基于不同状态方程压缩因子的煤吸附CO_2等温线的比较

Comparison of CO_2 adsorption isotherms on coals based on compressibility factor from different equation of state

为了考察不同状态方程对CO2吸附量测定的影响，通过比较3种通用气体方程和3种CO2经验状态方程计算所得CO2压缩因子，进而利用3个煤样研究6种状态方程所得的CO2吸附值。结果表明：状态方程对Gibbs吸附量的影响在平衡压力不高于6MPa时较小，而在中高压力条件下较大，且随平衡压力增加该影响增大。研究表明：中高压条件下不同状态方程所获得吸附量的差异主要通过6～12MPa吸附增量的变化而引起，低压和高压条件下状态方程对吸附增量影响较小。状态方程对吸附量的影响不仅取决于计算CO2压缩因子所采用的状态方程，而且取决于参比缸和自由空间的容积。

To know the effect of Equation of state （EoS） on CO2 adsorption measurement, CO2 compressibility factors calculated from three universal EoSs and three empirical EoSs for CO2 were compared, then three coal samples were used to investigate CO2 adsorptions obtained from the six EoSs. The results show that the EoSs have less effect on CO2 Gibbs adsorption at equilibrium pressure less than 6 MPa, while the effect is great at middle-high pressure and increases with increasing equilibrium pressure. The research suggests that the adsorption difference among various EoSs at middle-high pressure is caused by the adsorption increment at pressures of 6-12 MPa. The effect of EoS on the adsorption increment is small at low and high pressure. The effect of EoS on adsorption not only depends on the EoS used to calculate compressibility factor of CO2 and also on the volume of reference cell and free volume of sample cell.