煤吸附/解吸甲烷过程的能量迁移及其控制作用机理研究

Methane movement in coalbed is a complex motion composed of three interrelated components which are desorption, diffusion and seepage. The model of methane movement in coalbed by which many scholars, is simplified to two components of diffusion and seepage. But it is ignored the gas desorption processgas and control. With coalbed methane in the adsorption and desorption process, it is not only the exchange of energy, but also caused by the deformation of the coal body. Therefore, methane adsorption/desorption process is not only the movement of gas but also is the energy exchange process. So the gas adsorption / desorption process is determined by the energy level and its transfer proess. Based on the basic theory of statistical thermodynamics and adsorption theory, this study is focused on adsorption heat for conversion of coal methane in free or adsorb state. Beyond these, experimental methods of the different ranks of coal methane adsorption/desorption and adsorption heat with coal deformation relationship were adopted, and the coal body external stress and the thermal conductivity were revealed. Futhermore, mechanical, physical and chemical parameters of the microscopic pore structure of coal, and chemical composition of coal methane adsorption/desorption process were also investigated. The study is provided the methane movement theory in coalbed and actual application in coalbed methane exploitation.

煤层中的瓦斯运动是由解吸- - 扩散- - 渗流三个相互关联的运动方式组成，目前建立瓦斯运动的模型将煤中瓦斯运动简化为扩散和渗流两个运动方式，忽略了瓦斯解吸过程对瓦斯运动的控制作用。瓦斯在吸附和解吸过程中不仅与煤发生能量的交换，而且还引起煤体的变形。因此，瓦斯的吸附/解吸过程既是瓦斯的运动过程，也是瓦斯与煤之间发生能量交换的过程。能量的量级及其迁移过程决定瓦斯吸附/解吸的进程。 本项研究运用统计热力学的基本理论及吸附理论，以研究煤中甲烷的游离态与吸附态相互转换的吸附热能为基础，采用试验方法研究不同变质程度煤中甲烷吸附/解吸能力和吸附热能与煤体变形的关系，揭示煤体外部应力、煤体热传导系数、煤体微观孔隙结构、煤化学组成等煤体的力学、物理、化学参数对甲烷吸附/解吸过程的控制作用。为进一步研究瓦斯在煤层中的运动理论提供理论基础。研究结果对于解决低渗透煤层的瓦斯抽采提供一定的实际应用。

煤层中的瓦斯运动是由解吸——扩散——渗流三个相互关联的运动方式组成，项目采用绝热吸附装置，研究了煤吸附甲烷过程中，由甲烷的气体内能转变为吸附热和煤体变形能的过程。解释了瓦斯在吸附和解吸过程中不仅与煤发生能量的交换，而且还引起煤体的变形。并对变形能、吸附热进行测量和计算。揭示了瓦斯与煤之间发生能量交换的过程。项目采用热红外成像技术，研究了煤吸附甲烷时的热能分布，基于吸附动力学，提出了煤的非均匀吸附势阱的概念，研究了吸附过程的能量迁移。.本项基于吸附过程的在线CT扫描，以及吸附前后的煤样电镜图像，研究煤中甲烷吸附/解吸能力和吸附热能与煤体变形的关系，揭示煤体外部应力、煤体热传导系数、煤体微观孔隙结构、煤化学组成等煤体的力学、物理、化学参数对甲烷吸附/解吸过程的控制作用。在微观尺度上观察到煤吸附甲烷时的变形非均匀性，进一步揭示了煤吸附甲烷产生损伤的机理，为进一步研究瓦斯在煤层中的运动理论提供理论基础。研究结果对于解决低渗透煤层的瓦斯抽采提供一定的实际应用。