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7th International symposium on process systems Engineering

作者： Sato, C Ohtani, T Nishitani, H Yokogawa Elect Corp Tokyo 1808750 Japan Nara Inst Sci & Technol Nara 6300101 Japan

In an industrial gas-phase polymerization process, dynamics change globally due to grade changes and load changes, and these changes present a difficult control problem. In this paper, a nonlinear physical model was effectively used for the control system design. First, we developed a set of physical models of an industrial ethylene polymerization process with reference to McAuley's model. Parameters in the model were adjusted to simulate the actual process behavior. Second, in the control system design, the system is regarded as a two-input and two-output system. The two inputs are the feed rates of fresh hydrogen and butene, and the two outputs are cumulative melt index and density. An optimal servo controller with integral actions is designed according to the optimal regulator theory using a model linearized at a nominal operating point. Third, we examined the changes of process dynamics under typical operating points for different grade products. As a result, a nonlinear compensator was attached to the optimal servo controller to cope with remarkable changes in the process gain due to the product grade. This method resulted in good control performances during various grade changes. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： industrial polymerization reactor modeling grade transition product property control nonlinear compensation

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On-line dynamic optimization of olefins plants

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COMPUTERS & CHEMICAL ENGINEERING 2000年第2-7期24卷 533-538页

作者： Nath, R Alzein, Z Honeywell Int Hi Spec Solut Houston TX USA Honeywell Int Hi Spec Solut Phoenix AZ 85053 USA

Over the years, olefins plants have evolved into highly integrated, highly flexible processing systems that can profitably adjust to ever changing landscape of raw material availability and market demand for high purity olefins products. Advanced process control technologies such as model predictive control (MPC) are commonplace in olefins plants and have greatly improved the consistency of product quality and constraint protection, and have typically resulted in quick payback on investment. Another advanced technology, that of on-line optimization promises even greater benefits. Application of traditional on-line optimization technology however remains a challenging task primarily because of long process dead times, mixed process dynamics and frequent disturbances. The steady state models used in traditional optimization are inadequate representation of the on-line behavior of most commercial olefins plants. A unique approach to on-line optimization of dynamic processes is presented in this paper. In this approach plant steady state is not a requirement for on-line optimization. This approach fully utilizes the MPC dynamic models for optimization. Application of this on-line optimization technology has resulted in continuous savings for some very dynamic olefins plants. This paper briefly describes this dynamic optimization technology and summarizes experiences from several completed and in-progress olefins plant optimization projects. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： olefins plants on-line dynamic optimization integrated control and optimization

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Incorporation of dynamic behaviour in an automated process synthesis system

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COMPUTERS & CHEMICAL ENGINEERING 2000年第2-7期24卷 189-194页

作者： Fraga, ES Hagemann, J Estrada-Villagrana, A Bogle, IDL UCL Dept Chem & Biochem Engn London WC1E 7JE England

Incorporating non-economic criteria into an automated process synthesis procedure enables an engineer to prune, more easily and more effectively, the large design space early in the design process. Although existing synthesis procedures are based on the use of steady state modelling, issues such as operability and flexibility are best handled through the use of dynamic models. This paper describes a discrete programming approach, implemented in the Jacaranda synthesis tool, incorporating dynamic modelling for the generation of process designs, which meet specified criteria for operability or flexibility. Particular attention is given to implementation issues, including especially how to incorporate dynamic modelling efficiently in an automated environment. An example of the design of separation sequences with good start-up and feed disturbance behaviour is presented. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： process synthesis optimisation dynamics modelling control operability automated design

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Application of a neural predictive controller in boost converter input current control

Application of a neural predictive controller in boost conve...

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Proceedings of the 2000 IEEE International symposium on Intelligent control

作者： Petrovic, Ivan Baric, Miroslav Magzan, Ante Peric, Nedjeljko Univ of Zagreb Zagreb Croatia

The application of a non-linear predictive controller in the cascade control structure of boost converter is investigated. The neuro-predictive controller is realized as a non-linear optimizer, using the Levenberg-Marquardt unconstrained optimization procedure. For the prediction of future process responses, two MLP neural networks are used. One network is used for modeling the converter dynamics and the other for on-line estimation of the converter's input voltage. This structure ensures good system performance in all operating regions and inherent compensation of ripples in converter's input current caused by variations of the input voltage. The advantages of the proposed control structure are demonstrated through experimental comparison with a linear GPC with manually adjusted feed forward compensator.

关键词： Predictive control systems

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Development of high performance operational strategies for polymerization reactor

Development of high performance operational strategies for p...

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7th International symposium on process systems Engineering

作者： de Toledo, ECV Martini, RF Maciel, R State Univ Campinas Sch Chem Engn BR-13081970 Campinas SP Brazil

This work presents the modeling and control of the temperature of a CSTR polymerization reactor connected to a semi-flooded horizontal condenser. The objectives of this work were to evaluate the cooling potential and the development of different algorithms to control the reactor temperature where bulk polymerization reactions take place via styrene free radicals. The control algorithms studied were classic PI, long-range predictive GPC and predictive-adaptive STGPC (GPC connected to the identification algorithm 'RLS'). The results obtained here show that the system provides quick, efficient and highly competitive refrigeration compared with other systems when this system is associated with a control algorithm which adapts perfectly to its dynamics characteristics. The new approach presented in this work, which associates the system 'CSTR + semi-flodded horizontal condenser' to the control algorithm (GPC and STGPC), makes the process highly competitive regarding refrigeration and performance. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： polymerization reactor autorefrigeration advanced control

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Operation of a bench-scale ideal heat integrated distillation column (HIDiC): an experimental study

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COMPUTERS & CHEMICAL ENGINEERING 2000年第2-7期24卷 495-499页

作者： Naito, K Nakaiwa, M Huang, K Endo, A Aso, K Nakanishi, T Nakamura, T Noda, H Takamatsu, T Natl Inst Mat & Chem Res Tsukuba Ibaraki 3058565 Japan Maruzen Petrochem Co Chiba 2908503 Japan Kansai Univ Ind Technol Inst Suita Osaka 5648680 Japan

Experimental study of an ideal heat integrated distillation column (HIDiC) is introduced in this work. It is found that the ideal HIDiC can be operated very smoothly, with no special difficulties compared with its conventional counterparts. The higher energy efficiency of the ideal HIDiC is confirmed by the bench-scale experiments. Reflux-free and/or reboil-free operations of the ideal HIDiC are also demonstrated to be feasible by the experiments. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： distillation process dynamics control configuration startup process operation

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On-line dynamic optimization of olefins plants

On-line dynamic optimization of olefins plants

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7th International symposium on process systems Engineering

作者： Nath, R Alzein, Z Honeywell Int Hi Spec Solut Houston TX USA Honeywell Int Hi Spec Solut Phoenix AZ 85053 USA

关键词： olefins plants on-line dynamic optimization integrated control and optimization

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A simple Self-Tuning Speed controller

A simple Self-Tuning Speed Controller

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IEEE International symposium on Industrial Electronics (ISIE 2000)

作者： Romeral, L Aldabas, E Arias, A Llaquet, J Tech Univ Catalonia UPC Dept Elect Engn Terrassa 08222 Spain

ISBN: (纸本)0780366069

It is presented a Self-Tuning PID Adaptive Speed controller for AC motor speed regulation with a very low computational algorithm. The traditional industrial solution to obtain acceptable characteristics for tracking and process regulation consists to find a compromise point for both two situations, or in advanced regulators, to adopt a simple two degrees of freedom PID control, whose parameters are fixed by Auto-Tuning. But when plant parameters vary strongly this Auto-Tuning algorithm have to be continuously started. In those cases this work propose a single self-tuning PID control method with a simple adaptation mechanism. The controller is based in a novel fuzzy adaptation method that changes the parameters of an standard PID controller, concretely integral constant K-1, for adapting it to the plant evolution according to the dynamics of the system. This fuzzy logic adaptive strategy has been readily implemented, with very fast learning features and very good tracking characteristics. The developed controller has been also compared with other classical controls, and experimental results demonstrate the robustness of the suggested algorithm in contending with varying load and torque disturbance.

关键词： Adaptive control systems

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Incorporation of dynamic behaviour in an automated process synthesis system

Incorporation of dynamic behaviour in an automated process s...

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7th International symposium on process systems Engineering

作者： Fraga, ES Hagemann, J Estrada-Villagrana, A Bogle, IDL UCL Dept Chem & Biochem Engn London WC1E 7JE England