【作者】 李佳；

【导师】 安维中；

【作者基本信息】 中国海洋大学 ， 化学工程， 2011， 硕士

【摘要】 乙氧基化（Ethoxylation）是环氧乙烷（EO）与含有活泼氢的化合物发生开环加成的反应,常用于生产非离子表面活性剂。由于乙氧基化反应强放热,环氧乙烷化学性质活泼、易分解、易燃、易爆、有毒,在很多情况下通过实验的方法来分析和掌握反应器的特征是不现实的,因此,利用数学模型和模拟技术从理论上认识反应器的行为及规律性,对指导工业装置的优化操作和改进设计具有重要意义。本文研究的目的是建立乙氧基化反应器的数学模型与模拟方法,并将其用于工业反应器的模拟分析与优化。本文的主要研究内容、采用的方法及取得的结果结论如下:一、开展半间歇反应器的数学模型和模拟计算研究分析了半间歇操作的搅拌釜式反应器、外循环喷雾式乙氧基化反应器的传质特性,在合理简化的基础上,建立了工业规模的、同时考虑动力学、汽液平衡、反应体积变化和惰性气氮气影响等的工业乙氧基化反应器的数学模型。自行开发了模拟计算程序,针对数学模型的非线性动态特征开发了基于四阶Runge-Kutta法及Aitken法的数值计算法,并对方法的可靠性进行了验证。二、建立数学模型中模型参数计算方法,以合成聚乙二醇为例,取得模型参数首先,针对环氧乙烷的特殊性（难以通过实验来测定汽液平衡数据问题）,提出用基于基团贡献法的UNIFAC方程来估算液相活度系数,并通过理论计算取得模型参数。研究表明,建立的UNIFAC模型能很好预测体系的相平衡行为,同时简单易实施。其次,开展了强碱为催化剂的反应动力学研究。在2L半间歇反应釜中测定了动力学数据,取得90℃¹30℃温度范围内本征动力学方程参数,其中引发反应的活化能E =73490 J·mol^-1,指前因子A = 5.97×10⁶ m³·mol^-1·s^-1,链传递反应的活化能E =70840 J·mol^-1,指前因子A = 8.746×10⁷ m³·mol^-1·s^-1。最后,通过实验数据拟合得到密度的关联方程。三、开展工业规模反应器的模拟研究对聚乙二醇工业搅拌釜式反应器、外循环喷雾式反应器的操作行为进行了模拟,考察了环氧乙烷进料速率对反应器操作的影响,得到安全限制下适宜的环氧乙烷进料速率。在此基础上,模拟得到反应器中温度、压力、环氧乙烷汽、液相组成及乙氧基化产物随时间和空间位置的分布,模拟结果与工业试验数据相吻合,结果表明了模型的可靠性。更多还原

【Abstract】 Ethoxylation is used to produce nonionic surfactants that are ring-opening addition reactions of hydrophohic substrates containing active hydrogen with ethylene oxide. However, due to ethoxylation is highly exothermic reaction, and ethylene oxide is reactive, flammable, explosive and toxic, the experimental investigations of such commercial reactor seem to be expensive, time consuming and sometimes impossible. Thus, developing a mathematic model that can provide an alternative to detailed experimental investigations becomes very essential. In this work, the modeling and simulation of industrial ethoxylation reactor will be discussed, aiming at establishing an important foundation on the simulation and optimization of ethoxylation reactor.The approach adopted in this work consisted of the following steps:（1） The mathematical model and simulation method of semi-batch reactor were proposed. The mass transfer characteristics of ethoxylation reactors were analyzed, include well-stirred reactor and spray tower loop reactors. Based on reasonable hypothesis on the ethoxylation reactor, the mathematical model had been developed to describe the behavior of industrial reactor, which taking the kinetics, vapor-liquid equilibrium, variation of reactive volume, as well as the effect of inert gas nitrogen on the reactor into account. A numerical simulation program was developed to solve the mathematic model. Due to the non-linear dynamic characteristic of reactive process, the fourth order Runge-Kutta method and Aitken method were used, and the accuracy of the methods was validated.（2） All of the relative model parameters calculation methods and correlations were established, obtaining the corresponding parameters by taking the synthesis of polyethylene glycol as example. Firstly, a vapor-liquid equilibrium model was developed to describe the nonideality of the system. To deal with the difficulties in determining vapor-liquid equilibrium data through experimental approach due to the existence of EO, the UNIFAC based method was employed to estimate the liquid activity coefficients, in which the parameters related could be obtained by means of theoretical calculation. The results obtained show that UNIFAC equation was suitable for the description of the nonideality of the system because the predicted results from model agreed well with the experimentally measured one. Secondly, the reaction kinetic study of ethylene glycol ethoxylation under base-catalyzed conditions was carried out and the kinetic equations were established. The results showed that under the operation temperature range of 90 to 130℃, the activation energy of initiation step was 73490 J·mol^-1, the pre-exponential factor was 5.97×10⁶ m³·mol^-1·s^-1; The activation energy of propagation was 70840 J·mol^-1, the pre-exponential factor was 8.746×10⁷ m³·mol^-1·s^-1. Finally, the correlation of density was obtained by fitting experimental data.（3） With the developed mathematic model, the simulation was further performed to investigate the behaviour of stirred reactor and spray tower loop reactors in industrial production of polyethylene glycol. The effect of ethylene oxide feed flow rate on the reactor performance was investigate, so as to obtain the suitable EO feed flow rate within safety limits. The simulation results provided the typical dynamic profiles of the reactor temperature, pressure, the molar fraction of ethylene oxide in vapor and liquid, as well as the ethoxylated oligomer distributions. The simulation results were successfully validated against the experimental data, which showed the reliability of the developed mathematical model.更多还原