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液液平衡数据的测定及热力学模型的研究是化学工程中的重要内容之一,虽然目前已有大量的液液平衡数据发表,但仍有很多物系的相平衡数据有待于人们来测定和研究。本研究选取甘油作为乙酸乙酯液液萃取分离的萃取剂。采用色谱法测定乙醇在甘油中的无限稀释活度系数,并采用单参数法关联UNIQUAC方程中的模型参数;采用液液平衡釜测定乙酸乙酯-水、乙酸乙酯-甘油二元体系和乙酸乙酯-乙醇-甘油、乙酸乙酯-水-甘油、乙酸乙酯-乙醇-水三元体系LLE数据,采用最小方差法关联UNIQUAC方程中的模型参数,并关联二元及三元LLE数据;利用六对模型参数模拟四元LLE数据,并与实验值相比较,实验与计算误差均小于5%。实验值与模拟值吻合较好,精度满足要求,从而可以为液液萃取的工艺改进模拟计算提供可靠的热力学基础数据。另外该体系的液液相平衡数据对于乙酸乙酯的提纯有实际的应用价值。
The determination of liquid-liquid equilibrium data and the study of thermodynamic model are one of the important contents in chemical engineering. Although a large number of liquid-liquid equilibrium data have been published, there are still many phase equilibrium data to be determined and studied by people . In this study, glycerol was selected as the extractant for liquid-liquid extraction of ethyl acetate. The infinite dilution activity coefficient of ethanol in glycerol was determined by chromatography. The parameters of UNIQUAC equation were correlated by single parameter method. The liquid-liquid equilibrium reactor was used to determine the ethyl acetate-water, ethyl acetate-glycerin binary system and acetic acid Ethyl acetate - water - glycerol, ethyl acetate - ethanol - water ternary system LLE data, the least squares method was used to correlate the model parameters in the UNIQUAC equation, and the binary and ternary LLE data were correlated. Four pairs of model parameters were used to simulate quaternary LLE data, and compared with the experimental data, the experimental and calculation errors were less than 5%. The experimental value is in good agreement with the simulated value, and the accuracy meets the requirements, which can provide reliable thermodynamic basic data for the process simulation of liquid-liquid extraction. In addition, the liquid-liquid equilibrium data of the system has practical application value for the purification of ethyl acetate.