【作者】 童立威；

【导师】 漆志文；

【作者基本信息】 华东理工大学 ， 过程系统工程， 2014， 博士

【摘要】 反应精馏将化学反应和精馏分离两种过程耦合在同一设备内进行,利用精馏分离作用提高反应过程的效果,已成为化工行业的关键过程强化技术,并得到了很好的应用。然而,反应精馏技术的优点往往因为体系特殊的物理和化学性质而受到限制。为此,本文研究利用辅助化学反应来直接强化反应精馏过程,通过引入辅助反应改变原有反应精馏体系的诸多性质,例如共沸物组成、体系的最轻与最重组分以及化学反应速率等,最终从精馏和化学反应两个方面同时对原有反应精馏过程进行强化；以乙酸甲酯水解反应精馏过程为例,研究了以甲醇脱水为辅助反应的过程强化机理,并以此开发了乙酸甲酯回收利用新工艺。主要研究工作摘要如下：基于化工过程模拟软件gPROMS发展了反应精馏过程分析和模拟计算平台。构建了反应精馏过程平衡级和非平衡级模型；拓展了拟弧长延拓算法,可搜索体系的分岔点以及多稳态,可对包括反应精馏在内的化工过程进行分岔计算。利用外部测试函数与gPROMS进行对接的方式来确定分岔点的精确数值,并计算雅克比矩阵的特征值来判断平衡点的稳定性。以CSTR反应器、共沸精馏以及乙酸甲酯反应精馏过程为例,详细描述了该平台的结构与使用方法。基于剩余曲线图的概念建立了针对包含两个反应和多个组分体系强化机理的分析方法。分别从精馏和化学反应两个方面,分析了甲醇脱水反应来强化乙酸甲酯水解反应精馏过程的强化机理。结果表明,甲醇脱水反应的引入可以为体系提供额外的水,从而避免了在进料中因加入过量的水而导致下游分离能耗升高等问题。同时,由于不停地将甲醇转化成水,使得水解反应平衡向正反应方向移动,极大地提高了乙酸甲酯的水解率。此外,进料中以及乙酸甲酯水解得到的甲醇,可以通过脱水反应转换为副产品二甲醚。利用所开发的模拟计算平台,对甲醇脱水反应强化的乙酸甲酯水解反应精馏过程进行了概念设计。考察了各种操作参数,如操作压力、反应区间、进料位置、回流比以及催化剂用量对体系的影响。结果表明,在优化条件下,当进料为等摩尔的甲醇和乙酸甲酯时,甲醇和乙酸甲酯可以完全转化,塔顶和塔底分别得到高纯度的二甲醚和乙酸,也验证了辅助化学反应的强化效果。同时,由于甲醇脱水反应的速率过慢,需在反应精馏塔前设置预反应器,将部分甲醇提前脱水,以降低反应精馏塔的能耗。利用甲醇脱水反应强化乙酸甲酯水解反应精馏的优势,针对目前聚乙烯醇生产废液回收利用所存在的问题,设计出了两种新的工艺流程。考察了各种操作参数对新工艺的影响,从而得出优化的操作条件。与传统工艺流程相比,新的工艺流程更为简化,能耗更低,设备更少。同时,通过甲醇脱水反应可以生产出高附加值的产品二甲醚。更多还原

【Abstract】 Reactive distillation (RD) is an integration of distillation and reaction, which takes the advantage of distillation to improve the effect of chemical reaction. It has been an important intensification technology and successfully applied in the chemical industry. However, RD processes may be inhibited by their particular properties of the reaction systems. In this dissertation, the concept of RD intensified by an auxiliary reaction is studied. By introducing an auxiliary reaction, the characteristics of original system such as composition of azeotrope, reaction rates, alternative lightest and heaviest components are modified, which will intensify the system in the respect of distillation and chemical reaction. The methyl acetate (MeOAc) hydrolysis intensified by methanol (MeOH) dehydration is studied as an example where the latter serves as the auxiliary reaction. The main research works are listed as follows:The platform of analysis and simulation for the process of RD was developed based on the process simulator gPROMS. In the platform, the equilibrium and non-equilibrium models of RD were established while the arc-length continuation was extended to search the bifurcation points and multiply steady states for the chemical process including RD. The stability analysis of solutions was realized by evaluating the eigenvalues of the Jacobian matrix that was accessible to users in gPROMS. The examples of a classic adiabatic CSTR, a homogenous azeotropic distillation and methyl acetate synthesis by RD were used to specify the configuration and application of platform.A residue curve maps (RCMs) was developed to analyze the mechanism of intensification for the case with two chemical reactions and multiple components. The mechanism of intensification of MeOAc hydrolysis intensified by MeOH dehydration was studied in the respect of distillation and chemical reaction. The results show that, extra water can be supplied for the system by introducing MeOH dehydration, which avoids excessive water in the feed and high energy consumption in the downstream separation. Meanwhile, converting MeOH into H2O in the dehydration reaction facilitate the chemical equilibrium to forward direction, which enhance the conversion of MeOAc. Furthermore, MeOH as the product in the MeOAc hydrolysis reaction can be transferred into dimethyl ether as the byproduct.The conceptual design of MeOAc hydrolysis intensified by MeOH dehydration in the RD was implemented based on the developed platform. The effect of operating parameters such as pressure, reaction zone, feed stage, reflux ration and catalyst loading on the process were analyzed. The results reveal that, in the case of equal mole of MeOH and MeOAc as feed, MeOH and MeOAc can achieve100%conversion in the RD column while pure dimethyl ether and acetic acid are the top and bottom product, respectively. Thus, the effect of intensification is proved. Furthermore, as the rate MeOH dehydration is low, a pre-reactor was set before the RD column to convert MeOH into water in advance so that the energy consumption of RD column could be saved.As the advantange of effect of intenficaiton, two novel processes of recovery of MeOAc in the production of poly vinyl alcohol were developed. The optimal conditons were obtained by analysis of various operating parameters. Compared with traditional processes, high MeOAc conversion and high purity products could be reached and the equipment costs and energy consumption are significantly reduced with the help of these new processes. Furthermore, high purity DME could be produced as a more valuable product.更多还原