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The Effects of Baffles and Gas Superficial Velocity on a Bubble Fluidized Bed Reactor's Applications

Document Type : Research Paper

Authors

Abstract

Baffles are used for decreasing bubbles diameter in order to increase the conversion rate along the bubbling fluidized bed reactors. The appearance of this phenomenon is due to bursting of the bubbles during the pass of bubbles from baffles. In this work, a computerized modeling and simulation have been performed in order to obtain a fundamental knowledge of the influence of the baffles on the bubble diameter and the specific mass transfer area. The height of the bed is 5m and its diameter is 0.3m. Paffles are located at 1 and 2m from the bottom of the bed. A two phase model together with a comprehensive fluid dynamical description of bubbling fluidized is presented. The effects of baffles and gas superficial velocity on the operating behavior of fluidized bed reactors are considered. The results are compared to the previously reported documents, and the experiments which have been carried out. MATLAB software is used in this simulation.

Highlights

  1. 1.    C.E. Jahning, D.L. Campbell, H.Z. Martin, Fluidization, (3rd edition, 3 Plenum Press, New York (1980).

 

  1. 2.    J.G. Yates, “Fundamentals of fluidized-bed chemical processes,” Thetford Press (1983).

 

  1. 3.    Zenz, “Encyclopedia of chemical technology,” 3rd Ed, 10, 548, Kirk Othmer (1978).

 

  1. 4.    J.F. Davidson, R. Clift, D.Harricson, (Eds), Fluidization, 2nd Edition, Academic Press, London (1985).

 

  1. 5.    J.R. Johnson, J.J. Grace, Graham, Fluidized-bed reactor model verification on a reactor of industrial scale, AIChE J, 33, 619-627 (1986).

 

  1. 6.    M. Pell, Gas fluidization, Elsevier, Amsterdam (1990).

 

  1. 7.    D. Kunni, O. Levenspiel, Fluidization engineering, 2nd Edition, Boston, MA (1991).

 

  1. 8.    N. Mostoufi, H. Cui, J. Chaouki, A Comparison of two and single-phase models for fluidized-bed reactors, Ind. Eng. Chem. Res, 40, 5526-5532 (2001).

 

  1. 9.    M. Aoyagi, D. Kunii, Importance of dispersed solids in bubbles for exothermic reactions in fluidized beds. Chem. Eng. Commun, 1, 191 (1974).

 

  1. 10.              C. Guenther and M. Syamlal, “The effect of numerical diffusion on isolated bubbles in a gas-solids fluidized bed,” Powder Technology, 116, 142-154 (2001).

 

  1. 11.              A.M.S. Costa and M.L. de Souza-Santos, “A novel mechanism for bubble formation in fluidized systems: the effects of granular temperature on the stability in fluidization,” Brazilian Journal of Chemical Engineering, 21, No. 03, 479-486, July-September (2004).

 

  1. 12.              A. Kumar and G.K. Roy, “Effect of co-axial rod, disk and blade type promoters on bed fluctuation in a gas-solid fluidized bed with varying distributor open area,” Journal of The Institution of Engineers (India), 82, pt CH2, March 61 (2002).

 

 

  1. 13.              G.K.     Batchelor, J.M. Nitsche, “Explosion of particles from a buoyant blob in a gas fluidized bed,” J. Fluid Mech, 278, 63 (1994).

 

  1. 14.              M.A. Gilbertson, J.G. Yates, “The motion of particles near a bubble in a gas fluidized-bed,” J. Fluid Mech, 323, 377 (1996).

 

  1. 15.              A.A. Ghorbanpour, M.Ghanadi, M. Kolahian, “Modeling and simulation for production of maleic anhydride from n-butane in a bubble fluidized bed reactor with and without baffles,” ISMR3 (Symposium), Bath University, Bath, England, 142-145 (27-30 August 2003).

 

  1. 16.              N. Mostoufi, J. Chaouki, “On the axial movement of solids in gas-solid fluidized beds,” Trans. Inst. Chem. Eng. A, 78, 911 (2000).

 

  1. 17.              A.A. Ghorbanpour, M.Ghanndi, “The effects of bed height on bubble diameter and mass transfer area in a bubbling fluidized bed risers,” (Iranian) Journal of Nuclear Science and Technology (Persian), 28, 19-22 (2003).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. 18.              S. Todd, Pugsley, G.S. Patience, F. Berruti, J. Chaouki, “Modeling the catalytic oxidation of n-butane to maleic anhydride in a circulating fluidized bed reactor,” Ind. Eng.  Chem. Res, 31, 2652-2660 (1992).

 

19. L.M. Thompson, H. Bi, J.R. Grace “Ageneralized bubbling/turbulent fluidized-bed reactor model. Chem. Eng. Sci, 54, 5175 (1999).

 

  1. 20.              J.          Wherther, Chem. Eng. Sci, 47 (9-11), 2475-2462 (1992).

 

  1. 21.              D.        Geldart, “Types of gas fluidization,” Powder Technol, 7, 285-292 (1973).

 

22. J.F. Davidson, D. Harrison, “Fluidized particles,” Cambridge University Press, New York (1963).

 

Keywords

References
  1. 1.    C.E. Jahning, D.L. Campbell, H.Z. Martin, Fluidization, (3rd edition, 3 Plenum Press, New York (1980).

 

  1. 2.    J.G. Yates, “Fundamentals of fluidized-bed chemical processes,” Thetford Press (1983).

 

  1. 3.    Zenz, “Encyclopedia of chemical technology,” 3rd Ed, 10, 548, Kirk Othmer (1978).

 

  1. 4.    J.F. Davidson, R. Clift, D.Harricson, (Eds), Fluidization, 2nd Edition, Academic Press, London (1985).

 

  1. 5.    J.R. Johnson, J.J. Grace, Graham, Fluidized-bed reactor model verification on a reactor of industrial scale, AIChE J, 33, 619-627 (1986).

 

  1. 6.    M. Pell, Gas fluidization, Elsevier, Amsterdam (1990).

 

  1. 7.    D. Kunni, O. Levenspiel, Fluidization engineering, 2nd Edition, Boston, MA (1991).

 

  1. 8.    N. Mostoufi, H. Cui, J. Chaouki, A Comparison of two and single-phase models for fluidized-bed reactors, Ind. Eng. Chem. Res, 40, 5526-5532 (2001).

 

  1. 9.    M. Aoyagi, D. Kunii, Importance of dispersed solids in bubbles for exothermic reactions in fluidized beds. Chem. Eng. Commun, 1, 191 (1974).

 

  1. 10.              C. Guenther and M. Syamlal, “The effect of numerical diffusion on isolated bubbles in a gas-solids fluidized bed,” Powder Technology, 116, 142-154 (2001).

 

  1. 11.              A.M.S. Costa and M.L. de Souza-Santos, “A novel mechanism for bubble formation in fluidized systems: the effects of granular temperature on the stability in fluidization,” Brazilian Journal of Chemical Engineering, 21, No. 03, 479-486, July-September (2004).

 

  1. 12.              A. Kumar and G.K. Roy, “Effect of co-axial rod, disk and blade type promoters on bed fluctuation in a gas-solid fluidized bed with varying distributor open area,” Journal of The Institution of Engineers (India), 82, pt CH2, March 61 (2002).

 

 

  1. 13.              G.K.     Batchelor, J.M. Nitsche, “Explosion of particles from a buoyant blob in a gas fluidized bed,” J. Fluid Mech, 278, 63 (1994).

 

  1. 14.              M.A. Gilbertson, J.G. Yates, “The motion of particles near a bubble in a gas fluidized-bed,” J. Fluid Mech, 323, 377 (1996).

 

  1. 15.              A.A. Ghorbanpour, M.Ghanadi, M. Kolahian, “Modeling and simulation for production of maleic anhydride from n-butane in a bubble fluidized bed reactor with and without baffles,” ISMR3 (Symposium), Bath University, Bath, England, 142-145 (27-30 August 2003).

 

  1. 16.              N. Mostoufi, J. Chaouki, “On the axial movement of solids in gas-solid fluidized beds,” Trans. Inst. Chem. Eng. A, 78, 911 (2000).

 

  1. 17.              A.A. Ghorbanpour, M.Ghanndi, “The effects of bed height on bubble diameter and mass transfer area in a bubbling fluidized bed risers,” (Iranian) Journal of Nuclear Science and Technology (Persian), 28, 19-22 (2003).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. 18.              S. Todd, Pugsley, G.S. Patience, F. Berruti, J. Chaouki, “Modeling the catalytic oxidation of n-butane to maleic anhydride in a circulating fluidized bed reactor,” Ind. Eng.  Chem. Res, 31, 2652-2660 (1992).

 

19. L.M. Thompson, H. Bi, J.R. Grace “Ageneralized bubbling/turbulent fluidized-bed reactor model. Chem. Eng. Sci, 54, 5175 (1999).

 

  1. 20.              J.          Wherther, Chem. Eng. Sci, 47 (9-11), 2475-2462 (1992).

 

  1. 21.              D.        Geldart, “Types of gas fluidization,” Powder Technol, 7, 285-292 (1973).

 

22. J.F. Davidson, D. Harrison, “Fluidized particles,” Cambridge University Press, New York (1963).

 

Journal of Nuclear Science, Engineering and Technology (JONSAT)
Volume 28, Issue 4 - Serial Number 42
March 2008
Pages 7-13
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