摘要
采用巨正则系综蒙特卡洛(GCMC)方法研究了储层温度、压力条件以及CO2/CH4混合气中CO2摩尔分数对煤中狭缝型孔分离CO2/CH4的影响。气体分子之间作用均采用单点Lennard-Jones(LJ)模型,气体分子与孔壁之间的作用势则用Steele10-4-3模型描述。研究结果表明:CO2相对CH4的平衡分离系数SCO2/CH4最初都是随着压力的增加而增加,直到达到峰值,然后随着压力的增加而减小,在20MPa时趋于恒定;压力低于20MPa时,SCO2/CH4随着温度的增加而增加,压力高于20MPa后,SCO2/CH4对于温度的变化不敏感;压力为10、20MPa时,SCO2/CH4先是随着CO2摩尔分数的增加而增加,直到达到最大值,而后随着CO2摩尔分数的增加而减少。因此,在现场实施CO2不可采煤层封存时,需要综合考虑各种因素对于CO2/CH4二元吸附的影响,对实际操作条件进行优化。
Grand canonical ensemble Monte Carlo（GCMC） simulations were carried out to investigate the adsorption and separation of CO2 /CH4 in slit-shape pores,then the influence of temperature,pressure,pore width and mole fraction of carbon dioxide on competition adsorption of carbon dioxide and methane.Both CO2 and CH4 were modeled as a single site spherical Lennard-Jones（LJ） molecules.The classical Steele 10-4-3 potential was used to describe the interaction between pore wall and fluid molecules.The results show that as the pressure is increased,the equilibrium separation factor of CO2 with respect to CH4 initially increases to a maximum value and then decrease before becoming constant with pressure at 20 MPa.While the quilibrium separation factor increases with temperature as the pressure below 20 MPa,when the pressure above 20 MPa,quilibrium separation factor keeps constant and is temperature insensitive,upon the high pressure conditions,the selective with mole fraction of carbon dioxide also decreases after reaching a maximum.All different equilibrium separation factors demonstrates that many factors can affect adsorption separation for CO2 /CH4 mixture gas,therefore,optimization of the conditions is needed in practical CO2 sequestration in unminable coalbed.
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2010年第9期1512-1517,共6页
Journal of China Coal Society
基金
国家自然科学基金创新研究群体科学基金资助项目(50621403)
国家自然科学基金青年基金(50904082)
教育部科学技术研究重点项目(109130)
关键词
CO2/CH4
吸附
分子模拟
CO2封存
平衡分离因子
carbon dioxide/methane
adsorption
molecular simulation
carbon dioxide sequestration
equilibrium separation factor
