Prediction of concentration and temperature profiles for non-isothermal ethane cracking in a pipe reactor

Rajeev Kumar Garg; Venkatesan Venkat Krishnan; Vinod Kumar Srivastava

Korean Journal of Chemical Engineering, Vol.23, No.4, 531-539, July, 2006

DOI10.1007/BF02706790 Export Citation

Prediction of concentration and temperature profiles for non-isothermal ethane cracking in a pipe reactor

Rajeev Kumar Garg, Venkatesan Venkat Krishnan, and Vinod Kumar Srivastava^†

Department of Chemical Engineering, Indian Institute of Technology, Hauz Khas, New Delhi-110016, India

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Thermal crackers are mostly modeled as plug flow systems, disregarding the lateral gradients present. In this paper, a 2-dimensional model has been established for ethane cracking in a thermal cracker in laminar flow, using a molecular mechanistic model for ethane cracking. The model, consisting of 9-coupled partial differential equations, is solved using the backward implicit numerical scheme. The resulting product distribution and temperature profiles are predicted throughout the reactor. The concentrations of acetylene and propylene show a maximum within the reactor. The effect of certain operational parameters - tube radius, wall temperature and mass flow rate - is also studied on these profiles. The parameters are varied in the range of 0.005-0.0125 m for tube radius, 1.25 kg/hr-2.5 kg/hr for mass flow rate and 850-1,050 °C for tube wall temperature. It is observed that an increase in wall temperature and an increase in tube radius or decrease in flow rate favours the conversion of ethane.

Keywords:Thermal Cracker;Pipe Reactor;Coupled Partial Differential Equations;2-Dimensional Modeling;Operational Parameters

[References]

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[2] Edwin EH, Balchen JG, Chem. Eng. Sci., 56(3), 989 (2001)

[3] Maciel R, Sugaya MF, Comput. Chem. Eng., 25(4-6), 683 (2001)

[4] Froment GF, Chem. Eng. Sci., 47, 2163 (1992)

[5] Geankoplis CJ, Transport processes and unit operations, Prentice Hall of India, New Delhi, 3rd Ed (1997)

[6] HOLMEN A, OLSVIK O, ROKSTAD OA, Fuel Process. Technol., 42(2), 249 (1995)

[7] Moringiu A, Faravelli T, Bozzano G, Dente M, Ranzi E, J. Anal. Appl. Pyrolysis, 70, 519 (2003)

[8] Niaei A, Towfighi J, Sadrameli SM, Karimzadeh R, Appl. Therm. Eng., 24, 2251 (2004)

[9] Pant KK, Kunzru D, J. Anal. Appl. Pyrolysis, 36, 103 (1996)

[10] Pareek V, Srivastava VK, Adesina AA, Korean J. Chem. Eng., 20(2), 328 (2003)

[11] Perry RH, Green DW, Perry’s chemical Engineers’ handbook, 7th Ed., Mc Graw Hill (1998)

[12] Ramana Rao MV, Pliehers PM, Froment GF, Chem. Eng. Sci., 43, 1223 (1988)

[13] Srivastava VK, The thermal cracking of benzene in a pipe reactor, Ph.D. Thesis, University of Wales, Swansea, U.K. (1983)

[14] Sundaram KM, Froment GF, Chem. Eng. Sci., 34, 117 (1979)

[15] Sundaram KM, Froment GF, Chem. Eng. Sci., 35, 364 (1980)

[16] Sundaram KM, Froment GF, Chem. Eng. Sci., 32, 601 (1977)

[17] Xu Q, Chen B, He X, Hydrocarb. Process., 81, 65 (2002)

[18] Yaws CL, Chemical properties handbook: physical, thermodynamic, environmental, McGraw Hill, NY (1999)