical points can be used to derive the coal temperature.The concentration of CO and the ratio of CO/CO₂ rise rapidly when the coal temperature reaches the critical temperature for fast-oxidation.The CO concentration is nearly in an exponential relationship with the coal temperature,and the correlation between the CO concentration and the coal temperature could be used to judge the progress of low-temperature oxidation of coal,which could provide some guidance to the early-stage detection of underground coal fires.更多还原