基于CPA状态方程计算天然气-甲醇-水气液相平衡

摘要

A Cubic-Plus-Association (CPA) Equation of Sate (EoS) was applied to calculate the vapor-liquid phase equilibrium of natural gas-methanol-water mixtures.The binary interaction parameters (BIP) for methane/water,ethane/water,hexane/water,and methanol/water binaries were fitted from corresponding experimental vapor-liquid equilibrium data.Moreover,a new general BIP formula for alkane-water binaries was correlated to the alkane's molecular mass.Finally,the vapor-liquid phase equilibrium of one natural gas-methanol-water mixture was calculated.The results show that,within 382-293 K and 5.86-34.34 MPa,the average relative deviation (ARD) between the experimental and calculated water contents in the vapor phase is 5.55％,and the ARD for the methanol contents is 8.09％.The achievement provides a practical way to calculate the vapor-liquid phase equilibrium of natural gas-methanol-water mixtures.Also,it can be applied to other mixtures involving the hydrogen-bond.%采用考虑了极性分子间氢键缔合作用的立方型附加缔合项(CPA)状态方程计算了天然气-甲醇-水体系气液相平衡.根据实验测试的甲烷-水、乙烷-水、丙烷-水、正己烷-水、甲醇-水二元体系气液相平衡实验数据,拟合了CPA状态方程中甲烷、乙烷、丙烷、正己烷、甲醇与水的二元交互作用系数,提出了与烷烃摩尔质量相关的烷烃-水二元交互作用系数关联式.在此基础上,预测了天然气-甲醇-水多组分体系的气液相平衡.结果表明:在温度为283-298 K,压力为5.86-34.34 MPa的范围内,预测的气相水含量、甲醇含量与实验值之间的平均相对偏差分别为5.55％和8.09％.CPA状态方程不仅为准确预测天然气-甲醇-水体系的气液相平衡提供了依据,还可应用于其他含极性物质体系的热力学物性参数和相平衡的计算.