一种改进的锅炉主蒸汽温度多级智能控制系统的应用研究

针对电厂锅炉主蒸汽温度多级控制系统中减温水流量扰动对蒸汽温度的影响,且运行过程中控制系统超调量大、响应速度慢、系统具有非线性,对单回路常规控制系统进行了改进,提出了一种双单内环智能串级控制方法。主控制器采用内模控制方式,根据末级出口主蒸汽温度实测值与设定值之间的偏差经过智能PID在线修正控制参数。仿真结果表明:改进后的控制系统比原单回路控制系统具有更好的鲁棒性和动态特性,并能保持较好的调节性能。     

氯碱生产过程中氯氢压力控制分析

介绍了氯碱生产过程中氯氢压力控制方式。重点介绍了:电解槽阴阳极出口压力控制,氯氢总管压力控制,氯氢调节回路PID设置,电解槽跳停氯氢压力的应急控制。控制好氯氢压力,可以提高氯碱生产的稳定性。     

“双重调节”在酒精粗馏塔控制中的应用

对粗馏塔顶部温度采用“双重调节”系统，通过两个调节量（蒸汽流量、进醪流量），克服了锅炉蒸汽压力的扰动对塔顶温度的影响。     

聚合入料温度的调节

在悬浮法PVC生产过程中,入料温度的调节非常重要。通过改进入水调节回路,入料过程温度偏差明显缩小,而且不需要手动干预,聚合温度稳定,聚合过程中分散体系运行平稳,产品质量稳定。     

氢气站氢气回流量探讨

离子膜法制烧碱和隔膜法制烧碱生产工艺中的调节回路很多,氢气回流调节是诸多调节回路中的关键控制点。在生产过程中,电解系统要求氢气压力必须保持稳定,为了解决这一问题,一般通过设置氢气站氢气回流调节装置才能够保证电解系统安全稳定运行。但如果回流量不够,将给生产操作带来极为不利的因素。     

基于DMC-PID控制的催化剂温控系统设计

通过对动态矩阵控制(DMC)算法和传统PID控制的分析,提出一个基于DMC-PID串级控制的催化剂温控系统。仿真结果表明:DMC-PID控制效果优于PID-PID控制;电流副回路采用PID控制,能够快速有效调节电流进而控制燃烧炉内温度;温度主回路采用DMC控制,克服了传统温控系统存在的超调量大、时延及滞后性等问题,避免了多种不可测扰动的影响。     

模糊-PID在聚合釜温控中的应用

针对被控对象惯性延迟大、被调节信号反馈慢的特点,笔者采用恒流量温度控制方案对原聚合釜温度控制系统的单回路控制方案进行了改造,应用模糊-PID控制使聚合釜夹套水温与聚合反应温度保持较小的温差,将调节温度的过程变得更加平缓,经过实际应用取得了令人满意的效果.     

电厂蒸汽多点引入尿素装置的实现方法

针对原压力调节串联回路存在的技术难题,提出在回路中增加MTL5042安全栅的解决方案,并对该方案进行了组态。改进后,在使用调点命令时系统能够显示出正确的电厂蒸汽流量值,保证了生产装置的安全、稳定、长周期运作。     

基于PLC的纯水高压泵串级变频控制

在纯水处理系统中,利用PLC串级控制回路调节高压泵变频器,成功地解决了原来纯水生产过程中反渗透（RO）膜进口压力波动、产水量不稳、工频运行下电机发热的问题,实现了纯水产水量和RO膜压力的自动控制。     

用SLPC改进酸碱比值控制

酸碱比值控制是氰化钠生产中关键的控制回路,论述了控制对象的工艺特性和主要扰动因素及其应用SLPC改善比值控制品质的方法.     

An experimental study of multiobjective dynamic optimization of a semibatch copolymerization process

Optimal open loop control strategies are developed for a semibatch free radical copolymerization of methyl methacrylate and vinyl acetate using the multiobjective dynamic optimization method. A detailed kinetic model is validated through experimentation and used for the design of optimal controls. Both monomer feed rate and reactor temperature are varied to produce the copolymer of desired composition and molecular weight. The open loop control policies are implemented in a process control computer and tested on an experimental stirred tank polymerization system. Excellent agreement between the model predictions and the experimental data have been obtained.     

载人航天器环热控一体化仿真分析

采用系统建模及仿真方法搭建了一种典型载人航天器环热控一体化系统模型，分析了系统的性能。针对3人7天载人飞行工况开展了仿真分析，结果表明，经过合理设计，该系统可将舱内温湿度、压力、氧分压等参数控制在航天医学指标要求范围内。环热控系统仿真结果较好地预测了系统工作过程，显示了主要参数的变化情况，结果合理，验证了仿真方法、系统仿真模型的正确性。通过控制流体回路外回路旁通阀门开度，可准确控制外回路控温点温度，保证舱内温湿度在合理范围之内。此外，外回路控温点的设定会对环热控系统状态带来影响，通过合理设计外回路控温点，可保证舱内温湿度满足航天医学指标要求。     

串级控制对过程预测控制的影响分析与对策

化工过程控制中普遍设置以流量控制为副回路的串级控制来实现对温度、液位和成分等被控变量的控制。预测控制的操作变量在很多情况下也是流量,其控制作用的实现要靠底层的流量控制回路。本文针对由于现场串级控制结构不允许改变,流量副回路只能接收温度等主控制器的输出作为其给定值,造成上层预测控制的操作变量无法直接下载到流量控制回路的问题,分别提出了一种将上层优化输出通过一阶惯性滤波作用于主回路控制器和一种将串级控制中流量对主被控变量的传递函数嵌入预测控制模型的实施方案,通过Shell标准重油分馏塔的控制问题进行仿真实验证明了两种方案的可行性,并对其控制性能进行了比较分析。两种方法理论上构思简单,实际中易于实现,具有普遍适用性。     

Closed‐loop Fault Detection Using the Local Approach

Fault detection and isolation (FDI) has become a crucial issue for industrial process monitoring in order to increase availability, reliability and production safety. Model‐based FDI methods rely on a mathematical model and input‐output data of a process to perform detection. The local approach is a new model‐based FDI method that aims to detect slight changes of a system's parametric properties. Closed‐loop detection is an important issue for the local approach since all control systems work under closed‐loop conditions. A new algorithm was proposed to revise the original detection algorithm in order to make it work for closed‐loop data. Simulation results show that the proposed method can detect the changes of parameters of a system that can affect closed‐loop performance.     

注塑制品重量的闭环控制

基于注塑数值模拟技术,研究注塑工艺特性、熔体在模腔中的状态及制品质量特性之间的关系,建立了制品质量控制环和工艺控制环串联的制品质量闭环控制理论。以该控制理论为基础,应用神经网络内模控制策略,建立了注塑制品重量控制的理论和方法,并设计了制品质量控制器和工艺控制器。根据上述理论,基于注塑数值模拟技术,在Matlab平台上开发了注塑制品质量闭环控制系统,实现了制品质量闭环控制仿真。对一工业产品重量的控制表明制品质量控制环和工艺控制环串联的制品质量闭环控制具有较好的控制性能。     

Control of pure time delay processes

The general problem of controlling a physical process with predominant time delay is analysed. An effective method of controlling such a process is proposed and successfully applied. The control scheme consists of a two-loop configuration: a fast auxiliary loop consisting of a proportional controller and a simple lag element, and a main (process) loop provided with another proportional controller operating on the process. While the auxiliary loop output acts as common feedback to both the controllers, the process output adjusts the set point of the auxiliary controller. Disturbances entering the process, for which compensation is desired, are transmitted to the auxiliary loop where a corrective action is generated even before an error appears in the controlled variable. Digital simulation study reveals that, by suitable choice of the compensator parameters, this control arrangement results in remarkably superior performance compared to other known methods of dead time control. The technique is applied to a real process having a dead time of 2·7 min to demonstrate its easy implementability and to confirm its superiority over existing control schemes.     

A new approach to evaluate the energetic efficiency of batch‐jacketed reactors

This paper presents a new heat transfer configuration for exothermic batch‐jacketed reactors. The proposed design for the heat transfer scheme comprises an additional heat exchanger in the jacket‐cooling loop. A detailed comparison study considering the new concept and the conventional process is presented in terms of energetic efficiency (refrigerated fluid consumption per batch cycle) and process control (control of reaction temperature). The simulation results of the new heat transfer configuration show a substantial decrease in the total volume of refrigerated fluid injected in the cooling loop, whereas the process control performance was practically unaffected.     

Applying the constrained minimum variance control theory on in-line viscosity control in the extrusion molding process

In this study, the constrained minimum variance (CMV) control strategy was applied on the extrusion process. An in-line viscometer was designed and used to measure the viscosity of the polymer melt between the screw end and the die. Under constant temperature, the screw speed was treated as the plant control input, and the viscosity of the polymer melt was treated as the output. The system transfer function and the disturbance dynamic model of the plant were obtained experimentally. Comparing the CMV control strategy with the open loop control method, the variance decreased 39.1% in the simulation, and it also decreased 24.3% in experimental results. This shows that the CMV control method is effective on reducing the fluctuation of viscosity in an extruder. Improved stabilization of the viscosity of the polymer melt in the barrel was thus achieved.     

Closed loop model reduction applied to a tank reactor process

The subject of this article is the direct assessment of model simplification from a feedback control perspective. Normally, dynamic systems are simplified dimensionally and structurally from an open loop perspective. In spite of the intentions, the resulting models still often tend to be unnecessary complex for controller design and synthesis. Here, a four step method is proposed that incorporates a feedback controller, and makes use of the closed loop sensitivity functions to indicate significant impact on the closed loop behaviour from a performed model simplification. The method is applied to a first order reaction in an ideally stirred tank reactor with a cooling system. For this system a general and detailed model is derived. The model includes temperature dependent parameters such as specific heat capacities and densities. This reference model is locally unstable in most operating points, making open loop simplification impractical. The proposed closed loop simplification method makes it possible to evaluate which approximations of the system that can be justified.     

宽域废气氧传感器的控制方法研究

宽域废气氧传感器在汽车发动机空燃比控制系统中应用广泛,它对工作温度有严格要求,可通过控制泵电流实现空燃比测量。笔者研究温度和泵电流控制方法。将冷启动和PI控制方法相结合,缩短了传感器冷启动时间并提高了温度控制精度;针对泵电流模型参数的不确定性,研究了基于H∞回路成形的鲁棒PID参数整定方法。仿真实验结果表明:宽域废气氧传感器冷启动速度快,温度控制精度较高;泵电流控制调节时间短,稳态精度高。