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基于渗流型催化剂填装内构件的催化精馏过程研究
Study of Catalytic Distillation Process Based on the Seepage Catalysts Packing Internal
【作者】 张慧;
【导师】 李鑫钢;
【作者基本信息】 天津大学 , 化学工程, 2013, 博士
【摘要】 催化精馏研究的三大热点问题主要有催化剂装填方式、反应精馏匹配问题以及催化精馏过程设计与模拟。围绕三大热点问题,本文基于一种新型催化剂填装内构件渗流型催化剂填装内构件(简称SCPI),从流体力学和反应精馏耦合两个角度出发对内构件进行研究,分别建立适合内构件结构特点的CFD模型与反应精馏过程模型,为优化内构件结构和研究反应精馏过程提供基础与参考。基于SCPI特殊结构,分别建立了干压降、湿压降以及催化剂网盒持液高度的物理模型及数学模型。其中,对于干压降的求解,采用气体单相流模型进行模拟,并通过间接考虑波纹板阻力对流动影响的多孔介质模型实现。对于湿板压降的求解,采用多尺度分步模拟策略,并采用虚拟单相流方法对两相流问题进行处理。对于催化剂网盒持液高度的求解,采用欧拉-欧拉两相流模型进行模拟,其中,催化剂床层被当作多孔介质处理,并采用类似于欧根方程的多孔介质模型进行描述。通过将模拟结果与实验值对比,验证了模拟方法和模型的适用性。基于SCPI特殊结构形式,建立适合内构件结构特点的严格数学模型对反应精馏过程进行模拟,该模型不是建立在传统理论级概念基础之上,而是基于内构件具体结构形式建立的严格连续机理模型。此外,为方便用户更改参数和变量,研究反应精馏匹配关系,本文还对模型中各单元模块进行GUI界面设计和端口(port)设计,最终建立一套符合内构件结构的工艺流程。针对模拟计算中物性求解的难题,建立了gPROMS与ASPEN软件联用平台对物性进行计算。同时,针对所建催化精馏数学模型的特点及求解的困难性,本文还提出一些求解方法对催化精馏过程进行模拟计算,经验证这种方法不仅能使程序容易收敛而且能使计算稳定进行。本文基于SCPI型催化填料开发的流体力学计算模型和反应精馏耦合模型,可用于深入的研究反应精馏匹配关系,指导内构件优化和设计;其研究方法和思路可以为其他类型塔内件的研究提供物理建模、数学建模等方面的指导。
【Abstract】 Three hot issues in the process of the catalytic distillation are catalyst loadingmethod, the matching relationship between reaction and distillation, and catalyticdistillation process design and simulation. A new type of catalytic distillationinternal seepage catalytic packing internal (SCPI) is development. In the perspectiveof hydrodynamics and reactive distillation,the research is developed based on the newinternal around the three hot issues. CFD models and the reactive distillation modelwhich can provide a basis for optimizing the structure of the internal and study thereactive distillation process are established respectively.Models used for predicting pressure drop of SCPI and the height of liquid abovecatalyst bed were built by using different simulation strategies. Taking into accountthe structure of the corrugated metal sheets indirectly, porous media model was usedto acquire the dry pressure drop of SCPI. Pseudo single phase formulation wasutilized to process two-phase flow simulation for irrigated pressure dropdetermination. Euler-Euler two-fluid model was employed to simulate the height ofliquid above catalyst bed and aid designing the height of catalyst containers withavert-overflow baffles. The catalyst bed was treated as a porous medium, which canbe described by the revised Eugen equation. And their accuracy was determined bycomparison of the simulation results and the experimental data.Based on the special structure of SCPI, establish strict continuous mechanismmodel to describe reactive distillation process within the internal. The model is notbuilt on the basis of the traditional theoretical stage concept, but based on the specificstructure of the internal and more accurate in theory. In addition, Graphical UserInterface (GUI) design and the corresponding port design were implemented for eachunit module in order to clearly represent the flow-sheet of catalytic distillation process.Thermodynamic properties package Aspen Properties was integrated into thegPROMS software, to calculate the physical properties. In the process of solving themodel, a new approach was proposed to avoid difficulties connected withconvergence and stability of calculations. This approach was demonstrated to beefficient, it can reduce the simulation time and still accurately predict the results. On the one hand, the mathematical models built in the paper can be used forin-depth study the reactive distillation matching relationship, and can also providetheoretical support for structural optimization of the internals. On the other hand, theresearch methods can provide the guidance for other types of column internals onphysical modeling and mathematical modeling.
【Key words】 Catalytic distillation; gPROMS; Porous media model; Computational fluid dynamics; Mathematic model;