准南低阶煤孔隙结构对瓦斯吸附热力学特性影响实验研究
发布时间：2018-11-14 16:02
【摘要】：矿井瓦斯灾害的防治和煤层气的开发利用与煤体的微观结构特征及瓦斯吸附规律密切相关,研究低阶煤的孔隙结构对其瓦斯吸附特性影响有利于准确评价低阶煤的储层特征。选取新疆准南煤田10个典型实验矿井的低阶煤煤样,结合煤体孔隙结构特征从热力学角度分析其对煤体瓦斯吸附特性影响。(1)利用低温氮吸附实验分析准南低阶煤孔隙结构,结果表明准南低阶煤的孔隙较为发育,孔隙结构复杂,相同孔径段比表面积和孔容大小及占比存在不同程度的差异,比表面积以过渡孔和微孔为主,孔容则以过渡孔和中孔为主,微孔较小,相同孔径段比表面积和孔容随孔隙直径变化规律相似。(2)基于PCT-C80吸附量热实验系统测定实验低阶煤的瓦斯吸附热数据,通过四种吸附模型的拟合对比表明D-A吸附理论模型更适合描述实验低阶煤的瓦斯吸附特性。通过(Clausius-Clapeyron)和(Gibb-Helmholtz)方程计算瓦斯等量吸附热及吸附摘变,建立考虑标准平衡压力常数的吸附自由能方程计算瓦斯吸附自由能变。表明理论方程计算值与实验实测吸附热值存在差别,温度升高煤体瓦斯等量吸附热及煤体吸附热均减小,瓦斯吸附自由能变增大,吸附熵变减小,从热力学角度证实升温不利于煤体瓦斯吸附,其瓦斯吸附热力学参数适用于表述煤体瓦斯吸附特性。(3)通过分析孔隙结构对其瓦斯吸附热力学特性影响,得到低阶煤孔隙结构与煤体瓦斯吸附热关系,表明除实验煤样过渡孔比表面积以外,随着BET比表面积及其余各孔径段比表面积增大,瓦斯吸附热Q、吸附自由能变AG、吸附熵变△S均线性增大,其中微孔比表面积对Q的影响起主要作用,随着BJH孔体积及微孔孔体积增大,Q、AG、△S均线性增大,微孔体积对Q的影响起主要作用。本文为新疆准南煤田低阶煤的瓦斯抽采工作提供一定的实验数据基础和理论依据。
[Abstract]:The prevention and cure of mine gas disaster and the exploitation and utilization of coalbed methane are closely related to the microstructure of coal body and the law of gas adsorption. It is helpful to accurately evaluate the reservoir characteristics of low rank coal by studying the influence of pore structure of low rank coal on its gas adsorption characteristics. The low-rank coal samples from 10 typical experimental coal mines in the quasi-southern coal field of Xinjiang are selected. According to the pore structure characteristics of coal body, the influence of coal pore structure on gas adsorption characteristics of coal body is analyzed from the point of view of thermodynamics. (1) the pore structure of low rank coal is analyzed by nitrogen adsorption experiment at low temperature. The results show that the pore structure of low rank coal is relatively developed. The pore structure is complex, the specific surface area and pore volume size and proportion of the same pore size are different, the specific surface area is mainly transition pore and micropore, the pore volume is mainly transition pore and mesopore, and the micropore is small. The specific surface area and pore volume of the same pore size vary with the pore diameter. (2) based on the PCT-C80 adsorption calorimetry experimental system, the gas adsorption heat data of experimental low-rank coal are measured. The comparison of four adsorption models shows that the D-A adsorption model is more suitable to describe the gas adsorption characteristics of experimental low-rank coal. Through (Clausius-Clapeyron) and (Gibb-Helmholtz) equations to calculate the gas adsorption heat and adsorption variation, the adsorption free energy equation considering the standard equilibrium pressure constant was established to calculate the gas adsorption free energy variation. The results show that there is a difference between the calculated values of the theoretical equation and the experimental measured adsorption calorific values. When the temperature rises, the adsorption heat of coal body gas and the adsorption heat of coal body decrease, the free energy of gas adsorption increases and the adsorption entropy decreases. From the thermodynamics point of view, it is proved that heating temperature is unfavorable to gas adsorption of coal body, and the thermodynamic parameters of gas adsorption are suitable for describing the gas adsorption characteristics of coal body. (3) the influence of pore structure on the thermodynamic characteristics of gas adsorption is analyzed. The relationship between pore structure of low-rank coal and gas adsorption heat of coal body is obtained. The results show that with the increase of BET specific surface area and other pore specific surface area, the gas adsorption heat Q and adsorption free energy change AG, with the exception of experimental coal sample transition pore specific surface area. The adsorption entropy is increasing with the increase of S mean linearity, and the specific surface area of micropore plays a major role in the influence of Q. With the increase of BJH pore volume and micropore volume, QG and S mean linearity increase, and the micropore volume plays a major role in the influence of Q. This paper provides some experimental data and theoretical basis for the gas extraction of low rank coal in Zhongnan coalfield, Xinjiang.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712
本文编号：2331639
[Abstract]:The prevention and cure of mine gas disaster and the exploitation and utilization of coalbed methane are closely related to the microstructure of coal body and the law of gas adsorption. It is helpful to accurately evaluate the reservoir characteristics of low rank coal by studying the influence of pore structure of low rank coal on its gas adsorption characteristics. The low-rank coal samples from 10 typical experimental coal mines in the quasi-southern coal field of Xinjiang are selected. According to the pore structure characteristics of coal body, the influence of coal pore structure on gas adsorption characteristics of coal body is analyzed from the point of view of thermodynamics. (1) the pore structure of low rank coal is analyzed by nitrogen adsorption experiment at low temperature. The results show that the pore structure of low rank coal is relatively developed. The pore structure is complex, the specific surface area and pore volume size and proportion of the same pore size are different, the specific surface area is mainly transition pore and micropore, the pore volume is mainly transition pore and mesopore, and the micropore is small. The specific surface area and pore volume of the same pore size vary with the pore diameter. (2) based on the PCT-C80 adsorption calorimetry experimental system, the gas adsorption heat data of experimental low-rank coal are measured. The comparison of four adsorption models shows that the D-A adsorption model is more suitable to describe the gas adsorption characteristics of experimental low-rank coal. Through (Clausius-Clapeyron) and (Gibb-Helmholtz) equations to calculate the gas adsorption heat and adsorption variation, the adsorption free energy equation considering the standard equilibrium pressure constant was established to calculate the gas adsorption free energy variation. The results show that there is a difference between the calculated values of the theoretical equation and the experimental measured adsorption calorific values. When the temperature rises, the adsorption heat of coal body gas and the adsorption heat of coal body decrease, the free energy of gas adsorption increases and the adsorption entropy decreases. From the thermodynamics point of view, it is proved that heating temperature is unfavorable to gas adsorption of coal body, and the thermodynamic parameters of gas adsorption are suitable for describing the gas adsorption characteristics of coal body. (3) the influence of pore structure on the thermodynamic characteristics of gas adsorption is analyzed. The relationship between pore structure of low-rank coal and gas adsorption heat of coal body is obtained. The results show that with the increase of BET specific surface area and other pore specific surface area, the gas adsorption heat Q and adsorption free energy change AG, with the exception of experimental coal sample transition pore specific surface area. The adsorption entropy is increasing with the increase of S mean linearity, and the specific surface area of micropore plays a major role in the influence of Q. With the increase of BJH pore volume and micropore volume, QG and S mean linearity increase, and the micropore volume plays a major role in the influence of Q. This paper provides some experimental data and theoretical basis for the gas extraction of low rank coal in Zhongnan coalfield, Xinjiang.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712
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