【作者】 杨天宇；

【导师】 马沛生；

【作者基本信息】 天津大学 ， 化学工艺， 2008， 博士

【摘要】 密度数据和汽液相平衡数据是液体流动、传热和传质过程研究和工程计算中不可缺少的数据,也是PTA生产过程中所必需的数据。本论文是中国石化总公司委托项目的一部分,涉及的内容主要是PTA生产过程中相关物系的密度和汽液相平衡数据测定与研究。PTA的生产是在加压条件下进行的,与常压相比,高温加压下的物性数据的测定要困难得多,且高温加压下的物性数据的相关文献报道也很少。另外,在PTA相关体系中,醋酸作为溶剂是生产过程中一个重要的组分,醋酸的强腐蚀性是实验装置的设计和选型的一大难题。为此,本论文自行研制了一种可用于测量高温带压条件下液体密度的压力计式密度计并验证了该装置的可靠性。该装置主体为厚壁毛细玻璃管,可耐醋酸腐蚀并可承受最高10.0MPa的压力和573.15K的工作温度。用此密度仪测定了对二甲苯-醋酸、间二甲苯-醋酸和邻二甲苯-醋酸三个二元体系的液体密度(温度范围313.15K～473.15K,压力范围0.20～2.0MPa)。用实验所得密度数据计算出了该体系的超额摩尔体积VE,用Redlich-Kister方程分别对VE进行了回归。本论文还自行设计了一套流动法测定高温高压汽液相平衡装置并验证了该装置的可靠性。该装置主体为耐醋酸腐蚀的钛材,设计压力为10.0MPa,设计温度为573.15K。采用该装置测定了对二甲苯-醋酸、间二甲苯-醋酸和邻二甲苯-醋酸三个二元体系的汽液相平衡数据(温度范围433.15K～473.15K)。为PTA的工程设计提供了充足可靠的基础数据。分别选用CPA状态方程、HBT模型和ISH2模型对实验条件范围内二甲苯-醋酸体系的密度数据进行了计算或估算。对HBT模型和ISH2模型进行了修正,使用修正后的模型对实验条件范围内二甲苯-醋酸体系的密度数据进行了估算,结果表明,修正后的m-HBT模型和m-ISH2模型的估算精度均好于原有模型,其中m-HBT模型估算精度提高明显。采用Wilson和NRTL活度系数模型方程对二甲苯-醋酸体系的汽液平衡实验数据进行了关联计算,得到了各个体系的模型参数。由关联结果可以看出,对于二甲苯-醋酸体系,Wilson模型方程和NRTL模型方程都能得到很好的关联结果,且两模型的关联精度相当。利用本论文实验所得二甲苯-醋酸体系的汽液平衡数据回归了A-UNIFAC缔合模型的ACCH2基团与CH2基团的交互作用参数以及ACCH2基团与COOH基团的交互作用参数。在A-UNIFAC缔合模型的基础上,提出了mA-UNIFAC缔合模型,根据文献数据回归了mA-UNIFAC模型所需的模型参数。分别使用A-UNIFAC模型和mA-UNIFAC模型对实验所得VLE数据进行了计算或估算,结果表明本论文提出的mA-UNIFAC法的计算精度与A-UNIFAC缔合模型计算精度相当,在对汽相组成的预测上mA-UNIFAC模型好于A-UNIFAC模型。更多还原

【Abstract】 Liquid densities and vapor-liquid phase equilibrium data of pure compound and their mixtures are needed for the design of chemical processes involving heat and mass transfers or fluid mechanics, and are indispensable for PTA process. This thesis is partially supported by Chinese Petroleum Chemical Engineering Company. It includes the measurement and research of density and vapor-liquid phase equilibrium data related to the production of PTA.PTA is manufactured under pressure condition. Comparing to the atmospheric pressure, it is more difficult to measure the physical properties at high temperature and pressure. The data that related to the high temperature and pressure are even scarce. In addition, as the solvent, acetic acid is an important component in the PTA process. The strong corrosion of the acetic acid makes it difficult to select and design the measurement apparatus. In this paper, a new piezometric densimeter was designed and manufactured by ourselves. The main part of this densimeter is a thick-walled glass capillary, which can resist corrosion and can bear up to 10.0MPa in pressure and 573.15K in temperature. With the densimeter, the reliability of it was confirmed with literature data. The liquid densities of p-xylene-acetic acid, o-xylene-acetic acid, and m-xylene-acetic acid were measured by this densimeter at T from 313.15K to 473.15K and p from 0.20 to 2.0MPa. Excess molar volumes were calculated by the measurement results and being fitted by the Redlich-Kister equation. A flow-type apparatus for measuring vapor-liquid phase equilibrium under high pressures was also set up. The main part of this apparatus is made by titanium, which has good corrosion resistence. The design working pressure and temperature are 10.0MPa and 573.15K. The reliable and accurate of this apparatus were also proved. The VLE data of p-xylene-acetic acid, o-xylene-acetic acid, and m-xylene-acetic acid were measured by this apparatus at T from 433.15K to 473.15K. These results provide adequate and reliable data for PTA engineering design.CPA-EOS, HBT model and ISH2 model were selected to calculate and estimated the liquid densities of xylenes-acetic acid binary mixtures under experimental conditions. The HBT model and ISH2 model were modified and used to estimate the liquid densities of xylenes-acetic acid binary mixtures. Compared to the original models, the estimation results of the two modified models are both better than the original models, especially the m-HBT model. Wilson and NRTL models were used to correlate the VLE experimental data, and the corresponding model parameters were regressed also. It can be found from the correlation results that both models can get good correlation accuracy.Interaction parameters of the A-UNIFAC model corresponding to the ACCH2-CH2 groups and ACCH2-COOH groups were obtained by fitting the experimental data. A mA-UNIFAC model was proposed based on A-UNIFAC model. The interaction parameters of the mA-UNIFAC model were also obtained by fitting the literature data. The experimental VLE data were calculated and estimated by A-UNIFAC and mA-UNIFAC models. The results show that mA-UNIFAC model has the similar calculation accuracy as A-UNIFAC model. In the aspect of predicting vapor phase compositions the accuracy of mA-UNIFAC model is better.更多还原