467923 Differences in the Dynamics of Cylindrical and Spherical Particles in a Rotating Drum Using Multiple Radioactive Particle Tracking

Tuesday, November 15, 2016: 2:36 PM
Bay View (Hotel Nikko San Francisco)
Majid Rasouli, Fran├žois Bertrand and Jamal Chaouki, Department of Chemical Engineering, Ecole Polytechnique de Montreal, Montreal, QC, Canada

Differences in the Dynamics of Cylindrical and Spherical Particles in a Rotating Drum Using Multiple Radioactive Particle Tracking

 

Majid Rasouli, François Bertrand*, Jamal Chaouki*

 

Department of Chemical Engineering, École Polytechnique de Montréal, P. O. Box 6079, Succ. Centre-ville, Montréal, QC, Canada, H3C 3A7, jamal.chaouki@polymtl.ca, francois.bertrand@polymtl.ca

 

Rotating drums are widely used to process granular materials in the chemical, pharmaceutical, food-processing, polymer, and waste treatment industries, among others, for applications such as mixing, size reduction, sintering, coating, heating, cooling, drying, and chemical reactions. This broad array of applications is made possible by the ability of rotating drums to handle heterogeneous feedstock and to ensure satisfactory mixing and heat transfer of the solid phase1. Since the flow dynamics of particles determines to a great extent the mass and heat transfer rates, it plays a critical role in controlling and/or limiting the processes mentioned above2. The optimal design and operation of rotating drums require in-depth fundamental knowledge of the phenomena that occur inside them, including the transverse flow that controls primary effects such radial particle movement and particle mixing and/or segregation, as well as secondary effects such as bed temperature, reaction rates, and the rate of axial particle movement.

The flow behavior of spherical particles has been often studied. However, investigations of cylindrical particles, which are not numerous in the literature,  are required since these particles have many uses (biomass pellets, capsules, rice, candy, etc.) and, more importantly, since their shape is known to affect their flow behavior3 in terms of shear resistance, dilation under shear, compaction efficiency, transfer of momentum between translational and rotational movements, and their ability to form arches and block the flow4.

The goal of the present study was to compare the flow behavior of spherical and cylindrical particles in a rotating drum. We used the RPT technique to determine the positions of the spherical particles over time. We used the MRPT technique5 to track the positions and orientations of the cylindrical particles and calculate the components of their transverse flow dynamics in the rotating drum. To illustrate, Fig. 1 shows velocity vectors of the transverse flow of spherical and cylindrical particles at the same rotational speed (10 RPM) in the rotating drum.

(a)

(b)

Figure 1: Velocity vectors for (a) spherical and (b) cylindrical particles at a rotational speed of 10 RPM6

Literature cited

1.         Dube O, Alizadeh E, Chaouki J, Bertrand F. Dynamics of non-spherical particles in a rotating drum. Chemical Engineering Science. Sep 20 2013;101:486-502.

2.         Mellmann J, Specht E, Liu X. Prediction of rolling bed motion in rotating cylinders. AIChE Journal. 2004;50(11):2783-2793.

3.         Ridgway K, Rupp R. Mixing of powder layers on a chute. The effect of particle size and shape. Powder Technology. 1971;4(4):195-202.

4.         Cleary PW. DEM prediction of industrial and geophysical particle flows. Particuology. 2010;8(2):106-118.

5.         Rasouli M, Bertrand F, Chaouki J. A multiple radioactive particle tracking technique to investigate particulate flows. AIChE Journal. 2015;61(2):384-394.

6.         Rasouli M, Dubé O, Bertrand F, Chaouki J. Investigating the dynamics of cylindrical particles in a rotating drum using multiple radioactive particle tracking. AIChE Journal. 2016.

Acknowledgments

This work was made possible by financial support from Praxair and the Natural Sciences and Engineering Research Council of Canada (NSERC). The authors are grateful to Cornelia Chilian and Cristina Cimpan (Institute of Nuclear Engineering) for activating the tracers, Sepehr Hamzelouia for helping to measure the static repose angle, and Amin Esmaeili for helping to determine the positions of the RPT detectors.


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