The evolution law of nanopore properties during underground in-situ pyrolysis of tar-rich coal
许涛陈杰伍永平柯于斌解盘石吕文玉
XU Tao;CHEN Jie;WU Yongping;KE Yubin;XIE Panshi;LYU Wenyu
西安科技大学 能源学院中国散裂中子源 广东 东莞 523803
富油煤地下热解是一种可有效提取煤中油气资源的绿色低碳技术,是煤炭清洁低碳利用的前沿方向。煤中纳米孔隙是地下热解过程中吸附和解吸焦油气的主要空间,因此探明地下热解条件下纳米孔隙结构特性演化规律,是提高富油煤地下热解工艺油气产率的关键科学问题。利用中国散裂中子源(CSNS)-小角中子散射(SANS)技术,模拟煤层地下热解环境,定量表征富油煤在无围限压力条件下不同加热速率与温度下纳米孔隙的散射强度、平均孔径与分形维数演变,结合低温吸附(BET)、热重实验(TG)、扫描电镜(SEM)等多种物理表征方法,揭示富油煤地下热解过程中纳米孔隙结构特性演化规律。研究结果表明:在地下热解过程中,纳米孔隙的平均孔径随温度的升高逐渐增大,在热解干燥脱气阶段(< 300 ℃)发育较缓慢,在活泼阶段(300~500 ℃)纳米孔隙发育最为剧烈,增长幅度为57.1%,在随后二次脱气阶段发育再次减缓;在低−中−高温(≤800 ℃)条件下热解没有引起富油煤表面分形维数
Underground pyrolysis of tar-rich coal is a green and low-carbon technology that effectively extracts oil and gas resources from coal. It represents the forefront of clean and low-carbon utilization of coal. The nano-pores present in coal play a vital role in the adsorption and desorption of tar and gas during the underground pyrolysis process. Therefore, understanding the evolution of nano-pore structure under underground pyrolysis conditions is a key scientific issue for enhancing the oil and gas yield of tar-rich coal through this process. To address this, the China Spallation Neutron Source (CSNS) - Small-Angle Neutron Scattering (SANS) technique was employed to simulate the in-situ pyrolysis environment of coal seams. This allows for the quantitative characterization of the scattering intensity, average pore size, and fractal dimension evolution of nano-pores in tar-rich coal in different heating rates and temperatures under unconfined pressure conditions. The complementary physical characterization methods such as physical adsorption (BET), thermogravimetric analysis (TG), and scanning electron microscopy (SEM) were also utilized. The research findings reveal the evolution of nano-pore structure characteristics during the underground pyrolysis of tar-rich coal. The research results demonstrate that during the underground pyrolysis process, the average pore size of nano-pores gradually increases with the rise in temperature. Nanopore development is relatively slow during the pyrolysis drying and degassing stage ( < 300 ℃), while the most significant growth occurs during the active stage (300-500 ℃), resulting in a 57.1% increase. Subsequently, nanopore development slows down during the secondary degassing stage. Importantly, it was observed that the low-medium-high temperature (≤800 ℃) pyrolysis conditions does not cause any significant changes in the surface fractal dimension (
富油煤地下热解原位分析纳米孔隙小角中子散射
tar-rich coal;underground pyrolysis;in-situ analysis;nanopores;small-angle neutron scattering
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会