用MATLAB模拟氨合成反应器及其GUI设计

用MATLAB编制轴向与径向流动的氨合成反应器的一维拟均相数学模型的模拟计算程序,借助MATLAB的GUIDE设计程序,开发了氨合成反应器设计计算图形用户界面(GUI)。该程序可用于不同类型轴向床、径向床,及其组合的氨合成反应器的模拟设计。结果表明,所开发的氨合成反应器模拟程序,大大降低了设计程序编写的难度,为用户提供有良好交互功能的界面,降低了氨合成反应器的设计难度,提高氨合成反应器设计的效率。     

乙烯氧化反应器模拟优化软件功能集成与界面设计开发

采用Visual Basic开发工具,对原有乙烯氧化反应器模拟优化程序进行了集成和输入输出界面设计。充分利用了原有的程序资源,又对其功能进行了改进,形成了一个可以平稳运行在Windows平台上的实现乙烯氧化反应器模拟优化的软件系统。系统可以独立发行安装,用于指导工业反应器的优化,也可用于操作人员技术培训。     

LabVIEW在快堆控制系统仿真的应用

快中子增殖反应堆作为一种新型的核能系统将成为未来核电领域的主要发展方向。在实验快堆的设计过程中,利用计算机仿真技术参与其控制系统设计有助于缩短设计周期、降低设计费用和提高设计质量。本文结合国外典型钠冷快堆的有关文件及数据,研究了反应堆系统的建模和仿真技术,并利用LabVIEW平台上对该系统进行了仿真程序的开发与计算。并对钠冷快堆的各种工况,在各种扰动时的瞬态进行了仿真运行和分析。本论文建立的控制仿真系统的方法及所编写的各子程序也具有较强的可移植性,为快堆控制系统的设计提供了研究方向和基本数据。     

催化裂化提升管反应器数学模拟新方法

催化裂化提升管反应器数学模型基本上都是基于平推流反应器的假设建立起来的,但是由于其内部流动、传热以及反应过程非常复杂、偏离平推流较大,所以在模型的实际应用中必须用装置因数去校正,表现出较强的经验性,为了改变这种状况,本文通过研究分析,提出了对催化裂化提升管反应器进行多维微分模拟的研究方法,从根本上把反应器结构尺寸、物流入口条件,流动特征及传热特征等影响考虑进来,把流动、传热、传质、裂化反应以及湍流脉动作用全部纲入模型中,建立催化裂化提升管反应器的流动反应综合模型,通过对模型的求解,可以得到提升管反应器内催化剂颗粒及油气的速度分布、温度分布以及组分分布,从而揭示工业提升管反应器内的化学工程信息。这些数据对工业提升管反应器的设计、操作优化及新技术的实施都是十分重要的。     

低压高密度聚乙烯装置反应系统模型开发

低压高密度聚乙烯(HDPE)装置稳态模拟模型可用于消除操作约束条件的瓶颈，提高产品产量与质量等。软件的应用又以具反应系统的建模最为关键。本文讨论了应用POLYMERSPLUS软件开发HDPE装置反应系统稳态模型的方法，包括确定系统组分、热力学参数、催化剂活性中心数目以及拟合反应动力学参数等，并对所建的模型进行了验证。     

Development of a Windows-based indoor air quality simulation software package

A Microsoft Windows-based indoor air quality (IAQ) simulation software package has been developed and has completed a small-scale beta test and quality assurance review. Tentatively named Simulation Tool Kit for Indoor Air Quality and Inhalation Exposure, or STKi for short, this package complements and supplements existing IAQ simulation packages and is designed mainly for advanced users. STKi Version 1 consists of a general-purpose simulation program and four stand-alone, special-purpose programs. The general-purpose program performs multi-zone, multi-pollutant simulations and allows gas-phase chemical reactions. With a large collection of models for sources, sinks, and air filters/cleaners, it can perform simulations for a wide range of indoor air pollution scenarios. The special-purpose programs implement fundamentally based models, which are often excluded from existing IAQ simulation programs despite their improved performance over statistical models. In addition to performing conventional IAQ simulation, which generates time–concentration profiles, STKi can estimate the adequate ventilation rate when certain air quality criteria are given, a unique feature useful for product stewardship and risk management. STKi will be developed in a cumulative manner. More special-purpose simulation programs will be added to the package. Key numerical methods used in STKi are discussed. Ways to convert the STKi programs into language-independent simulation modules that can be used by multi-pathway exposure models are also being explored.     

光气合成反应器动态仿真

该文对光气合成管式反应器的动态仿真技术进行了研究.根据物料及焓守恒方程建立了管式反应器的动态机理模型,并根据模型的形式和特点选择了适当的数值计算方法,开发了光气反应器的动态模拟程序模块.模块应用结果表明,达到稳态时的结果能比较真实地反映生产实际情况,动态过程能很好地反映生产的变化趋势,并能完成对非正常工况的模拟.该模型对光气合成反应器动态特性和控制方式的研究以及光气合成相关工艺仿真培训系统软件的开发等都有重要的意义.     

The Glansdorff–Prigogine stability criterion for biochemical reaction networks

Local stability analysis of steady states in mathematical models of biochemical reaction networks is an important tool for systems biology. The second variation of the Gibbs energy around a steady state is a positive definite function and a candidate for a Lyapunov function. A sufficient condition for the local stability is the local negative definiteness of the time derivative of this function. This is expressed by the Glansdorff–Prigogine stability criterion. Previously, the criterion was criticized to be overly conservative and difficult to check. Here, we derive an easily testable form of the criterion for models of biochemical networks. The criterion can be evaluated with incomplete knowledge of the parameters. For ideal mass-action kinetics, it depends only on the steady state fluxes. For reaction systems in ideal solutions, the Glansdorff–Prigogine criterion is overly conservative and we give a tighter criterion that depends on the same subset of the parameters as the Glansdorff–Prigogine criterion. Whenever these criteria are indefinite, there exist parameter values such that the steady state is unstable. By means of simple example systems we explore these aspects and discuss the possible uses of the criteria for systems biology.     

Modelling and controller design for distributed parameter systems via residence time distribution

For chemical reactors with non-linear fluid dynamics, a linear model realisation is proposed. The inputs are the ingoing concentration of a certain component in the fluid, and the reaction rate. The output is the outgoing concentration. The realisation makes use of a first-order reaction equation, and the residence time distribution of the fluid particles inside the reactor. Also dead time is incorporated in the modelling. The method is tested on two non-linear models for which the residence time distributions are known analytically. The first model is a series of mixed tanks, and it is shown by simulation that the method gives an accurate approximation of the original model. The second model is a UV disinfection reactor, which has a dead time. For this model, the residence time distribution is first fitted by a form that is suitable for our realisation method. Simulations show that for realistic disturbances a high-performance linear controller can be designed. After that, the residence time distribution of a real life UV reactor (for which we have no model) is fitted by a suitable form. The fit is of the same quality as for the UV reactor model. This indicates that also for the real life UV reactor a high-performance controller can be designed.     

Computation of optimal feed rates and operation intervals for tubular reactors

We consider mathematical models for tubular reactors in the form of dynamic distributed parameter systems. The goal is to maximize the overall profit over a fixed time horizon, where the number of cleaning operations, the length of the reactor operation between successive cleanings, and the reactor feed rates for each time interval are to be computed. We assume that product prices and consumer demands are time-dependent. It must be guaranteed that the decrease of the free cross-sectional area of the tube caused by coke deposition never exceeds a certain limit. Moreover, there are time and position dependent constraints for the state and control variables such as a maximum bound for the temperature. The mathematical model and the applied discretization scheme are outlined in detail. Numerical results are presented for a case study, where optimal input feeds and maintenance times of an acetylene reactor are computed. Of special interest is the behaviour of the program under real-time conditions, when changes in the process data or price and user demand functions require a restart of the calculation.     

Nonlinear stability analysis for a class of differential-integral systems arising from nuclear reactor dynamics

A nonlinear stability analysis has been performed for mixed differential-integral equations particularly applicable to nuclear reactors. New general theorems of stability in bounded domains of initial perturbations have been introduced for a class of reactor models with an arbitrary reactivity feedback. Also, effective stability criteria have been established for reactors with linear reactivity feedbacks. For many kinds of models of phenomena typically encountered in nuclear reactors, these new criteria give sharper stability bounds than criteria previously published. The theoretical results obtained have been illustrated with examples of selected reactor models.     

Trajectory analysis of nonisothermal tubular reactor nonlinear models

The existence and uniqueness of the state trajectories (temperature and reactant concentration) are analyzed for nonisothermal plug flow and axial dispersion tubular reactor models. It is mainly shown that these trajectories exist on the whole (nonnegative real) time axis and the set of all physically feasible state values is invariant under the dynamics equations. The main nonlinearity in the model originates from the Arrhenius-type kinetics term in the model equations. The analysis essentially uses Lipschitz and dissipativity properties of the nonlinear operator involved in the dynamics and the concept of state trajectory positivity.     

SIMFIT: a microcomputer software-toolkit for modelistic studies in biochemistry

A software package suitable for personal computers and designed to handle simulation and fitting problems related to the study of biomolecules under pre-steady and steady state conditions is presented, and its overall architecture as well as the implemented algorithms illustrated. The peculiar features of the package are: (i) integrated capability of simulating dynamic models and fitting to them experimental data; (ii) handling of stiff problems; (iii) free use of algebraic as well as differential equations; (iv) objective comparison of models of different complexity. The above features are discussed through a number of examples taken from the direct experience of the authors in enzyme kinetics and ligand binding.     

Lurgi型甲醇合成反应器的动态模拟

为了能更好地预测甲醇合成系统的动态特性、合成与分析控制系统、模拟开停车及事故和培训操作人员等,对Lurgi型甲醇合成反应器的模型化与动态模拟技术进行了研究。根据物料及热量守恒方程建立了Lurgi型甲醇合成固定床反应器的动态模型,并根据模型的形式和特点选择了适当的数值计算方法,开发了动态模拟程序模块,并据此通过模拟计算获得了适宜的操作参数范围,这对于优化合成工艺,提高甲醇产量有明确的指导意义。应用结果表明,达到稳态时的结果能真实地反映生产实际情况,动态过程能很好地反映生产变化趋势。该模型对Lurgi型甲醇合成反应器动态特性和控制方案的研究,以及甲醇合成相关工艺仿真培训系统软件的开发等都有重要的意义。     

HERSIM: a microcomputer program designed to compute the limits of conversion for real homogeneous isothermal enzymic reactors

HERSIM is a program written in BASIC designed to aid the investigator interested in determining the substrate conversion in a real homogeneous isothermal enzymic reactor, for various kinetic equations. The program runs after tracer data relative to a Dirac impulse to the reactor have been entered, and computes the two limits of real conversion: total segregation and maximum mixedness. The kinetic constants of the reacting system are input as data, and the variation of conversion with reactor temperature between given limits is computed as accurately as requested.     

基于微机的200Wm核供热堆仿真系统PCNHR1.0的研究

为了使更多的技术人员形象地了解低温堆供热站的原理 ,在国际原子能机构的支持下 ,清华大学核研院研究开发了基于微机的 2 0 0Mw低温核供热堆仿真系统。它采用两回路、一维漂移流热工水力学模型 ,点中子堆物理以及控制系统模型。能对核供热堆的稳态运行、瞬态过程和事故进行仿真 ,仿真精度接近系统分析结果。在奔腾或以上的微机上 ,WIN DOWS95 /98/NT操作系统下 ,能对过程进行实时仿真 ,而且大多数过程能达到 10倍以上超实时。软件采用VisualC+ + 和FORTRAN混合语言编程 ,运用先进的多线程编程模型、进程通讯和进程控制技术实现了耦合计算和同步控制。     

乙炔法合成氯乙烯转化器的动态仿真

研究乙炔法合成氯乙烯转化器的动态仿真技术,以分析氯乙烯转化器的特征,建立动态机理模型,针对模型的形式和特点,采用适当的数值计算方法,开发氯乙烯转化器的动态仿真程序模块。仿真计算表明,当达到稳态时其结果跟生产数据较为吻合,动态过程跟生产的变化趋势相一致。模型对优化操作有一定的指导意义,对顺利开发整个氯乙烯合成工艺的仿真系统软件,也有重要价值。     

同轴圆柱介质阻挡放电半周不对称等效负载模型

同轴圆柱反应器常用于发生介质阻挡放电。实验表明在大气环境的放电中,仅单侧电极有介质的同轴圆柱反应器,放电特性不同于两侧电极都有介质的反应器。前者正反半周放电机理不同,等效电气参数区别很大,不能再用传统的非线性箝位模型作为其等效负载模型。针对此类反应器,提出一种新的半周不对称分段等效模型,并给出了基于李萨如图形的模型参数计算方法,使之能更精确地描述此类介质阻挡放电反应器的电气特性。     

Steady state optimization of an ammonia reactor

A hybrid simulation technique for identification and steady state optimization of a tubular reactor used in ammonia synthesis is presented. The parameter identification program finds the catalyst activity factor and certain heat transfer coefficients that minimize the sum of squares of deviation from simulated and actual temperature measurements obtained from an operating plant. The optimization program finds the values of three flows to the reactor to maximize the ammonia yield using the estimated parameter values. Powell's direct method of optimization is used in both cases. The results obtained here are compared with the plant data.     

On the global stability of conventional PID control for a class of chemical reactors

The stabilization properties of derivative control for chemical reactor stabilization have been rarely studied in the literature. In a pioneering work, Aris and coworkers (textitChem. Eng. Sci. 1959; 11 :199–206.) used linear analysis to show that derivative control offers greater stabilization flexibility than proportional control. The aim of this work is to show that mixed derivative and proportional control can yield global stabilization for a large class of continuously stirred tank reactors (CSTR) characterized by having stable isothermical dynamics. The stability proof exploits the structure of CSTR models where the nonlinearity is concentrated in the chemical reaction kinetics. It is shown that the proportional mode is a type of energy shaping to induce a unique equilibrium point, while the derivative mode can be interpreted as a global damping injection to reduce undesired transient effects, such as temperature overshooting and oscillations. A numerical example is used to illustrate the different features of mixed proportional and derivative control in chemical reactor dynamics. Copyright © 2011 John Wiley & Sons, Ltd.