PROCESS CONTROL GROUP

Department of Chemical Engineering, NTNU

Head of group: Professor Sigurd Skogestad

ANNUAL REPORT 1995.

By the end of 1995 the group consisted of 11 persons (one professor, nine Ph.D students and one postdoc.

The objectives of our research are:

• To educate engineers with a strong background in both chemical engineering and control. We attempt to bridge the gap in understanding, that has traditionally existed between the two disciplines.
• To perform high-quality and relevant research. In addition to being valuable in itself, research is vital in order to give out engineers the right training. It also keeps us updated with international research, and thus enables us to bring international research to industry.

Summary of main results for 1995.

• No Ph.D. candidates graduated in 1995, but John Morud competed his thesis on "Studies on the dynamics of integrated plants" in December 1994 and he will defend his thesis on 15 April 1996 with Professor Manfred Morari, ETH as the main opponent. By finishing his thesis in 1994 John will get his degree from NTH (Norwegian Institute of Technology) rather from the new NTNU (Norwegian University of Science and Technology) which from 1. Jan. 1996 replaces the old NTH.
• Sigurd Skogestad was on sabaticcal leave at the University of California at Berkeley for 11 months in 1994-95. During this time he worked with Prof. Alan Foss in the Chemical Engineering Department on plantwide control and process control teaching, as well as with Professors A. Packard and K. Poola in the Mechanical Engineering Department on robust control. The most important activity during his stay was to work on a text book on "Multivariable feedback control - Analysis and design" which will be published by Wiley in 1996. The book is coauthored by Ian Postlethwiate who also spend 4 months at Berkeley during 1994. The main aim of the book is to present advanced control theory such that it can be used in practice.
• Bernd Wittgens and Rajab Litto got our experimental multi-vessel batch distillation column into opertaion, and our preliminary results conform the results from dynamic simulations and show that our simple scheme with indirect level control based on temperature measurements works also in practice (in spite of what some skeptics believed).
• The group has during 1995 published 7 papers in international journals and book chapters, and 7 papers at international conferences. In addition the group members have presented 12 talks without a written paper. A complete list of publications is enclosed.
• We have establisehed an internet web site where most of our latest publications are available; and also the five resent Ph.D. thesises of Mathisen, Wolff, Sørensen, Lundstrøm and Morud, see http://www.kjemi.unit.no/kjtek/groups/prosdyn
• A new project on complex (Petlyuk) distillation supported by the European Union' Joule project was approved and is due to start early in 1996. The project is coordinated by Robin Smith at UMIST in Manchester, and our role is to envestigate the operation, optimization and control of such units.
• Only one Diploma student graduated from the group in 1995 (Gunnar Østgaard: «Reactive distillation») - this is mainly because of Prof. Skogestad's sabattical leave.

Ph.D. Students 1995

Atle C. Christiansen: Studies on dynamics and control of integrated plants. Atle is now focusing his work on integrated (Petlyuk) distillation columns.

Pål Flatby: Modelling and control of distilation columns. Pål is now back with Statoil Research Center in Trondheim, but has yet to write up his thesis.

Audun Faanes: Plantwide control. Audun is with Norsk Hydro Research Center in Porsgrunn. He has finished most of his course work, but he has not yet started his research work.

Kjetil Havre: Control structure selection for integrated plants. Kjetil spends part of his time at IFE at Kjeller near Oslo.

Eva-Katrine Hilmen: Batch distillation. Katrine is spending 1995-96 at University of Massachucetts with professors Doherty and Malone. She is focusing on azeotropic batch distillation.

Rajab M. Litto: New strategies for multicomponent batch distillation. Rajab has discontinued his Ph.D. work and returned to Tanzania in February.

John C. Morud: Studies on the dynamics and operation of integrated plants. John finished his thesis in December 1995, and defends his work on 15 April 1996. The thesis is available over the internet.

Bernd Wittgens: Experimental verifation of robust control theory. Bernds works involves experimental dynamic and control studies of continous and batch distillation. He plans to finish his thesis in December 1996.

Ying Zhao: Modelling identification and control of biochemical processes. Ying plans to finish her thesis in August 1996.

New Ph.D. projects (starting in 1996).

Ivar Halvorsen (from 16 April 1996): Control and optimization of complex industrial processes. Ivar works with SINTEF Automatic Control, and will initially he be involved in the European project on complex distillation columns - DISC.

Truls Larsson (from 1 May 1996): Optimization and control of methanol processes. Truls has his siv.ing. degree from Porsgrunn and presently works with Borealis.

International colloboration

It has already been mentioned that Sigurd Skogestad spend his sabattical leave at Berkeley during 1994-95. Atle Christiansen and Kjetil Havre also came over in March 1995 and spent one month. We have also visited various other institutions, and we have attended a large number of workshops and conferences.

This information is given separately and in the list of publications.

• We are a member of EU network on chemical process control.
• We are a member of the informal European network on computer aided process engineering (CAPE network)
• Valeri Kiva from Karpov institute in Moscow spent one week with us in August 1995.
• Joachim Blume from RWTH Aachen spent 2 weeks with us in October 1995.
• Yi Cao from Exeter spent 3 months with us a postdoc from October 1995 to January 1996. He was mainly involved in the book project on multivariable control.
• Sigurd Skogestad was the external opponent for Ghassan Murad's Ph.D. in Leicester in October 1995: Robust multivariable control of industrial processes: A discrete time multi-objective approach.

Plans for 1996/1997:

• The European Union project on complex distillation is due to start in April 1996.
• The new book on "Multivariable control - analysis and design" by Skogestad and Postlethwaite is due to be published by Wiley in May 1996.
• Valeri Kiva from Karpov Institute in Moscow will spend about one year as a visiting fellow starting from August 1996.
• We will organize the next Nordic Process Control Workshop (NPC'97) at Wadahl Høyfjellshotell near Lillehammer 12 Jan - 14 Jan.1997.
• Sigurd Skogestad is the chairman if the international program committe for the PSE- ESCAPE-97 conference in Trondheim 26 May - 29 May 1997.

Publications

International journals/ books:

• E.A. Wolff and S. Skogestad, «Operation of integrated three-product (Petlyuk) distillation columns», Ind.Eng.Chem.Res., 34, 6, 2094-2103 (1995).
• S. Skogestad and M. Hovd, Letter to the editor on decentralized versus multivariable control, J. Process Control, 5, 399-400 (1995).
• P. Lundstrøm, J.H. Lee, M. Morari and S. Skogestad, «Limitations of Dynamic Matrix Control», Comp. & Chem. Engng., 19, 409-421, 1995.
• P. Lundstrøm and S. Skogestad, «Opportunities and difficulties with 5 x 5 distillation control», J. Process Control, 5, 249-261, 1995.
• E.W. Jacobsen and S. Skogestad, «Multiple steady-states and instability in distillation - implications for operation and control», Ind.Eng.Chem.Res., 34, 4395-4405, 1995.
• S. Skogestad, «Frequency-domain methods for analysis and design. I. H-infinity methods and robust control». Methods of Model Based Process Control - Proc. of NATO-ASI in Antalya, Turkey, Aug. 1994), R. Berber (Ed.), Kluwer Academic Publishers, Netherlands, 1995, 113-152.
• S. Skogestad, «Frequency-domain methods for analysis and design. II. Controllability analysis of SISO Systems», Methods of Model Based Process Control - Proc. of NATO-ASI in Antalya, Turkey, Aug. 1994», R. Berber (Ed.), Kluwer Academic Publishers, Netherlands, 1995, 153-191.

International Conference Papers.

• Y. Zhao and S. Skogestad, «Modeling and control of a continuous bioreactor with cross-flow filtration», Proc. 6th Intl Conf on Comp Appl in Biotechnology, Garmish-Partenkirchen, Germany, May 1995, Publ. by DECHEMA, A. Munack and K. Schugerl (Eds.), 344-348.
• E. Sørensen and S. Skogestad, «Comparison of inverted and regular batch distillation», Preprint IFAC Symposium DYCORD+95, 4th IFAC Symposium on Dynamics and Control of Chemical Reactors, Distillation Columns and Batch Processes, Helsingør, Denmark, 7-9 June 1995, 141-146. Proposed paper for the Journal of Chem. Eng. Science, 1994.
• B. Wittgens and S. Skogestad, «Evaluation of dynamic models of distillation columns with emphasis on the initial response», Preprint IFAC Symposium DYCORD+95, 4th IFAC Symposium on Dynamics and Control of Chemical Reactors, Distillation Columns and Batch processes, Helsingør, Denmark, 7-9 June 1995, 261-267.
• J.C. Morud and S. Skogestad, «The dynamics of chemical reactors with heat integration», Proc. 1993 European Control Conference, Rome, Italy, Sept. 1995, 2333-2338.
• S. Skogestad, B. Wittgens, E. Sørensen, E. and R.J. Litto, «Multivessel batch distillation», AIChE Annual Meeting, Miami Beach, Nov. 1995, Paper 184i.
• A.C. Christiansen, E.W. Jacobsen, J.D. Perkins and S. Skogestad, «On the dynamics of batch distillation: A study of parametric sensitivity in ideal binary columns», AIChE Annual Meeting», Miami Beach, Nov. 1995, Paper 184d.
• J.C. Morud and S. Skogestad, «The dynamic behavior of cascade processes with application to distillation columns», AIChE Annual Meeting, Miami Beach, Nov. 1995, Paper 189b.

Lectures S. Skogestad 1995:

• S. Skogestad, «A systems approach to distillation processes - The rebirth of a research area», Chemical Engineering Departmental seminars, University of California at Berkeley Jan. 23 1995,
  • University of California at Davis Feb. 13 1995, and
  • University of California at Santa Barbara May 9 1995.
• S. Skogestad, «A systems approach to distillation processes - The rebirth of a research area'', Seminar, University of Nassachusetts at Amherst, 31 March 1995.
• S. Skogestad, «Controllability analysis of SISO systems», Seminar, Department of Electrical Engineering, University of California at Berkeley, April 5, 1995.
• S. Skogestad, «A systems approach to distillation processes - The rebirth of a research area», Plenary lecture, IFAC Symposium DYCORD+95, Helsingor, Denmark, June 8, 1995.
• S. Skogestad, «Controllability analysis of SISO systems», Seminar, DuPont experimental Station, Wilmington, Delaware, USA, July 28, 1995.
• S. Skogestad, «Multivessel batch distillation», Nordic Process Control Workshop, Åland, August 1995.
• S. Skogestad and K. Havre, «Control strategy selection and partial control», Lecture and poster, European HCM meeting on chemical process control, Imperial College, London, 14-15 September 1995.
• S. Skogestad and J. Morud, «Analyse av ustabilitet i ammoniakk-reaktorer», Servomøtet 1995, Trondheim, Nov. 1995.