大型折流杆与单程浮头结构结合换热器设计

介绍了一种折流杆与单管程浮头结构相结合的气-气换热器的设计,阐述了折流杆换热器相对于普通换热器的优点,并结合工程实际案例描述了折流杆结构与单管程浮头结构相结合的结构特点及设计要点。并对气-气换热器从结构选型、材料的选择到各部件强度计算方法,进行了比较详细的介绍。此为广大工程技术人员今后遇到类似换热器设计时提供参考。     

套管换热器温度前馈——反馈控制系统的实验研究

本文通过实验性的套管换热器的前馈——反馈控制系统试验及其电模拟,对应用常规仪表实现简单的前馈——反馈控制问题作了实验研究。文章介绍了前馈模型的简化、实施;前馈——反馈系统品质改善;前馈模型的工程整定方法以及前馈系统设计等有关问题。以供工业应用参考。所介绍的内容对应用计算机实现前馈控制同样可作参考。由于试验装置的局限性,所得结论难免带有片面性,有待今后工业装置的试验而逐步完善。     

螺旋板式换热器气-液换热时流阻及传热计算

提出了螺旋板式换热器用于气-液热交换时的流动阻力以及传热设计的计算方法。螺旋板的设计采用不等间距、气体轴向流动、液体螺旋流动。文中描述了随介质参数的改变,换热器结构的相应变化。结构设计通过迭代计算而达优化目的,设计计算具有通用性。结果表明,与其它形式换热器相比,其传热系数高,流动阻力小。     

运用ASPEN B-JAC设计管壳式换热器

描述了运用ASPEN B-JAC换热器计算软件进行管壳式换热器设计的步骤,讨论了换热器管程壳程优化设计的要点以及利用ASPEN B-JAC进行换热器设计优化过程中应注意的问题,为管壳式换热器的优化设计提供了参考。     

改进型前馈-内模控制算法及在热工系统中的应用

在内模控制的基础之上引入前馈控制,并对反馈回路做了改进.使改进后的前馈-内模控制算法不仅拥有内模控制的优点,而且提升了其抗干扰能力.以热工系统中的主汽温控制为例,由MAT-LAB仿真结果表明:改进的前馈-内模控制消除干扰的能力比内模控制强很多.     

高压铝制板翅式换热器的钎焊技术

介绍了高压铝制板翅式换热器钎焊工艺特点及一些重要的钎焊操作经验,对产品钎焊的3个温度阶段具体控制进行了描述,并提出了高压铝制板翅式换热器钎焊过程的关键控制要求。     

蒸汽加热导热油系统的设计思路

文章主要探讨用高压蒸汽加热导热油系统的设计思路。重点描述了导热油的特性,换热器和冷凝水罐及其它工艺设备的设计原则和相关仪表控制等,同时尽可能采取各种安全措施来保证系统的安全性,确保该系统能够连续稳定运转。     

核电站蒸汽发生器水位模糊控制系统的设计与仿真

针对蒸汽发生器水位控制系统存在的非线性及时变特性等问题,提出了一种前馈-串级模糊控制策略。主调节器为模糊控制器,实现对水位的准确、快速控制;副调节器为比例控制器,实现对给水流量扰动的快速响应;同时引入前馈环节,实现对蒸汽流量扰动的前馈补偿控制。对前馈-串级模糊控制系统进行了水位阶跃输入、给水扰动输入和负荷扰动输入下的仿真实验,与传统前馈-串级PID控制相比,该方法可更有效地控制蒸汽发生器的水位,其鲁棒性强、超调量小、无静态偏差。     

双排对折型微通道换热器仿真模型开发

针对双排对折型微通道换热器,建立三维分布参数模型,基于双排对折的独特结构分别划分换热区和集流管的控制单元,并创新性提出一种基于流程的制冷剂流路描述方法。调研并整理了公开发表文献中记载的适用于微通道换热器的制冷剂侧和空气侧的换热及压降关联式,使模型能够应用于各类工况。建立模型的控制方程,并开发一种换热-压降交替迭代的快速求解算法,基于此计算换热器性能,并用试验数据验证模型的计算精度。结果表明,基于此仿真模型计算的换热器平均换热误差小于5%,制冷剂侧平均压降误差小于10%,满足实际工程需求。     

基于PLC的40T混合磁体低温分配阀箱压力控制系统

基于S7-300 PLC设计混合磁体低温分配阀箱压力控制系统,阀箱内部各处压力控制的PID实现方法相对独立,并未考虑到相互影响。为此,在PID控制方案中加入了前馈控制,使过冷槽压力波动在安全范围内。     

基于改进DOB的矿物研磨过程最优运行先进反馈控制(英文)

Advanced feedback control for optimal operation of mineral grinding process is usually based on the model predictive control (MPC) dynamic optimization. Since the MPC does not handle disturbances directly by controller design, it cannot achieve satisfactory effects in controlling complex grinding processes in the presence of strong disturbances and large uncertainties. In this paper, an improved disturbance observer (DOB) based MPC advanced feedback control is proposed to control the multivariable grinding operation. The improved DOB is based on the optimal achievable H 2 performance and can deal with disturbance observation for the nonminimum-phase delay systems. In this DOB-MPC advanced feedback control, the higher-level optimizer computes the optimal operation points by maximize the profit function and passes them to the MPC level. The MPC acts as a presetting controller and is employed to generate proper pre-setpoint for the lower-level basic feedback control system. The DOB acts as a compensator and improves the operation performance by dynamically compensating the setpoints for the basic control system according to the observed various disturbances and plant uncertainties. Several simulations are performed to demonstrate the proposed control method for grinding process operation.     

Optimal averaging level control for the tennessee eastman problem

This paper focuses on an industrial test problem, the Tennessee Eastman problem. The Tennessee Eastman process is moved to three operation modes with 90/10, 50/50 and 10/90 product G/H ratios. The base control system proposed in an earlier paper can properly control the process at all the three operation modes. Optimal averaging level control is added to the base control to improve the control of product flow during random and step feed disturbances. A new implementation of the optimal feedback averaging control algorithms (McDonald et al., 1986) is presented in order to deal with random disturbances. Simulation results show that control of product flow rate is significantly improved by using the optimal feedback averaging level control at all three operation modes.     

DeltaV系统在VE蒸馏上的应用

艾默生过程管理公司于1996年推出了Delta V系统,它是现场总线系统中最为成功的一套总线控制系统,本文将就该系统的特点和在VE蒸馏装置上的应用作一简单介绍。     

DeltaV系统在乙醛、乙酸装置中的应用

介绍了扬子石化股份有限公司化工厂乙醛、乙酸装置所用DeltaV系统的基本物理结构及软件构成,以及系统的应用情况。使用情况表明,DeltaV系统能满足乙醛、乙酸装置的控制要求。     

乐东15-1气田天然气压缩机远程控制改造

乐东15-1气田的天然气压缩机控制系统是一套独立的AB PLC控制系统,中控室操作站只能监视天然气压缩机的部分参数,而不能对天然气压缩机进行控制。通过对中控DeltaV DCS系统进行通信改造,实现中控DeltaV系统与天然气压缩机PLC控制系统的MODBUS双向通信,并且在中控操作站增加天然气压缩机操控人机界面,最终通过MOD-BUS通信实现中控DCS系统对天然气压缩机的远程监控。     

Disturbance rejection of ball mill grinding circuits using DOB and MPC

Ball mill grinding circuit is essentially a multivariable system with couplings, time delays and strong disturbances. Many advanced control schemes, including model predictive control (MPC), adaptive control, neuro-control, robust control, optimal control, etc., have been reported in the field of grinding process. However, these control schemes including the MPC scheme usually cannot achieve satisfying effects in the presence of strong disturbances. In this paper, disturbance observer (DOB), which is widely used in motion control applications, is introduced to estimate the disturbances in grinding circuit. A compound control scheme, consisting of a feedforward compensation part based on DOB and a feedback regulation part based on MPC (DOB-MPC), is thus developed. A rigorous analysis of disturbance rejection performance is given with the considerations of both model mismatches and external disturbances. Simulation results demonstrate that when controlling the ball mill grinding circuit, the DOB-MPC method possesses a better performance in disturbance rejection than that of the MPC method.     

Process control of polymer extrusion. Part II: Feedforward control

A feedforward plus feedback control method (FFC) and an adaptive feedforward plus feedback control method (AFFC) were proposed in this study to control the extrudate thickness of polymer extrusion. They were tested by step changes of screw speed and feedstock, and square wave type of screw speed changes. It is found that these feedforward control methods worked very well for various load disturbances but they required a good process model and accurate on-line measurements of manipulated variables and load variables. The feedback function was necessary to compensate the over- or under-corrections of the feedforward controllers and to handle other disturbances which were not considered in the feedforward model.     

Iterative learning reliable control of batch processes with sensor faults

An iterative learning reliable control (ILRC) scheme is developed in this paper for batch processes with unknown disturbances and sensor faults. The batch process is transformed into and treated as a two-dimensional Fornasini-Marchesini (2D-FM) model. Under the proposed control law, the closed-loop system with unknown disturbances and sensor faults not only converges along both the time and the cycle directions, but also satisfies certain H_∞ performance. For performance comparison, a traditional reliable control (TRC) law based on dynamic output feedback is also developed by considering the batch process in each cycle as a continuous process. Conditions for the existence of ILRC scheme are given as biaffine and linear matrix inequalities. Algorithms are given to solve these matrix inequalities and to optimize performance indices. Applications to injection packing pressure control show that the proposed scheme can achieve the design objectives well, with performance improvement along both time and cycle directions, and also has good robustness to uncertain initialization and measurement disturbances.     

DeltaV系统在PVC装置中的应用

介绍了艾默生过程控制有限公司的DehaV系统在株化20万吨／年PVC扩改工程二期项目中的应用情况。着重陈述DeltaV系统的特点、项目配置、网络结构、软件组态及其他一些先进自控系统技术应用。     

Neural network‐based optimal iterative controller for nonlinear processes

A new optimal iterative neural network‐based control (OINNC) strategy with simple computation and fast convergence is proposed for the control of processes with nonlinear dynamics. The process dynamics is captured by a forward neural network, and the control is determined by a simple iterative optimization during each sampling interval based on a linearized neural network model. In addition, a feedback control is incorporated into the system to compensate for any model mismatches and to reject disturbances. With the proposed system, the tracking error is shown to be confined to the origin. An application of the proposed OINNC scheme to a nonlinear process results in superior performance when compared with a well‐tuned conventional PID controller.