Comparison of flow microdynamics for a continuous granular mixer with predictions from periodic slice DEM simulations

Abstract Using periodic slice discrete element method (DEM) simulations to model sections of a full continuous blender offers significant savings in computation cost. Before development of a periodic slice based continuous mixer model, the accuracy of periodic slice models for predicting full blender behavior needs to be examined. Flow microdynamics obtained from periodic slice simulations are compared against full blender results by examining speed and velocity frequency distributions. The periodic slice models are found to replicate full blender flow microdynamics well for central sections of the full blender. Reasonably good agreement is obtained for the inlet and outlet regions where the periodic boundary assumption is less valid. Results suggest that the use of periodic slice simulations to represent full blender behavior is a feasible approach which may be extended in the future to develop a full blender model. A small change in particle size is observed to have a negligible effect on the fill level of the continuous mixer, suggesting that larger particles may be used in DEM simulations to predict bulk flow quantities.

[1]  Masami Nakagawa,et al.  Steady particulate flows in a horizontal rotating cylinder , 1998 .

[2]  Jennifer S. Curtis,et al.  Modeling granular segregation in flow from quasi-three-dimensional, wedge-shaped hoppers , 2008 .

[3]  Melany L. Hunt,et al.  Local measurements of velocity fluctuations and diffusion coefficients for a granular material flow , 1995, Journal of Fluid Mechanics.

[4]  Marianthi G. Ierapetritou,et al.  Periodic section modeling of convective continuous powder mixing processes , 2012 .

[5]  Marianthi G. Ierapetritou,et al.  Effects of rotation rate, mixing angle, and cohesion in two continuous powder mixers—A statistical approach , 2009 .

[6]  Fernando J. Muzzio,et al.  Characterization of continuous convective powder mixing processes , 2008 .

[7]  Fernando J. Muzzio,et al.  Investigation on the effect of blade patterns on continuous solid mixing performance , 2011 .

[8]  A. Sarhangi Fard,et al.  Analysis and optimization of mixing inside twin-screw extruders , 2010 .

[9]  Carl Wassgren,et al.  Using the discrete element method to predict collision-scale behavior: A sensitivity analysis , 2009 .

[10]  Carl Wassgren,et al.  Continuous blending of cohesive granular material , 2010 .

[11]  Christopher E. Brennen,et al.  Computer simulation of granular shear flows , 1985, Journal of Fluid Mechanics.

[12]  B. H. Ng,et al.  Analysis of particle motion in a paddle mixer using Discrete Element Method (DEM) , 2011 .

[13]  Aditya U. Vanarase,et al.  Effect of operating conditions and design parameters in a continuous powder mixer , 2011 .

[14]  Aditya U. Vanarase,et al.  Real-time monitoring of drug concentration in a continuous powder mixing process using NIR spectroscopy , 2010 .

[15]  Henri Berthiaux,et al.  Experimental study of the stirring conditions taking place in a pilot plant continuous mixer of particulate solids , 2005 .

[16]  Paul W. Cleary,et al.  Screw conveyor performance: comparison of discrete element modelling with laboratory experiments , 2010 .

[17]  Vadim Mizonov,et al.  Influence of stirrer type on mixture homogeneity in continuous powder mixing: A model case and a pharmaceutical case , 2008 .

[18]  Douglas W. Fuerstenau,et al.  The influence of operating variables on the residence time distribution for material transport in a continuous rotary drum , 1974 .

[19]  Melany L. Hunt,et al.  Shear-induced particle diffusion and longitudinal velocity fluctuations in a granular-flow mixing layer , 1993, Journal of Fluid Mechanics.

[20]  J. Bridgwater,et al.  Self-diffusion of spherical particles in a simple shear apparatus , 1976 .

[21]  Yutaka Tsuji,et al.  Lagrangian numerical simulation of plug flow of cohesionless particles in a horizontal pipe , 1992 .

[22]  Paul W. Cleary,et al.  Prediction of screw conveyor performance using the Discrete Element Method (DEM) , 2009 .

[23]  J. Bridgwater.  Self-diffusion coefficients in deforming powders , 1980 .

[24]  Lakshman Pernenkil,et al.  A review on the continuous blending of powders , 2006 .

[25]  Harles S. Campbell.  Self-diffusion in granular shear flows , 1997, Journal of Fluid Mechanics.

[26]  S. Savage,et al.  Studies of granular shear flows Wall slip velocities, ‘layering’ and self-diffusion , 1993 .

[27]  J. M. Huntley,et al.  Self-diffusion of grains in a two-dimensional vibrofluidized bed. , 1999, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[28]  Aditya U. Vanarase,et al.  Investigation of the effect of impeller rotation rate, powder flow rate, and cohesion on powder flow behavior in a continuous blender using PEPT , 2010 .

[29]  L. Fan,et al.  Recent developments in solids mixing , 1990 .

[30]  Marianthi G. Ierapetritou,et al.  Computational Approaches for Studying the Granular Dynamics of Continuous Blending Processes, 1 – DEM Based Methods , 2011 .

[31]  Avik Sarkar,et al.  Simulation of a continuous granular mixer: Effect of operating conditions on flow and mixing , 2009 .

[32]  Vadim Mizonov,et al.  Modeling Continuous Powder Mixing by Means of the Theory of Markov Chains , 2004 .

[33]  John Bridgwater,et al.  Geometric and dynamic similarity in particle mixing , 1969 .

[34]  Christopher E. Brennen,et al.  Chute Flows of Granular Material: Some Computer Simulations , 1985 .

[35]  Jamal Chaouki,et al.  Axial dispersion in the three-dimensional mixing of particles in a rotating drum reactor , 2003 .

[36]  Paul W. Cleary,et al.  How well do discrete element granular flow models capture the essentials of mixing processes , 1998 .

[37]  F. Bertrand,et al.  DEM-based models for the mixing of granular materials , 2005 .

[38]  Vadim Mizonov,et al.  FLOW ANALYSIS AND MARKOV CHAIN MODELLING TO QUANTIFY THE AGITATION EFFECT IN A CONTINUOUS POWDER MIXER , 2006 .

[39]  Continuous Mixing of Solids , 2000 .

[40]  C. Wassgren,et al.  Stress results from two-dimensional granular shear flow simulations using various collision models. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.