Skip to main content Accessibility help

We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.

Close cookie message
×
Hostname: page-component-848d4c4894-cjp7w Total loading time: 0 Render date: 2024-07-05T16:31:13.892Z Has data issue: false hasContentIssue false

8 - Particle mixing and segregation

Published online by Cambridge University Press:  04 February 2011

By
Giorgio Rovero  and
Norberto Piccinini
Edited by
Norman Epstein  and
John R. Grace
Norman Epstein
Affiliation:
University of British Columbia, Vancouver
John R. Grace
Affiliation:
University of British Columbia, Vancouver
Get access

Summary

This chapter starts from the state of the art on particle mixing in spouted beds, as presented in the classical book by Mathur and Epstein. In subsequent years, segregation has been considered in fundamental studies aimed at describing real systems of various bed compositions.

Gross solids mixing behavior

The mixing properties of spouted beds result from interaction among the spout, fountain, and annulus. In a continuously operated unit, the positioning of the solids inlet port with respect to the discharge opening is of fundamental importance to prevent bypassing. Dead zones could arise from problematic solids circulation – for example, because of an incorrect base design. To prevent segregation, the simplest conceivable operating condition corresponds to a mono-sized particulate material and a single unit in which each particle undergoes many cycles before being discharged. In such cases and for continuous operation, the internal circulation far exceeds the net in-and-out flow of solids in all cases studied. The very different particle residence times in the spout (progressively loaded with solids along its height), in the fountain (where the particles have both axial and radial velocity components), and in the annulus (where particles travel downward in nearly plug flow) generate nearly well-mixed overall solids residence time distributions (RTDs).

Stimulus-response techniques have been applied to determine the RTD of particles. A typical downstream normalized tracer concentration at the discharge, called the F curve, generated in response to an upstream step input of colored particles, is given in Figure 8.1.

Type
Chapter
Information
Spouted and Spout-Fluid Beds
Fundamentals and Applications
 , pp. 141 - 160
Publisher: Cambridge University Press
Print publication year: 2010

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Mathur, K. B. and Epstein, N.. Spouted Beds (New York: Academic Press, 1974).Google Scholar
Velzen, D., Flamm, H. J., Langenkamp, H., and Casile, A.. Motion of solids in spouted beds. Can. J. Chem. Eng., 52 (1974), 156–161.CrossRefGoogle Scholar
Mann, U. and Crosby, E. J.. Cycle time distribution measurements in spouted beds. Can. J. Chem. Eng., 53 (1975), 579–581.CrossRefGoogle Scholar
Takeda, H. and Yamamoto, Y.. Mixing of particles in a spouted bed. J. Nucl. Sci. Technol., 13 (1976), 372–381.CrossRefGoogle Scholar
McNab, G. S.. Prediction of spout diameter. Brit. Chem. Eng. Proc. Tech., 17 (1972), 532.Google Scholar
Roy, D., Larachi, F., Legros, R., and Chaouki, J.. A study of solid behavior in spouted beds using 3-D particle tracking. Can. J. Chem. Eng., 72 (1994), 945–952.CrossRefGoogle Scholar
Larachi, F., Grandjean, B. P. A., and Chaouki, J.. Mixing and circulation of solids in spouted beds: particle tracking and Monte Carlo emulation of the gross flow pattern. Chem. Eng. Sci., 58 (2003), 1497–1507.CrossRefGoogle Scholar
José, M. J. San, Olazar, M., Izquierdo, M. A., Alvarez, S., and Bilbao, J.. Solid trajectories and cycle times in spouted beds. Ind. Eng. Chem. Res., 43 (2004), 3433–3438.CrossRefGoogle Scholar
Berghel, J., Nilsson, L., and Renstrom, R.. Particle mixing and residence time when drying sawdust in a continuous spouted bed. Chem. Eng. Proc., 47 (2008), 1246–1251.CrossRefGoogle Scholar
Ishikura, T., Tanaka, I., and Shinohara, H.. Residence time distribution of particles in the continuous spouted bed of solid-gas system with elutriation of fines. J. Soc. Powder Tech. Japan, 15 (1978), 453–457.CrossRefGoogle Scholar
Piccinini, N.. Coated nuclear fuel particles. In Advances in Nuclear Science and Technology, Volume 8, ed. Henley, E. J. and Lewins, J. (New York: Academic Press, 1975), pp. 304–341.Google Scholar
Devahastin, S. and Mujumdar, A. S.. Some hydrodynamic and mixing characteristics of a pulsed spouted bed dryer. Powder Technol., 117 (2001), 189–197.CrossRefGoogle Scholar
Piccinini, N., Bernhard, A., Campagna, P., and Vallana, F.. Segregation phenomenon in spouted beds. Can. J. Chem. Eng., 55 (1977), 122–125.CrossRefGoogle Scholar
Piccinini, N.. Particle segregation in continuously operating spouted beds. In Fluidization III, ed. Grace, J. R. and Matsen, J. M. (New York: Plenum Press, 1980), pp. 279–285.CrossRefGoogle Scholar
McNab, G. S. and Bridgwater, J.. Solids mixing and segregation in spouted beds. In Third European Conference on Mixing (York, UK: BHRA, 1979), pp. 125–140.Google Scholar
Piccinini, N. and Rovero, G.. Thick coatings by thermo-chemical deposition in spouted beds. Can. J. Chem. Eng., 61 (1983), 448–453.CrossRefGoogle Scholar
Cook, H. H. and Bridgwater, J.. Segregation in spouted beds. Can. J. Chem. Eng., 56 (1978), 636–638.CrossRefGoogle Scholar
Kutluoglu, E., Grace, J. R., Murchie, K. W., and Cavanagh, P. H.. Particle segregation in spouted beds. Can. J. Chem. Eng., 61 (1983), 308–316.CrossRefGoogle Scholar
Uemaki, O., Yamada, R., and Kugo, M.. Particle segregation in a spouted bed of binary mixtures of particles. Can. J. Chem. Eng., 61 (1983), 303–307.CrossRefGoogle Scholar
Rovero, G.. Baffle-induced segregation in spouted beds. Can. J. Chem. Eng., 61 (1983), 325–330.CrossRefGoogle Scholar
Rovero, G. and Watkinson, A. P.. A two stage spouted bed process for autothermal pyrolysis or retorting. Fuel Process. Technol., 26 (1990), 221–238.CrossRefGoogle Scholar
Aguado, R., Olazar, M., José, M. J. San, Aguirre, G., and Bilbao, J.. Pyrolysis of sawdust in a conical spouted bed reactor. Yields and product composition. Ind. Eng. Chem. Res., 39 (2000), 1925–1933.CrossRefGoogle Scholar
Olazar, M., José, M. J. San, Penas, F. J., Aguayo, A. T., and Bilbao, J.. Stability and hydrodynamics of conical spouted beds with binary mixtures. Ind. Eng. Chem. Res., 32 (1993), 2826–2834.CrossRefGoogle Scholar
José, M. J. San, Olazar, M., Penas, F. J., and Bilbao, J.. Segregation in conical spouted beds with binary and ternary mixtures of equidensity spherical particles. Ind. Eng. Chem. Res., 33 (1994), 1838–1844.CrossRefGoogle Scholar
José, M. J. San, Alvarez, S., Morales, A., Olazar, M., and Bilbao, J.. Solid cross-flow into the spout and particle trajectories in conical spouted beds consisting of solids of different density and shape. Chem. Eng. Res. Des., 84 (2006), 487–494.CrossRefGoogle Scholar
Bacelos, M. S. and Freire, J. T.. Stability of spouting regimes in conical spouted beds with inert particle mixtures. Ind. Eng. Chem. Res., 45 (2006), 808–817.CrossRefGoogle Scholar
Huang, H. and Hu, G.. Mixing characteristics of a novel annular spouted bed with several angled air nozzles. Ind. Eng. Chem. Res., 46 (2007), 8248–8254.CrossRefGoogle Scholar
Huang, H., Hu, G., and Wang, F.. Experimental study on particles mixing in an annular spouted bed. Energy Convers. Mgmt, 49 (2008), 257–266.Google Scholar
Taha, B. and Koniuta, A.. Hydrodynamics and segregation from the Cerchar FBC fluidization grid. In Poster Session, Fluidization VI Conference (Banff, Canada, 1989).
Saidutta, M. B. and Murthy, D. V. R.. Mixing behavior of solids in multiple spouted beds. Can. J. Chem. Eng., 78 (2000), 382–385.CrossRefGoogle Scholar
Beltramo, C., Rovero, G., and Cavaglià, G.. Hydrodynamics and thermal experimentation on square-based spouted bed for polymer upgrading and unit scale-up. Can. J. Chem. Eng., 87 (2009), 394–402.Google Scholar
Chou, T.-C. and Uang, Y.-M.. Separation of particles in a modified fluidized bed by a distributor with dead-zone collector. Ind. Eng. Chem. Process Des. Dev., 24 (1985), 683–686.CrossRefGoogle Scholar
Waldie, B.. Separation and residence times of larger particles in a spout-fluid bed. Can. J. Chem. Eng., 70 (1992), 873–879.CrossRefGoogle Scholar

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×