Abstract:

The vapor-liquid equilibrium data of the ethanol (1)-water (2) and ethanol (1)-water (2)-potassium acetate (3) systems at atmospheric pressure were measured using Ellis vapor-liquid two-phase double-circulation equilibrium distillation apparatus. The results show that an effect of salting-out on ethanol(1)-water(2) binary system appears by adding potassium acetate, and the relative volatility of ethanol to water increases. The azeotropic point of the mixture of ethanol and water does not exist under the concentration of potassium acetate equating 10% (mass), which shows that it can be used as a separating agent for extractive distillation with salt. The equilibrium data for ethanol(1)-water(2) binary system, as well as the system containing 10%(mass) potassium acetate were correlated by using activity coefficient models of electrolyte non-random two-liquid (eNRTL), Wilson and universal quasi-chemical (UNIQUAC), as well as electrolyte non-random two-liquid (eNRTL) integrated with the authorized Aspen Plus simulation software. The calculated results showed that average absolute deviations (AADs) of the equilibrium temperature and vapor phase molar composition are 0.72℃ (eNRTL), 0.78℃ (Wilson) and 0.71℃ (UNIQUAC); 0.0083 (eNRTL), 0.0077 (Wilson) and 0.0101 (UNIQUAC), as well as 0.25℃ and 0.0168 (eNRTL) for the system containing salt respectively. The calculated results are well consistent with the experimental data.

Key words: water, ethanol, potassium acetate, vapor-liquid equilibrium, eNRTL model

摘要：

采用Ellis汽液两相双循环平衡蒸馏仪测定了常压下乙醇(1)-水(2)和乙醇(1)-水(2)-醋酸钾(3)物系的汽液平衡数据，结果表明：醋酸钾对乙醇(1)-水(2)系统具有盐析效应，乙醇对水的相对挥发度α₁₂上升。系统中10%(质量)的醋酸钾已经消除了乙醇-水间的共沸点，可作为加盐萃取精馏的分离剂。采用已授权的Aspen Plus软件自带的eNRTL、Wilson和UNIQUAC模型，以及eNRTL模型分别对乙醇(1)-水(2)、乙醇(1)-水(2)-10%(质量)醋酸钾(3)系统实验数据进行了关联，计算结果表明：乙醇(1)-水(2)系统中，平衡温度的平均绝对偏差（AAD）为0.72℃(eNRTL)、0.78℃(Wilson)和0.71℃(UNIQUAC)，气相组成计算值的平均绝对偏差为0.0083(eNRTL)、0.0077(Wilson)和0.0101(UNIQUAC)。而在乙醇(1)-水(2)-10%(质量)醋酸钾(3)系统中平衡温度和气相组成平均绝对偏差分别为0.25℃和0.0168(eNRTL)。

关键词: 水, 乙醇, 醋酸钾, 汽液平衡, eNRTL模型