Segregation in heaps and silos: Comparison between experiment, simulation and continuum model

Abstract Segregation is a very common phenomenon in industrial processes wherever granular materials are handled. It can occur at different stages in an industrial process and it is usually undesired. To support the industrial design, it is necessary to understand the mechanisms of segregation and to develop a tool which is able to predict the propensity of segregation depending on product and process properties. The underlying mechanisms of segregation during filling and discharge of silos are discussed in detail. To study the effects for different configurations of silos (flat bottom vs. inclined hopper; with and without belt conveyor) a bimodal mixture of differently sized particles is employed. A useful tool to support the analysis of segregation processes is the discrete element method (DEM). A calibrated and validated DEM simulation has been used to simulate a pilot scale silo with a belt conveyor at the outlet. In this context, the influence of some common procedures in DEM, which are used to reduce the computational effort (way of filling, upscaling, periodic boundary condition) as well as their effect on the measured segregation is presented. Moreover, a continuum approach is presented which fits the segregation effects using a simplified model to experimental data. This approach is useful in a first stage to predict the segregation behaviour based on a convective/diffusive model.

[1]  Jin Y. Ooi,et al.  Micromechanical analysis of cohesive granular materials using the discrete element method with an adhesive elasto-plastic contact model , 2014, Granular Matter.

[2]  Colin Thornton,et al.  Numerical analysis of density-induced segregation during die filling , 2010 .

[3]  Christophe Ancey,et al.  Multi-component particle-size segregation in shallow granular avalanches , 2011, Journal of Fluid Mechanics.

[4]  Jörg Schwedes,et al.  Experimental Investigation of Silo Stresses under Consideration of the Influence of Hopper/Feeder Interface , 1990 .

[5]  James W. Landry,et al.  Discrete element simulations of stress distributions in silos: crossover from two to three dimensions , 2003 .

[6]  K. Sommer.  Mixing of Particulate Solids , 1996 .

[7]  H. Enriquez,et al.  Segregation induced by inelasticity in a vibrofluidized granular mixture. , 2008, Physical review. E, Statistical, nonlinear, and soft matter physics.

[8]  A. Tripathi,et al.  Density difference-driven segregation in a dense granular flow , 2013, Journal of Fluid Mechanics.

[9]  Virendra M. Puri,et al.  Development and Validation of a Constitutive Model for Size-Segregation during Percolation , 2003 .

[10]  C. González-Montellano,et al.  Numerical effects derived from en masse filling of agricultural silos in DEM simulations , 2012 .

[11]  J. Khazaei,et al.  New method for simultaneously measuring the angles of repose and frictional properties of wheat grains. , 2010 .

[12]  Bruno C. Hancock,et al.  Granular segregation in discharging cylindrical hoppers: A discrete element and experimental study , 2007 .

[13]  Giovanna Ferrari,et al.  Discharge of Size-Segregated Powders from a 2D-aerated Silo , 2006 .

[14]  Virendra M. Puri,et al.  Modeling and Validation of Percolation Segregation of Fines from Coarse Mixtures during Shear Motion , 2011 .

[15]  T. Weinhart,et al.  Effects of packing density on the segregative behaviors of granular systems. , 2014, Physical review letters.

[16]  A. W. Jenike.  Quantitative design of mass-flow bins☆ , 1967 .

[17]  J Braun.  Segregation of granular media by diffusion and convection. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[18]  A Samadani,et al.  Size segregation of granular matter in silo discharges. , 1999, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[19]  Jennifer S. Curtis,et al.  Segregation of cohesive granular materials during discharge from a rectangular hopper , 2010 .

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

[21]  J. van de Velde,et al.  The flow of granular solids through orifices , 1961 .

[22]  William Thielicke,et al.  PIVlab – Towards User-friendly, Affordable and Accurate Digital Particle Image Velocimetry in MATLAB , 2014 .

[23]  Mark Cross,et al.  Micro-mechanical parameterisations for continuum modellingof granular material using the discrete element method , 2002 .

[24]  J Baxter,et al.  Application of simulation technologies in the analysis of granular material behaviour during transport and storage , 2005 .

[25]  J. Gray,et al.  Particle-size segregation and diffusive remixing in shallow granular avalanches , 2006, Journal of Fluid Mechanics.

[26]  Jin Y. Ooi,et al.  Silo pressure predictions using discrete–element and finite–element analyses , 1998, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[27]  Paul W. Cleary,et al.  The effect of particle shape on simple shear flows , 2008 .

[28]  R. T. Fowler,et al.  The flow of granular solids through orifices , 1959 .

[29]  S. Subramaniam,et al.  Granular Flow in Silo Discharge: Discrete Element Method Simulations and Model Assessment , 2013 .

[30]  Scott M. Johnson,et al.  DEM Simulations of the Effects of Particle Shape, Interparticle Cohesion, and Gravity on Rotating Drum Flows of Lunar Regolith , 2010 .

[31]  C. J. Coetzee,et al.  Discrete element parameter calibration and the modelling of dragline bucket filling , 2010 .

[32]  Pierre Chapelle,et al.  A hybrid numerical model for predicting segregation during core flow discharge , 2006 .

[33]  Aibing Yu,et al.  Flow characteristics and discharge rate of ellipsoidal particles in a flat bottom hopper , 2014 .

[34]  Kerry Johanson,et al.  Quantitative measurement of particle segregation mechanisms , 2005 .

[35]  A. Kwade,et al.  Segregation of particulate solids: Experiments and DEM simulations , 2014 .

[36]  M. Hasegawa,et al.  Effect of size distribution on tapping properties of fine powder , 2001 .

[37]  Paul W. Cleary,et al.  DEM modelling of industrial granular flows: 3D case studies and the effect of particle shape on hopper discharge , 2002 .

[38]  W. A. Take,et al.  Soil deformation measurement using particle image velocimetry (PIV) and photogrammetry , 2003 .

[39]  S. Savage,et al.  Particle size segregation in inclined chute flow of dry cohesionless granular solids , 1988, Journal of Fluid Mechanics.

[40]  Jian Fei Chen,et al.  Assessment of rolling resistance models in discrete element simulations , 2011 .

[41]  Gisle G. Enstad,et al.  Theoretical and experimental testing of a scaling rule for air current segregation of alumina powder in cylindrical silos , 2008 .

[42]  Nicholas Christakis,et al.  Predictions of segregation of granular material with the aid of PHYSICA, a 3‐D unstructured finite‐volume modelling framework , 2002 .

[43]  Jörg Schwedes,et al.  Application of Particle Image Velocimetry for velocity measurements during silo discharge , 2005 .

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

[45]  Torsten Kraft,et al.  Die filling optimization using three-dimensional discrete element modeling , 2009 .

[46]  David R. Owen,et al.  On upscaling of discrete element models: similarity principles , 2009 .

[47]  D. Jeffrey,et al.  Kinetic theories for granular flow: inelastic particles in Couette flow and slightly inelastic particles in a general flowfield , 1984, Journal of Fluid Mechanics.

[48]  Seiichi Koshizuka,et al.  Large-scale discrete element modeling in pneumatic conveying , 2009 .

[49]  Robertas Navakas,et al.  The role of friction in mixing and segregation of granular material , 2009 .

[50]  Henrik Saxén,et al.  Experimental and DEM study of segregation of ternary size particles in a blast furnace top bunker model , 2010 .

[51]  Matthew J. Metzger,et al.  Effect of particle size distribution on segregation in vibrated systems , 2013 .