An Optimization Study on the Pyrolysis of Polystyrene in a Batch Reactor

Hyun-Seob Song; Jae Chun Hyun

Korean Journal of Chemical Engineering, Vol.16, No.3, 316-324, May, 1999

DOI10.1007/BF02707119 Export Citation

An Optimization Study on the Pyrolysis of Polystyrene in a Batch Reactor

Hyun-Seob Song, and Jae Chun Hyun^†

Department of Chemical Engineering, Korea University, Seoul, Korea

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The pyrolysis process of polystyrene (PS) has been investigated to find optimal temperature profiles which minimize the reaction time and the reaction energy required for a given conversion in a batch reactor. Assuming that the fragmentation of PS in pyrolysis is described by the mechanism of random and/or specific degradations we used a continuous kinetic model for solving three moment equations to determine the transient change of molecular weight distributions (MWD) of the polymers. We then converted this independent-variable minimization problem using a coordinate transformation to a dependent-variable minimization emblem that yields the optimal temperature profiles as its solution. The optimization results obtained in this study encompass the cases of different objective functions which cover minimum reaction time, minimum energy consumed, or any combination of these. It has turned out that maintaining the reaction temperature constant at an optimal level is the best solution in this optimization problem. An economic cost function also has been introduced as the third objective function to be minimized in addition to the reaction time and the reaction energy. This new function can serve as a convenient measure to judge the performance of the pyrolysis process minimizing the involved cost.

Keywords:Batch Reactor;Cost Minimization;Coordinate Transformation Objective Functions;Optimization Polymer Pyrolysis;Polystyrene (PS)

[References]

Flynn JH, Florin RE, "Degradation and Pyrolysis Mechanisms," Pyrolysis and GC in Polymer Analysis, Liebman, S.A. and Levy, E.J., Eds., Marcel Dekker, Inc., New York (1985)
Kaminsky W, "Pyrolysis of Polymers," Emerging Technologies in Plastics Recycling, Andrews, G.D. and Subramanian, P.M., Eds., American Chemical Society, Philadelphia, 60 (1992)
Kirk DE, "Optimal Control Theory: An Introduction," Prentice-Hall, London (1970)
Kwon YD, Evans LB, AIChE J., 21, 1158 (1975)
Madras G, McCoy BJ, AIChE J., 44(3), 647 (1998)
Madras G, Chung GY, Smith JM, Mccoy BJ, Ind. Eng. Chem. Res., 36(6), 2019 (1997)
Madras G, Smith JM, McCoy BJ, Polym. Degrad. Stabil., 58, 131 (1997)
Mccoy BJ, Madras G, AIChE J., 43(3), 802 (1997)
Odian G, "Principles of Polymerization," 3rd ed., Wiley-Interscience, New York (1991)
Rao SS, "Engineering Optimization: Theory and Practice," John Wiley & Sons, Inc., New York (1996)
Reklaitis GV, Ravindran A, Ragsdell KM, "Engineering Optimization: Methods and Applications," Wiley-Interscience, New York (1983)
Sato S, Murakata T, Baba S, Saito Y, Watanabe S, J. Appl. Polym. Sci., 40, 2065 (1990)
Song HS, Park YD, Hyun JC, Korean J. Chem. Eng., 13(4), 369 (1996)
Van Krevelen DW, "Properties of Polymers," 3rd ed., Elsevier, New York (1990)
Wang M, Smith JM, Mccoy BJ, AIChE J., 41(6), 1521 (1995)
Westerhout RW, Waanders J, Kuipers JA, Vanswaaij WP, Ind. Eng. Chem. Res., 36(6), 1955 (1997)

[Referenced By]

[1] Flynn JH, Florin RE, "Degradation and Pyrolysis Mechanisms," Pyrolysis and GC in Polymer Analysis, Liebman, S.A. and Levy, E.J., Eds., Marcel Dekker, Inc., New York (1985)

[2] Kaminsky W, "Pyrolysis of Polymers," Emerging Technologies in Plastics Recycling, Andrews, G.D. and Subramanian, P.M., Eds., American Chemical Society, Philadelphia, 60 (1992)

[3] Kirk DE, "Optimal Control Theory: An Introduction," Prentice-Hall, London (1970)

[4] Kwon YD, Evans LB, AIChE J., 21, 1158 (1975)

[5] Madras G, McCoy BJ, AIChE J., 44(3), 647 (1998)

[6] Madras G, Chung GY, Smith JM, Mccoy BJ, Ind. Eng. Chem. Res., 36(6), 2019 (1997)

[7] Madras G, Smith JM, McCoy BJ, Polym. Degrad. Stabil., 58, 131 (1997)

[8] Mccoy BJ, Madras G, AIChE J., 43(3), 802 (1997)

[9] Odian G, "Principles of Polymerization," 3rd ed., Wiley-Interscience, New York (1991)

[10] Rao SS, "Engineering Optimization: Theory and Practice," John Wiley & Sons, Inc., New York (1996)

[11] Reklaitis GV, Ravindran A, Ragsdell KM, "Engineering Optimization: Methods and Applications," Wiley-Interscience, New York (1983)

[12] Sato S, Murakata T, Baba S, Saito Y, Watanabe S, J. Appl. Polym. Sci., 40, 2065 (1990)

[13] Song HS, Park YD, Hyun JC, Korean J. Chem. Eng., 13(4), 369 (1996)

[14] Van Krevelen DW, "Properties of Polymers," 3rd ed., Elsevier, New York (1990)

[15] Wang M, Smith JM, Mccoy BJ, AIChE J., 41(6), 1521 (1995)

[16] Westerhout RW, Waanders J, Kuipers JA, Vanswaaij WP, Ind. Eng. Chem. Res., 36(6), 1955 (1997)