煤炭自然发火的介尺度现象分析及建模

Analysis and modeling of mesoscale phenomenon on coal spontaneous combustion

针对煤炭自然发火研究中宏观层面过于简化无法揭示反应机理,而微观层面过于细化直接应用到工程效果不理想的瓶颈,借鉴复杂系统理论和多尺度科学研究思路,分析了煤炭自然发火的反应粒子、颗粒内孔、单煤颗粒、颗粒聚团、堆积煤体的多尺度行为和特征,提出了破碎煤体堆积系统自然发火的介尺度概念,并探讨了描述型、关联型和极值型3种多尺度方法在煤炭自然发火介尺度研究中的适用性.基于关联型研究方法,通过分析颗粒聚团内部及聚团间的热力学和动力学的复杂作用,引入"树叉"模型并考虑孔隙率分布的非均匀特征,使单煤颗粒尺度与堆积煤体尺度相关联,实现了从实体模型到物理模型,再到数学模型的煤炭自然发火介尺度模型的构建过程.

The existing study on coal spontaneous combustion is focused on macroscopic scale without revealing the mechanism of chemical reaction,while the microscopic scale investigation is so complex that it could not be applied to actual engineering.Based on basic theory of the complex system and research approaches of Meso-science,the mesoscale phenomenon and behaviors for five scales,namely reaction particle,particle bore,single coal particle,particle cluster and coal pile,are described in detail in this paper.The concept of mesoscopic scale on coal spontaneous combustion is also presented.Then,applicabilities of descriptive,correlative and variational multi-scale methodologies in the field of coal spontaneous combustion are compared.According to the correlative method,the complex thermodynamics process inside coal particle clusters and in between are analyzed.By introducing branch model and non-homogeneous porosity,the two scales between single coal particle and coal pile are related.At last,a mesoscale model of the coal spontaneous combustion process is developed from entity form to physical model,and then to mathematical model.