A Simplified Model for Particle Internal Temperature Calculation in Fluidized Bed

Abstract:

Thermal mechanism analysis of heat exchange between a gas phase flow and the internal region of a particulate is still a subject of interest among researchers, mainly due to its complexity and lack of a simplified (in terms of computational effort) solution. Main goal of present work is to develop a simplified model capable of predict internal particle temperature, as a function of its surface temperature and flow conditions, in a fluidized bed, transporting spherical particles. Proposed model was implemented in C++ programming language and an algorithm was developed to solve two energy equations, for gas and particulate phases, and an algebraic equation to determine internal particle temperature. As a result, predicted particle temperature decreases while gas temperature rises. At approximate 12 m, both temperatures reach the equilibrium at 755 K which remains unaltered up to the riser outlet section. Energy balance verification, between inlet and outlet riser sections, showed that proposed model and balance calculated temperatures agree with a difference of 1.804E−11 kW on the outlet. In terms of internal particle temperature, results showed that it remains higher than surface temperature from riser entrance up to approximated 32.8 m. After this point it reaches surface temperature, which already is in equilibrium with the gas phase temperature.

• Periodical: Defect and Diffusion Forum (Volume 396)
• Pages: 135-144
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.396.135
• Online since: August 2019
• Authors: Rafael Ferreira*, Jeferson Avila Souza, Rodrigo Davesac
• Keywords: Fluidized-Bed, Heat-Transfer, Multiphase-Flow, Transient-Condution

References

[1] Taitel, Y., Bornea, D., & Dukler, A. (1980). Modelling flow pattern transitions for steady upward gas-liquid flow in vertical tubes. AIChE Journal, 26(3), 345-354.

DOI: 10.1002/aic.690260304

[2] Romero Luna, C. M. (2009). Análise e demonstração do comportamento do escoamento bifásico gás-sólido.

[3] Georg, I. C., et Al.(2005). Modelagem e simulação numérica tridimensional transiente do escoamento gás-sólido em um reator de craqueamento catalítico em leito fluidizado.

DOI: 10.11606/t.18.2003.tde-21102015-123706

[4] Li, H., Shen, B., Kabalu, J., & Nchare, M. (2009). Enhancing the production of biofuels from cottonseed oil by fixed-fluidized bed catalytic cracking. Renewable Energy,34(4), 1033-1039.

DOI: 10.1016/j.renene.2008.08.004

[5] Adjaye, J. D., & Bakhshi, N. (1995). Production of hydrocarbons by catalytic upgrading of a fast pyrolysis bio-oil. Part I: Conversion over various catalysts. Fuel Processing Technology, 45(3), 161-183.

DOI: 10.1016/0378-3820(95)00034-5

[6] Thomas, J. M., & Thomas, W. J. (2014). Principles and practice of heterogeneous catalysis. John Wiley & Sons.

[7] Souza, J. (2004). Simulação numérica e otimização termodinâmica de risers de fcc para a máxima produção de combustíveis. 191f (Unpublished doctoral dissertation). Tese (Doutorado em Energia e Ciências Térmicas) - Programa de Pós-Graduação em Engenharia de Materiais e Processos - PIPE, Universidade Federal do Paraná, Curitiba.

DOI: 10.18605/2175-7275/cereus.v10n2p12-25

[8] Incropera, F. P., DeWitt, D. P., & Bergman, T. L. (2000). Fundamentals of Heat and Mass Transfer.