Issue
Korean Journal of Chemical Engineering,
Vol.23, No.4, 531-539, 2006
Prediction of concentration and temperature profiles for non-isothermal ethane cracking in a pipe reactor
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.
[References]
  1. Bockhorn H, Hornung A, Hornung U, Jakobstroer P, Kraus M, J. Anal. Appl. Pyrolysis, 49, 97, 1999
  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