基于负压取样的煤层瓦斯含量精准测定理论研究

Coal seam gas content plays an important role in coal gas disasters prevention and prediction. The method applied nowadays always leading to lower gas content value than that of actual .Precision determination of gas content is an effective way to overcome the shortcoming of above mentioned. The previous research results showed that the sampling method of negative pressure pneumatic conveying meets the demand well. To further study the method the pressure drop characteristics of solid-gas flow during sampling are investigated in this project. In addition, three pressure drop prediction models are proposed, i.e. the pressure drop prediction model of solid-gas flow in drilling pit, drilling pipeline and the whole sampling system. Furthermore, the solid-gas flow characteristics during sampling are studied by FLUENT-EDEM coupling simulation with drilling pipeline rotation under different working conditions. The drilling pit structure and other parameters are optimized on basis of the results. Finally, the gas emission law of coal particle under negative pressure then one atmosphere are researched, a new pseudo-steady state gas emission model considering coal matrix shrinkage is established, thus presenting a gas loss calculation model for the Sampling method of negative pressure pneumatic conveying. The results of this project can provide a new perspective to determine the gas content precisely and render simultaneous production of coal and gas more safely.

煤层瓦斯含量是瓦斯灾害防治、煤层气资源开发与评估的重要基础参数。煤层瓦斯含量的精准测定取决于取样方法，由于目前常用的方法难以做到“快速定点取样”，使得煤层瓦斯含量测值普遍偏低。负压取样可实现快速定点取样，然而基于取样钻杆转动的取样过程压降预测模型、煤屑-气两相流动规律以及取样过程瓦斯损失量推算等问题亟待研究。本项目基于前期工作，实验研究取样钻杆转动时煤屑-气两相流动压降特征，建立负压取样系统压降预测模型；FLUENT-EDEM数值模拟研究取样钻杆转动时不同工况下负压取样时煤屑-气两相流动规律；研究负压取样过程颗粒煤瓦斯恒负压-负压转常压放散规律，构建基于煤基质形变的拟稳态解吸-扩散-渗流颗粒煤瓦斯负压-负压转常压统一放散模型，提出负压取样瓦斯损失量推算方法。研究结果可为实现煤层瓦斯含量精准测定、助推煤与瓦斯安全高效共采提供理论基础。

煤层瓦斯含量是煤矿瓦斯灾害防治的重要基础参数，实现煤层瓦斯含量精准测定对煤炭安全高效生产具有重要意义。钻孔负压排渣定点取样（简称负压取样）是一种具有发展潜力的用于煤层瓦斯含量精准测定的取样方法。本项目以负压取样时煤屑-气两相流动为研究对象，建立了钻孔-钻头-钻杆一体化流体域模型，采用理论分析与数值模拟（CFD-DEM）相结合的研究方法，研究取样钻杆转动及钻孔倾角对取样时煤屑-气流动特性的影响，从流场速度、压力分布及煤屑运动等多个方面对钻杆转速、煤屑质量流量对煤屑-气流动特性的影响进行了分析，确定了最佳取样钻杆转速的范围，建立了负压取样压降预测模型，为实现对负压取样系统装备的优化设计提供理论基础。采用自主搭建的颗粒煤瓦斯负压-负压转常压解吸实验系统，实现了对负压取样测定煤层瓦斯含量全过程瓦斯解吸物理模拟，开展了负压取样背景下不同吸附平衡压力、不同取样时间颗粒煤瓦斯解吸规律研究，确定了煤颗粒负压解吸瓦斯扩散系数，建立了颗粒煤瓦斯负压-负压转常压瓦斯解吸放散统一模型，确立了负压取样瓦斯损失量推算模型。项目研究成果进一步丰富完善了负压取样精准测定煤层瓦斯含量理论基础，相关技术在平煤集团、义煤集团、郑煤集团等工程应用取得了良好效果。在项目支持下，发表学术论文7篇，其中SCI检索5篇，出版学术专著1部，授权发明专利2项，获得省部级奖励2项；项目负责人职称由讲师晋升为副教授，培养硕士研究生3名。