Experimental and Computational Fluid Dynamics Study of Dense

5102

Ind. Eng. Chem. Res. 2010, 49, 5102–5109

Experimental and Computational Fluid Dynamics Study of Dense-Phase, Transition Region, and Dilute-Phase Spouting Marcos A. S. Barrozo,*,†,‡ Claúdio R. Duarte,‡ Norman Epstein,† John R. Grace,† and C. Jim Lim† Department of Chemical and Biological Engineering, UniVersity of British Columbia, 2360 East Mall, VancouVer, Canada V6T 1Z3, and School of Chemical Engineering, Federal UniVersity of Uberlaˆndia, Bloco K - Santa Moˆnica, 38400-902, Uberlaˆndia, MG, Brazil

In this work, the transition between conventional dense-phase spouting and dilute-phase spouting is quantified and characterized on the basis of experimental particle velocity and bed voidage data, obtained with an optical fiber probe, as well as from the evolution of pressure with air velocity. The high gas velocities associated with the dilute-phase spouted bed (DSB) flow regime result in voidages exceeding 0.9 over the entire bed, with no discernible distinction between spout and annulus. The downward particle velocities for the DSB regime differ in magnitude from those in the dense-phase spouting regime. Computational fluid dynamics simulations using the Eulerian granular multiphase model show good agreement with experimental data for the three reproducible flow regimes: dense-phase spouting, transition regime, and dilute-phase spouting. 1. Introduction Spouted beds have been studied for many processes such as drying, coating, granulation, and pyrolysis.1-4 This technique is an alternative to fluidization for particulate solids too coarse for good fluidization. In addition to their ability to handle coarse particles, spouted beds have structural and cyclic flow patterns with effective fluid-solid contact. Gas-solids flow in a conventional spouted bed (CSB) can be divided into three regions: a spout at the center, where the gas and particles rise at high velocity and the particle concentration is low; a fountain zone, where particles rise to their highest positions and then rain back onto the surface of the annulus; and an annulus zone between the spout and the column wall where particles move slowly downward as a dense phase, with counter-current percolation of the fluid. Thus, a cyclic pattern of solids movement is established. The gas enters the column through an orifice and then flows upward quickly through the spout and more slowly through the interstices in the annulus zone. Despite the versatility of conventional spouted beds, there are situations in which the fluid-solid contact is unsatisfactory. Some applications need more vigorous contact; for example, when the solids are sticky and tend to fuse (e.g., in catalytic polymerization) or in fast reactions (e.g., ultrapyrolysis) with short residence time of the fluid phase.5 Some research on the drying of suspensions also indicates limitations of the CSB. A low particle circulation rate and the required long residence time reduce the drying efficiency and have an adverse effect on material properties, particularly for heat-sensitive products. In many cases, excessive accumulation of the suspended material causes bed blockage.6 Continued expansion of a shallow spouted bed can lead to a regime that has variously been dubbed as “jet spouted bed”5-7 or, more accurately, “dilute-phase spouting”,8 in contrast to conventional dense-phase spouting. The high gas velocities associated with this regime result in high voidages in the entire column, with little distinction between the spout and the annulus. * To whom correspondence should be addressed. Fax: 55-3432394188. E-mail: [email protected]; masbarrozo@ ufu.br. † University of British Columbia. ‡ Federal University of Uberlaˆndia.

In the case of sticky solids, a dilute-phase spouted bed (DSB), compared with the CSB, has the advantages of higher particle velocity and higher bed voidage. The modification of the bed geometry and the reduction of the static bed height result not only in greater gas-solid dilution, but also in shorter particle cycle times in dilute-phase spouting.9 Higher gas velocities in the DSB can also be an advantage for some drying process. Olazar et al.5 observed a transition regime between conventional and dilute-phase spouting. Hence, three flow regimes are of interest: (a) conventional spouting, (b) transition regime, and (c) dilute-phase spouting. Operations in dilute-phase spouting and in the transition regime are sensitive to the geometry of the equipment and to the particle diameter. The following ranges of the geometric parameters for stable operations in DSB and transition regimes have been suggested: • Cone included angle (γ): the angle must be between 28 and 45°.5 For smaller angles, mainly operating with small particles (ds < 2 mm), there is a mixing regime, without the cyclic movement characteristic of the spouting regime. For angles greater than 45°, a rotation phenomenon is produced in the gas circulation leading to bed instability.5 • Inlet diameter/particle diameter (Do/ds): Do/ds should be between 1 and 80. The lower limit corresponds to voidages of the order of 0.7, whereas the upper limit corresponds to voidages of 0.99 for DSB.5 • Static bed height/inlet diameter (Ho/Do): Ho/Do can be between 2 and 5.10 In conical columns of low static bed depth, a small cone angle (28-45°), and with inlet diameter/cone bottom diameter ratio (Do/Di) between 1/2 and 1, Olazar et al.11 proposed the following correlations for the minimum dense-phase spouting velocity (Uoms) and the minimum dilute-phase spouting velocity (Uomj): (Reo)ms ) 0.126Ar0.5(Db /Do)1.68[tan(γ/2)]-0.57

(1)

(Reo)mj ) 6.89Ar0.35(Db /Do)1.46[tan(γ/2)]-0.53

(2)

The spatial distributions of voidage and particle velocity are of great importance in applications of spouted beds. He et al.12 used a fiber-optic probe to measure the vertical particle velocity profiles in the spout, annulus, and fountain regions of a full-

10.1021/ie9004892 CCC: $40.75  2010 American Chemical Society Published on Web 07/02/2009

Ind. Eng. Chem. Res., Vol. 49, No. 11, 2010

5103

Figure 2. Schematic diagram of the optical fiber probe.30

2. Experimental Setup Figure 1. Schematic diagram of a spouted bed column and its main dimensions.

column conventional spouted bed. Benkrid and Caram13 adopted a fiber-optic technique to determine particle velocities in the annulus of a full column and concluded that there is plug flow in the upper part of the annulus, where particles in the annulus move vertically downward and radially inward. On the basis of optical fiber probes, Olazar’s group studied the particle velocity distribution14 and local voidage distribution15,16 of conical spouted beds of different geometries (cone angle and gas inlet diameter), for operation close to minimum conventional spouting. Most previous studies on the distribution of local voidage and particle velocity in spouted beds were carried out in conventional spouted beds (dense-phase spouting regime).12-16 Knowledge of particle velocity and voidage is also key to understanding the transition between the CSB and DSB. In addition to experimental work, computational fluid dynamics (CFD) studies have become popular recently. The two approaches used in simulating multiphase flows are the Eulerian-Lagrangian and the Eulerian-Eulerian. The first, which involves the balance of forces at work upon individual particles, requires considerable computational effort and is suitable for particle volume fractions less than 0.1. The Eulerian-Eulerian approach considers the dispersed particles as a continuous phase and is based on the equations of motion applied to each phase. Many recent studies of spouted bed hydrodynamics are based on CFD.17-28 These were carried out in conventional spouted beds (dense-phase regime). However, the CFD technique can also be important for understanding the transition between conventional and dilute-phase spouted beds and behavior in the higher-velocity flow regimes. In this work, particle velocity, bed voidage, and pressure drop evolution with increasing air velocity were determined experimentally in conventional dense-phase spouting and dilute-phase spouting, as well as in the transition regime between them. The Eulerian multiphase CFD model is used to simulate spouted bed fluid dynamics in these three flow regimes. The simulated results are then compared with the experimental data.

The particles in this study were glass beads of 1.16, 1.55, and 2.12 mm Sauter mean diameter, 2500 kg/m3 particle density, and sphericity of 1.0. For these particles, the loosely packed voidage was found to be 0.39. The experimental apparatus was similar to that used by Wang,29 with air from a compressor as the spouting gas. The air flow rate was determined by an orifice flow meter, and two pressure transducers measured the operating pressure upstream of the orifice and the pressure drop across the orifice. To investigate the axial variation of pressure drop, static pressure probes were installed in ports along the wall of the column. All signals from pressure transducers were logged into a computer via a data acquisition system. A schematic representation of the Plexiglas spouted bed column is shown in Figure 1. Its main dimensions were: cone included angle (γ) 45°, gas inlet orifice diameter (Do) 0.019 m, basal diameter (Di) 0.038 m, height of cone section (Hc) 0.50 m, and diameter of cylindrical section (Dc) 0.45 m. The pressure drop across the bed for each superficial air velocity was estimated by subtracting the grid pressure drop in the absence of a bed.5 Minimum spouting was determined by plotting spout pressure drop as a function of decreasing inlet air velocity. The point at which the spout collapses defined the minimum spouting air velocity. Once the dilute-phase regime was reached, it was found to remain stable with further increases in air velocity, with a constant pressure drop. Therefore, the minimum dilute-phase spouting velocity was determined from the same plot of pressure drop vs superficial air velocity, as the intersection between the constant pressure drop line (dilute phase) and the descending line (transition), as well as by visual observation. Particle velocity and local voidage were measured by an optical fiber probe. The optical fiber probe measurement system in the present work (particle velocity meter PV-4A) was obtained from the Institute of Process Engineering of the Chinese Academy of Sciences. It consists of a probe, a light source, two photomultipliers, and a high-speed data acquisition card connected to a computer. The probe contains three vertically aligned optical fiber bundles with the one in the middle as the light projector and the other two as light receivers. When a particle passes near the head of the probe, it reflects light emitted by the central bundle of fibers. The reflected light was collected in succession by the two fiber bundles located above and below,

5104


separated by an effective distance (De). The probe was 4 mm (Dprobe) in outside diameter. To eliminate the influence of the blind zone,29,30 a glass window was added in front of the probe tip. A schematic representation of the optical fiber probe is shown in Figure 2. By off-line cross-correlation of sampled signals from the two light receivers (A and B), the time delay (τ) can be obtained, and the particle velocity (Vs) can be calculated for a known De between the two light receivers (i.e., Vs ) De/τ). The effective distance between the light-projection and light-receiving fibers of the optical velocity probe was determined using a disk rotating at known angular velocity with particles glued to it.29 By off-line averaging of sampled signals from the two light receivers, the local voidage was also measured on the basis of pre-established calibration between the voidage and the amplitude of the signal. 3. CFD Simulations 3.1. Model. The granular Eulerian model is a complex multiphase model predicting granular flows, such as those in fluidized beds, spouted beds, risers, and other suspension systems.17,21-28,31-35 In this approach, the gas and solid particles are treated as interpenetrating continua and the concept of phase volume fractions representing the space occupied by each phase is adopted, so that the laws of conservation of mass and momentum are satisfied by both phases. Interphase momentum transfer between the gas and solid phases is one of the dominant terms in the gas-phase and solidphase momentum balances. Several correlations for calculating the momentum exchange coefficient for gas-solid systems are available in the literature. In the present work, the momentum exchange coefficient was based on the drag model of Giadspow et al.,36 which combines the Wen and Yu37 model for dilute conditions (ε > 0.8) and the Ergun38 equation for dense conditions (ε e 0.8). The constitutive equations for shear and bulk viscosities estimation are defined by the granular kinetic theory derived by Lun et al.,39 analogous to the kinetic theory of gases. The concepts of granular temperature and solids pressure are also utilized in this model. For this approach39 in the dilute part of the flow, grains fluctuate randomly; this form of viscous dissipation and stress is called kinetic stress. At higher concentrations, in addition to the previous dissipation form, grains can collide briefly, giving rise to further dissipation and stress, called collisional stress. At very high concentrations (>50% by volume), grains undergo long sliding and rubbing contacts, leading to a totally different form of dissipation and stress, called frictional stress. In the present work, the solids shear viscosity was calculated as proposed by Giadspow et al.36 The equation for solids bulk viscosity, which accounts for the resistance of the granular particles to compression and expansion, was calculated as defined by Lun et al.39 The basic idea underlying granular kinetic theory is that particles are in a state of continuous and chaotic restlessness within the fluid. On the basis of an analogy with a gas, a “granular temperature”, θs, of the solid phase is defined, proportional to the kinetic energy of the random motion of the particles. In the granular model, the pressure exerted on the containing wall by the particles and the transfer of momentum caused by particle streaming is calculated by a solids pressure. The solidpressure model40 is used to represent the interparticle forces produced by the particles settling on top of each other and to

Figure 3. Grid adopted in the CFD simulations.

ensure that the correct maximum packing limit of the settled layer is upheld. In the present work, the equation of Ogawa et al.41 was used to calculate the radial distribution function in the solid-pressure equation. 3.2. Simulation Conditions. The simulation strategy used by Duarte et al.17 was adopted in this work. The set of conservation and constitutive equations was solved by finite volume elements using Fluent 12.0.7 software. The following conditions were adopted in the simulations: • Axial symmetry was assumed. • The computational domain was discretized by 96 000 structured grid cells (as shown in Figure 3). • The SIMPLE algorithm was adopted for the pressurevelocity coupling. • The first-order upwind algorithm was adopted in the spatial discretization for momentum and volume fraction. • The inlet velocity was assumed to be uniform as the inlet boundary condition. • Atmospheric pressure was adopted as the outlet boundary condition. • The no-slip boundary condition was assumed on the wall for both gas and solids. • The particle-particle coefficient of restitution was taken as 0.9. • The solution was considered to have converged when the scaled residuals were less than 1 × 10-3 with a time step of 1 × 10-4 s. 4. Results and Discussion 4.1. Experimental Results. Pressure-Drop Evolution. Figure 4 shows the experimental pressure drop across the bed as a function of the superficial air velocity for four static bed heights: 22, 32, 52, and 82 mm for particles of 1.55-mm diameter. The


5105

Figure 7. Radial distributions of voidage at three levels for particles of ds ) 1.55 mm, Ho of 60 mm, and air velocity (Uo) of 7Uoms. Figure 4. Pressure drop across bed as a function of superficial air velocity for different static bed depths (ds ) 1.55 mm).

three reproducible spouted bed flow regimes can be recognized. Beyond the conventional spouting regime (a), on increasing the superficial air velocity, there was a decrease in pressure drop, over an extended transition regime (b) between conventional and dilute solids spouting in which solid flow characteristics were intermediate between those regimes, while maintaining the cyclic particle movement characteristic of conventional spouted beds. The transition developed until the spout and annular zones were no longer distinguishable, and the bed voidage became almost uniform, leading to a new situation that corresponds to a dilute-phase spouted bed (c). Once this flow

regime (c) was reached, the pressure drop remained constant with further increases in velocity.5 When our experimental data for 1.55-mm glass beads are compared with predictions of Olazar et al.’s11 correlations, the mean deviations between calculated and experimental data for minimum dense-phase and minimum dilute-phase spouting velocities are, respectively, +20.8 and +9.1%. For this particle size, the minimum dense-phase spouting velocity is overpredicted, and there is better agreement for the minimum dilutephase spouting velocity. For the 2.12-mm particles, there was better agreement in both cases, with the mean deviation between calculated and experimental data for minimum dense-phase spouting and minimum dilute-phase spouting velocities of +10.3 and +7.7%, respectively. Better prediction for larger particles

Figure 5. Radial distribution of local voidage at z ) 37 mm for particles of ds ) 1.16 mm and Ho of 62 mm.

Figure 6. Radial distribution of voidage at z ) 37 mm for particles of ds ) 1.55 mm and Ho of 52 mm.

5106


Figure 8. Radial distribution of particle velocity at z ) 37 mm for particles of ds ) 1.16 mm and Ho of 62 mm at four superficial air velocities.

Figure 9. Radial distribution of particle velocity at z ) 37 mm for particles of ds ) 1.55 mm and Ho of 52 mm at five superficial air velocities.

Figure 10. Experimental results compared with CFD predictions of radial distribution of voidage at z ) 37 mm for particles of ds ) 1.55 mm, Ho of 52 mm, and Uo ) 1.6Uoms (CSB).

Figure 11. Experimental results compared with CFD predictions of radial distribution of voidage at z ) 37 mm for particles of ds ) 1.16 mm, Ho of 62 mm, and Uo ) 3.0Uoms (transition regime).

by Olazar et al.’s11 correlations was also observed by Wang26 for the minimum dense-phase spouting velocity. Particle Velocity and Voidage. Figure 5 shows experimental data for radial distribution of voidage 37 mm above the base of the column, with particles of ds ) 1.16 mm and static bed height (Ho) of 62 mm, for four superficial air velocities, corresponding to 1.5, 3.0, 6.0, and 8.0 times the minimum dense-phase spouting velocity (Uoms). Figure 6 plots the distribution of voidage, at the same height (z ) 37 mm), for 1.55-mm particles and Ho of 52 mm with Uo/Uoms ) 1.6, 2.8, 4.2, 5.4, and 6.9. Figures 5 and 6 show radial distribution of voidage for the conventional spouting regime, Uo ) 1.5 × Uoms and 1.6 × Uoms, qualitatively similar to those reported in the literature.12,15,16 In this dense-phase spouting regime, there is a clear distinction between the annular and spout zones, with high voidage in the

spout zone and a sharp drop at the spout-annulus interface. In the annulus, where particles are in close contact with each other, the voidage is uniform and almost equal to the initial packed bed voidage. For the DSB regime conditions, it can be clearly seen in Figures 5 and 6 that the bed voidage differs radically from that in the CSB regime. High expansion of the bed creates a very dilute system with high bed voidage. In this dilute flow regime, the voidage in the annular region was similar to that in the spout zone (i.e., the boundaries between zones disappeared), and the bed voidage was almost uniform across the whole bed. In the transition flow regime, the voidages were higher than those for the conventional spouting regime, with the difference between the spout and annular zones decreasing with increasing air velocity (Figure 6).


Figure 12. Experimental results compared with CFD predictions of radial distribution of voidage at z ) 37 mm for particles of ds ) 1.55 mm, Ho of 52 mm, and Uo ) 4.2Uoms (transition regime).

Figure 13. Experimental results compared with CFD predictions of radial distribution of voidage at z ) 37 mm for particles of ds ) 1.16 mm, Ho of 62 mm, and Uo ) 8.0Uoms (dilute-phase regime).

Figure 14. Experimental results compared with CFD predictions of radial distribution of particle velocity at z ) 37 mm for particles of dp ) 1.55 mm, Ho of 52 mm, and Uo ) 1.6Uoms (conventional spouting regime).

The experimental data on radial distribution of voidage for the DSB regime (Uo ) 7.0 × Uoms), at three different heights, z ) 37, 88, and 139 mm for 1.55-mm particles and Ho of 60 mm, are plotted in Figure 7. It was observed that for the DSB regime there was an increase in bed voidage with increasing height, z, above the base. Figures 8 and 9 show the radial distributions of particle velocity at z ) 37 mm for different air velocities, respectively, for 1.16-mm particles with Ho of 62 mm, and for 1.55-mm particles with Ho of 52 mm. For the conventional spouting regime, the radial distribution of particle velocities was qualitatively similar to those reported in the literature.9,12,14 In this dense-phase spouting regime, particles descend slowly in the annulus zone, whereas much higher particle velocities are obtained in the spout, with a maximum at the axis. The experimental results of Figures 8 and 9 also indicate that, as expected, the upward particle velocity in the spout zone

5107

Figure 15. Experimental results compared with CFD predictions of radial distribution of particle velocity at z ) 37 mm for particles of dp ) 1.55 mm, Ho of 52 mm, and Uo ) 2.8Uoms (transition regime).

Figure 16. Experimental results compared with CFD predictions of radial distribution of particle velocity at z ) 37 mm for particles of dp ) 1.55 mm, Ho of 52 mm, and Uo ) 5.4Uoms (transition regime; near minimum dilute-phase condition).

increases significantly with increasing superficial gas velocity. The upward particle velocities in the DSB regime were higher than those for the other flow regimes, but of the same order of magnitude. However, the downward particle velocities for the DSB regime exceeded in magnitude those in the conventional spouting regime. This must be due to nearly free-falling movement of the particles along the containing wall of the column, giving rise to much shorter particle cycle times in this dilute flow regime.9 4.2. CFD Results. Voidage. The experimental data and CFD results of radial distribution of voidage (at z ) 37 mm) for the dense-phase spouting regime (Uo ) 1.6 × Uoms) are plotted in Figure 10, for particles of ds ) 1.55 mm and Ho of 52 mm. It can be observed that there is very good agreement between simulated results and experimental data for the CSB. Comparisons between CFD predictions and experimental voidage data for the transition regime at z ) 37 mm are shown in Figures 11 and 12. Figure 11 presents results for 1.16-mm particles and a static bed height of 62 mm with Uo ) 3.0 × Uoms, whereas Figure 12 is for 1.55-mm particles and a static bed height of 52 mm with Uo ) 4.2 × Uoms. It can be observed in Figure 11 that the voidage is underpredicted for the smaller particles (ds ) 1.16 mm) at the interface between the spouted and annular zones. However, these results also show that for these two very distinct conditions of the transition regime, and hence with different annular and spout zone characteristics, the CFD simulations were still able to predict the trends and the radial voidage distribution in reasonably good agreement with the experimental values. Figure 13 shows the experimental voidage data and CFD predictions for the dilute-phase regime, for particles of ds ) 1.16 mm, a static bed height of 62 mm, and Uo ) 8.0 × Uoms.

5108


to predict the hydrodynamic behavior of all three flow regimes of spouting: CSB, transition regime, and DSB. Acknowledgment We are thankful for financial aid from CNPq, Brazil, and from the Natural Sciences and Engineering Research Council of Canada. Nomenclature

Figure 17. Experimental results compared with CFD predictions of radial distribution of particle velocity at z ) 37 mm for particles of dp ) 1.55 mm, Ho of 52 mm, and Uo ) 6.9Uoms (DSB).

Although there was slight overprediction (4.5%), the CFD simulations were able to predict the characteristic trend of the radial distribution of voidage for the dilute-phase regime, with no clear boundary between spouted and annular zones, and the bed voidage nearly constant over the entire cross section.6 Particle Velocity. The experimental data and CFD predictions for the radial distribution of particle velocity (at z ) 37 mm) for the dense-phase spouting regime (Uo ) 1.6 × Uoms) are plotted in Figure 14 for 1.55-mm particles and a static bed height of 52 mm. As for the voidage, the CFD simulations were again able to give good predictions of the radial distribution of particle velocity for the CSB. Figures 15 and 16 compare the CFD predictions and experimental particle velocities at z ) 37 mm in the transition regime for particles of ds ) 1.55 mm and a static bed height of 52 mm. Figure 15 shows the CFD predictions for a transition condition near the conventional spouting regime (Uo ) 2.8 × Uoms), whereas Figure 16 is for a condition near the dilute-phase regime (Uo ) 5.4 × Uoms). These figures again show good agreement between the CFD predictions and experimental data for these two very distinct conditions in the transition-flow regime. The CFD results show more clearly the inflection point at the interface between the spouted and annular zone than the experimental data. Figure 17 demonstrates that the CFD simulation model was also able to predict the particle velocity distribution for the DSB regime at Uo ) 6.9 × Uoms, giving good agreement with the experimental data. 5. Conclusions From the experimental data of particle velocity, bed voidage, and evolution of pressure drop with increasing air velocity, it was possible to characterize the transition between conventional dense-phase spouting and dilute-phase spouting. Three experimentally reproducible flow regimes of spouted beds can be clearly identified. The experimental results obtained with an optical fiber probe system indicate quantitative characteristics of the DSB regime. The high gas velocities associated with the DSB regime resulted in voidages exceeding 0.9 over the entire column, with no distinction between spout and annulus. Downward particle velocities for the DSB regime exceeded in magnitude those in conventional low-velocity spouting. The CFD simulations based on an Eulerian granular multiphase model showed good agreement with experimental voidage and particle velocity data over the entire range of conditions studied. CFD therefore provides a useful technique

Ar ) Archimedes number, Ar ) ds3F(Fs - F)/µ2 [-] Db ) top diameter of static bed [m] Dc ) diameter of cylindrical section [m] De ) effective distance between two light receivers (optical fiber probe) [mm] Di ) diameter of base [m] Do ) diameter of gas inlet orifice diameter [m] ds ) particle diameter [mm] Hc ) height of cone section [m] Ho ) static bed height [mm] ∆P ) pressure drop [Pa] (Reo)ms ) FdsUoms/µ, particle Reynolds numbers for minimum dense-phase spouting (Reo)mj ) FdsUomj/µ, particle Reynolds numbers for minimum dilutephase spouting t ) time [s] Uo ) superficial gas velocity, referred to Do [m s-1] Uoms ) superficial gas velocity at minimum spouting based on Do [m s-1] Uomj ) superficial gas velocity at minimum dilute-phase spouting based on Do [m s-1] Greek Letters γ ) cone angle [degrees] ε ) voidage [-] θs ) granular temperature [m2 s-2] µ ) gas viscosity [Pa s] F ) gas density [kg m-3] F ) particle density [kg m-3] τ ) time delay [s]

Literature Cited (1) Conceiçaõ Filho, R. S.; Barrozo, M. A. S.; Limaverde, J. R.; Ataı´de, C. H. The Use of a Spouted Bed in the Fertilizer Coating of Soybean Seeds. Drying Technol. 1998, 16, 2049. (2) Aguado, R.; Olazar, M.; San Jose, M. J.; Aguirre, G.; Bilbao, J. Pyrolysis of Sawdust in a Conical Spouted Bed Reactor. Yields and Product Composition. Ind. Eng. Chem. Res. 2000, 39, 1925. (3) Duarte, C. R.; Vieira Neto, J. L.; Lisboa, M. H.; Murata, V. V.; Barrozo, M. A. S. Experimental Study and Simulation of Mass Distribution of Covering Layer of Soybean Seeds Coated in a Spouted Bed. Braz. J. Chem. Eng. 2004, 21, 59. (4) Marreto, R. N.; Freitas, L. A. P.; Freire, J. T. Drying of Pharmaceuticals: The Applicability of Spouted Beds. Drying Technol. 2006, 24, 327. (5) Olazar, M.; San Jose, M. J.; Aguayo, A. T.; Arandes, J. M.; Bilbao, J. Stable Operational Conditions for Gas-Solid Contact Regimes in Conical Spouted Beds. Ind. Eng. Chem. Res. 1992, 31, 1784. (6) Markowski, A.; Kaminski, W. Hydrodynamic Characteristics of Jet Spouted Beds. Can. J. Chem. Eng. 1983, 61, 377. (7) Markowski, A. Drying Characteristics in a Jet Spouted Bed Dryer. Can. J. Chem. Eng. 1992, 70, 938. (8) Epstein, N. Introduction and Overview. Can. J. Chem. Eng. 1992, 70, 833. (9) Uemaki, O.; Tsuji, T. Particle Velocity and Solids Circulation Rate in a Jet-Spouted Bed. Can. J. Chem. Eng. 1992, 70, 925. (10) Epstein, N.; Grace, J. R. Spouting of Particulate Solids. In Handbook of Powder Science and Technology; Chapman & Hall: New York, 1997.

Ind. Eng. Chem. Res., Vol. 49, No. 11, 2010 (11) Olazar, M.; San Jose, M. J.; Aguayo, A. T.; Arandes, J. M.; Bilbao, J. Design Factors of Conical Spouted Beds and Jet Spouted Beds. Ind. Eng. Chem. Res. 1993, 32, 1245. (12) He, Y. L.; Qin, S. Z.; Lim, C. J.; Grace, J. R. Particle Velocity Profiles and Solid Flow Patterns in Spouted Beds. Can. J. Chem. Eng. 1994, 72, 561. (13) Benkrid, A.; Caram, H. S. Solid Flow in the Annular Region of a Spouted Bed. AIChE J. 1989, 35, 1328. (14) Olazar, M.; San Jose, M. J.; Alvarez, S.; Morales, A.; Bilbao, J. Measurement of Particle Velocities in Conical Spouted Beds Using an Optical Fiber Probe. Ind. Eng. Chem. Res. 1998, 37, 4520. (15) Olazar, M.; San Jose, M. J.; Izquierdo, M. A.; Alvarez, S.; Bilbao, J. Local Bed Voidage in Spouted Beds. Ind. Eng. Chem. Res. 2001, 40, 427. (16) San Jose´, M. J.; Olazar, M.; Alvarez, S.; Bilbao, J. Local Bed Voidage in Conical Spouted Beds. Ind. Eng. Chem. Res. 1998, 37, 2553. (17) Duarte, C. R.; Murata, V. V.; Barrozo, M. A. S. A Study of the Fluid Dynamics of the Spouted Bed Using CFD. Braz. J. Chem. Eng. 2005, 22, 263. (18) Takeuchi, S.; Wang, X. S.; Rhodes, M. J. Discrete Element Study of Particle Circulation in a 3-D Spouted Bed. Chem. Eng. Sci. 2005, 60, 1267. (19) Du, W.; Bao, X.; Xu, J.; Wei, W. Computational Fluid Dynamics (CFD) Modeling of Spouted Bed: Assessment of Drag Coefficient Correlations. Chem. Eng. Sci. 2006, 61, 4558. (20) Zhong, W.; Chen, X.; Zhang, M. Hydrodynamic Characteristics of Spout-Fluid Bed: Pressure Drop and Minimum Spouting/Spout-Fluidizing Velocity. Chem. Eng. J. 2006, 118, 37. (21) Wu, Z.; Mujumdar, A. S. CFD Modeling of the Gas-Particle Flow Behaviour in Spouted Beds. Powder Technol. 2008, 183, 260. (22) Vieira Neto, J. L.; Duarte, C. R.; Murata, V. V.; Barrozo, M. A. S. Effect of a Draft Tube on the Fluid Dynamics of a Spouted Bed: Experimental and CFD Studies. Drying Technol. 2008, 26, 299. (23) Takeuchi, S.; Wang, X. S.; Rhodes, M. J. Discrete Element Method Simulation of Three-Dimensional Conical-Base Spouted Beds. Powder Technol. 2008, 184, 141. (24) Duarte, C. R.; Olazar, M.; Murata, V. V.; Barrozo, M. A. S. Numerical Simulation and Experimental Study of Fluid-Particle Flows in a Spouted Bed. Powder Technol. 2009, 188, 195. (25) Cunha, F. G.; Santos, K. G.; Ataide, C. H.; Epstein, N.; Barrozo, M. A. S. Annatto Powder Production in a Spouted Bed: An Experimental and CFD Study. Ind. Eng. Chem. Res. 2009, 48, 976. (26) Be´ttega, R.; Almeida, A. R. F.; Correâ, R. G.; Freire, J. T. CFD Modelling of a Semi-Cylindrical Spouted Bed: Numerical Simulation and Experimental Verification. Can. J. Chem. Eng. 2009, 87, 177.

5109

(27) Be´ttega, R.; Correâ, R. G.; Freire, J. T. Scale-Up Study of Spouted Beds Using Computational Fluid Dynamics. Can. J. Chem. Eng. 2009, 87, 193. (28) Santos, K. G.; Murata, V.V.; Barrozo, M. A. S. ThreeDimensional Computational Fluid Dynamics Modelling of Spouted Bed. Can. J. Chem. Eng. 2009, 87, 211. (29) Wang, Z. Experimental Studies and CFD Simulations of Conical Spouted Bed Hydrodynamics. Ph.D. Thesis, University of British Columbia, Vancouver, Canada, 2006. (30) Liu, J. Z.; Grace, J. R.; Bi, X. T. Novel Multifunctional OpticalFiber Probe: I. Development and Validation. AIChE J. 2003, 49, 1405. (31) Giadspow, D.; Huilin, L.; Yurong, H. Hydrodynamic Modelling of Binary Mixture in a Gas Bubbling Fluidized Bed Using the Kinetic Theory of Granular Flow. Chem. Eng. Sci. 2003, 58, 1197. (32) Sundaresan, S.; Srivastava, A. Analysis of a Frictional-Kinetic Model for Gas-Particle Flow. Powder Technol. 2003, 129, 72. (33) Cadoret, L.; Reuge, N.; Pannala, S.; Syamlal, M.; Coufort, C.; Caussat, B. Silicon CVD on Powders in Fluidized Bed: Experimental and Multifluid Eulerian Modelling Study. Surf. Coat. Technol. 2007, 201, 8919. (34) Du, W.; Bao, X.; Xu, J.; Wei, W. Computational Fluid Dynamics (CFD) Modeling of Spouted Bed: Influence of Frictional Stress, Maximum Packing Limit and Coefficient of Restitution of Particles. Chem. Eng. Sci. 2006, 61, 4558. (35) Syamlal, M.; O’Brien, T. J. Computer Simulation of Bubbles in a Fluidized Bed. AIChE Symp. Ser. 1989, 85, 22. (36) Giadspow, D.; Bezburuah, R.; Ding, J. Hydrodynamics of Circulating Fluidized Beds, Kinetic Theory Approach in Fluidization. Proc. 7th Eng. Found. Conf. Fluid. 1992, 75. (37) Wen, C. Y.; Yu, Y. H. Mechanics of Fluidization. Chem. Eng. Prog. Symp. 1966, 62, 100. (38) Ergun, S. Fluid Flow through Packed Columns. Chem. Eng. Prog. 1952, 48, 892. (39) Lun, C. K.; Savage, S. B.; Jeffrey, D. J.; Chepurniy, N. Kinetic Theories of Granular Flow: Inelastic Particles in a Couette Flow and Slightly Inelastic Particles in a General Flow Field. J. Fluid Mech. 1984, 140, 223. (40) Giadspow, D. Multiphase Flow and Fluidization; Academic Press: Boston, 1994. (41) Ogawa, S.; Umemura, A.; Oshima, N. On the Equations of Fully Fluidized Granular Materials. J. Appl. Math. Phys. 1980, 31, 483.

ReceiVed for reView March 24, 2009 ReVised manuscript receiVed June 2, 2009 Accepted June 3, 2009 IE9004892

Experimental and Computational Fluid Dynamics Study of Dense

Recommend Documents