Gas and particle flow patterns in cyclones at room and elevated temperatures

Patterson, P. A.; Munz, R. J.

doi:10.1002/cjce.5450740206

Cited by 47 publications

(27 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Figures 6b and 6c show grade-efficiency curves obtained by Bohnet and Lorentz and by Hoffmann et al (1996) for 0.20 m diameter cyclones, respectively, for flowrates of 2.22 x 10 and 4.07 x 1W2 m 3 d and mean mass diameters of 3.4 and 5.32 pm. In both cases, both Equations (1) and (2) give reasonable redictions, while again a fixed value of 0, shows that an excellent agreement may be found by using a relation similar to Equation (1) obtained if the tangential velocity is determined by an empirical correlation found by Patterson and Munz (1996). However, this correlation may not be of general applicability, since it was determined for a single cyclone geometry.…”

Section: Graiim~ficiency Curvessupporting

confidence: 54%

Turbulent dispersion coefficients in cyclone flow: An empirical approach

Salcedo

Coelho

1999

Can J Chem Eng

View full text Add to dashboard Cite

types of cyclone collectors can be found in Ogawa (1 997).The design and scale-up of cyclones has evolved through various approaches, from the cut-diameter of Lapple (195 1) and the equilibrium static particle of Barth (1956), to the back-mixing model of Leith and Licht (1972), improved by Dietz ( I 981), and lately to the finite diffbsivity theories of Mothes and Loffler (1 988) and Li and Wang (1989 Among the various theories available to predict cyclone collection efficiency, the finite diffusivity theory of Mothes and Loffler ( I 988) has been shown to give the best fit of the observed grade-efficiency curves. However, lack of knowlcdgc on the dependence of the particles' turbulent dispersion coefficient with cyclone geometry, operating conditions and particle size has so far hindered the application of this theory for predictive purposes and for improved cyclone design. In this work, this theory is applied for predictive purposes, through the use of an empirical relation for the particles turbulent dispersion coefficient. The proposed relation is based on an analogy with turbulent dispersion in packed beds, and correlates the particle radial Peclet and Reynolds numbers. Laboratory-scale reverse-flow cyclones of previously unpublished geometries were built to test the applicability of the proposed relation. The Mothes and Loffler (1988) theory, when coupled with the proposed estimates of turbulent dispersion coefficients, is a powerful tool for predicting cyclone collection efficiency, short of using computational fluid dynamics tools.Parmi les differentes theories existantes pour predire I'efficacite de collection des cyclones, on motnre que la theorie de diffusivite de Mothes et Loffler (1988) donne le meilleur calage des courbes d'efficacite des grades observees. Toutefois, le manque de connaissances sur la dependance du coefficient de dispersion turbulente des particules en fonction de la geometrie du cyclone, des conditions de fonctionnement et de la taille des particules a empkche jusqu'a present I'application de cette theorie a des fins de prediction ou d'amelioration de la conception des cyclones. Dans ce travail, on applique cette theorie a des fins de prediction, en recourant a une relation empirique pour le coefficient de dispersion turbulente des particules. La relation proposee s'appuie sur une analogie avec la dispersion turbulente en lits garnis et s'exprime sous forme d'une correlation faisant intervenir les nombres de Peclet et de Reynolds, radiaux de particules. Des cyclones a ecoulement inverse a I'echelle de laboratoire ayant des geometries non encore publiees ont ete construits afin de tester I'applicabilite de la relation proposee. La theorie de Mothes et Loffler (1 988), lorsqu'elle est couplee aux estimations de coefficients de dispersion turbulente proposees, est un outil puissant pouyr predire I'efficacite de collection des cyclones, sauf si on recourt a des outils de simulation de la dynamique des fluides.

show abstract

Section: Graiim~ficiency Curvessupporting

confidence: 54%

Turbulent dispersion coefficients in cyclone flow: An empirical approach

Salcedo

Coelho

1999

Can J Chem Eng

View full text Add to dashboard Cite

show abstract

“…Regarding the tangential velocity profile, there is no data available in Patterson and Munz (1989) for case 1 (conventional cyclone). We extract points for tangential velocity considering another study (Patterson and Munz, 1996), where the same conventional cyclone was used under the same operational conditions. In this work the authors used the axial position of 12cm below the cylindrical cyclone body top.…”

Section: Qualitative Results: Fluid Dynamics Profilesmentioning

confidence: 99%

Evaluation of cyclone geometry and its influence on performance parameters by computational fluid dynamics (CFD)

Martignoni

Bernardo

Quintani

2007

Braz. J. Chem. Eng.

View full text Add to dashboard Cite

-Cyclone models have been used without relevant modifications for more than a century. Most of the attention has been focused on finding new methods to improve performance parameters. Recently, some studies were conducted to improve equipment performance by evaluating geometric effects on projects. In this work, the effect of cyclone geometry was studied through the creation of a symmetrical inlet and a volute scroll outlet section in an experimental cyclone and comparison to an ordinary single tangential inlet. The study was performed for gas-solid flow, based on an experimental study available in the literature, where a conventional cyclone model was used. Numerical experiments were performed by using CFX 5.7.1. The axial and tangential velocity components were evaluated using RSM and LES turbulence models. Results showed that these new designs can improve the cyclone performance parameters significantly and very interesting details were found on cyclone fluid dynamics properties using RSM and LES.

show abstract

“…where n represents the vortex exponent, C c is the Cunningham correction coefficient, v tw is the tangential velocity at the wall, and they can be given by the following expressions [15,21]:…”

Section: Particle Motionmentioning

confidence: 99%

An Extended Model for Determining the Separation Performance of a Cyclone

Qian

Zhang

2006

Chem Eng & Technol

View full text Add to dashboard Cite

Most models on the working of cyclones are based on cylinders and cones whereby the vertical tube and dustbin should also be included in their geometries. These separation models of conventional cylinder-on-cone cyclones do not consider the effect of the dust collection system on the flow field. In actual fact, the inclusion of the dust collection system had a considerable effect on the flow pattern in the gas cyclone as well as on the separation efficiency. In this paper, an extended model is presented, which is based on the time-of-flight approach. In this model, the gas residence time is modified so that the entire cyclone geometry is used. The lift force of a particle in the boundary layer is considered because of the larger velocity gradient here. The availability of the extended model is verified by comparison of the calculated grade efficiency with experimental data and theoretical counterparts in the literature.

show abstract

Gas and particle flow patterns in cyclones at room and elevated temperatures

Cited by 47 publications

References 15 publications

Turbulent dispersion coefficients in cyclone flow: An empirical approach

Turbulent dispersion coefficients in cyclone flow: An empirical approach

Evaluation of cyclone geometry and its influence on performance parameters by computational fluid dynamics (CFD)

An Extended Model for Determining the Separation Performance of a Cyclone

Contact Info

Product

Resources

About