The Experts below are selected from a list of 2367 Experts worldwide ranked by ideXlab platform
Leo A Behie - One of the best experts on this subject based on the ideXlab platform.
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axial dispersion in the three dimensional mixing of particles in a rotating Drum reactor
Chemical Engineering Science, 2003Co-Authors: Richard G Sherritt, Jamal Chaouki, Anil K Mehrotra, Leo A BehieAbstract:Horizontal Drum reactors are widely used in industry for the processing of granular material. They are ideally suited for chemical processes that require high temperatures at near-atmospheric pressure. However, the complexities of these reactors have resulted in empirical design procedures that lead to very conservative and costly reactors. This study first reviews critically the extensive literature on experimental results obtained on rotary kilns (without flights) and proposes new design equations for the axial-dispersion coefficient in terms of rotational speed, degree of fill, Drum Diameter, and particle Diameter. A total of 179 data points from the literature, encompassing both the batch and the continuous operational modes, yielded design correlations for slumping, rolling/cascading and cataracting bed behaviours. Additionally, new measurements were made on a pilot-scale rotary Drum by tracking a single radioactive particle (emitting gamma-rays) using a battery of nine scintillation counters; these data confirmed the correctness of the proposed design correlations.
David Parker - One of the best experts on this subject based on the ideXlab platform.
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axial and radial dispersion in rolling mode rotating Drums
Powder Technology, 2005Co-Authors: A Ingram, David Parker, J P K Seville, R G ForsterAbstract:Abstract Single particle trajectories, obtained using the Positron Emission Particle Tracking (PEPT) technique, have been used to characterise axial and radial dispersion of granular media in the rolling Drum operated in batch and continuous mode. Axial dispersion can be quantified in terms of axial displacement or angle of descent through the active layer, both of which follow a Gaussian distribution. Radial dispersion is quantified in terms of the change in radius of the particle in the passive layer following each passage through the active layer. The distribution of this change is also Gaussian. The mean angle of descent obtained in the continuous (inclined Drum) experiments agrees well with the predictions of Saeman [W.C. Saeman, Passage of solids through rotary kilns, Chem. Eng. Prog., 47 (10) (1951), 508–514.]. Furthermore, the axial and radial dispersion coefficients obtained from batch and continuous experiments are comparable, giving confidence in the use of batch data to predict mixing and residence time distribution in continuous operation. The effects of Drum speed, Drum Diameter and Drum fill level on the axial and radial dispersion coefficients are inconsistent and it appears that other factors, not considered here, such as particle shape and even electrostatics may be important. Very large differences are observed between the dispersion coefficients of monodisperse sand and polydisperse TiO2. Yet the effects of particle size within the TiO2 system appear relatively small. It is shown that mixing in the active layer can be far from complete: there is a correlation between the radii at which the particle enters and leaves the active layer. The implications for heat transfer models based on penetration theory are discussed.
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positron emission particle tracking studies of spherical particle motion in rotating Drums
Chemical Engineering Science, 1997Co-Authors: David Parker, A E Dijkstra, T W Martin, Jonathan SevilleAbstract:Positron emission particle tracking has been used to track the motion of a single radioactively labelled tracer particle within a bed of similar particles in a partially filled horizontal rotating Drum. Runs were performed using 1.5 mm glass spheres in a 136 mm Diameter Drum and using 3 mm glass spheres in 100 and 144 mm Diameter Drums, at Drum rotation speeds from 10 to 65 rpm. An active surface layer approximately two-thirds as thick as the underlying bed layer was apparent in all cases. Considerable slip of the bed at the walls was observed in most runs, which is attributed to a rolling motion of the outermost layer of spheres. The axial dispersion coefficient was determined for each run and was found to be proportional to the frequency at which particles circulate around the bed, and to be strongly dependent on particle size but independent of Drum Diameter.
Jonathan Seville - One of the best experts on this subject based on the ideXlab platform.
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positron emission particle tracking studies of spherical particle motion in rotating Drums
Chemical Engineering Science, 1997Co-Authors: David Parker, A E Dijkstra, T W Martin, Jonathan SevilleAbstract:Positron emission particle tracking has been used to track the motion of a single radioactively labelled tracer particle within a bed of similar particles in a partially filled horizontal rotating Drum. Runs were performed using 1.5 mm glass spheres in a 136 mm Diameter Drum and using 3 mm glass spheres in 100 and 144 mm Diameter Drums, at Drum rotation speeds from 10 to 65 rpm. An active surface layer approximately two-thirds as thick as the underlying bed layer was apparent in all cases. Considerable slip of the bed at the walls was observed in most runs, which is attributed to a rolling motion of the outermost layer of spheres. The axial dispersion coefficient was determined for each run and was found to be proportional to the frequency at which particles circulate around the bed, and to be strongly dependent on particle size but independent of Drum Diameter.
Stuart A Scott - One of the best experts on this subject based on the ideXlab platform.
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axial dispersion of granular material in horizontal rotating cylinders
Powder Technology, 2010Co-Authors: J R Third, D M Scott, Stuart A ScottAbstract:The discrete element method is used to calculate axial dispersion coefficients for approximately monosized particles in a rotating horizontal cylinder. Axial dispersion within the cylinder is shown to follow Fick's second law, in that the mean squared deviation of axial position of a pulse of particles is proportional to time. The axial dispersion coefficient is found to depend on the particle size, gravity and Drum rotation speed, allowing a dimensionless group to be formed using these four quantities. For sufficiently large cylinders, the axial dispersion coefficient is found to be independent of Drum Diameter. A general argument is given which suggests that axial dispersion in physical beds of approximately monosized particles should follow Fick's second law.
Richard G Sherritt - One of the best experts on this subject based on the ideXlab platform.
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axial dispersion in the three dimensional mixing of particles in a rotating Drum reactor
Chemical Engineering Science, 2003Co-Authors: Richard G Sherritt, Jamal Chaouki, Anil K Mehrotra, Leo A BehieAbstract:Horizontal Drum reactors are widely used in industry for the processing of granular material. They are ideally suited for chemical processes that require high temperatures at near-atmospheric pressure. However, the complexities of these reactors have resulted in empirical design procedures that lead to very conservative and costly reactors. This study first reviews critically the extensive literature on experimental results obtained on rotary kilns (without flights) and proposes new design equations for the axial-dispersion coefficient in terms of rotational speed, degree of fill, Drum Diameter, and particle Diameter. A total of 179 data points from the literature, encompassing both the batch and the continuous operational modes, yielded design correlations for slumping, rolling/cascading and cataracting bed behaviours. Additionally, new measurements were made on a pilot-scale rotary Drum by tracking a single radioactive particle (emitting gamma-rays) using a battery of nine scintillation counters; these data confirmed the correctness of the proposed design correlations.
