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含临界区流体混合物汽液平衡等热力学性质的研究是化工热力学的一个难题。本文用改进的统计缔合流体理论方程(SAFT-CP)结合范德华单流体混合规则(vdW1)计算了含临界点的二元混合物的汽液平衡。与原始的SAFT方程相比,SAFT-CP方程以非球形的硬体项作为参考流体,代替原来的硬球项,考虑了分子成链对色散作用的影响,对于极性流体,考虑了分子的偶极-偶极相互作用而忽略了缔合作用。本文计算的二元体系包括非极性-非极性体系:二氧化碳-丙烷、二氧化碳-丁烷和二氧化碳-戊烷,以及非极性-极性体系:硫化氢-戊烷、甲烷-丙酮和二氧化碳-甲醇。含临界点在内的计算结果与文献实验值符合很好,表明该方程适用于二元混合物含临界区的相平衡计算,具有广阔的应用前景。
The study of the thermodynamic properties such as the vapor-liquid equilibrium of fluid mixtures with critical region is a difficult problem in chemical engineering thermodynamics. In this paper, the vapor-liquid equilibrium of binary mixture with critical point is calculated by using the improved statistical association fluid theory (SAFT-CP) and van der Waals mixing rule (vdW1). Compared with the original SAFT equation, the SAFT-CP equation takes the non-spherical hardware term as the reference fluid instead of the original hard-ball term and considers the effect of molecular chain on the dispersion. For the polar fluid, the molecular even Polar-dipole interaction ignores the association. The binary systems calculated in this paper include nonpolar - apolar systems: carbon dioxide - propane, carbon dioxide - butane and carbon dioxide - pentane, and nonpolar - polar systems: hydrogen sulfide - pentane, methane - acetone and carbon dioxide - methanol. The calculated results with the critical point are in good agreement with the experimental data, which shows that the equation is suitable for the phase equilibrium calculation of the critical mixture with binary mixtures and has broad application prospects.