甲乙酮-水-醋酸体系等压汽液平衡研究

Isobaric Vapor-Liquid Equilibria for Methyl Ethyl Ktone+Water+Acetic Acid Sytem

用改进Rose釜测定了甲乙酮-醋酸、甲乙酮-水-醋酸体系在101.33kPa下的汽液平衡数据,其中二元体系汽液平衡数据均通过了热力学一致性检验。考虑醋酸的缔合效应,利用化学理论模型和Hayden-O’Connell(HOC)模型计算各组分的汽相逸度系数,校正汽相的非理想性,液相的非理想性全部归结到液相活度系数中予以校正。用NRTL、UNIQUAC模型对甲乙酮-醋酸的汽液平衡数据进行关联,并得到相应的模型参数、温度偏差和汽相组成偏差。用2组甲乙酮-水体系模型参数、5组水-醋酸体系模型参数结合本研究关联得到的甲乙酮-醋酸体系模型参数对甲乙酮-水-醋酸体系的汽液平衡数据进行了预测,通过比较预测偏差的大小筛选出了最优模型参数组合,用最优模型参数组合进行预测的结果为:温度的平均绝对偏差为0.51℃,甲乙酮、水、醋酸的汽相组成平均绝对偏差分别为0.0047、0.0065、0.0067。预测精度较好,说明采用的模型参数是可靠的,能够为精馏的设计和模拟计算提供基础热力学数据。

Isobaric VLE data for （methyl ethyl ketone （MEK） ＋ acetic acid） and （MEK ＋ water ＋ acetic acid） systems were measured at 101.325 kPa by using a improved Rose kettle, and the VEL data for binary systems have passed the thermodynamic consistency test. Considering the association of acetic acid molecules, chemical theory model and Hayden-O＇Connell （HOC） model were used to correct the nonideality of vapor phase, while the nonideality of liquid phase was corrected in the calculation of its activity coefficient. NRTL and UNIQUAC modrls were applied to correlate the VLE data for （MEK ＋ acetic acid） system, and the model parameters together with the deviations of temperature and molar fraction in vapor phase were obtained. Two groups of model parameters for （MEK＋water） system, five groups for model parameters of （water ＋ acetic acid） system and one group of model parameters for （MEK ＋ acetic acid） system correlated in this work were used to predict the VLE data of the ternary system studied. The optimum combination of model parameters was selected through comparing the predictive deviations of different combinations. The detail of the predictive deviations obtained by using the selected optimum combination are as follows： the average absolute deviation （AAD） for temperature is 0.51℃, the AAD for vapor phase molar fraction of MEK, water and acetic acid are 0.0047, 0.0065 and 0.0067, respectively. So it can be concluded that the above selected model parameters is reliable, and these model parameters can be used as basic thermodynamic data for the design and simulation of the distillation of the （MEK ＋ water ＋ acetic acid） system.