Permeability variations of lignite and bituminous coals under elevated pyrolysis temperatures (35–600 °C): An experimental study
Permeability variations of lignite and bituminous coals under elevated pyrolysis temperatures (35–600 °C): An experimental study
复制标题
DOI：
10.1016/j.energy.2022.124187
复制
发表时间：
2022-05
期刊：
影响因子：
9
通讯作者：
Xin Li;Jijun Tian;Y. Ju;Yanpen Chen
中科院分区：
文献类型：
--
作者：
Xin Li;Jijun Tian;Y. Ju;Yanpen Chen
热解温度（PT）下渗透率的研究可以为地下煤气化（UCG）合成气生产提供指导。研究了褐煤、高挥发性烟煤 (HVBC) 和中挥发性烟煤 (MVBC) 在升高温度 (35°C–600°C) 下的渗透率变化。通过显微结构观察、核磁共振、热重分析、产液测量等方法对煤的结构、失重和成熟度进行了研究和澄清，探讨影响渗透率变化的因素。结果表明：（1）褐煤、HVBC 和 MVBC 的渗透率在 35-200 °C 期间增加。褐煤渗透率在 200–600 °C 期间下降，而 HVBC 和 MVBC 渗透率在 200–400 °C 期间下降，然后在 400–600 °C 期间上升； (2) 对于不同成熟度的煤，热解反应强度控制着渗透率。在温度为 125–500 °C 时，褐煤渗透率始终最大，其次是 HVBC，MVBC 渗透率始终最低； (3)对于单个煤来说，渗透率变化由积极因素(水和挥发物的排放、稳定的焦结构、惰性物质含量增加和焦的高孔隙率)和消极因素(焦油或焦粉或两者的混合物堵塞渗透通道、大孔隙和裂缝的闭合以及不稳定的焦结构)之间的相对强度控制。
Studies on permeability under pyrolysis temperatures (PTs) can provide instructions for syngas production of underground coal gasification (UCG). Permeability variations of lignite, high volatile bituminous coal (HVBC) and medium volatile bituminous coal (MVBC) under elevated PTs (35°C–600 °C) were studied. Structure and weightlessness as well as maturity of coal detected by methods of micro structure observation, nuclear magnetic resonance, thermogravimetric analysis, and liquid yield measurement, were investigated and clarified to probe the factors influencing permeability variation. The results showed: (1) permeability of lignite and HVBC as well as MVBC increased during 35–200 °C. Lignite permeability decreased during 200–600 °C while HVBC and MVBC permeability decreased during 200–400 °C and then increased during 400–600 °C; (2) for coals with different maturities, pyrolysis reactive strength controlled the permeability. Lignite permeability were always the greatest followed by HVBC, and MVBC permeability were always the lowest, at PTs of 125–500 °C; (3) for an individual coal, permeability variation was controlled by the relative strength between positive factors (water and volatiles’ discharge, stable char framework, increased inertoid content, and high porosity of char) and negative factors (blocking of penetration channels by tars or char fines or a mix of these two, closure of macro-pores and fractures, and unstable char framework).