间歇釜式反应器最佳反应时间的确定：计算机辅助计算

本文采用计算机模拟图解法和数值法确定间歇釜式反应器最佳反应时间,较传统的手工图解法更为直观、快速和准确,为反应器设计计算和教学提供了简捷有效的方法。     

半间歇搅拌釜式乙氧基化反应器的数学模拟

以KOH催化条件下乙二醇乙氧基化为例,建立了工业规模的、同时考虑动力学、气液平衡、气液传质、反应体积变化和惰性气体氮气影响等的半间歇搅拌釜式乙氧基化反应器的数学模型。通过数学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,模拟得到反应器中压力、环氧乙烷在气液相中的组成及乙氧基化产物随时间的分布,并同工业试验数据进行了比较。结果表明了模型的可靠性。     

在串联的半间歇搅拌釜式反应器中丙酮氯化反应的研究

一、前言由于丙酮分子中α碳上氢原子受羰基的影响,容易被氯原子取代,因此,氯化丙酮的制备即采用丙酮直接氯化的途径。1,1,3-三氯丙酮是生产叶酸的重要原料。目前国内制药厂是采用四个串联的200 L 搪瓷反应釜,在不带机械搅拌的半间歇或半流动条件下,进行丙酮氯化生产1,1,3-三氯丙酮。其操作特点是,丙酮一次性加入反应釜,因氯气在丙酮及氯化丙酮中是不易溶解的气体,所以氯气加入量的速率仅能按在反应温度下的溶解度而定,不仅     

间歇与半间歇反应热失控危险性评估方法

针对间歇、半间歇反应器中频繁更换物系和/或反应工艺,受时间和经济条件限制往往不可能对发生在其中的反应动力学进行深入研究的特点,建立适用于它们的热失控危险评估方法具有重要意义。本文对此做了简要的综述并且认为,尽管迄今还没有普适性的方法,但是对于某些类型的重要反应,安全界限图方法和反应失控情景分析方法还是较为适用的。前者虽然涉及参数较多,且没有考虑高温下物料二次分解的可能性,但能按照反应结果将量纲1操作参数平面划分为无积累、反应失控、未充分引发及无害4个子区域,从而可以先验地获取更多的信息;后者虽然忽略了均相与非均相反应的不同,但该方法可对一定工艺条件下目标反应失控和二次分解反应进行分析评估,简单易行,考虑更全面。     

间歇釜的配置及其优化

系统地从技术经济角度讨论了间歇釜的配置及其优化的程序,即先根据相邻两工序的生产负荷确定各自的方案,然后再从可能的方案组合中,筛选出最经济的衔接方案。     

反应器若干操作优化问题

分别对间歇操作反应器的最佳反应时间和连续操作反应器及其最佳进料方式进行分析，对实际生产有一定的指导意义。     

多级串联釜式反应器的优化设计

对于多级串联釜式反应器,以反应器的总体体积最小为目标函数,利用图解法,确定各釜最佳的出口转化率,从而计算各釜体积。     

釜式反应器的计算机处理及选型

建立了求解分批操作釜式反应器的数学模型,首先用四阶龙格一库塔法（Runge－Kutta）计算初值,然后转用阿当姆斯一摩尔顿法（Adams-Moulton）进行了计算处理,最后结合实际生产厂可选用的K型反应釜讨论了这种反应器的选型问题。     

化工行业釜式反应器选型关键环节探讨

为了正确指导化工行业中釜式反应器的设计选型问题，笔者选取了2021—2022年发生的2起典型釜式反应器的事故，并结合实际工作中的方法经验，通过对釜式反应器进行结构论述和工艺性能解析，总结出5个关键性的选型环节，为化工行业釜式反应器的选型提供了参考和依据。     

间歇放热反应系统热失控参数敏感性研究

以参数敏感性定义作为理论基础和数学依据,证明了一级间歇放热反应系统操作曲线与温度最大点曲线的拐点轨迹相切的点是反应系统热失控的参数敏感点,从理论上给出了反应系统的安全操作所允许的温度上限。利用敏感点和超临界操作曲线的拐点关系,推导出反应系统安全操作的临界判据。将该临界判据与Adler和Enig、van Welsenaere和Froment以及Wu等的经典判据进行比较,结果与文献值基本一致。将该临界判据和经典判据与Allen和Rice的实验结果进行对比,该标准也能很好地预测出偶氮甲烷分解爆炸的压力。     

Optimizing the catalyst distribution for countercurrent methane steam reforming in plate reactors

Microscale autothermal reactors remain one of the most promising technologies for efficient hydrogen generation. The typical reactor design alternates microchannels where reforming and catalytic combustion of methane occur, so that exothermic and endothermic reactions take place in close proximity. The influence of flow arrangement on the autothermal coupling of methane steam reforming and methane catalytic combustion in catalytic plate reactors is investigated. The reactor thermal behavior and performance for cocurrent and countercurrent are simulated and compared. A partial overlapping of the catalyst zones in adjacent exothermic and endothermic channels is shown to avoid both severe temperature excursions and reactor extinction. Using an innovative, optimization‐based approach for determining the catalyst zone overlap, a solution is provided to the problem of determining the maximum reactor conversion within specified temperature bounds, designed to preserve reactor integrity and operational safety. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Dynamic optimization of a semi-batch reactor for polyurethane production

In this work, the dynamic optimization of a polyurethane copolymerization reactor is addressed. A kinetic-probabilistic model is used to describe the nonlinear step-growth polymerization of a mixture of low- and high-molecular-weight diols, and a low-molecular-weight diisocyanate. The dynamic optimization formulation gives rise to a highly complex and nonlinear differential-algebraic equation (DAE) system. The DAE optimization problem is solved using a simultaneous approach (SDO) wherein the differential and algebraic variables are fully discretized leading to a large-scale nonlinear programming (NLP) problem. The main reactor operation process control objective is the maximization of the molecular weight distribution (MWD) under a desired batch time, subject to a large set of operational constraints, while simultaneously avoiding the formation of polymer network (gel molecule). Typically, polyurethane formation is carried out using batch reactors. However, batch operation leads to attain relatively low MWD values and, if the process is not efficiently operated, there is always the possibility of obtaining a polymer network. In this work, it was found that process operation is greatly enhanced by the semi-batch addition of 1,4-butanediol and diamine, and the manipulation of the reactor temperature profile, allowing to obtain high molecular weights while avoiding the onset of the gelation point.     

Optimal operation of ethylene polymerization reactors for tailored molecular weight distribution

This work presents a comprehensive steady‐state model of the high‐pressure ethylene polymerization in a tubular reactor able to calculate the complete molecular weight distribution (MWD). For this purpose, the probability generating function technique is employed. The model is included in an optimization framework, which is used to determine optimal reactor designs and operating conditions for producing a polymer with tailored MWD. Two application examples are presented. The first one involves maximization of conversion to obtain a given MWD, typical of industrial operation. Excellent agreement between the resulting MWD and the target one is achieved with a conversion about 5% higher than the ones commonly reported for this type of reactor. The second example consists in finding the design and operating conditions necessary to produce a polymer with a bimodal MWD. The optimal design for this case involves a split of the initiator, monomer, and modifier feeds between the main stream and two lateral injections. To the best of our knowledge, this is the first work dealing with the optimization of this process in which a tailored shape for the MWD is included. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Real-time optimal control of an anti-solvent isothermal semi-batch crystallization process

This study presents a novel approach for the implementation of a real-time dynamic optimal control methodology on a seeded, anti-solvent batch crystallization process. The novel features of the approach include online estimation of the nucleation, growth rates and moments of paracetamol in isopropanol-water solution using the FBRM^® probe, and the real-time single and multi-objective optimization. In addition, the supersaturation was measured by ATR-FTIR spectroscopy. The crystallization model, which involved population and mass balance, was solved based on the finite difference method. The results of the multi-objective optimization showed a substantial improvement of the end of batch properties expressed in terms of the volume-weighted mean size and yield. The effect of mean size of seeds was studied as well, and it was found that the seeds with smaller mean volume-weighted mean size promoted the growth rate. The multi-objective optimal control resulted in an increase in the volume-weighted mean size by compared to the seeds and 51% of theoretical yield, which showed better performance compared to other optimal control policies.     

Periodic operation of transport reactors for catalytic reactions

Based on plug flow of gas and catalyst particles and concentration dependent deactivation kinetics, the performance of transport reactors under a periodic (rectangular pulse) inlet concentration is analysed for improvement in conversion and extent of catalyst decay. The effects of reaction and deactivation orders, reaction and deactivation constant groups, and γ (cycle split) on the performance of the reactors are evaluated theoretically. For reaction orders greater than one, periodic operation improves conversion. Resonance behaviour is observed for certain combinations of parameters. For identical operating conditions vertical upflow, downflow and horizontal flow reactors are compared. Conversion in upflow reactors is higher than that in either horizontal flow or downflow reactors. However, catalyst decay is the least in downflow reactors.     

Challenges for the periodic operation of trickle-bed catalytic reactors

Since the earliest publications just over a decade ago, the literature on periodic operation of trickle beds has grown rapidly. There are now over 30 published papers. Two applications, flow and feed composition modulation, for control of hot spots in large-scale reactors are sufficiently advanced for full-scale implementation if that has not already taken place. Models are now available that are capable of representing the time-average performance of periodically operated trickle beds, but these are not detailed enough to reproduce all of the transient behavior observed. Much about performance under periodic operation remains to be discovered. Research challenges are discussed under separate types of periodic operation: flow interruption, flow augmentation for hot spot control, feed composition modulation for hot spot control and to improve rate and/or to modify selectivity, and flow variation for enlargement of the pulse flow regime.     

间歇反应器的热参数敏感性及其临界判据(Ⅰ)

以参数敏感性定义作为理论基础和数学依据,证明了间歇反应器操作曲线与温度最大点曲线的拐点轨迹相切的点是反应系统的参数敏感点,从理论上给出了间歇反应器中进行一级反应时,反应系统安全操作所允许的温度上限,并利用临界操作曲线温度最大点和超临界操作曲线的拐点关系,推导出反应系统安全操作的临界判据.将该临界判据用于冷却介质温度与物料入口温度相等的反应系统,并与Adler和Enig,van Welsenaere和Froment以及Wu,Morbidelli和Varma的经典判据进行了比较.该临界判据与Allen和Rice的实验结果吻合良好.     

A feedback control framework for safe and economically‐optimal operation of nonlinear processes

Maintaining safe operation of chemical processes and meeting environmental constraints are issues of paramount importance in the area of process systems and control engineering, and are ideally achieved while maximizing economic profit. It has long been argued that process safety is fundamentally a process control problem, yet few research efforts have been directed toward integrating the rather disparate domains of process safety and process control. Economic model predictive control (EMPC) has attracted significant attention recently due to its ability to optimize process operation accounting directly for process economics considerations. However, there is very limited work on the problem of integrating safety considerations in EMPC to ensure simultaneous safe operation and maximization of process profit. Motivated by the above considerations, this work develops three EMPC schemes that adjust in real‐time the size of the safety sets in which the process state should reside to ensure safe process operation and feedback control of the process state while optimizing economics via time‐varying process operation. Recursive feasibility and closed‐loop stability are established for a sufficiently small EMPC sampling period. The proposed schemes, which effectively integrate feedback control, process economics, and safety considerations, are demonstrated with a chemical process example. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2391–2409, 2016