气体吸附过程中煤比表面Gibbs函数变化规律
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摘要
煤体瓦斯吸附为放热过程,解吸为吸热过程,其温度能量变化的幅度与煤的变质程度、瓦斯吸附平衡压力等有关。以往的研究都采用等温吸附实验得出气体相关吸附数据,并通过其孔隙结构、相互作用力等来分析煤吸附气体的影响因素,但是鲜有学者从比表面Gibbs函数变化角度来探讨煤吸附气体机理。为此,研究了气体吸附过程中煤比表面Gibbs函数变化的相关特征参数计算公式,利用凤凰山矿和裴沟矿两种煤样进行等温吸附实验,得到了在4个不同温度(20,30,40,50℃)以及6个压力(0. 2,1. 2,1. 5,2. 5,3. 0,4. 0 MPa)下的等温吸附实验数据,利用单层吸附和多层吸附模型分别计算出不同煤样吸附气体过程中的比表面Gibbs函数变化。研究表明:采用两种不同方式计算煤样吸附甲烷的比表面Gibbs函数,随着温度的升高比表面Gibbs函数变化量减少,随着压力的升高比表面Gibbs函数变化增加。而应用单层吸附和多层吸附计算的能量相差较大,对这种现象分析了原因;计算了气体吸附解吸过程的热量,对比分析可知采用多层BET吸附模型得出的比表面Gibbs函数变化更接近实际;探讨了气体吸附能量变化的机理,表明气体吸附能量变化影响着吸附量的变化,而能量变化又同样受到煤样微观结构以及内部化学结构的影响。因此,煤样吸附解吸是一个复杂多变的过程,可以从改变能量的角度去探讨如何影响瓦斯解吸,达到提高瓦斯抽采效果的目的。
The gas adsorption process of coal is an exothermic process and the desorption process is an endothermic process.The extent of temperature and energy changes is related to the degree of coal metamorphism,and the equilibrium pressure of gas adsorption,etc. The data of gas adsorption were obtained by using isothermal adsorption experiments,and the influencing factors of coal adsorption gas was analyzed through its pore structure and interaction force.However,few scholars have explored the mechanism of coal adsorbing gas from the perspective of the change of surface Gibbs function.Therefore,the calculation formulas of relevant characteristic parameters of the change of Gibbs function of coal specific surface in gas adsorption process were studied.Isothermal adsorption experiments were carried out using two coal samples from Fenghuangshan Mine and Qigou Mine in China.The data of isothermal adsorption experiment at four different temperatures( 20,30,40 and 50 ℃) and six different pressures( 0.2,1.2,1.5,2.5,3.0 and 4.0 MPa)were obtained.The specific surface Gibbs functions during the gas adsorption of different coal samples were calculated by using single-layer adsorption and multi-layer adsorption models. Studies showed that the specific surface Gibbs function of methane adsorbed on coal samples was calculated in two different ways,the change of Gibbs function of specific surface decreases with the increase of temperature and increases with the increase of pressure. The results of single-layer adsorption and multi-layer adsorption were quite different and this phenomenon was analyzed.The heat of the gas adsorption and desorption process was calculated.It can be seen from the calculation of heat that the specific surface Gibbs function obtained by using the multi-layer BET adsorption model is closer to the actual situation. The mechanism of energy change in gas adsorption was discussed.The results show that the change of gas adsorption energy affects the change of adsorption capacity,and the change of energy is also affected by the microstructure and internal chemical structure of coal samples.Therefore,the adsorption and desorption of coal samples is a complex and changeable process.To explore how to influence gas desorption can improve the gas extraction effect from the perspective of changing energy.
The gas adsorption process of coal is an exothermic process and the desorption process is an endothermic process.The extent of temperature and energy changes is related to the degree of coal metamorphism,and the equilibrium pressure of gas adsorption,etc. The data of gas adsorption were obtained by using isothermal adsorption experiments,and the influencing factors of coal adsorption gas was analyzed through its pore structure and interaction force.However,few scholars have explored the mechanism of coal adsorbing gas from the perspective of the change of surface Gibbs function.Therefore,the calculation formulas of relevant characteristic parameters of the change of Gibbs function of coal specific surface in gas adsorption process were studied.Isothermal adsorption experiments were carried out using two coal samples from Fenghuangshan Mine and Qigou Mine in China.The data of isothermal adsorption experiment at four different temperatures( 20,30,40 and 50 ℃) and six different pressures( 0.2,1.2,1.5,2.5,3.0 and 4.0 MPa)were obtained.The specific surface Gibbs functions during the gas adsorption of different coal samples were calculated by using single-layer adsorption and multi-layer adsorption models. Studies showed that the specific surface Gibbs function of methane adsorbed on coal samples was calculated in two different ways,the change of Gibbs function of specific surface decreases with the increase of temperature and increases with the increase of pressure. The results of single-layer adsorption and multi-layer adsorption were quite different and this phenomenon was analyzed.The heat of the gas adsorption and desorption process was calculated.It can be seen from the calculation of heat that the specific surface Gibbs function obtained by using the multi-layer BET adsorption model is closer to the actual situation. The mechanism of energy change in gas adsorption was discussed.The results show that the change of gas adsorption energy affects the change of adsorption capacity,and the change of energy is also affected by the microstructure and internal chemical structure of coal samples.Therefore,the adsorption and desorption of coal samples is a complex and changeable process.To explore how to influence gas desorption can improve the gas extraction effect from the perspective of changing energy.
引文
[1]刘珊珊,孟召平.等温吸附过程中不同煤体结构煤能量变化规律[J].煤炭学报,2015,40(6):1422-1427.LIU Shanshan,MENG Zhaoping. Study on energy variation of different coal-body structure coals in the process of isothermal adsorption[J].Journal of China Coal Society,2015,40(6):1422-1427.
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[3]孟召平,田永东,李国富.煤层气开发地质学理论与方法[M].北京:科学出版社,2010:23-29.
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[5]降文萍,崔永君,张群,等.不同变质程度煤表面与甲烷相互作用的量子化学研究[J].煤炭学报,2007,32(3):292-295.JIANG Wenping,CUI Yongjun,ZHANG Qun,et al. The quantum chemical study on different rank coals surface interacting with methane[J].Journal of China Coal Society,2007,32(3):292-295.
[6]崔永君.煤对CH4,N2,CO2及多组分气体吸附的研究[D].西安:煤炭科学研究总院西安分院,2003.CUI Yongjun. Adsorption of CH4,N2,CO2single and multicomponent gas on coal[J]. Xi’an:Xi’an Branch of China Coal Research Institute,2003.
[7]崔永君,张庆玲,杨锡禄.不同煤的吸附性能及等量吸附热的变化规律[J].天然气工业,2003,23(4):130-131.CUI Yongjun,ZHANG Qingling,YANG Xilu. Adsorption performance of different coals and the variation law of equal adsorption heat[J].Natural Gas Industry,2003,23(4):130-131.
[8]陈振宏,王一兵,宋岩,等.不同煤阶煤层气吸附、解吸特征差异对比[J].天然气工业,2008,28(3):30-32.CHEN Zhenhong,WANG Yibing,SONG Yan,et al. Compatison of adsorption/desorption properties of CBM in different rank coals[J].Natural Gas Industry,2008,28(3):30-32.
[9] ABUNOWARA M,BUSTAM M A,SUFIAN S,et al. Description of carbon dioxide adsorption and desorption onto malaysian coals under subcritical condition[J]. Procedia Engineering,2016,148:600-608.
[10] ARIUNAA A,LIOU Y H,TSATSRAL G,et al.Selective adsorption of greenhouse gases on the residual carbon in lignite coal liquefaction[J]. Journal of the Taiwan Institute of Chemical Engineers,2018,85(3):170-175.
[11] LI Wei,CHENG Yuanping,WU Dongmei,et al.CO2Isothermal adsorption models of coal in the Haishiwan coalfield[J].International Journal of Mining Science and Technology,2010,20(2):281-285.
[12]周来,冯启言,秦勇.CO2和CH4在煤基质表面竞争吸附的热力学分析[J].煤炭学报,2011,36(8):1307-1311.ZHOU Lai,FENG Qiyan,QIN Yong. Thermodynamic analysis of competitive adsorption of CO2and CH4on coal matrix[J].Journal of China Coal Society,2011,36(8):1307-1311.
[13]白怀东.CH4与CO2吸附解吸特征对比研究[D].西安:西安科技大学,2014.BAI Huaidong. Comparative study of CH4and CO2adsorption-desorption characteristics[D]. Xi’an:Xi’an University of Science and Technology,2014.
[14] RUDOLPH M,HARTMANN R.Specific surface free energy component distributions and flotabilities of mineral microparticles in flotation-An inverse gas chromatography study[J].Colloids&Surfaces A:Physicochemical&Engineering Aspects, 2016:S0927775716309050,513.
[15] LUCYNA Hoysz.Surface free energy and floatability of low-rank coal[J].Fuel,1996,75(6):737-742.
[16] BRONISLAW Janczuk,WIESTAW Wojcik,ANNA Zdziennicka,et al.Components of the surface free energy of low rank coals in the presence of n-alkanes[J].Powder Technology,1996,86(3):229-238.
[17] BURDZIK A,STAHLER M,CARMO M,et al.Impact of reference values used for surface free energy determination:An uncertainty analysis[J].International Journal of Adhesion&Adhesives,2018,82:1-7.
[18] ZHANG L,AZIZ N,REN T X,et al. Influence of temperature on coal sorption characteristics and the theory of coal surface free energy[C]. International Symposium on Mine Safety Science&Engineering,2011,26(4):1430-1439.
[19]谢克昌.煤的结构与反应性[M].北京:科学出版社,2002.
[20]聂百胜,何学秋,王恩元.煤的表面自由能及应用探讨[J].太原理工大学学报,2000,31(4):346-348.NIE Baisheng,HE Xueqiu,WANG Enyuan. Surface free energy of coal and its calculation[J].China University of Mining&Technology,2000,31(4):346-348.
[21]谢建林,郭勇义,吴世跃.常温下煤吸附甲烷的研究[J].太原理工大学学报,2004,35(5):562-564,567.XIE Jianlin,GUO Yongyi,WU Shiyue.Study on adsorption of methane on coal at normal temperature[J]. Mining College of Taiyuan University of Technology,2004,35(5):562-564,567.
[22]郭平,曹树刚,张遵国,等.煤体吸附膨胀变形模型理论研究[J].岩土力学,2014,35(12):3467-3472.GUO Ping,CAO Shugang,ZHANG Zunguo,et al. Theoretical study of deformation model of coal swelling induced by gas adsorption[J].Rock and Soil Mechanics,2014,35(12):3467-3472.
[23]陈新志,蔡振云.化工热力学[M].北京:化学工业出版社,2004.
[24]顾惕人,朱步瑶,李外郎,等.界面化学[M].北京:科学出版社,1994.
[25] LANGMUIR I.The constitution and fundamental properties of solids and lliquids.part I.Solids[J].Journal of the American Chemical Society,1915,38(5):102-105.
[26] BRUNAUER S,EMMETT P H,TELLER E. Adsorption of gases in multimolecular layers[J].Journal of the American Chemical Society,1938,60(2):309-319.
[27] GRIGORIY L,ARANOVICH,DONOHUE,et al.A new approach to analysis of multilayer adsorption[J]. Journal of Colloid&Interface Science,1995,173(2):515-520.
[28] WANG Gongda,WANG Kai,REN Tingxiang. Improved analytic methods for coal surface area and pore size distribution determination using 77K nitrogen adsorption experiment[J].International Journal of Mining Science and Technology,2014,24(3):329-334.
[29]卢守青,王亮,秦立明.不同变质程度煤的吸附能力与吸附热力学特征分析[J].煤炭科学技术,2014,42(6):130-135.LU Shouqing,WANG Liang,QIN Liming.Analysis on adsorption capacity and adsorption thermodynamic characteristics of different metamorphic degree coals[J]. Journal of China Coal Society,2014,42(6):130-135.
[30]戴闽光.固体表面上吸附分子的截面积[J].化学通报,1981(7):46-50.DAI Minguang. Cross-sectional area of adsorbed molecules on a solid surface[J].Chemical Bulletin,1981(7):46-50.
[31]吴俊.煤表面能的吸附法计算及研究意义[J].煤田地质与勘探,1994(2):18-23.WU Jun.Coal adsorption method of calculating-coal surface energy and it’s significance[J]. Coalfield Geology and Exploration,1994(2):18-23.
[32]杨庆贤.实际气体的多分子层吸附[J].化学物理学报,1991(6):458-463.YANG Qingxian. Adsorption of real gases in multimolecular layers[J].Chinese Journal of Chemical Physics,1991(6):458-463.
[33]张天军,许鸿杰,李树刚,等.温度对煤吸附性能的影响[J].煤炭学报,2009,34(6):802-805.ZHANG Tianjun,XU Hongjie,LI Shugang,et al. The effect of temperature on the adsorbing capability of coal[J]. Journal of China Coal Society,2009,34(6):802-805.
[34]杨涛.煤体瓦斯吸附解吸过程温度变化实验研究及机理分析[D].北京:中国矿业大学(北京),2014:44-50.YANG Tao.Experimental study and mechanism analysis on temperature variation during the process of gas adsorption and desorption[D]. Beijing:China University of Mining and Technology(Beijing),2014:44-50.
[35]傅鹰.化学热力学导论[M].北京:科学出版社,2010.
[36]张时音,桑树勋,杨志刚.液态水对煤吸附甲烷影响的机理分析[J].中国矿业大学学报,2009,38(5):707-712.ZHANG Shiyin,SANG Shuxun,YANG Zhigang. Mechanism analysis on the effect of liquid water on coal adsorbing methane[J].China University of Mining and Technology(Beijing),2009,38(5):707-712.
[37]刘纪坤.煤体瓦斯吸附解吸过程热效应实验研究[D].北京:中国矿业大学(北京),2012:90-100.LIU Jikun.Experimental research on thermal effect during coal gas adsorption and desorption[D]. Beijing:China University of Mining and Technology(Beijing),2012:90-100.
[2]俞启香.矿井瓦斯防治[M].徐州:中国矿业大学出版社,1990.
[3]孟召平,田永东,李国富.煤层气开发地质学理论与方法[M].北京:科学出版社,2010:23-29.
[4]聂百胜,段三明.煤吸附瓦斯的本质[J].太原理工大学学报,1998(4):88-92.NIE Baisheng,DUAN Sanming. The preliminary study on diffusion and permeation regularity of coal gas[J].Journal of Taiyuan University of Ttechnology,1998(4):88-92.
[5]降文萍,崔永君,张群,等.不同变质程度煤表面与甲烷相互作用的量子化学研究[J].煤炭学报,2007,32(3):292-295.JIANG Wenping,CUI Yongjun,ZHANG Qun,et al. The quantum chemical study on different rank coals surface interacting with methane[J].Journal of China Coal Society,2007,32(3):292-295.
[6]崔永君.煤对CH4,N2,CO2及多组分气体吸附的研究[D].西安:煤炭科学研究总院西安分院,2003.CUI Yongjun. Adsorption of CH4,N2,CO2single and multicomponent gas on coal[J]. Xi’an:Xi’an Branch of China Coal Research Institute,2003.
[7]崔永君,张庆玲,杨锡禄.不同煤的吸附性能及等量吸附热的变化规律[J].天然气工业,2003,23(4):130-131.CUI Yongjun,ZHANG Qingling,YANG Xilu. Adsorption performance of different coals and the variation law of equal adsorption heat[J].Natural Gas Industry,2003,23(4):130-131.
[8]陈振宏,王一兵,宋岩,等.不同煤阶煤层气吸附、解吸特征差异对比[J].天然气工业,2008,28(3):30-32.CHEN Zhenhong,WANG Yibing,SONG Yan,et al. Compatison of adsorption/desorption properties of CBM in different rank coals[J].Natural Gas Industry,2008,28(3):30-32.
[9] ABUNOWARA M,BUSTAM M A,SUFIAN S,et al. Description of carbon dioxide adsorption and desorption onto malaysian coals under subcritical condition[J]. Procedia Engineering,2016,148:600-608.
[10] ARIUNAA A,LIOU Y H,TSATSRAL G,et al.Selective adsorption of greenhouse gases on the residual carbon in lignite coal liquefaction[J]. Journal of the Taiwan Institute of Chemical Engineers,2018,85(3):170-175.
[11] LI Wei,CHENG Yuanping,WU Dongmei,et al.CO2Isothermal adsorption models of coal in the Haishiwan coalfield[J].International Journal of Mining Science and Technology,2010,20(2):281-285.
[12]周来,冯启言,秦勇.CO2和CH4在煤基质表面竞争吸附的热力学分析[J].煤炭学报,2011,36(8):1307-1311.ZHOU Lai,FENG Qiyan,QIN Yong. Thermodynamic analysis of competitive adsorption of CO2and CH4on coal matrix[J].Journal of China Coal Society,2011,36(8):1307-1311.
[13]白怀东.CH4与CO2吸附解吸特征对比研究[D].西安:西安科技大学,2014.BAI Huaidong. Comparative study of CH4and CO2adsorption-desorption characteristics[D]. Xi’an:Xi’an University of Science and Technology,2014.
[14] RUDOLPH M,HARTMANN R.Specific surface free energy component distributions and flotabilities of mineral microparticles in flotation-An inverse gas chromatography study[J].Colloids&Surfaces A:Physicochemical&Engineering Aspects, 2016:S0927775716309050,513.
[15] LUCYNA Hoysz.Surface free energy and floatability of low-rank coal[J].Fuel,1996,75(6):737-742.
[16] BRONISLAW Janczuk,WIESTAW Wojcik,ANNA Zdziennicka,et al.Components of the surface free energy of low rank coals in the presence of n-alkanes[J].Powder Technology,1996,86(3):229-238.
[17] BURDZIK A,STAHLER M,CARMO M,et al.Impact of reference values used for surface free energy determination:An uncertainty analysis[J].International Journal of Adhesion&Adhesives,2018,82:1-7.
[18] ZHANG L,AZIZ N,REN T X,et al. Influence of temperature on coal sorption characteristics and the theory of coal surface free energy[C]. International Symposium on Mine Safety Science&Engineering,2011,26(4):1430-1439.
[19]谢克昌.煤的结构与反应性[M].北京:科学出版社,2002.
[20]聂百胜,何学秋,王恩元.煤的表面自由能及应用探讨[J].太原理工大学学报,2000,31(4):346-348.NIE Baisheng,HE Xueqiu,WANG Enyuan. Surface free energy of coal and its calculation[J].China University of Mining&Technology,2000,31(4):346-348.
[21]谢建林,郭勇义,吴世跃.常温下煤吸附甲烷的研究[J].太原理工大学学报,2004,35(5):562-564,567.XIE Jianlin,GUO Yongyi,WU Shiyue.Study on adsorption of methane on coal at normal temperature[J]. Mining College of Taiyuan University of Technology,2004,35(5):562-564,567.
[22]郭平,曹树刚,张遵国,等.煤体吸附膨胀变形模型理论研究[J].岩土力学,2014,35(12):3467-3472.GUO Ping,CAO Shugang,ZHANG Zunguo,et al. Theoretical study of deformation model of coal swelling induced by gas adsorption[J].Rock and Soil Mechanics,2014,35(12):3467-3472.
[23]陈新志,蔡振云.化工热力学[M].北京:化学工业出版社,2004.
[24]顾惕人,朱步瑶,李外郎,等.界面化学[M].北京:科学出版社,1994.
[25] LANGMUIR I.The constitution and fundamental properties of solids and lliquids.part I.Solids[J].Journal of the American Chemical Society,1915,38(5):102-105.
[26] BRUNAUER S,EMMETT P H,TELLER E. Adsorption of gases in multimolecular layers[J].Journal of the American Chemical Society,1938,60(2):309-319.
[27] GRIGORIY L,ARANOVICH,DONOHUE,et al.A new approach to analysis of multilayer adsorption[J]. Journal of Colloid&Interface Science,1995,173(2):515-520.
[28] WANG Gongda,WANG Kai,REN Tingxiang. Improved analytic methods for coal surface area and pore size distribution determination using 77K nitrogen adsorption experiment[J].International Journal of Mining Science and Technology,2014,24(3):329-334.
[29]卢守青,王亮,秦立明.不同变质程度煤的吸附能力与吸附热力学特征分析[J].煤炭科学技术,2014,42(6):130-135.LU Shouqing,WANG Liang,QIN Liming.Analysis on adsorption capacity and adsorption thermodynamic characteristics of different metamorphic degree coals[J]. Journal of China Coal Society,2014,42(6):130-135.
[30]戴闽光.固体表面上吸附分子的截面积[J].化学通报,1981(7):46-50.DAI Minguang. Cross-sectional area of adsorbed molecules on a solid surface[J].Chemical Bulletin,1981(7):46-50.
[31]吴俊.煤表面能的吸附法计算及研究意义[J].煤田地质与勘探,1994(2):18-23.WU Jun.Coal adsorption method of calculating-coal surface energy and it’s significance[J]. Coalfield Geology and Exploration,1994(2):18-23.
[32]杨庆贤.实际气体的多分子层吸附[J].化学物理学报,1991(6):458-463.YANG Qingxian. Adsorption of real gases in multimolecular layers[J].Chinese Journal of Chemical Physics,1991(6):458-463.
[33]张天军,许鸿杰,李树刚,等.温度对煤吸附性能的影响[J].煤炭学报,2009,34(6):802-805.ZHANG Tianjun,XU Hongjie,LI Shugang,et al. The effect of temperature on the adsorbing capability of coal[J]. Journal of China Coal Society,2009,34(6):802-805.
[34]杨涛.煤体瓦斯吸附解吸过程温度变化实验研究及机理分析[D].北京:中国矿业大学(北京),2014:44-50.YANG Tao.Experimental study and mechanism analysis on temperature variation during the process of gas adsorption and desorption[D]. Beijing:China University of Mining and Technology(Beijing),2014:44-50.
[35]傅鹰.化学热力学导论[M].北京:科学出版社,2010.
[36]张时音,桑树勋,杨志刚.液态水对煤吸附甲烷影响的机理分析[J].中国矿业大学学报,2009,38(5):707-712.ZHANG Shiyin,SANG Shuxun,YANG Zhigang. Mechanism analysis on the effect of liquid water on coal adsorbing methane[J].China University of Mining and Technology(Beijing),2009,38(5):707-712.
[37]刘纪坤.煤体瓦斯吸附解吸过程热效应实验研究[D].北京:中国矿业大学(北京),2012:90-100.LIU Jikun.Experimental research on thermal effect during coal gas adsorption and desorption[D]. Beijing:China University of Mining and Technology(Beijing),2012:90-100.
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