新型气动阀

<正> 西德一公司研制生产出一种新型的气动阀门。与普通气动阀门相比,这种阀门的独特优点是,在相同的工艺参数条件下,由于控制阀杆升降动作所需的动力     

基于模糊聚类的气动阀门粘滞检测方法

由于传统气动阀门粘滞检测方法,在实际操作过程中出现误检现象,且检测结果一致性系数值较大,为此提出基于模糊聚类的气动阀门粘滞检测方法研究。采集气动阀门粘滞数据信号;将采集到的粘滞数据利用模糊聚类算法进行分析,计算出气动阀门粘滞概率,根据概率判断气动阀门是否存在粘滞问题,以此完成基于模糊聚类的气动阀门粘滞检测。经实验证明,设计方法检测结果一致性系数值接近零,低于传统方法,适用于气动阀门粘滞检测。     

技能大赛中气动薄膜控制阀的组装与校验

针对全国化工仪表维修工技能大赛中对“气动薄膜调节阀的组装与校验”的考核,详细阐述了在控制阀组装、推杆行程校验以及阀门定位器安装环节的关键点,提出了气动薄膜控制阀与阀门定位器联校的新方法。利用该方法,可以快速准确地完成控制阀的组装,并在很短的时间内调校到所要求的精度。     

常见智能阀门定位器的基本原理及对比分析(下)

在化工生产过程中,智能阀门定位器作为气动控制阀的主要附件,在提高控制阀的运行品质等方面发挥着重要的作用。笔者对定位器的概念、气动元件结构、工作原理以及性能参数等指标进行了说明和对比,有助于在化工生产中正确选用和使用阀门定位器。     

常见智能阀门定位器的基本原理及对比分析(上)

在化工生产过程中,智能阀门定位器作为气动控制阀的主要附件,在提高控制阀的运行品质等方面发挥着重要的作用。笔者对定位器的概念、气动元件结构、工作原理以及性能参数等指标进行了说明和对比,有助于在化工生产中正确选用和使用阀门定位器。     

直通单座控制阀流场的数值模拟与结构改进

应用SOLIDWORKS和CFD软件,对直通单座控制阀建立了3D流道模型,并对控制阀在相同压差不同开度的内部三维粘性流场进行了数值模拟,分析了流量系数与阀门开度的关系,并与文献进行了比较,验证了文中所建的模型和方法的可靠性。并且根据不同开度下控制阀内部流场的压力和速度云图、速度等值线图和矢量图等可视化图形,对流场进行了分析。对控制阀内能量损失严重的部位进行流道优化改进和模拟,并与改进前的流道进行了比较,为控制阀优化设计提供了依据。     

基于声发射理论的气体介质阀门内漏检测研究

针对气体介质阀门内漏问题,建立了一套气体介质阀门内漏检测系统,根据声发射技术的原理,基于不同压力条件下,检测声发射的各种参数随泄漏率的变化,并运用Parseval原理对泄漏率与参数进行数值模拟,并对声发射信号进行信号波形和功率谱分析,可初步判断气体介质阀门内部是否存在内漏现象。     

飞灰储罐下灰锁斗控制阀的改造

河南煤业化工集团中原大化公司500kt／a甲醇项目采用荷兰壳牌公司粉煤加压气化技术,于2008年5月建成投产并顺利生产出合格甲醇产品。煤化工气化装置飞灰气提冷却罐（V1504A）至中间飞灰储罐（V1505A）的下灰锁斗控制阀（15XV-0015）采用气动活塞式执行机构、硬密封切断球阀。该阀门系从西班牙进口,价格十分昂贵。在使用过程中,由于该阀门经常出现卡塞而无法下灰,造成气化炉加不上负荷,     

二氧化碳汽提装置尿塔液位控制阀的选择

通过分析尿塔液位控制阀在开车过程中的作用,并对该阀在开车过程的泄露量进行定量计算,分析了该阀门密封等级对开车过程的影响,提出使用Ⅳ级密封角阀方案。     

石油化工大型罐区中控制阀的安全应用与研究

控制阀是石油化工罐区中的主要元件之一,它的安全性能是衡量阀门质量优劣的重要指标,阀门检验标准中对阀门的安全等级有明确的规定。通过对控制阀的类型与结构分析,并在工程设计中充分考虑其使用工况,使控制阀在石油化工大型罐区中尤其在安全方面能够合理的进行选型及应用,力求选用的阀门满足安全、合理和经济的原则。     

Control valve stiction detection using Markov transition field and deep convolutional neural network

Control valve stiction is an industrial problem that often causes oscillations in process control loops. Oscillating control loops are not capable of maintaining key process variables near or at their desired values, thus yielding low-quality products, inducing economic loss, and increasing environmental impacts. Therefore, it is of vital importance to detect stiction in industrial control valves. In this regard, the present work proposes a new method based on the Markov transition field and convolutional neural network (CNN) to identify sticky control valves in industrial control loops. The Markov transition field is employed to convert process variable (PV) and controller output (OP) into two-dimensional images, which are then utilized by CNN to learn to distinguish stiction induced oscillations from oscillations brought out by a non-stiction condition. A transfer learning strategy is adopted to improve the stiction detection capability of the proposed method. Its performance is evaluated via its application to benchmark control loops taken from the chemical, paper, mining, and metal industries. Results demonstrate that the proposed method obtains the correct verdict for the majority of the control loops studied.     

A convolutional neural network (CNN)-based direct method to detect stiction in control valves

Control valves are considered important capital assets in any process industry. A properly maintained control valve can have a significant impact on how well the process is controlled as well as the overall cost of the plant. However, control valves can suffer from poor control performance due to valve non-linearities. One of the main reasons for non-linearity is control valve stiction. Stiction not only causes oscillations in the process variables but also shortens the life of the control valve, resulting in an economic loss for the process. In a process plant, a control engineer generally analyzes the time series plot of process value (PV), set point (SP), and controller output (OP) data and identifies stiction based on the typical shape pattern of PV/SP/OP plot. In this study, the same shape pattern methodology is adapted to identify stiction using convolutional neural network (CNN) technique. A one-dimensional convolution neural network (Conv1D) algorithm is developed, which works directly on PV/SP/OP time series data for stiction detection. The proposed CNN algorithm is tested on both simulated and industrial control loop data. The suggested method provides promising results with a combined stiction prediction accuracy of 92% (92.2% in predicting non-sticky and 91.53% in predicting sticky loops) for the industrial loops data studied.     

Improved stiction compensation in pneumatic control valves

The oscillations caused by static friction (stiction) in control valves cause losses in quality and expense of raw materials. The effects of friction can be reduced through compensation techniques, until the maintenance of the valve is made in the next programmed plant shutdown. In this work, a well-known stiction compensation method that reduces variability both at process variable and valve stem movement is revisited. Limitations of this method are overcome through two proposed methods using a similar approach. The effectiveness of the proposed compensators is demonstrated using simulation examples and a flow control loop in a pilot plant.     

高压气动开关阀动态特性仿真分析

根据先导式高压气动开关阀的结构原理和细分理论,采用MATLAB的Simulink对其进行仿真分析,得出先导阀控制口有效面积、控制腔驱动活塞面积、主阀芯开关面积及控制气体压力等参数是影响高压气动开关阀动态性能的主要因素。     

Detection and Diagnosis of Plant‐Wide Oscillations

This paper presents some emerging techniques for detection and root‐cause diagnosis of plant‐wide oscillations, and demonstrates their efficacy through a successful industrial case study. The recently proposed autocorrelation function based method (Thornhill et al., J. Proc. Control 13, 91–100, 2003a) is used for detection of oscillations in the process measurements. Signals having common oscillations are analyzed for the presence of valve stiction using higher order statistical methods (Choudhury et al., Automatica 40, 1719–1728, 2004b) . A method employing changes in controller gain is proposed for distinguishing an internally generated oscillation from an external oscillatory disturbance. This method of changing controller gain is used to confirm the presence of control valve stiction. The proposed techniques have been used successfully to identify the root cause of plant‐wide oscillations in an industrial case study using routine operating data.     

一种控制阀粘滞特性快速检测方法研究

控制阀粘滞特性是导致工业过程中控制回路振荡的主要原因之一。首先对控制阀粘滞特性进行了详细的定义和描述,在此基础上提出了一种可快速在线实现,并且适用范围较广的控制阀粘滞特性检测方法,克服了目前许多方法只适用于特定方法的局限性。通过仿真研究以及对工业数据的分析,表明了该方法的有效性。     

基于Boost变换器光伏发电MPPT控制方法

在基于Boost变换器的光伏发电系统中,以MCUTMS320F2812为主要控制芯片．采用检测发电系统Boost变换部分输出电流的控制策略,并调节变换器PWM的占空比输出,实现最大功率点更好地跟踪．并通过Mat．1ab／simulink验证该策略的可行性。     

Actuator stiction compensation via model predictive control for nonlinear processes

The problem of valve stiction is addressed, which is a nonlinear friction phenomenon that causes poor performance of control loops in the process industries. A model predictive control (MPC) stiction compensation formulation is developed including detailed dynamics for a sticky valve and additional constraints on the input rate of change and actuation magnitude to reduce control loop performance degradation and to prevent the MPC from requesting physically unrealistic control actions due to stiction. Although developed with a focus on stiction, the MPC‐based compensation method presented is general and has potential to compensate for other nonlinear valve dynamics which have some similarities to those caused by stiction. Feasibility and closed‐loop stability of the proposed MPC formulation are proven for a sufficiently small sampling period when Lyapunov‐based constraints are incorporated. Using a chemical process example with an economic model predictive controller (EMPC), the selection of appropriate constraints for the proposed method is demonstrated. The example verified the incorporation of the stiction dynamics and actuation magnitude constraints in the EMPC causes it to select set‐points that the valve output can reach and causes the operating constraints to be met. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2004–2023, 2016     

ADHDP方法在静止无功补偿器优化控制中的应用

介绍了静止无功补偿器SVC和自适应动态规范的执行方法ADHDP的基本原理,基于PI控制法的电压负反馈控制策略,应用ADHDP方法对输入PI调节器的电压偏差进行了优化,并在Matlab/Sim-ulink环境下对SVC控制系统进行了仿真实验。仿真结果表明,经优化后的控制系统响应速度明显提高,动态性能得到了较好的改善。     

多效蒸发注射用水系统的热力过程优化

针对生产注射用水多效蒸发过程中能耗大及产水不稳定的问题,进行了多效蒸发热力过程系统优化。依据质量守恒和能量守恒方程,建立了蒸发器、预热器和冷凝器数学模型,考虑蒸汽流动阻力损失,基于Matlab/Simulink多体工具箱,以等面积法为原则进行迭代求解。通过模拟计算分析效数、预热方式对系统热力性能的影响。结果表明,效数增加使得系统比传热面积、造水比增加以及比?耗减小,且后两者的变化幅度会逐渐降低。效数低于5时,使用产水预热的方案更优;效数高于5时,混合预热方案更优。混合预热方案下,系统效数较大时,蒸汽在管道内流动引起的温降和压降快速上升,最终导致造水比下降以及比?耗值趋于恒定。