【作者】 张峰；

【导师】 赵玲；

【作者基本信息】 华东理工大学 ， 化学工程， 2013， 硕士

【摘要】 以PTA装置氧化单元为研究对象,利用Aspen Plus进行流程模拟与分析。首先,确定PX氧化体系热力学性质和固体溶解度的计算方法,采用文献数据对相应的计算模型进行了参数回归。其次,对氧化单元进行分段建模与分析,采用基于自由基反应机理的PX氧化动力学,并考虑燃烧副反应的影响,利用盐沉降反应平衡描述固体的溶解与析出特性,从而耦合反应、结晶、蒸发过程,建立了氧化反应器的模型,并考虑了氧化段内4个循环回路的影响,实现了氧化反应段的模拟,计算得到物流组成信息及固相物质含量；考虑第一结晶器中的二次氧化过程,建立了耦合二次氧化、结晶、蒸发的结晶器模型,并对整个CTA结晶过程进行了模拟,重点分析了停留时间变化对第一结晶器内二次氧化和结晶过程的影响,并考察了绝热条件下操作压力变化对结晶过程的影响,发现降低压力有利于固体析出；建立了带有4个循环回路的溶剂脱水过程的模型,确定了断裂流股、收敛方法和策略从而能使所有循环回路收敛；分段模拟的结果吻合工业装置设计值。最后,基于分层建模思想对氧化单元进行结构划分,建立了分层式结构模型,综合分段模拟模块,选择合理的收敛方法及断裂流股收敛顺序,实现了氧化单元全流程模拟,全流程模拟结果与工业装置设计数据也相符。本文所开展的工作可以为PTA氧化单元全流程的设计和操作优化提供平台。更多还原

【Abstract】 Process simulation and analysis of oxidation unit of purified terephthalic acid (PTA) plant using Aspen Plus have been conducted, which could provide development platform for design and optimization for para-Xylene oxidation unit.Firstly, the methods and models including thermodynamic property and solubility involved in PX oxidation system were studied, and the corresponding parameters were regressed based on literature data.Secondly, modeling blocks of major sections in oxidation unit, including oxidation reaction section, oxidation and crystallization section, solvent dehydration section, solvent recovery section, filtering and drying section, have been built. Kinetic model of PX oxidation based on free radical reaction mechanism was applied, and side reactions were also considered. Meanwhile salt precipitation reactions were selected to describe the formation and dissolution of solids in equilibrium. Therefore, an oxidation reactor model coupling reaction, crystallization and evaporation was established. The simulation of oxidation reaction section was further completed with four circulation loops. So both composition information and solid product content of slurry is figured out. Similarly, the model of the first crystallizer involving secondary oxidation, crystallization and evaporation also has been built, and the oxidation and crystallization section was simulated, the effect of residence time on reaction and crystallization in the first crystallizer was investigated, the result of operation pressure influence on crystallization under adiabatic condition showed that reducing pressure would benefit the formation of solid. What’s more, a model of solvent dehydration section containing four circulation loops was generated, all of the loops could converged with appropriate tears and reasonable convergence method. It was verified that the calculated results of major subsidiary models of each sections were in good agreement with design value of industrial plant.Finally, segment partition of oxidation unit was carried out following the theory of hierarchical mechanism, and a hierarchical model for the whole process was created. With appropriate convergence method and sequence, the simulation of oxidation unit was realized. The calculated results also indicated a good fit with design value.更多还原