基于分布式偏差的加热炉支路温度一致控制

针对现有集中式温度支路平衡控制存在的问题,提出基于分布式偏差的支路温度一致性控制方案:仅利用相邻支路的温度信息,将各支路与相邻支路的温度偏差作为控制输入,使加热炉所有支路的温度达到一致的同时,确保调节过程中总进料流量不变。由于仅利用了相邻支路的温度信息,使得所提分布式偏差控制方案在大规模支路情形下更显优势。最后仿真实例表明了该分布式控制方案的有效性与可行性。     

乙烯裂解炉支路温度平衡先进控制系统的开发与应用

针对某乙烯裂解炉支路温度偏差较大的情况,设计开发了一套乙烯裂解炉支路温度平衡先进控制系统。首先,在原有常规控制方案的基础上设计了裂解炉支路温度平衡先进控制方案;其次,提出了一种基于T-S模型的多变量模糊自适应状态空间预测控制(MFASSPC)算法,并作为支路温度平衡控制器;最后,开发和实施了乙烯裂解炉支路平衡先进控制系统。对比于原有控制方案,支路温度偏差由原来的±5℃降低到±1℃,支路温度的标准偏差分别降低了78.6%和74.4%。     

支路平衡系统在烷基化反应器中的应用

利用浙江某公司先进控制平台APC-i SYS为烷基化反应器设计支路平衡优化系统,实现了稳定控制、优化工况,并降低了反应床层温升的偏差,从而提高了能量利用率和目标产品收率。     

加热炉支路平衡控制中流量控制回路的取舍分析

由于加热炉支路平衡控制是一个带约束的多变量强耦合的控制问题,具有非线性、大滞后及强干扰等的特点,多偏差法的多层串级控制结构会增加系统的复杂性和不确定性。针对上述问题提出了一种改进的多偏差控制方案,通过舍去流量控制回路,避免了回路过多造成的系统稳定性变差的问题,简化了控制结构,改善了控制性能。     

四川乙烯裂解炉APC先进控制改造

以中国石油四川石化800 kt/a乙烯装置裂解炉为研究对象,针对采用常规控制方案导致裂解炉炉管平均温度(COT)波动大、支路温度不平衡、负荷提/降量控制不平稳等问题,设计并实施了8台USC裂解炉先进控制系统(APC),包括提降量与支路温度平衡先进控制和平均COT先进控制。介绍了先进控制系统的开发背景及现实需求、先进控制系统构架、先进控制操作界面、先进控制安全保护逻辑等。应用结果表明,相比于常规控制方案,所设计的先进控制系统具有良好的跟踪性、鲁棒性和抑制干扰的能力,体现了良好的工业应用价值。     

百万吨级乙烯装置裂解炉先进控制系统设计与应用

以恒力石化(大连)化工有限公司1500 kt/a乙烯装置裂解炉为例,详细描述裂解炉的工艺流程,分析常规控制方案存在的问题,进而重新设计控制系统,该系统包括平均COT控制、支路温度平衡控制、支路温度“高控”“低控”和总进料流量提/降量控制。并且还介绍控制系统的工程实施,其中包括先进控制系统硬软件平台、先进控制与常规控制的切换逻辑、先进控制系统操作界面等。本系统的投用提高了裂解炉控制的平稳度,延长了裂解炉的运行周期,带来了显著的经济效益。     

多液位与加热炉复合系统的协调控制

多液位与加热炉复合系统是一类具有液位和加热炉支路间的强耦合性及大滞后与非线性等特性的复杂工业过程。针对这类系统的多液位控制与加热炉支路温度平衡控制问题,根据解耦与平衡的思想,提出了一种基于总容量平衡的变周期液位控制的协调控制方法,从结构上实现了多液位控制与支路温度平衡控制的分离,耦合性分析也说明了方法的可行性,最终实现了复合系统的整体协调控制。基于HYSYS流程模拟的仿真实验表明了所提出控制方法的有效性。     

油浸式变压器绕组分布式参数热路模型研究

为了及早发现油浸式变压器长期运行时可能存在的异常升温问题,基于热电类比法和传热理论,利用试验方法获取变压器绕组饼间热阻,代入建立的变压器绕组分布式参数热路模型,用Matlab获取仿真结果,分析变压器绕组热点温度及其位置。通过搭建变压器温升试验平台,采集变压器关键点温度信息对绕组热点温度进行测试分析。实测数据与仿真数据对比结果表明:在额定功率下,热点位于42～47cm,仿真数据与实测数据偏差不大于0.5℃;在1.3倍额定功率下,热点位于42～47cm,仿真结果与实测结果偏差不大于0.7℃,证实了模型的可行性。     

精密注塑机机筒温度控制与抗干扰研究

针对机筒温度控制偏差较大问题,提出时间最优控制与模糊PID控制相结合对精密注塑机机筒温度进行实时控制的方式。利用模糊控制可在线调整PID控制器的参数,兼顾时间最优控制快速消除大偏差和PID控制精度高的优点,获得动态性能指标,达到了升温快速、超调量小和稳态误差小的要求。通讨Matlab对该方案进行仿真,并通过实验进行了验证。结果表明,模糊PID控制算法动态响应好,控制精度高,能够实现温度偏差在±1. 5℃范围的控制要求。     

反应精馏法生产醋酸丁酯动态模拟

目前反应精馏法生产醋酸丁酯工艺发展迅速,但主要集中于对催化剂的探索与研究,在实际生产中仍缺乏较好的控制方法。利用Aspen Dynamics软件对醋酸丁酯反应精馏塔的操作进行了动态模拟,提出了两点温度控制法及温度浓度控制法两种控制方案,对系统进行了进料流量±10%,乙醇及醋酸进料浓度-5%,-10%的扰动测试。研究了不同扰动对产品组成的影响并比较了两种方案分别在面对不同扰动时的控制效果。实验结果表明:进料流量及醋酸进料组成对产品组成影响较大;两点温度控制法在面对不同扰动时均展现出了比温度组成控制法更好的控制效果,该控制方法具有响应速度快,产品组成偏差小的优点。     

Dynamic control analysis of interconnected pressure-swing distillation process with and without heat integration for separating azeotrope

Dynamic controls of pressure-swing distillation with an intermediate connection(PSDIC) process of ethyl acetate and ethanol separation were investigated.The double temperature/composition cascade control structure can perfectly implement effective control when ±20% feed disturbances were introduced.This control structure did not require the control of the flowrate of the side stream.The dynamic controllability of PSDIC with partial heat integration(PHIPSDIC) was also explored.The improved control structure can effectively control ±20% feed disturbances.However,in industrial production,simple controller,sensitive and easy to operate,is the optimal target.To avoid the use of component controllers or complex control structure,the original product purities could be maintained using the basic control structure for the PSDIC process if the product purities in steady state were properly increased,albeit by incurring a slight rise in the total annual cost(TAC).This alternative method without a composition controller combined with the energy-saving PSDIC process provides a simple and effective control scheme in industrial production.     

乙烯裂解炉先进控制系统开发与应用

以中国石油兰州石化公司46万吨/年乙烯装置裂解炉为对象,设计并实施了5台SC-1型乙烯裂解炉先进控制系统,包括平均COT温度控制、管间温度平衡控制、总进料流量控制.详细描述了该系统的工程实施,介绍了先进控制系统硬软件结构、先进控制与常规控制的切换逻辑、先进控制DCS操作界面.本系统的投用极大地提高了裂解炉控制的平稳性和...     

State‐Space Digital PI Controller Design for Linear Stochastic Multivariable Systems with Input Delay

In this paper, a centralized digital PI control scheme is proposed for linear stochastic multivariable systems with input delay. The discrete linear quadratic regulator (LQR) approach with pole placement is used to achieve satisfactory set‐point tracking with guaranteed closed‐loop stability. In addition, the innovation form of Kalman gain is employed for state estimation with no prior knowledge of noise properties. Compared with existing designs, the proposed scheme provides an optimal closed‐loop design via the digitally implementable PI controller for linear stochastic multivariable systems with input delay. Its effectiveness will be demonstrated by the simulation study on examples from both industrial process control and aircraft control.     

Control structure selection of increased-pressure extractive distillation process for DMC-MeOH azeotropic mixture

Producing dimethyl carbonate (DMC) as a green chemical with the desired purity is important in the industry. Although studies on the steady-state design of energy-efficient extractive distillation processes are important for the purification of DMC-methanol (DMC-MeOH) azeotropic mixtures, the dynamic controllability of these processes is also critical in the case of feed condition changes, and it should be investigated carefully. Results of the limited studies in the literature show that changing the operating pressures in extractive distillation processes might have different effects on the dynamic controllability of different systems. Thus, in this study, alternative control strategies are developed for a recently proposed increased-pressure extractive distillation process to separate DMC-MeOH mixture. All control structures are designed using inferential temperature controllers, which have a general acceptance in industrial applications. Effects of different ratio controllers are investigated by evaluating the dynamic responses of control structures for disturbances in feed flowrate and composition. Two metrics including integral absolute error and steady-state deviation of purities are used in the evaluation of alternatives. Results of dynamic simulations show that a control structure including reflux ratio controller is not a suitable strategy for this process. It is demonstrated that a control structure including reflux to feed ratio controller for both distillation columns is necessary for the robust and efficient control of a pressure-increased extractive distillation process. These efficient dynamic results support the economic advantage of increased-pressure extractive distillation process separating DMC-MeOH azeotropic mixtures.     

流化床反应器中气相丙烯聚合反应的动力学和预测控制(英文)

A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temperature. The open loop analysis revealed the nonlinear behavior of the polypropylene fluidized bed reactor, jus- tifying the use of an advanced control algorithm for efficient control of the process variables. In this case, a central- ized model predictive control （MPC） technique was implemented to control the polypropylene production rate and reactor temperature by manipulating the catalyst feed rate and cooling water flow rate respectively. The corre- sponding MPC controller was able to track changes in the setpoint smoothly for the reactor temperature and pro- duction rate while the setpoint tracking of the conventional proportional-integral （PI） controller was oscillatory with overshoots and obvious interaction between the reactor temperature and production rate loops. The MPC was able to produce controller moves which not only were well within the specified input constraints for both control vari- ables, but also non-aggressive and sufficiently smooth for practical implementations. Furthermore, the closed loop dynamic simulations indicated that the speed of rejecting the process disturbances for the MPC controller were also acceotable for both controlled variables.     

MULTIVARIABLE CONTROL OF CATALYTIC CRACKING PROCESSES

Simple, explicit and physically intuitive Feedforward and Feedback control policies are designed for Fluidized Catalytic Cracking Processes. The Feedforward (FF) control algorithm compensates for changes in the feed rate and feed coking tendency by the use of the air flow and catalyst circulation rates as control variables to maintain the conversion and the reactor temperature at fixed levels. Through steady state and dynamic simulations the FF controller is shown to be very effective. To improve the dynamic response of the process and to account for the process/model mismatch a feedback (FB) controller is also designed to complement the FF action. The FB action is designed by use of the transformation related to the physical modes which correspond to the extensive variables of the process. It is shown that the required control structure consists of two loops. One uses the air flow rate to control the total sensible heat content of the reactor and regenerator solid phases. The other loop controls the regenerator enthalpy by changes in the catalyst circulation rate. The air flow rate controller includes an integral action to avoid reactor temperature offsets, while the catalyst circulation rate controller requires a nonlinear static observer to predict the coke concentration on the regenerated catalyst from dense bed and flue gas regenerator temperatures. The performance of the controller for changes on the oil feed rate, caking tendency of the feed, as well as for reactor temperature set point changes is faster and smoother than Kurihara's scheme.     

基于危险和可操作性和模拟计算的氯乙烯精馏定量风险分析

为提高工业过程风险分析的准确性,通过危险和可操作性（HAZOP）定量分析方法建立了基于HAZOP定量分析模型。本文将传统的HAZOP分析和化工模拟软件Aspen Plus相结合,建立工艺流程模型。通过灵敏度分析功能模拟过程参数产生偏差大小对系统影响的程度,从而对偏差进行量化,确定过程参数的安全操作范围。将此方法应用于某化工厂氯乙烯精馏的风险分析中,结果表明,该方法可以准确反映进料参数偏差对氯乙烯精馏系统的影响：当进料温度相对偏差高于25%时,低沸塔再沸器热负荷超出安全阈值;进料量相对偏差高于20%时,两塔冷凝器热负荷超出安全阈值;进料组成绝对偏差高于1.5%时,高沸塔冷凝器热负荷超出安全阈值,塔顶产品质量下降。通过进料参数偏差量化,实现氯乙烯精馏定量风险分析,为企业提出更为有效的安全措施。     

乳酸提纯新工艺动态建模仿真和控制系统设计

基于非平衡级和拟均相假设,建立了乳酸提纯反应精馏新工艺实验装置的动态机理模型.通过改进的数值计算方法提高了模型的求解效率,设计并实现了包含物性估算系统的模型仿真平台,以促进新工艺的工业化应用.利用仿真平台对新工艺装置进行了动态特性分析,在此基础上设计了两种单端质量控制方案:直接物料平衡和间接物料平衡方案.在不同类型和幅度的过程扰动下,分析比较了两种控制方案的调节性能.结果表明直接物料平衡方案控制品质优于间接物料平衡方案,可在不同扰动情况下满足过程的产品质量和转化率的联合控制要求.非平衡级动态机理模型能够反映反应精馏过程的动态特性,分析发现反应精馏过程有着独特的过程特性,基于机理模型的仿真平台是分析反应精馏特性的有效工具.     

Dynamic Matrix Control of a Bubble‐Column Reactor for Microbial Synthesis Gas Fermentation

A spatiotemporal metabolic model of a representative syngas bubble‐column reactor was applied to design and evaluate dynamic matrix control (DMC) schemes for regulation of the desired by‐product ethanol and the undesired by‐product acetate. This model was used to develop linear step response models for controller design and also served as the process in closed‐loop simulations. A 2 × 2 DMC scheme with manipulation of the liquid and gas feed flows to the column provided a superior performance to proportional integral (PI) control due to slow process dynamics combining the multivariable and constrained nature of the control problem. Ethanol concentration control for large disturbances was further improved by adding the flow of a pure hydrogen stream as a third manipulated variable. The advantages of DMC for syngas bubble‐column reactor control are demonstrated and a design strategy for future industrial applications is provided.