三维微米尺度条件下瓦斯吸附-解吸热力学特性研究

As one of the most important theoretical bases of the prevention and control of mine gas disasters, the thermal dynamic property of coal gas absorption and desorption mechanism is critical to prevent the coal disasters such as coal and gas outburst. The micro-scale research method is adopted to study the adsorption and desorption thermodynamic properties of coal gas. The porosity, pore volume distribution, frequency of pore distribution of equivalent diameter and other physical parameters are scanned and a 3D model which extremely similar to the experimental sample is established. With the relevant initial and boundary conditions, the directly pore scale simulation is used to obtain the major parameters of the samples, such as effective thermal conductivity, permeability, convective heat transfer coefficient, adsorption constant, Dupuit-Forchheimer coefficient and so on. The influence of vapour content, temperature, porosity would be analyzed and then contrasted with empirical equation or experimental data. Finally, the sensibility of coal gas against multi-factors and the gas sorption properties would be discussed by high pressure gas adsorption equipment, pressure composition isotherms experiment system and heat and mass transfer experiment system. Based on the influence of temperature, pressure, particle size and the metamorphic degree of coals, the exactly adsorption and desorption quantity of coal gas would be studied. A revised thermal dynamic equation on coal gas adsorption and desorption would also be established to supply a quantitative scientific criterion for the dynamic procedure of gas adsorption and desorption.

瓦斯吸附解吸机理作为矿井瓦斯灾害防治的重要理论基础之一，其热力学特性研究对预防煤与瓦斯突出等灾害事故具有极其重要的意义。本研究选取具有典型多孔结构的煤体和附着的瓦斯为研究对象，通过三维微米尺度真实煤孔隙结构重构，获得煤样孔隙率、孔隙体积分布以及孔隙当量直径分布频率等参数。在此基础上建立三维微米尺度瓦斯吸附解吸流动换热模型，计算得到测试煤样的有效导热系数、对流换热系数、吸附常数及Dupuit-Forchheimer系数等重要参数。然后，修正瓦斯吸附解吸热力学模型，得到水蒸气含量、温度、孔隙率等参数对煤体中瓦斯吸附解吸的影响规律。最后，依据煤体的孔隙结构特性，结合HCA高压瓦斯吸附实验、PCT高压吸附量热实验以及相关的瓦斯基础参数测定实验，分析温度、压力、粒径以及煤变质程度等因素对瓦斯的影响，并根据实验结果验证数值模拟和公式推导的合理性与正确性，为定量研究瓦斯吸附解吸这一动态过程提供科学判据。

瓦斯吸附解吸过程的热力学特性研究作为矿井瓦斯防治与利用的重要研究方向之一，对预防瓦斯事故、提高瓦斯利用率具有极其重要的意义。本项目采用实验室实验、理论分析、数值模拟等方法，对煤体多尺度条件下孔隙结构特征、瓦斯吸附-解吸特性、孔隙特征对瓦斯放散的影响以及瓦斯吸附热力学特征等进行了系统研究。分析了煤样全孔径段的孔隙分布规律及分形特征，得到了中低煤阶煤孔隙微观结构的分布规律及结构特征，探讨了中低阶煤瓦斯不同因素对吸附热力学参数的影响机理，建立了煤瓦斯吸附解吸换热模型，获得了瞬态条件下煤体瓦斯吸附解吸量与吸附解吸温度、解吸压力之间的影响规律。为定量研究瞬态瓦斯吸附解吸热力学过程提供科学判据。