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05AIChE: 2005 AIChE Annual Meeting and Fall Showcase

作者： Luís, Dário A. F. Astolfi, A. Kershenbaum, L. Centre for Process Systems Engineering Department of Chemical Engineering and Chemical Technology Imperial College London Department of Electrical and Electronic Engineering Imperial College London

This work examines a nonlinear algorithm to control a class of chemical reactors in which a highly exothermic reaction takes place, and gives relevance to the controller's experimental performance in a real application equivalent to what is encountered in industry. The control objective is to maintain the temperature inside the reactor by manipulating two variables. Several options are available;in this work, we consider as controls the cooling supplied by the jacket and the inlet concentration of one reactant (or, alternatively, the concentration of a homogenous catalyst or promoter of the flow rate of a diluent). These variables are most easily adjusted in the experimental set-up used to test the performance of the Lyapunov-based nonlinear robust controller developed previously. This work fills a gap caused by the lack of experimental applications of the numerous different nonlinear controller proposals to relevant real life situations. It provides some experimental results, which were obtained in a pilot plant CSTR. The reactor is a pilot plant among the facilities in the laboratories at Imperial College London. The results obtained are consistent with earlier simulation studies. They strongly suggest the ability of the proposed controller to globally stabilise the closed loop system and to achieve the desired setpoint(s) as long as the control problem is feasible within the available bounded inputs.

关键词： Nonlinear control systems

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Implementation of MPC on a deethanizer at Kårstø gas plant

Implementation of MPC on a deethanizer at Kårstø gas plant

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作者： Aske, Elvira Marie B. Strand, Stig Skogestad, Sigurd Department of Chemical Engineering Norwegian University of Science and Technology N-7491 Trondheim Norway Process Control Statoil RandD N-7005 Trondheim Norway

ISBN: (纸本)008045108X

Model predictive control (MPC) is implemented on several distillation columns at the Kårstø gas processing plant, Norway. The paper describes the procedure in the implementation of MPC at a deethanizer using the SEPTIC MPC tool, including design, estimator development, model development and tuning. For the deethanizer, the variance in the product quality has been reduced with about 50%. The number of flaring episodes has also been reduced. an increase in impurities has not been challenged yet, so the average reflux flow and steam consumption to feed ratios are almost unaltered. Copyright © 2005 IFAC.

关键词： Model predictive control

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Bayesian control limits for statistical process monitoring

Bayesian control limits for statistical process monitoring

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International Conference on control and Automation (ICCA)

作者： Tao Chen J. Morris E. Martin Centre for Process Analytics and Control Technology School of Chemical Engineering and Advanced Materials University of Newcastle Newcastle-upon-Tyne UK

This paper presents a Bayesian approach, based on infinite Gaussian mixtures, for the calculation of control limits for a multivariate statistical process control scheme. Traditional approaches to calculating control limits have been based on the assumption that the process data follows a Gaussian distribution. However this assumption is not necessarily satisfied in complex dynamic processes. A novel probability density estimation method, the infinite Gaussian mixture model (GMM), is proposed to address the limitations of the existing approaches. The infinite GMM is introduced as an extension to the finite GMM under a Bayesian framework, and it can be efficiently implemented using the Markov chain Monte Carlo method. Based on probability density estimation, control limits can be calculated using the bootstrap algorithm. The proposed approach is demonstrated through its use for the monitoring of a simulated continuous chemical process.

关键词： Bayesian methods Monitoring Gaussian distribution process control chemical processes Manufacturing processes Principal component analysis Kernel Probability density function Product safety

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BATCH process MONITORING THROUGH THE INTEGRATION OF SPECTRAL AND process DATA

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IFAC Proceedings Volumes 2005年第1期38卷 13-18页

作者： Julian Morris Elaine Martin David Stewart Centre for Process Analytics and Control Technology School of Chemical Engineering and Advanced Materials University of Newcastle Newcastle upon Tyne NE1 7RU UK

Most applications of MSPC have tended to focus upon the manufacture of a single product with separate models being developed to monitor individual recipes. With process manufacturing trends being influenced by customer demands there has been an increase in the manufacture of a wide variety of products, there is a real need for process models which allow a range of products, grades or recipes to be monitored using a single process model. With increasing attention now being paid to the FDA process Analytical Technologies (PAT) initiative, the use of spectro-chemical information for enhanced monitoring of reactions and is now gaining impetus. An application of the performance monitoring of a multi-recipe multi-reactor industrial batch polymer manufacturing is discussed in which NIR spectroscopic data is also integrated with process data to provide enhanced batch monitoring.

关键词： Multivariate Statistical process control Spectroscopic Data Multi-recipe Batch Reactors

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Corrosion of potential heat-exchanger materials in Singapore seawater

Corrosion of potential heat-exchanger materials in Singapore...

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Corrosion and Corrosion control in Saltwater Environments II - Proceedings of the International Symposium

作者： Blackwood, D.J. Qiping, Liu Fujita, K. Onishi, K. Department of Materials Science National University of Singapore Singapore 117542 Singapore Chemical and Process Engineering Centre National University of Singapore Singapore 117576 Singapore Materials and Plant Engineering Group Process and Production Technology Centre Sumitomo Chemical Co. Ltd. 5-1 Sobiraki-cho Niihama-City Ehime 792-8521 Japan

The petrochemical plants in Singapore are gathered on Jurong Island;as such the local seawater has a relatively high pollution level compared to other locations around the island. Furthermore the shortage of fresh water means that seawater has to flow through heat-exchangers. Seawater coupled with high inlet temperatures prevailing in Singapore, represents a high risk environment to materials particularly with respect to pitting and crevice corrosion. The corrosion behavior of seven materials has been assessed both in laboratory experiments and in a mock-up test system. It was found that crevice corrosion represents the most serious threat to heat exchangers operating with Singapore seawater;none of the high grade stainless steels or the two copper based alloys were immune to this form of attack. Only titanium proved to be completely corrosion resistant in Singapore seawater.

关键词： Corrosion

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A time varying state space approach for sugar crystallization process modelling and monitoring

A time varying state space approach for sugar crystallizatio...

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作者： Simoglou, A. Georgieva, P. Martin, E.B. Morris, A.J. De Azevedo, S. Feyo Center for Process Analytics and Control Technology Merz Court University of Newcastle Newcastle upon Tyne NE1 7RU United Kingdom Department of Chemical Engineering Faculty of Engineering University of Porto R. Dr. Roberto Frias 4200-465 Porto Portugal Department of Electronics and Telecomunications University of Aveiro Campus Universitario de Santiago 3810-193 Aveiro Portugal

ISBN: (纸本)008045108X

The present paper contributes to the issues of batch process modelling and monitoring by proposing a time-varying state space (TVSS) model for the evaporative sugar crystallization industrial process. The study is focused on issues of on-line detection of changes in crystallization process operation, the early warning of process malfunctions and potential production failures;problems that have not been directly addressed by existing statistical monitoring schemes. The TVSS methodology is compared with current state-of-the-art techniques and the results obtained demonstrate the superior performance of the TVSS approach to successfully detect abnormal events and periods of bad operation. Copyright © 2005 IFAC.

关键词： Statistical process control

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IMPLEMENTATION OF MPC ON A DEETHANIZER AT KÅRSTØ GAS PLANT

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IFAC Proceedings Volumes 2005年第1期38卷 437-442页

作者： Elvira Marie B. Aske Stig Strand Sigurd Skogestad Department of Chemical Engineering Norwegian University of Science and Technology N-7491 Trondheim Norway Statoil R&D Process Control N-7005 Trondheim Norway

Model predictive control (MPC) is implemented on several distillation columns at the Kårstø gas processing plant, Norway. The paper describes the procedure in the implementation of MPC at a deethanizer using the SEPTIC * MPC tool, including design, estimator development, model development and tuning. For the deethanizer, the variance in the product quality has been reduced with about 50%. The number of flaring episodes has also been reduced. An increase in impurities has not been challenged yet, so the average reflux flow and steam consumption to feed ratios are almost unaltered. * SEPTIC: Statoil Estimation and Prediction Tool for Identification and control

关键词： Model based control distillation columns implementation dynamic modelling estimators

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A TIME VARYING STATE SPACE APPROACH FOR SUGAR CRYSTALLIZATION process MODELLING AND MONITORING

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IFAC Proceedings Volumes 2005年第1期38卷 27-32页

作者： A. Simoglou P. Georgieva E.B. Martin A.J. Morris S. Feyo de Azevedo Center for Process Analytics and Control Technology Merz Court University of Newcastle Newcastle upon Tyne NE1 7RU UK Department of Electronics and Telecomunications University of Aveiro Campus Universitario de Santiago 3810-193 Aveiro Portugal Department of Chemical Engineering Faculty of Engineering University of Porto R. Dr. Roberto Frias 4200-465 Porto Portugal

The present paper contributes to the issues of batch process modelling and monitoring by proposing a time-varying state space (TVSS) model for the evaporative sugar crystallization industrial process. The study is focused on issues of on-line detection of changes in crystallization process operation, the early warning of process malfunctions and potential production failures; problems that have not been directly addressed by existing statistical monitoring schemes. The TVSS methodology is compared with current state-of-the-art techniques and the results obtained demonstrate the superior performance of the TVSS approach to successfully detect abnormal events and periods of bad operation.

关键词： Statistical process control dynamic principal component analysis batch sugar crystallization

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Online tuning procedures for crude distillation unit model

Online tuning procedures for crude distillation unit model

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2004 AIChE Spring National Meeting, Conference Proceedings

作者： Dave, Dhaval J. Dabhiya, Murtuza Z. Satyadev, S.V.K. Ganguly, Saibal Saraf, Deoki N. Process Control Laboratory Department of Chemical Engineering Indian Institute of Technology Kanpur - 208016

ISBN: (纸本)0816909423

Crude distillation unit (CDU) is an important refinery operation and its product properties play an important role in control and optimization. Various properties such as specific gravity, flash point and pour point are function of product composition, which is calculated by simulator requiring crude oil composition (in terms of True Boiling Point -TBP curve and average specific gravity) and process parameters. The exact feed TBP is often unavailable during the plant operation. Stratification of raw crude oil into layers in the large tank farm sections cause severe operating problems in terms of the stability of the column. Also, steady state simulator equations are based on ideal conditions where it is assumed that phase equilibrium is attained on each stage, but it is seldom achievable in real life owing to a variety of column nonidealities. Moreover, no single thermodynamic model can successfully predict the thermodynamic properties in the entire range of boiling points with the same accuracy. These reasons lead to deviation of the simulator results from the plant data. The present study aims to provide CDU simulator tuning methods for online applications such as inferential control and supervisory optimization. In-house developed tuning methods are described and performance of tuned simulator package with refinery data is compared.

关键词： Distillation

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Modelling temperature4nduced spectral variations in chemical process monitoring 7th

Modelling temperature4nduced spectral variations in chemical...

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7th IFAC Symposium on Dynamics and control of process Systems, DYCOPS 2004

作者： Chen, Zeng-Ping Morris, Julian Martin, Elaine Centre for Process Analytics and Control Technology School of Chemical Engineering and Advanced Materials University of Newcastle upon Tyne NE1 7RU United Kingdom

With a view to ensuring the validity of multivariate calibration models in the presence of temperature variations, a new methodology, individual contribution standardization (ICS), is proposed to correct for temperature-induced spectral variations. The methodology was applied to shortwave NIR spectral data sets recorded at different temperatures. The results showed that ICS can almost eliminate temperature effects resulting in calibration models that exhibit good predictive performance. Compared with other methods, such as continuous piecewise direct standardization, ICS has the advantages of easy implementation, simple selection of the calibration model and less restrictions on the training samples. © IFAC Dynamics and control of process Systems, Cambridge, Massachusetts, USA, 2004

关键词： Standardization

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