带有中间储罐的间歇精馏工艺动态控制模拟优化

甲酸甲酯-甲醇-水是化工生产过程中最常见的三元混合物之一。目前,间歇精馏工艺分离该三元混合物的研究较少,在动态控制方面也少有报道。本文研究了分离甲酸甲酯-甲醇-水的带有中间储罐的间歇精馏工艺动态控制模拟优化。利用Aspen Plus和Aspen Plus Dynamics软件,在稳态模拟的基础上,分别考察了液位控制结构和组分控制结构两种控制方案。结果表明,液位控制结构控制性能较差,达到稳定后甲醇和水的纯度较低。组分控制结构虽能提高产品纯度,但出现了较为严重的振荡现象。根据对组分控制结构的动态响应分析,本文提出了一种改进的组分控制结构,该控制结构能实现带有中间储罐的间歇精馏工艺的稳健控制,使各产品纯度得到提高。     

基于结构逼近式神经网络的间歇反应器优化控制

利用结构逼近式混合神经网络（SAHNN）建立了一类典型放热液相二级平行间歇反应的数学模型。基于主产物浓度和反应温度的递归神经网络（RNN）模型,使用混合PSO-SQP算法求解该间歇反应主产物产率最大化问题,进而得到反应温度优化曲线。鉴于反应温度实时可测,提出扩展的EISE指标,该指标把实时计算的模型误差引入控制策略,为基于模型的控制增加了反馈通道,增强了控制方法的鲁棒性和抗干扰性能。利用 原理对所提出的一步超前预测控制做了稳定性分析,证明了算法的正确性。研究的结果充分证明了基于SAHNN混合神经网络模型的优化控制策略的有效性。     

Control policies for an industrial acetylene hydrogenation reactor

This paper addresses the problem of finding optimal operational policies for an acetylene reactor for day to day operation. A lumped parameter model based on four main reactions is developed and used to examine the effects of the reactor manipulated variables on key reaction parameters. An optimal and a sub-optimal operational policy which minimize the ethylene loss over time are formulated and the solution techniques are presented. The results indicate that the reactor model is in good agreement with industrial plant data. The performance of the optimal control policy is very similar to the performance of the sub-optimal control policy. However, the sub-optimal formulation, while retaining the dominant features of the optimal response, reduces the computational requirements. Finally, some issues concerning the real-time implementation of an advanced acetylene reactor control scheme are presented. These include the estimation of the optimum regeneration cycle, a recursive model update algorithm, the process optimizer and their overall coordination. A preliminary analysis of the benefits associated with the advanced control scheme suggests a considerable reduction in the yearly ethylene loss.     

Polynomial chaos‐based robust design of systems with probabilistic uncertainties

A new algorithm is proposed for the design of nonlinear dynamical systems with probabilistic uncertainties. The dependence of the design objective and constraints on uncertainties is quantified by the polynomial chaos expansions (PCEs), while the relationships between the design parameters and the design objective/constraints are parameterized by Legendre polynomials. In two case studies, the polynomial chaos‐based algorithm reduces the number of system evaluations required by optimization by an order of magnitude. Quantifying the dependence on uncertain parameters via the PCEs and including the quantification in design optimization simultaneously improved the distribution of the performance index and the probability of constraint fulfillment. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3310–3318, 2016     

间歇萃取精馏技术的进展

对间歇萃取精馏分离技术和进展进行了评述,主要从萃取精馏溶剂选择,操作方式,新型塔设备的研究,操作优化及过程模拟等几个方面,介绍了国内外关于间歇萃取精馏新兴分离技术的最新研究动态,最后指出了萃取精馏技术目前存在的问题和今后发展的方向。     

间歇精馏模拟计算及试验验证

采用模型模拟计算处理间歇精馏过程,模拟计算采用两点隐合法处理积分方程,用改进的θ校正法校正浓度,组分加和平衡和能量平衡分别校正各板的温度和汽相流率,利用UNIFAC方程计算汽液平衡,通过计算得到间歇精馏塔塔内的动态变化数据.用间歇精馏的试验数据验证数学模型的正确性和计算方法的可靠性,并通过模拟优化试验参数.     

间歇精馏技术及其模拟优化研究进展

间歇精馏技术是一种重要的化工分离手段。文章综述了国内外间歇精馏技术及其常用的数学模型,其中主要阐述了严格模型和简捷模型,简要讨论了降价模型、半严格模型,同时探讨了间歇精馏优化的发展及其应用,并展望了间歇精馏系统的发展趋势。     

优化混凝-SBR法处理皮革加工废水

对皮革加工废水采用优化混凝-SBR法处理进行了研究,利用均匀设计法优化混凝除Cr3 条件,考察了曝气时间、污泥浓度、沉降时间对SBR反应器降解效果的影响.确定的混凝条件:聚铝投加质量浓度400mg/L、pH=10;SBR后续工艺最佳曝气时间为12 h、沉淀时间为2.0 h、污泥质量浓度为5 g/L.对皮革加工废水采用优化混凝SBR处理的试验结果表明,出水总Cr去除率＞98%,CODcr去除率＞93%,各项主要指标达到国家所规定的一级排放要求.     

Self-adaptive predictive functional control of the temperature in an exothermic batch reactor

In this paper we study a self-adaptive predictive functional control algorithm as an approach to the control of the temperature in an exothermic batch reactor. The batch reactor is located in a pharmaceutical company in Slovenia and is used in the production of medicines. Due to mixed discrete and continuous inputs the reactor is considered as a hybrid system. The model of the reactor used for the simulation experiment is explained in the paper. Next, we assumed an exothermic chemical reaction that is carried out in the reactor core. The dynamics of the chemical reaction that comply with the Arrhenius relation have been well documented in the literature and are also summarized in the paper. In addition, the online recursive least-squares identification of the process parameters and the self-adaptive predictive functional control algorithm are thoroughly explained. We tested the proposed approach on the batch-reactor simulation example that included the exothermic chemical reaction kinetic model. The results suggest that such an implementation meets the control demands, despite the strongly exothermic nature of the chemical reaction. The reference is suitably tracked, which results in a shorter overall batch-time. In addition, there is no overshoot of the controlled variable T, which yields a higher-quality production. Finally, by introducing a suitable discrete switching logic in order to deal with the hybrid nature of the batch reactor, we were able to reduce the switching of the on/off valves to a minimum and therefore relieve the wear-out of the actuators as well as reduce the energy consumption needed for control.     

基于广义预测控制的间歇生产迭代优化控制

针对间歇生产,提出了一种基于广义预测控制的批次迭代优化控制策略--BGPC,在间歇过程中引入批次间优化的思想,将迭代学习控制ILC和广义预测控制GPC相结合,在GPC实时结构参数辨识的基础上利用前面批次的模型预测误差修正当前批次的模型预测值.该算法能够有效地克服模型失配、扰动和系统参数变化等情况.文章最后以一个数值例子和间歇反应器为对象进行仿真试验,验证了该算法是有效的.     

间歇聚合反应过程的计算机控制及先进控制技术应用进展

间歇聚合反应过程由于其具有时变、非线性、反应机理复杂等特点,其控制问题一直是过程控制界具有挑战性的研究课题之一。本文分析了间歇聚合反应过程的特点,介绍了近年来间歇聚合反应过程的计算机控制和先进控制技术的研究与应用情况,包括预测控制、自适应控制、模糊控制等。     

Application of parametric control concepts to decoupler design and heating control design for a batch reactor

Parametric control involves expressing the manipulated variables of a process in terms of a new set of variables, called parametric variables. The control engineer can choose the functional relationships between the two sets of variables to provide added flexibility in control loop design. The design of a static decoupler and the linearization of a batch reactor heating system are provided as examples.     

Optimal potential–time programming in electrochemical batch reactors

In an electrochemical stirred batch reactor where a series of two reactions A harr B harr D takes place, two practical dynamic optimization problems were analysed. More specifically, the optimal profiles of electrode potential which achieve the following performances are determined: (i) maximize the final concentration of product B in a specified batch period tf and fixed final conversion rate of product A; (ii) minimize the terminal time tf required to reach a specified selectivity of B. The reaction considered here is the reduction of oxalic acid (A) to glyoxilic acid (B) followed by the reduction of glyoxilic acid to glycollic acid (D). The optimization is carried out by means of Pontryagin's maximum principle and the computational technique used is the control vector iteration method. The influence of the liquid/solid mass transfer coefficients is mainly investigated. It is shown that, for low conversion rates, the optimized and static operating modes achieve the same performances. For high conversion rates however, the performances obtained in realistic operating conditions by applying optimized electrode potential profiles, are substantially improved with respect to best static electrode potential values.     

基于免疫机制的多目标蚁群算法用于间歇反应器的约束动态多目标优化

含路径和终端约束的动态多目标优化是过程系统工程的一个重要研究方向,难度较高.传统蚁群算法仅适于离散问题,今采用混合正态分布描述信息素分布,并设计相应的解构造操作,使之拓宽至连续优化问题.通过对目标函数和约束矩阵的非劣捧序,确定解的等级,用以克服传统约束处理方法的局限性.借鉴了免疫系统的浓度概念,将其与解的等级结合,共同确定解的适应度,有助于保持种群的多样性.在更新信息素时将利用外部优解库和种群信息,可加快收敛速度.基于拥挤度距离更新外部优解库可更均匀地逼近Pareto最优解集.由此构建了一种基于免疫机制的多目标蚁群算法(Immune Mechanism based Multi-Objective Ant Colony Algorithm,IM-MOACA),并用于间歇反应器的动态多目标优化问题,效果良好,显示出较强的全局优化性能,能以较快的速度逼近真实的Pareto最优前沿,可为用户进行合理的决策分析提供有效的支持.     

CO2 methanation: Optimal start‐up control of a fixed‐bed reactor for power‐to‐gas applications

Utilizing volatile renewable energy sources (e.g., solar, wind) for chemical production systems requires a deeper understanding of their dynamic operation modes. Taking the example of a methanation reactor in the context of power‐to‐gas applications, a dynamic optimization approach is used to identify control trajectories for a time optimal reactor start‐up avoiding distinct hot spot formation. For the optimization, we develop a dynamic, two‐dimensional model of a fixed‐bed tube reactor for carbon dioxide methanation which is based on the reaction scheme of the underlying exothermic Sabatier reaction mechanism. While controlling dynamic hot spot formation inside the catalyst bed, we prove the applicability of our methodology and investigate the feasibility of dynamic carbon dioxide methanation. © 2016 American Institute of Chemical Engineers AIChE J, 63: 23–31, 2017