“Dynamic Optimization and Production Planning of Thermal Cracking Operation”

Authors: Emil H. Edwin and Jens G. Balchen,
Affiliation: Statoil and NTNU, Department of Engineering Cybernetics
Reference: 2003, Vol 24, No 2, pp. 99-113.

Keywords: Steam cracker, coke, dynamic simulation, modelling, economics, radiation

Abstract: This work addresses the dynamic optimization of the production period of thermal crackers with respect to coke formation in the cracking coil and transfer line exchanger. Optimal time dependent trajectories of feed rate, steam to hydrocarbon ratio, and reaction severity are calculated. The net earnings based on the price of hydrocarbons, kid, steam, decoking, and maintenance cost are maximized. All important operational constraints are included and the optimization problem is solved using parameterized free variable trajectories (piece wise constant) and a standard SQP package. Rigorous distributed physical models are used and calculation show that dynamic optimization gives up to 2( earnings - expenses) than conventional steady state optimization performed on the same models. This is in the same range as earnings reported from steady state optimization implementations alone.

PDF PDF (1756 Kb)        DOI: 10.4173/mic.2003.2.3

[1] DENTE, M. E. RANZI, E. M. (1983). Mathematical modelling of pyrolysis reactions, Industrial and Laboratory Pyrolysis. Chap. 7, Academic Press, New York.
[2] DENTE, M. E., RANZI, E. M., PIERUCCI, S. J., BUSSANI, G. M. MULLICK, S. (1990). Evolution of fundamental kinetic model for industrial applications of steam cracking processes, AIChE Annu. Meeting, Chicago.IL, November.
[3] DUNKLEMAN, J. J. ALBRIGHT, L. F. (1976). Pyrolysis of propane in tubular flow reactors constructed of different materials, Industrial and laboratory pyrolysis. ACS Symp. Series, Vol. 32, p. 261-273.
[4] EDWIN, E. H. (1994). Modeling, Model-based Control, and Optimization of Thermal Cracking and Ethylene Production. University of Trondheim, NTNU, Division of Engineering Cybernetics. Report No. 94-89 W.
[5] FROMENT, G. F., VAN DE STEENE, B.O. VAN DAMME, P. S. (1976). Thermal cracking of ethane and ethane propane mixtures, Ind. Eng. Chem. Proceaa. Dev., Vol. 15, No. 4.
[6] HOTTEL, H. C. SAROFIM, A. F. (1967). Radiative Transfer, McGraw-Hill.
[7] KOPINKE, F.D., ZIMMERMAN, G. NOWAK, S. (1988). On the mechanism of coke formation in steam cracking-conclusions from results obtained by tracer experiments, Carbon, Vol. 26, No. 2, p. 117-124 doi:10.1016/0008-6223(88)90027-9
[8] KOPINKE, F. D., ZIMMERMAN, G., REYNIERS, G. C. FROMENT, G. F. (1993). Relative rates of coke formation from hydrocarbons in steam cracking of naptha, 2. Paraffins, Naphthens, Mono-, Di-, and Cyclo-olefins, and Acetylenes. Ind. Eng. Chem. Res., Vol. 32, pp. 56-61 doi:10.1021/ie00013a009
[9] KRAFT, D. (1988). A software package for sequential quadratic programming, DFVLR Institiut für dynamik der flugsysteme. Oberpfaffenhofen.
[10] LAHAYE, J., BADIE, P. DUCRET, J. (1977). Mechanisms of carbon formation during steam cracking of hydrocarbons, Carbon, Vol. 15, pp. 87-93 doi:10.1016/0008-6223(77)90022-7
[11] MODEST, F. M. (1993). Radiative Heat Transfer, McGraw-Hill.
[12] ROSS, L. L. SHU, W. R. (1979). Computer Modelling of Hydrocarbon Pyrolysis for Olefin Production, Thermal Hydrocarbon Chemistry Advances in Chemistry Series, No. 183, Am. Chem. Soc.
[13] STANCATO, B. W., ALLSFORD, K. V., KIAYAMA, Y., MIYOSHI, T. KUWAJIMA, M. (1998). Analyzing the benefits of online optimization, 1998 Spring National Meeting 10. Ethylene Producers Conference, 9-13 March, New Orleans, Louisiana.
[14] TESNER, P. A. (1984). Kinetics of Pyrolytic carbon formation, Chem. Phys. Carbon, Vol. 19, p. 65.
[15] WILLEMS, P. A. FROMENT, G. F. (1988). Kinetic modelling of thermal cracking of hydrocarbons, 1. Calculation of frequency factors. Ind. Eng. Chem. Res., 1959-1966 doi:10.1021/ie00083a001
[16] WILLEMS, P. A. FROMENT, G. F. (1988). Kinetic modelling of thermal cracking of hydrocarbons, 2. Calculation of activation energies. Ind. Eng. Chem. Res., 1971-1977.

  title={{Dynamic Optimization and Production Planning of Thermal Cracking Operation}},
  author={Edwin, Emil H. and Balchen, Jens G.},
  journal={Modeling, Identification and Control},
  publisher={Norwegian Society of Automatic Control}