Numerical Study of Hydrodynamics of Tapered Fluidized Beds Using CFD-DEM

Document Type : Research Article

Authors

1 Department of Chemical Engineering, Ilam University, Ilam, I.R. IRAN

2 Department of Chemical Engineering, University of Sistan and Baluchestan, Zahedan, I.R. IRAN

Abstract

In the present study, the hydrodynamics of tapered fluidized beds (TFBs) for two types of particles, namely, Geldart D and Geldart B with mean diameters of 2 mm and 0.287 mm, respectively, were studied by CFD-DEM in 3D frameworks. The particles phase was simulated by dense discrete phase model (DDPM) in which the particle-particle collision was modeled by the discrete phase method (DEM). While the continuous phase (gas phase) was simulated by the Eulerian approach by considering k-ε turbulent model for this phase. The well-known drag model of Gidaspow was applied for computing the momentum exchange between the phases.  It was found that the bed pressure drop and the bed expansion ratio predicted by the proposed model were in close agreement with the corresponding measured data. By evaluating power spectral density in TFBs, it was found that the dominant frequency is about 2.3 Hz for a TFB which is quite different than that calculated in bubbling fluidized beds (BFBs).  Due to the fact that this study is one of the few Eulerian-Lagrangian works on TFBs, it can be a suitable basis for future studies in numerical simulation of TFBs.

Keywords

Main Subjects


[1] Sau D.C., Biswal K.C., Computational Fluid Dynamics and Experimental Study of the Hydrodynamics of Gas-Solid Tapered Fluidized Bed, Appl. Math. Model., 35:2265–2278 (2011).
[2] Shi Y.F., Yu Y.S., Fan L.T., Incipient Fluidization Condition for a Tapered Fluidized Bed, Ind. Eng. Chem. Fundam., 23:484–489 (1984).
[3] Peng Y., Fan L.T., Hydrodynamic Characteristics of Fluidization in Liquid-Solid Tapered Beds, Chem. Eng. Sci., 52:2277–2290 (1997).
[4] Depypere F., Pieters J.G., Dewettinck K., Expanded Bed Height Determination in a Tapered Fluidized Bed Reactor, J. Food Eng., 67:353–359 (2005).
[6] Kim H.G., Lee I.O., Chung U.C., Kim Y.H., Fluidization Characteristics of Iron ore Fines of Wide Size Distribution in a Cold Tapered Gas-Solid Fluidized Bed, ISIJ Int., 40:16–22 (2000).
[7] Schaafsma S.H., Marx T., Hoffmann A.C., Investigation of the Particle Flow Pattern and Segregation in Tapered Fluidized Bed Granulators, Chem. Eng. Sci., 61:4467–4475 (2006).
[8] Sau D.C., Mohanty S., Biswal K.C., Minimum Fluidization Velocities and Maximum Bed Pressure Drops for Gas-Solid Tapered Fluidized Beds, Chem. Eng. J., 132:151–157 (2007).
[10] Abdelmotalib H.M., Ko D.G., Im I.T., A Study on Wall-to-Bed Heat Transfer in a Conical fFluidized Bed Combustor. Appl. Therm. Eng. 99:928-937 (2016).
[12] Lun C.K.K., Savage S.B., Jeffrey D.J., Chepurniy N., Kinetic Theories for Granular Flow: Inelastic Particles in Couette Flow and Slightly Inelastic Particles in a General Flow Field, J. Fluid Mech., 140:223–256 (1984).
[13] Abdelmotalib H.M., Youssef M.A.M., Hassan A.A., Youn S.B., Im I.T., Influence of the Specularity Coefficient on Hydrodynamics and Heat Transfer in a Conical Fluidized Bed Combustor, Int. Commun. Heat Mass, 75:169–176 (2016).
[14] Abdelmotalib H.M., Im I.-T., Three Dimensional Modeling of Heat Transfer and Bed Flow in a Conical Fluidized Bed Reactor, Int. J. Heat Mass, 106:1335–1344 (2017).
[15] Lan X.Y., Xu C.M., Gao J.S., Al-Dahhan M., Influence of Solid-Phase Wall Boundary Condition on CFD Simulation of Spouted Beds, Chem. Eng. Sci., 69:419-430(2012).
[16] Taghipour F., Ellis N., Wong C., Experimental and Computational Study of Gas-Solid Fluidized Bed Hydrodynamics, Chem. Eng. Sci., 60:6857–6867 (2005).
[17] Hosseini S.H., Ahmadi G., Rahimi R., Zivdar M., Nasr Esfahany M., CFD Studies of Solids Hold-Up Distribution and Circulation Patterns in Gas-Solid Fluidized Beds, Powder Technol., 200: 202-215 (2010).
[19] Wang H., Lu Y., Numerical Simulation of Bubble Behavior in a Quasi-2D Fluidized Bed Using a Bubble-Based EMMS Model, Particuology (2019).
[20] Stewart P.S.B., Davidson J.F., Slug Flow in Fluidised Beds, Powder Technol. 1:61-80 (1967).
[21] Lettieri P., Saccone G., Cammarata L., Predicting the Transition from Bubbling to Slugging Fluidization Using Computational Fluid Dynamics, Chem. Eng. Res. Design, 8: 939-944 (2004).
[22] Baeyens, J. Geldart, D., An Investigation into Slugging Fluidized Beds, Chem. Eng. Sci., 29: 255–265 (1974).
[23] Zhang H., Liu M., Li T., Huang Z., Sun X., Bo H., Dong Y., Experimental Investigation on Gas-Solid Hydrodynamics of Coarse Particles in a Two-Dimensional Spouted Bed, Powder Technol., 307:175–183 (2017).
[24] Jang, J., Arastoopour, H., CFD Simulation of a Pharmaceutical Bubbling Bed Drying Process at Three Different Scales, Powder Technol., 263:14-25 (2014).
[25] Mahmoodi B., Hosseini S.H., Olazar M., Altzibar H., CFD-DEM Simulation of a Conical Spouted Bed with Open-Sided Draft Tube Containing Fine Particles, J. Taiwan Inst. Chem. E. 81: 275-287 (2017).