PROCESS MODELLING GROUP

Department of Chemical Engineering, NTNU

Head of group: Professor Terje Hertzberg

ANNUAL REPORT 1995

By the end of 1995, the group consisted of five persons (one professor, 4 Ph.D. students). Their objectives of the activities can be summarized as:

• Development of efficient methods and tools for process modeling, simulation and optimization through the synthesis of knowledge in mathematics, statistics, numerical methods, computer science and process technology. A thorough understanding of the different technologies and their interaction form the basis for our approach to the different problem areas.
• To educate candidates with a strong background in modeling of chemical engineering systems, from micro to full plant scale. Cooperate with industry and the international research community in our area to ensure the quality and relevance of our work.

Summary of main results for 1995

Dr. ing. candidates graduated

• Hanne M. Kvamsdal. The thesis Studies on Modeling, Simulation and Optimization of PSA Systems was defended in June with professor Tapio Westerlund from Åbo, Finland as the main external examiner. Hanne has joined Aker Engineering in Oslo.

Diploma students

Six diploma projects have been supervised by the group this autumn.

Linda Hanken, Optimization of a Methanol Reactor, was done in close cooperation with Statoil and considered operational optimization of the methanol reactor under catalyst deactivation.

Amund Saxrud, Optimization of Paper Tensile Strength, was done at Norske Skog's plant Follum. An empirical model relating tensile strength of paper to operational variables was developed and used for determining optimal set points for some of the manupulated variables of the paper machine.

Tore Kulset, Dynamic Modular Simulation with a Network Solver, examined the hybrid modular simulation strategy where the flow/pressure relations for all modules are solved simultaneously.

Christian L. Jensen, Modeling of a Catalytic Fluidized Bed Cracker for Real Time Simulation, was done at Norcontrol; Horten and implemented a FCC model in their real time simulator ProSim.

Ingvild Jensen, Dynamic Optimization of a Distillation Column, used the propane/butane column at the Mongstad Refinery as case and demonstrated how minimizing steam consumption and deviation from product specifications could be performed.

Morten Albriktsen, Nonlinear Parameter Estimation in MATLAB, implemented a graphic user interface to the Matlab version of our nonlinear parameter estimation program MODFIT.

Ongoing Dr. Ing. Projects

Håvard I. Moe

works with modeling and simulation of dynamic process systems. He submitted his dr.ing.-thesis in December 1995. The title is Dynamic Process Simulation. Studies on Modeling and Index Reduction. He has developed a modeling method that gives well posed models and has demonstrated its usefulness for a series of different dynamic modeling problems. He also presents two index reduction algorithms that transform a high index problem to an index one formulation. One case study on dynamic reactive flash calculation was presented in Bled at Escape 5, and a study that shows how stiffnes can be reduced in gas flow systems by an index formulation and subsequent index reductioin is accepted for presentation in Rhodos at Escape 6, spring 96.

Hans Christian Riksheim

has been busy finishing his course program. His field of interest is within numerical methods for dynamical simulation. IFE (Institutt for energiteknikk, Kjeller) funds his work, and his research project is going to be done in cooperation with IFE. He has initially looked into a stability analysis of IFE's network solver that is implemented in Norcontrols ProSim system.

Sverre Støren

works with efficient dynamic process simulation and optimization. He is expected to finish his Dr.ing. study in 1996. This year he has been only part time active as a graduate student since he has served as coordinator of a Nordic program on process integration. Despite this he has continued his research work on dynamic simulation and optimization, mainly on an algorithmic level. Part of this work was presented in Bled at Escape 5, 1995.

Helge Tørvi

has also been busy finishing his course program. His field of interest is uncertainty in dynamical simulation. An initial study on uncertainty calculations due to correlated errors in flash simulations was presented at the AIChE Annual Meeting, Miami, 1995.

Other activies

Teaching and administrative assignments

• I lectured one undergraduate course in process simulation and one graduate course, in empirical model building and parameter estimation.
• I have been dr.ing / Ph.D. examiner on several occasions and I have reviewed papers for Comp. & Chem. Eng., MIC and Chem. Eng. Sci.
• The main administrative assignments this year include:
• Head of Department,
• Assistant Dean of the Faculty,
• Chairman "Education and Curriculum Committee" at the Faculty
• Chairman "Continuing and Further Education Committee, NTH
• Chairman "Conference Committee", NTH
• Coordinator NFR program "Process System Engineering"
• Program board INPRO.
• Editorial board Computers & Chemical Engineering
• Editorial board Chemical Engineering and Processing

External courses

• Two courses in mathematical modeling has been given to external audiences this year. A two weeks continuing education course was completed with approx. 25 attendies, mainly from industry. A shorter modeling course was given to 30 mathematics teachers from engineering colleges. Both courses was developed and given together with Håvard I. Moe and Sverre Støren.
• In January 95 I gave a three week Ph.D. course in Advanced Process Simulation at DTU, Copenhagen together with R. Gani.

Conference attendance

The group participated at several conferences in 1995.

• The 1995 IchemE Research Event, First European Conference for Young Researchers in Chemical Engineering, Edinburgh, January 1995. (H. Kvamsdal)
• ESCAPE 5, Fifth European Symposium on Computer Aided Process Engineering, Bled, Slovenia, June 1995. (T. Hertzberg, H. Kvamsdal, H. Moe, H.C. Riksheim, S. Støren, H. Tørvi)
• American Institution of Chemical Engineers Annual Meeting, Miami, November 1995. (T. Hertzberg, H. Tørvi)

Collaboration

The group has close cooperation with our SINTEF counterpart and has during the last year been involved in many project initiatives towards industry and the Research Council of Norway, especially the PROSMAT 2000 program that starts up in 1996. We have continuous cooperation and contact with several Norwegian industrial companies, system firms, research institutes in addition to other departments at the university.

International academic contacts that we have visited or who have visited NTH the last year include R. Gani DTU, W. Marquardt RWTH, J.Ponton Edinburgh, L.Biegler and A: Westerberg Carnegie Mellon. T. Westerlund Åbo.

Plans for 1996

• The first activity in 96 will be Håvard's Dr.ing. defense primo February.
• The research work will continue along the same lines as in 1995. We will recruite one new dr.ing. student to work with dynamic simulation of a methanol reactor. The work will be done in close cooperation with STATOIL.
• Sverre Støren intends to finish his research work and defend his thesis early autumn 96.
• I plan to go to University of California, Berkeley for a sabbatical leave for one year from September 96.

Publications

8 international publications were produced by the group last year and two lecture notes for our modeling course and the advanced simulation course at DTU respectively. A full list of the publications is included.

Thesis

• H.M. Kvamsdal, Studies on Modeling, Simulation and Optimization of PSA, Dr.ing. thesis, report no. NTH 1995:50, NTH, Trondheim, 1995.

International journals and conferences

• Kvamsdal, H.M. and T. Hertzberg, Optimization of PSA Systems - Studies on Cyclic Steady State Convergence, The 1995 IchemE Research Event, First European Conference for Young Researchers in Chemical Engineering, Edinburgh, pp. 92-94, January 1995.
• Kvamsdal, H.M. and T. Hertzberg, Optimization of Pressure Swing Adsorption Systems - The Effect of Mass Transfer During the Blowdown Step, Chemical Engineering Science, 50, no7, pp.1203-1212, 1995
• Kvamsdal, H.M. and T. Hertzberg, Pressure Swing Adsorption - Optimization of a Trace Separation System, Computers and Chemical Engineering, 19, Suppl., pp 339-344, 1995.
• Moe, H.I., S. Hauan, K.M.Lien and T. Hertzberg, Dynamic Model of a System with Phase and Reaction Equilibrium, Computers and Chemical Engineering, 19, Suppl., pp. 513-518, 1995.
• Støren, S. and T. Hertzberg, The Sequential Linear Quadratic Programming Algorithm for Solving Dynamic Optimization Problems, Computers and Chemical Engineering,19, Suppl., pp. 495-500, 1995.
• Hauan, S., T.Hertzberg and K.M. Lien, Multiplicity in reactive distillation of MTBE, Computers and Chemical Engineering, 19, Suppl., pp. 327-332, 1995.
• Hauan, S., T.Hertzberg and K.M.Lien, Why Methyl tert-Bytyl Ether Production by Reactive Distillation May Yield Multiple Solutions, Ind. Eng. Chem. Res., 34, No. 3, pp. 987-991, 1995.
• Tørvi, H. and T. Hertzberg, Influence of Parameter-Correlations on Probabilistic Simulations of an Isothermal Flash, AIChE Annual Meeting, Miami, 1995.

Accepted

• Kvamsdal, H.M. and T. Hertzberg , Optimization of PSA Systems - Studies on Cyclic Steady State Convergence, Full-length paper, accepted for publication in Computers and Chemical Engineering, 1995.
• Kvamsdal, H.M. and T. Hertzberg, A Preliminary Design Study of a Multicomponent PSA Gas Separation System, Full-length paper, accepted for publication in Chemical Engineering and Processing, 1995.
• Moe, H.I., H.C. Riksheim and T. Hertzberg, Stiffness Reduction of Gas System Models, accepted presentation, ESCAPE-6, Rhodos, 1996.

Other publications:

• T. Hertzberg & R. Gani, Advanced Process Simulation, Lecture notes, Institutet for kemiteknik, DTU, Lyngby, 1995.
• Teknologiorientert etterutdanning i NTNU, Forslag til strategier og tiltak 1996 - 2006, T. Hertzberg ansvarlig, KEVU, NTH, 1995
• H. I. Moe og T. Hertzberg, Modellering og Simulering av Dynamikk i Prosessanlegg, Lecture notes, PROST - Institutt for kjemiteknikk, NTH, 1995