Computational study of particle distribution development in a cold-flow laboratory scale downer reactor

Keywords: Downer reactor, FCC, two-phase flow, CFD, flow development

Abstract

The use of downer reactors (gas-solid co-current downward flow) in the Fluid Catalytic cracking (FCC) process for the upgrading of heavy crude oil into more valuable products has gradually become more common in the last decades. This kind of reactor is characterized by having homogeneous axial and radial flow structures, no back mixing, and shorter residence times as compared with the riser reactor type. Although downer reactors were introduced a long time ago, available information in literature about the multiphase hydrodynamic behavior at FCC industrial scale is scarce. Therefore, it is necessary to conduct experimental and computational studies to enhance the understanding of the hydrodynamics of two-phase co-current downward flow. The Computational Fluids Dynamics (CFD) software, Ansys Fluent, is used to study two-dimensional gas (air) and solid (catalyst particle) flow in a downer section of a cold-flow circulation fluidized bed (CFB) system at a laboratory scale. The implemented computational model is validated by comparing numerical results for solid velocity and volume fraction with measurements carried out on a CFB system using a fiber-optic probe laser velocimeter. According to numerical results obtained for different gas velocity and solid flux, flow development cannot only be estimated by considering solid axial velocity changes along the reactor; it is also necessary to take into account solid volume fraction axial variations as radial profiles can change even when velocity profiles are developed.

References

Corma, A. & Sauvanaud, L. (2013). FCC testing at bench scale: New units, new processes, new feeds. Catalysis Today, 218(107-114). https://doi.org/10.1016/j.cattod.2013.03.038

Pavol, H. (2011). FCC catalyst - Key element in refinery technology. In 45th International Petroleum Conference, Bratislava.

Kalota, S. A. & Rahmim, I. I. (2003). Solve the Five Most Common FCC Problems. In AIChE Spring National Meeting. San Francisco.

McCarthy, S., Raterman, M. & Smalley, C. (1997). FCC technology upgrades: a commercial example. In NPRA Meeting. Washington.

Wolschlag, L. M. & Couch, K. A. (2010). Upgrade FCC performance-Part 1. Hydrocarbon Processing 89(9), 57-65.

Martinez-Cruz, F. L., Navas-Guzman, G. & Osorio-Suarez, J. P. (2009). Prediction of the FCC feedstocks crackability. CT&F-Ciencia, Tecnología y Futuro, 3(125-142).

Zhu, J., Yu, Z., Jin, Y., Grace, J. & Issangya A. (1995). Cocurrent down flow circulating fluidized bed (downer) reactors: a state of the art review, The Canadian Journal of chemical engineering, 73 (5), 662-667. doi: https://doi.org/10.1002/cjce.5450730510.

Kim, S. W., Kim, G. R., Shin, J. W., Yoo, I. S., Kang, H. S. & Park, S. H. (2010). Fluidization technology for stable startup of commercial FCC unit. In the 13th International Conference on Fluidization - New Paradigm in Fluidization engineering. Gyeong-ju.

Sinclair, J. L. & Jackson, R. (1989). Gas-particle flow in a vertical pipe with particle-particle interactions. AIChE Journal, 35(9), 1473-1486. https://doi.org/10.1002/aic.690350908

Ropelato, K., Meier, H. F. & Cremasco, M. A. (2005). CFD study of gas solid behavior in downer reactors: An Eulerian Eulerian approach, Powder Technology, 154(2-3), 179-184. https://doi.org/10.1016/j.powtec.2005.05.005.

Peng, G., Dong, P., Li, Z., Wang, J. & Lin, W. (2013). Eulerian simulation of gas solid ow in a countercurrent downer, Chemical Engineering Journal, 230(1), 406-414. https://doi.org/10.1016/j.cej.2013.06.108.

Zhao, Y., Cheng, Y., Ding, Y. & Jin, Y. (2007). Understanding the hydrodynamics in a two- dimensional downer by CFD-DEM simulation. In The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering, Vancouver, Canada.

Zhao, T., Liu, K., Cui, Y. & Takei, M. (2010). Three-dimensional simulation of the particle distribution in a downer using CFD DEM and comparison with the results of ECT experiments, Advanced Powder Technology, 21(6), 630-640, https://doi.org/10.1016/j.apt.2010.06.009.

Zhao, T. , Takei, M. & Doh, D.-H. (2010). ECT measurement and CFD DEM simulation of particle distribution in a down flow fluidized bed, Flow Measurement and Instrumentation, 21(3), 212-218, https://doi.org/10.1016/j.flowmeasinst.2009.12.008.

Taghipour, F., Ellis, N. & Wong, C. (2005). Experimental and computational study of gas solid fluidized bed hydrodynamics, Chemical Engineering Science, 60(24), 6857-6867, https://doi.org/10.1016/j.ces.2005.05.044.

Lun, C. K. K., Savage, S. B., Jeffrey, D. J. & Chepurniy, N. (1984). Kinetic theories for granular flow: inelastic particles in Couette flow and slightly inelastic particles in a general flow field, Journal of Fluid Mechanics, 140(1), 223-256, https://doi.org/10.1017/S0022112084000586.

Syamlal, M. & O'Brien, T. (1989). Computer simulation of bubbles in a fluidized bed. In AIChE. Symposium series, 85(1), 22-31. Publ by AIChE.

Wen C. Y. & YU H. (1966). Mechanics of fluidization. In Chemical Engineering Progress Symposium Series, 62(1), 100-111.

Gidaspow, D., Bezburuah, R. & Ding, J. (1992). Hydrodynamics of circulating fluidized beds, kinetic theory approach, In Fluidization VII, 7th engineering foundation conference on fluidization, Brisbane, Australia.

Cheng, Y., Guo, Y., Wei, F., Jin, Y. & Lin, W. (1999). Modeling the hydrodynamics of downer reactors based on kinetic theory, Chemical Engineering Science, 54(13-14), 2019-2027. https://doi.org/10.1016/S0009-2509(98)00293-0.

Chalermsinsuwan, B., Chanchuey, T., Buakhao, W., Gidaspow, D. & Piumsomboon, P. (2012). Computational fluid dynamics of circulating fluidized bed downer: Study of modeling parameters and system hydrodynamic characteristics, Chemical Engineering Journal, 189-190(1), 314-335. https://doi.org/10.1016/j.cej.2012.02.020.

Zimmermann, S. & Taghipour F. (2005). CFD modeling of the hydrodynamics and reaction kinetics of FCC fluidized-bed reactors, Industrial & engineering chemistry, 44(26), 9818-9827. https://doi.org/10.1021/ie050490.

Simonin, O. & Viollet, P.L. (1990). Prediction of an oxygen droplet pulverization in a compressible subsonic coflowing hydrogen flow, American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED, 91, 73-82

Johnson, P. C. & Jackson, R. (1987). Frictional Collisional constitutive relations for granular materials, with application to plane shearing, Journal of Fluid Mechanics, 176(1), 67-93. https://doi.org/10.1017/S0022112087000570.

Wang, Z., Bai, D. & Jin, Y. (1992). Hydrodynamics of cocurrent dowflow circulating fluidized bed (CDCFB), Powder Technology, 70(3), 271-275. https://doi.org/10.1016/0032-5910(92)80062-2.

Zhu, J.-X., Ma, Y. & Zhang, H. (1999). Gas Solids Contact Efficiency in the Entrance Region of a CoCurrent Downflow Fluidized Bed (Downer), Chemical Engineering Research and Design, 77((2), 151-158. https://doi.org/10.1205/026387699525909.

Zhang, H. & Zhu, J. (2000). Hydrodynamics in downflow fluidized beds (2):particle velocity and solids flux profiles, Chemical engineering science, 55(19), 4367-4377. https://doi.org/10.1016/S0009-2509(00)00087-7.

Lehner, P. & Wirth, K. E. (1999). Effects of the gas solid distributor on the local and overall Solids Distribution in a Downer Reactor, The Canadian Journal of Chemical Engineering, 77(4), 199-206. https://doi.org/10.1002/cjce.5450770203.

Nova, S., Krol, S. & de Lasa, H. (2004). Particle velocity and particle clustering in down flow reactors, Powder Technology, 148(2-3), 172-185. https://doi.org/10.1016/j.powtec.2004.09.008.

Qi, X.-B., Zhang, H. & Zhu, J. (2008). Friction between gas solid flow and circulating fluidized bed downer wall, Chemical Engineering Journal, 142(3), 318-326. https://doi.org/10.1016/j.cej.2008.03.009.

Qi, X.-B., Zhang, H. & Zhu, J. (2008). Solids concentration in the fully developed region of circulating fluidized bed downers, Powder Technology, 183(3), 417-425. https://doi.org/10.1016/j.powtec.2008.01.018.

Wang, C., Li, C. & Zhu, J. (2015). Axial solids flow structure in a high density gas solids circulating fluidized bed downer, Powder Technology, 272(1), 153-164, https://doi.org/10.1016/j.powtec.2014.11.041.

Geldart, D. & Baeyens, J. (1985). The design of distributors for gas-fluidized beds, Powder Technology, 42(1), 67-78, https://doi.org/10.1016/0032-5910(85)80039-5.

Gálvis Arroyave, J. L. (2018), Sistema de monitoreo portable y sonda híbrida a fibra óptica en el infrarrojo cercano para las medidas de velocidad y concentración de sólidos dentro de un reactor tipo downer. Trabajo de grado, Maestría en Ciencias Físicas, Universidad Nacional de Colombia, Medellín.

López, T., Bustamante, C. A. & Nieto-Londoño, C. (2015). Hydrodynamic study of gas particle interaction in an FCC downer reactor, In 25th CANCAM Canadian Congress of Applied Mechanics, London, Ontario.

Gómez-Velásquez, N., López-Montoya, T., Bustamante-Chaverra, C.A., & Nieto-Londoño, C. (2021). Parametric study of particles homogenization in cold-flow riser reactors, International Journal of Thermofluids, 9, 100058, https://doi.org/10.1016/j.ijft.2020.100058.

Herbert, P.M., Gauthier, T. A., Briens, C. L. & Bergougnou, M. A. (1994). Application of fiber optic reflection probes to the measurement of local particle velocity and concentration in gas-solid flow, Powder Technology, 80(3), 243-252. https://doi.org/10.1016/0032-5910(94)02859-1.

How to Cite
López-Montoya, T., Bustamante, C. A., Nieto-Londoño, C., & Gómez-Velásquez, N. (2021). Computational study of particle distribution development in a cold-flow laboratory scale downer reactor. CT&F - Ciencia, Tecnología Y Futuro, 11(1), 33–46. https://doi.org/10.29047/01225383.172

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Published
2021-06-30
Section
Scientific and Technological Research Articles

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