一种实用的温度测控系统设计

为了克服单回路温度测控系统只能测量和控制被控对象某一区域一点的温度而出现的问题,采用以单片机为核心的独立双回路温度测控方法,实现对被控对象某一区域两点的温度同时测量、同时显示、同时控制。实践证明,该系统能了解整个被控对象的温度状况,准确实现对温度的调节。     

基于ZigBee的电镀生产线温度集中监控系统

针对大型电镀生产线温度在集中监控过程中,温度的控制节点布置间距较远、布线复杂、维护不易的问题,设计了一种基于ZigBee的无线温度采集和控制系统.系统分别设置了MCGS上位机组态系统、网络协调器和温度测控终端.上位机组态系统设计了人机交互界面,可设置和显示各镀槽节点温度;温度测控终端采用DS18B20监测各槽温度并通过PID算法对温度进行实时控制;上位机和温度测控终端之间的通信,采用以CC2420为核心的ZigBee无线网络.将该系统投入实际工程中,系统投入成本低,运行稳定,易于扩展和变换测控槽位,能够有效监测和控制生产线上各镀槽温度,达到了高效便捷的目的.     

快速查找生料磨测控柜的电气故障

我厂生料磨采用的是沈阳重型机械厂的立磨系统。立磨测控柜采用ABPLCSLC500系列的1747-L531CPU控制,配有一台触摸屏,四个电控柜,以监控现场多种压力、温度以及电机的状态信号,实现对生料磨系统的运转保护。DCS系统则通过接收测控柜的综合"允启"信号     

基于物联网涂装RTO设备的远程测控系统设计

为了解决涂装废气处理环保设备的稳定运行和测控问题,提出了一种基于Android手机平台的环保蓄热式燃烧法(RTO)参数无线远程监控系统,该系统实现了对风阀开度、温度、燃烧器状态等RTO参数信息的测控。系统采用罗克韦尔PLC控制器,控制算法采用PID控制,控制指令由Android手机或触摸屏触发。本系统在上汽大通汽车有限公司涂装车间进行测试,温度监测实时可控,温度误差15%以内,风阀开度控制8%误差以内,VOC指标均能达到要求,本系统非常适合环保RTO的使用。     

增加故障捕捉程序快速查找电气故障

我公司生料立磨测控柜采用AB PLC SLC500系列的1747-l531CPU控制,配有一台触摸屏,4个电控柜.监控现场多种压力和温度,以及电动机的状态信号,实现对生料磨系统的运转保护.DCS系统则通过接收测控柜的综合"允起"信号来判断生料磨系统正常与否,一旦"允起"信号在运行过程中消失,中控则对生料磨停机.     

基于SOC单片机的模糊温度测控系统设计

提出一种基于SOC单片机的模糊温度测控系统的设计方案。采用SOC型单片机MSP430F149为控制核心,利用MSP430F149片内资源,实现温度采集信号的放大、ADC转换处理、PWM驱动控制等功能,以最小的硬件结构完成模糊温度闭环控制。同时,应用RS-485通讯协议,实现上位机与底层控制节点之间可靠的数据通讯。     

基于LonWorks现场总线的油罐测控系统

介绍了基于LonWorks现场总线的油罐测控系统,包括系统总体结构、现场总线测控节点硬件和软件主监控计算机的功能实现。相对于DCS和PLC构成的测控系统,该系统具有可靠性高、实时性好、测量精度`高控制性能好、成本低、易于扩展等特点。     

基于PROFIBUS总线的陶瓷生产测控系统

在对目前陶瓷生产测控系统特点及Profibus原理和应用研究的基础上,联系相关应用软件STEP 7、WINCC等,提出基于Profibus技术的陶瓷生产测控系统,给出相应的Profibus测控系统网络之总体构成方案,完成该网络的系统配置、组态设计和实现方案,从而真正体现现代陶瓷工业生产过程自动化的概念,实现陶瓷生产的先进控制及优化.     

制糖精炼过程的非接触温度测控系统研究

针对制糖精炼过程要求对精炼糖罐和出糖管道温度进行实时温度测控，提出了对糖液管的红外非接触式温度测控方法，解决了传统接触式温度测量方法由于糖液粘覆传感器造成测控误差大的技术难题，可以明显地提高精炼糖的温度测控精度和精炼糖的质量。     

闭环智能控制技术的探讨

随着油田自动化、数字化程度的不断提高,第七采油厂大部分站库已实现通过PLC测控系统采集、显示站内生产流程上的参数,如温度、压力、液位等,以及控制电动阀的启停。但仍有部分站库和岗位由于无电动阀、控制系统设计缺陷等原因,均采用手动控制,未实现闭环智能控制,需由岗位人员手动调节阀门开关、电机转速等操作。为此,提出闭环智能控制技术的探讨,通过PLC测控系统、触摸屏、现场电动阀、变频器的结合应用,实现岗位生产流程的闭环自动控制,提高了站内自动化水平,减轻了岗位员工的劳动强度。     

基于单片机AT89S51的温湿度控制仪

在对国内外同类产品分析研究的基础上,作者设计了一种基于单片机控制的温湿度控制仪,从硬件和软件两方面设计并实现了对温湿度的精确控制,该控制系统主要采用AT89S51、LED显示器、SHT11等芯片,并对其组成以及硬件电路进行了详细的介绍,阐述了温湿度控制系统的工作原理以及设计方法。最后通过系统软硬件联机调试,实现了温湿度信号检测与控制,达到了预期要求。     

Physical Model of Heat and Mass Transfer in a Spouted Bed Coffee Roaster

A key step in coffee processing is roasting, where green coffee beans are heated at high temperatures (over 190°C), initiating a series of complex chemical reactions. This process can be divided in two phases (drying < 160°C and roasting > 160°C). Therefore, the quality of coffee is highly correlated with bean temperature during roasting. The aim of this work is to measure and model coffee bean temperature and moisture content during the roasting process, in order to determine on-line quality of the product allowing the control of the process. A spouted bed roaster, using hot air flow as heating medium, was developed. The surface and center bean temperature, as well as input and output air temperatures, were measured on-line. At each minute interval of roasting, samples of coffee beans were taken to measure the moisture content.

A dynamical model, which takes in account heat and mass transfer at the surface and inside of the beans, is proposed. This model, where only the water diffusivity in the bean was adjusted, gave a good prediction of bean temperature (center and surface), average moisture content, and output air temperature for all the experiments. However, in the industry, only the output air temperature can be measured. Consequently, this model could assist in on-line determination of the bean temperature and hence constitutes the first stage in developing a smart sensor for on-line checking including quality control.     

塑料挤出机主辅电机联动系统设计

本文在分析国内外挤出机生产线主辅电机同步联调特点的基础上,提出了一种实用的联调控制系统设计方案,控制系统设计采用纯硬件方式,可以广泛适用于国内未采用同步联调技术的挤出生产线,进行技术改造,对原有设备改动极小,具有很高的性能/价格比。     

On the use of model-based tools to optimize in-line a pharmaceuticals freeze-drying process

This article is focused on the use of model-based tools to design and optimize in-line a pharmaceutical freeze-drying process. Two control systems have been compared, a predictive one that uses the pressure rise test to monitor the state of the system and to estimate in-line the values of model parameters, named LyoDriver in the previous literature, and a controller where a soft sensor uses the temperature measurement obtained by a thermocouple to get the same information and to calculate on-line the design space of the process. In both cases, the goal of the controller is to maintain product temperature as close as possible to a limit value, without trespassing it, throughout the primary drying stage. An extended experimental campaign has been performed, where various products, with different characteristics, have been processed, namely, aqueous solutions containing sucrose, mannitol, or polyvinylpyrrolidone. Results evidence that both systems are effective in optimizing in-line the freeze-drying process, but shorter cycles can be obtained using the soft sensor. This is due to the fact that the soft sensor is not responsible for any product overheating and, thus, product temperature can be maintained very close to the limit value, while when using the pressure rise test as monitoring tool, a safety margin has to be used, because of the temperature increase during the pressure rise test. Besides, when using the soft sensor no least-square optimization problem is solved to estimate model parameters, and this can improve the robustness of the system. The main drawback is represented by the fact that this system requires thermocouples to measure product temperature, and this can be difficult in industrial-scale freeze-dryers, used to process large batches of vials in sterile conditions, but it can be performed quite easily in lab-scale units used for process design.     

Design and control of butyl acrylate reactive distillation column system

In this study, the design and control of a reactive distillation column system for the production of butyl acrylate has been investigated. The proposed design is quite simple including only one reactive distillation column and an overhead decanter. The optimal design is selected based on the minimization of total annual cost (TAC) for the overall system. At this optimized flowsheet condition, output multiplicity was found with reboiler duty or feed ratio as the bifurcation parameter. The highest purity stable steady state was selected as the base case condition for the control study. The overall control of this system can be achieved with no on-line composition measurements. Simple single-point tray temperature control loop is designed to infer final product purity. From results of dynamic simulation, the proposed control strategy performs very well in rejecting various disturbances while maintaining butyl acrylate product at high purity. One of the important finding in this paper is that it is better to operate this reactive distillation column not at the exact feed stoichiometric balance point for better operability reason. The control performances of the proposed operating point and the operating condition right at the exact stoichiometric balance point will be compared.     

在线色谱模拟蒸馏分析仪中管式色谱柱室的开发

设计开发一种用于在线色谱模拟蒸馏的管式色谱柱室,经过线性的程序升温控制评价,温度控制精度在±0.1℃。正构烷烃校正样的重复性以及航煤样本重复性、准确性的测试表明,基于管式色谱柱室设计的在线色谱模拟蒸馏分析能够达到ASTM D2887及SH/T 0558标准的规定。管式色谱柱室的设计具有体积小、耗电少等优点,使得在线色谱仪表的整体结构简单,可靠性大大提高。     

微乳液-超临界CO_2流体技术的设备设计

本文设备设计用于微乳液-超临界CO2流体技术高压体系的紫外在线检测,高压池体侧端带有控温探针,能实时测量池内温度,同时高压池外部设有加热带能够自行调节温度,池体与萃取釜主体相连,通过阀门控制流量,这样的设计保证了池内所测的物质与萃取釜都在同等条件下,真正实现了在线检测。     

ON-LINE ROBUST CONTROL BASED ON AN EXTERNAL LOOP

A method of on-line robust control based on an external loop was proposed. The control structure was set up by adding an external loop to the conventional feedback control system. A filter was implemented in the external loop for robust control. Design of the filter was based on a robust stability index (RSI) which was on-line determined. The proposed robust control was carried out without changing the original feedback design of the control system.     

A self tuning controller for multicomponent batch distillation with soft sensor inference based on a neural network

Multicomponent batch distillation is an operation difficult to control not only for its nonlinear and transient behaviour, but because the product quality cannot be measured rapidly and with reliability. In the present work, a computational system for direct digital control is developed for a pilot plant batch distillation column. The development of a self tuning regulator and a soft sensor of composition based on a neural network is described. Top and reboiler temperature measurements are the basis for the on-line composition inference. The computational system was experimentally tested in a computer operated pilot column. It could be seen that the neural network soft sensor is a feasible and a reliable tool to solve on-line operational problems of the control engineering systems. The developed control system permits to operate the batch distillation column efficiently and is easy to be implemented and operated.     

螺杆出口熔体温度热平衡方程的建立和应用

本文从能量守恒和质量守恒的原理出发,就串接温控的熔纺螺杆出口处建立了热平衡方程。应用方程可准确地判断引起生产中异常温变的原因,精确地选取导生加热温度,并为计算机在纺丝工艺控制上的应用提供数学模型。