外部环流反应精馏塔的分散控制方案设计

对于具有最不利相对挥发度排序（即反应物为最轻和最重组分,生成物为中间组分）的四元反应分离物系而言,在反应精馏塔的顶部和底部之间引入外部环流能够提高系统的反应分离效率,从而大幅度地降低系统的能量消耗和固定投资成本。以理想四元可逆放热反应的分离为例,研究了外部环流反应精馏塔的分散控制方案的设计问题。结果表明外部环流的引入提高了系统的反应速率,使得外部环流反应精馏塔的闭环控制效果更好（与传统反应精馏塔相比）,对干扰的处理能力更强。另外,由于外部环流反应精馏塔比常规反应精馏塔有更多的操作变量（即外部环流流量）,利用该变量对出料浓度进行控制,可以进一步提高系统的闭环控制效果。     

反应精馏技术的关键问题分析

反应精馏是为增强反应与精馏效果而将两种单元操作进行耦合的多功能新技术。因既有化学反应又有精馏过程,反应精馏过程需考虑气液相平衡、气液质量传递、催化剂内扩散(非均相反应精馏)以及动力学等因素的相互作用,导致该过程存在定态多重性、动力学复杂性。文章系统地综述了近年来国内外科研工作者对反应精馏实验和理论的研究进展,分析了反应精馏技术工业应用中存在的关键问题,并对未来的发展方向进行了展望。     

Nonlinear state estimation and control of a batch reactive distillation

This paper deals with the advanced adaptive control of a batch reactive distillation (RD) column for the production of ethyl acetate. The nonlinear adaptive control law consists of the generic model controller (GMC) and an adaptive state estimator (ASE). In the first part of the present work, the design approach of the ASE scheme in two different forms, namely ASE1 and ASE2, has been addressed for a batch reactive rectifier. The predictor model of both the ASE estimators includes only a component mole balance equation around the condenser-reflux drum system and an extra state equation having no dynamics, and therefore, there is a large process/predictor mismatch. In presence of this structural discrepancy, the adaptive estimation schemes compute the imprecisely known parameters quite accurately based on the measured distillate composition under initialization error, disturbance and uncertainty. In the subsequent part, the adaptive GMC–ASE1 control structure has been formulated for the sample reactive column. This nonlinear control strategy shows comparatively better closed-loop performance than the gain-scheduled proportional integral (GSPI) controller due to the exponential error convergence capability of the estimation scheme and the high-quality control of the GMC law.     

Decentralized Control System Design for a Ternary Reactive Distillation with Inert Using Mixed Integer Optimization

Inferential control of ternary reactive distillation with inert is controversially discussed in recent literature. For further clarification, a systematic study based on mixed integer dynamic optimization is presented. Special emphasis is placed on robustness with respect to various disturbances arising in practice. This gives rise to a stochastic problem formulation which is extended step by step. Through this, significant improvements can be achieved and it is concluded that inferential control of ternary reactive distillation with inert is feasible.     

反应精馏过程图解设计法研究进展

反应精馏是伴有化学反应的精馏过程 ,具有设备紧凑、能量集成等优点。文章总结介绍了 80年代中期以来国内外有关反应精馏过程设计的研究进展 ,重点分析了图解设计法理论研究的现状和局限性 ,指出了反应精馏过程图解设计法的发展方向。     

连续反应精馏合成丁酸乙酯

本研究采用对甲苯磺酸为催化剂,用试验与Aspen Plus模拟相结合,研究了反应精馏合成丁酸乙酯的工艺。首先对反应精馏装置进行试验研究,并利用Aspen Plus对其进行模拟,模拟结果与试验结果较吻合。在此基础上,对本工艺流程进行了试验研究及模拟设计,得到了可行的工艺方案。该方案得到的产品纯度理论上可达到99.5%以上,且具有流程简单、废水排放量少,设备投资低等优点。     

反应精馏过程的研究进展

反应精馏是化学反应和精馏过程耦合为一体的单元操作,已成为当今的重要研究领域。本文综述了反应精馏过程的模拟计算和设计方法,介绍了过程控制中的多定态问题,总结了反应精馏的工业应用情况,指出了研究中应注意的重要因素,并指出了未来的研究方向。     

精馏过程实时动态模型

根据工业装置的实际控制要求,提出了一种新的精馏过程实时动态模型。与传统模型相比,该模型在计算速度及畏度方面作了一些改进。引入定容内蒸,逐板进行汽液平衡及水力学计算。基于该模型的软件能非常逼真地实时再现式业装置的正常及异常操作状况,为灵敏板选择及高级控制系统的开发设计提供了依据。     

精馏塔设备的设计与节能研究进展

精馏过程是化工过程中最耗能的过程之一。本文总结了常规精馏塔,反应精馏塔以及分隔壁精馏塔这几种类型精馏塔的研究进展。常规精馏塔的研究仍在进行,并主要体现在算法的改进与新算法的提出,以及常规精馏塔在化工高等教学的重要作用上,指出了反应精馏塔和分隔壁精馏塔是近几年精馏塔设计方面的研究热点,如反应精馏塔的模型、求解方法等,分隔壁精馏塔是一种全新的概念因而并未系统化,但却能够明显节省设备投资,并具有良好的节能前景,尤其是在与反应精馏结合后效果特别明显。文章最后对精馏塔的未来研究方向进行了展望。     

Comparative control study of ideal and methyl acetate reactive distillation

The control of an ideal reactive distillation column is compared with that of a similar, but somewhat different, real chemical system, the production of methyl acetate. Similarities and differences are observed. Three control structures are evaluated for both systems. A control structure with one internal composition controller and one temperature controller provides effective control of both systems for both high and moderate conversion designs. A two-temperature control structure is effective when the system is overdesigned in terms of number of reactive trays, holdup and/or catalyst load. Direct control of product purity for the high-conversion/high-purity design is difficult because of system nonlinearity and interaction. Tray temperature control avoids the nonlinearity problem.     

Design and control of an olefin metathesis reactive distillation column

This paper considers the design and control of a reactive distillation column in which one reactant is consumed and two products are formed (A?B+C). The volatilities are α_B>α_A>α_C, i.e. the reactant is intermediate boiling between the two products. The metathesis of 2-pentene is considered as the demonstrative example. The column has a single feed of the intermediate boiling reactant. The distillate contains mostly light component and the bottoms mostly heavy.Three designs are considered: the base case (low-conversion/low-pressure), a low-conversion/high-pressure case and a high-conversion/high-pressure case. The base design is obtained from the literature, and the other two steady-state designs are optimized with respect to the total annual cost. All the designs are found to be openloop stable. Five control structures are studied for the base design. Then the best two structures are applied to the remaining two designs. This category of reactive distillation exhibits less challenging problems than other categories since it uses a single feed, which eliminates the need for the control structure to perfectly balance two fresh feeds.Simulation results demonstrate that effective dynamic control is provided by a control structure that uses two temperatures to maintain the purities of both product streams. No internal composition measurement is required. This structure is found to be robust and stable and rejects loads and tracks setpoints very well.     

Systematic integrated process design and control of binary element reactive distillation processes

Integrated process design and control of reactive distillation processes is considered through a computer‐aided framework. First, a set of simple design methods for reactive distillation column (RDC) that are similar in concept to nonreactive distillation design methods are extended to design‐control of RDCs. These methods are based on the element concept where the reacting system of compounds is represented as elements. When only two elements are needed to represent the reacting system of more than two compounds, a binary element system is identified. It is shown that the same design‐control principles that apply to a nonreacting binary system of compounds are also valid for a reactive binary system of elements for distillation columns. Application of this framework shows that designing the reactive distillation process at the maximum driving force results in a feasible and reliable design of the process as well as the controller structure. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3137–3154, 2016     

反应精馏过程耦合强化技术基础与应用研究述评

反应精馏技术是过程强化概念在化学工业成功应用的典范。由于反应与精馏耦合的高度复杂性和非线性,反应-精馏相互影响机制、耦合方式及其过程能效调控与优化成为制约该技术广泛应用的关键科学问题。综述了近二十年来国内外反应精馏技术从基础研究到工业应用的概况,包括反应精馏过程的可行性分析与概念设计方法、稳态模拟过程优化与动态模拟控制策略设计、兼具催化反应与气液传质的高效内构件开发以及反应精馏在各领域的应用。探讨了目前制约反应精馏广泛应用关键问题的解决方法与途径,阐明了普适性的反应精馏过程开发方法,总结了基于反应精馏过程耦合的新型过程强化技术,指出了反应精馏技术的发展趋势。     

减压蒸馏系统管道设计

介绍减压蒸馏系统气体和液体管道的设计原则和注意事项     

丙酮缩甘油反应精馏工艺全流程模拟与优化

针对丙酮缩甘油的传统生产工艺单程转化率低、生产设备投资高、后处理过程长及环境污染等缺点,本文设计了一种高效节能的反应精馏（RD）生产工艺。基于反应动力学和热力学基础数据,建立丙酮缩甘油反应精馏严格数学模型对反应精馏工艺全流程进行理论探究。通过对塔内浓度分布的分析,揭示了产物水对丙酮缩甘油反应精馏合成效果的影响。探究不同丙酮循环量对全流程生产工艺的影响;并以反应精馏塔和丙酮回收塔塔釜再沸器负荷为目标函数,对全流程的参数进行探究和优化,结果表明全流程优化后相比单塔优化的总能耗可节约3.6%。同时与工业传统先反应后精馏流程相比,优化后的反应精馏全流程节约能耗15.1%。该结果可为丙酮缩甘油工业化生产工艺设计提供参考和依据。     

玉米芯制备糠醛的研究

对从玉米芯制备糠醛进行了研究。玉米芯水解催化剂为5%(m/m)的稀硫酸溶液,在100℃回流反应3.5 h,戊糖收率可达64.5%(以多缩戊糖计)。上述酸性水解液在170℃、甲苯存在下,反应蒸馏3 h,糠醛收率达到85%(以戊糖计)。蒸出液经精制,制得糠醛。与一步法相比,糠醛收率提高5%～8%(以原料玉米芯计),并且反应时间缩短,水蒸汽的用量减少。     

反应精馏研究进展及应用前景

对反应精馏技术在工艺和模拟方面的研究进展进行了概述 ,简单介绍了反应精馏的关键技术并对反应精馏的应用前景进行了展望。