Conversion and Residence Time Calculation for Gas-solid Solid Reactions of the Cylindrical-shaped Particles with Con-stant Size Using the Shrinking Core Model

Document Type: paper

Authors

Department of Chemical Engineering, Oil and Gas, Shiraz University of Technology

Abstract

In this paper, a mathematical model is developed to calculate the conversion and the residence time reaction for plug flow and mixed flow in the reactors filled with cylin-drical particles using the shrinking core model. In this modeling, the size of the particles is un-chamged during the reaction. Also, the reaction rate is controlled by the gas layer resistance, the ash layer resistance, and the reaction resistance as well as the combination of them. In addition, it is assumed that the gas diffuses radially from the side, whereas the effect of diffusion in the axial direction is neglected. Equations are solved by numerical methods. It can be said that the innovation of this paper is the study of the effect of combination of resistances on the conversion of the reaction. Model evaluation shows that the results of modeling have a good consistency with the experimental data. The results show that at a certain time, when the rate of reaction is controlled by each of the resistances individually, the conversion rate is greater when the reaction is controlled by the ash layer resistance than when it is controlled by the other two resistance regimes. Finally, the effect of the combination of different controlling regimes on the conversion and residence time of reaction for plug flow and mixed flow of particles is studied and it is found that the overall results are similar to each other.

Keywords


[1] Levenspiel, O. (1999). "Chemical Reaction Engineering." Third Edition, John Wiley & Sons, New York.

[2] Gbor, P. K., Jia, C. Q. (2004). "Critical evaluation of coupling particle size distribution with the shrinking core model." Chemical Engineering Science, Vol. 59, pp. 1979-1987.

[3] Noorman, S., Gallucci, F., Annaland, V.S.M., Kuipers, J.A.M. (2011). "A theoretical investigation of CLC in packed beds. Part 1: Particle model." Chemical Engineering Journal, Vol. 167, pp. 297-307.

[4] Tsinontides, S. C., Jackson, R. (1993). "The mechanics of gas fluidized beds with an interval of stable fluidization.” Journal Fluid Mechanic , Vol. 255, pp. 231-214.

[5] Fan, L.S. (1989). "Gas-Liquid-Solid Fluidization Engineering." Butterworths, Stoneham, MA, 1989.

[6] Ebrahimi, A.A., Ebrahim, H.A., Jamshidi, E. (2008). "Solving partial differential equations of gas–solid reactions by orthogonal collocation." Computers and Chemical Engineering, Vol. 32, pp.1746–1759.

[7] Movagarnejad, K., Sohrabi, M., Kaghazchi, T., Vahabzadeh, F. (2000). ''A model for the rate of enzymatic hydrolysis of cellulose in heterogeneous solid-liquid systems.''  Biochemical Engineering Journal, Vol. 4, pp. 197206.

[8] Yagi, S., Kunii, D. (1995). "Studies on combustion of carbon particles in flames and fluidized beds." The 5th Symposium on Combustion, New York, USA, pp. 231-236.

[9] Sleekly, J., Evans, J.W., Sohn, H.Y. (1976). "Gas-solid reactions." AcademicPress.

[10] Schmidt, L. D. (1998). "The Engineering of  Chemical Reactions." New York: Oxford University Press.

[11] Abad, A.,  Adanez, J., Cuadrat, A., Garcia – Labiano, F., Gayan, P., de Diego, L.F. (2011).  "Kinetics of redox reactions of ilmenite for chemical-looping combustion."  Chemical Engineering Science, Vol. 66, pp. 689 -702.

[12] Amiri, A., Ingram, G.D., Bekker, A.V., Livk, I.,  Maynard, N.E. (2013). "A multi-stage, multi-reaction shrinking core model for selfinhibiting gas-solid reactions."  Adv. Powder Technol., Vol. 24, pp. 728 -736.

[13] Gbor, P. K., Jia, C.Q. (2004). "Critical evaluation  of coupling particle size distribution with the shrinking core model." Chemical Engineering Science, Vol. 59, pp. 1979 -1987.

[14] Kruggel -Emden, H., Rickelt, S., Stepanek, F.  (2010). "Development and testing of an inter-connected multiphase CFD -model for chemical looping combustion."  Chemical  Engineering  Science, Vol. 65, pp. 4732-4745.

[15] Kruggel-Emden, H., Stepanek, F. (2011). "A  study on the role of reaction modeling in Multiphase CFD- based simulations of Chemical Looping Combustion." Oil and Gas Science and Technology, Vol. 66, pp. 313-331.

[16] Parisi, D.R., Laborde, M.A. (2004). "Modeling of counter-current moving bed gas-solid reactor used in the direct reduction of iron ore." Chemical Engineering  Journal , Vol. 104, pp.  35-43.

[17] Rodriguez F.,  Revenga J.,  Tijero J.  (1996).  ''Study of anthraquinone reaction with sodium sulfide. ''  The Chemical Engineering Journal and the Biochemical Engineering Journal , Vol. 63,  pp.  37-43.