Powders and bulk solids : behavior, characterization, storage and flow

Foreword to the First Edition
Preface
Contents
1 Introduction
	1.1 Common Problems with Bulk Solids
	1.2 Milestones of Bulk Solids Technology
	References
2 Fundamentals
	2.1 Particles or Continuum?
	2.2 Forces and Stresses
	2.3 The Behavior of Powders and Bulk Solids (Introduction)
	2.4 The Mohr Stress Circle
		2.4.1 Introduction of the Mohr Stress Circle
		2.4.2 Derivation of the Mohr Stress Circle
	2.5 Bulk Density, Porosity and Degree of Saturation
	2.6 Buoyancy
	2.7 Elastic and Plastic Deformation
	2.8 Adhesive Forces
	2.9 Influence of Particle Size on the Behavior of a Bulk Solid
	2.10 Particle Size Distribution (PSD)
		2.10.1 Cumulative Distribution and Density Distribution
		2.10.2 Type of Quantity
		2.10.3 Characteristic Values of Particle Size Distributions
		2.10.4 Conversion of the Type of Quantity
	2.11 Permeability
		2.11.1 Applications in Bulk Solids Handling
		2.11.2 Viscous Flow (Laminar Flow)
		2.11.3 Influence of Porosity
		2.11.4 Transition to Inertial Flow (Turbulent Flow)
	References
3 Flow Properties of Bulk Solids
	3.1 Uniaxial Compression Test
		3.1.1 Consolidation of Bulk Solids
		3.1.2 Time Consolidation
		3.1.3 Flowability
		3.1.4 Representation of Stresses Using Mohr Stress Circles
	3.2 Principles of Shear Testing
		3.2.1 Test Procedure
		3.2.2 Yield Locus and Flow Properties
		3.2.3 Time Consolidation (Caking)
	3.3 Wall Friction
		3.3.1 Test Procedure for Wall Yield Loci
		3.3.2 Wall Yield Locus and Wall Friction Angle
		3.3.3 Time Wall Yield Locus, Static Wall Friction
	3.4 Numbers to Characterize Flowability
		3.4.1 Flowability ffc
		3.4.2 Remarks on the Term “Flowability”
		3.4.3 Further Numbers to Indicate Flowability
	References
4 Practical Determination of Flow Properties
	4.1 Measurement with Shear Testers
		4.1.1 Measurement of Yield Loci with the Jenike Shear Tester
		4.1.2 Measurement of Yield Loci with the Ring Shear Tester
		4.1.3 Measurement of Time Consolidation
		4.1.4 Measurement of Kinematic Wall Friction
		4.1.5 Measurement of Static Wall Friction
		4.1.6 Attrition Test
		4.1.7 Compressibility Test
	4.2 Selection of Stresses
		4.2.1 Yield Locus (Flowability)
		4.2.2 Time Yield Locus (Flowability After Time Consolidation)
		4.2.3 Wall Yield Locus (Wall Friction)
	4.3 Application-Related Measurement of Flow Properties
		4.3.1 Comparative Tests
		4.3.2 Silo Design for Flow
	References
5 A More Detailed Look at Properties of Bulk Solids
	5.1 Anisotropy and Influence of Deformation on Stresses
		5.1.1 Stresses
		5.1.2 Bulk Density
		5.1.3 Unconfined Yield Strength (Compressive Strength)
	5.2 Shear Deformation, Shear Zones, Localization
		5.2.1 Idealization: Simple Shear and Pure Shear
		5.2.2 Shear Zones and Shear Bands
		5.2.3 Dilatancy
		5.2.4 Steady-State Flow and Dilation During Flow Property Testing
	5.3 Yield Locus
		5.3.1 Preshear Point, Shear Points and Mohr Stress Circles
		5.3.2 Tensile Strength and Cohesion
		5.3.3 Flow Properties at Very Small Stresses
	5.4 Influence of Velocity
	References
6 Discussion of Testers and Test Procedures
	6.1 Influences on Test Results
		6.1.1 Procedure and Principal Stresses
		6.1.2 Stresses in the Measuring Plane
	6.2 Requirements for Testers to Measure Flow Properties
	6.3 Measuring Techniques and Equipment (Overview)
		6.3.1 Funnel
		6.3.2 Angle of Repose
		6.3.3 Avalanching
		6.3.4 Imse Test
		6.3.5 Carr Flowability Index
		6.3.6 Stirrer
		6.3.7 Compressibility Test
		6.3.8 Cohesion Tester, Flowability Test
		6.3.9 Penetration and Indentation Tests
		6.3.10 Uniaxial Compression Test
		6.3.11 Monoaxial Shear Test
		6.3.12 Powder Bed Tester with Tensile Strength Test
		6.3.13 Uniaxial Tensile Strength Test
		6.3.14 Tensile Strength Test with Gas Flow
		6.3.15 Johanson Hang-Up Indicizer™, Similar Techniques
		6.3.16 Quality Control Tester
		6.3.17 Biaxial Compression Test
		6.3.18 Constant-Volume Shear Tester
		6.3.19 Jenike Shear Tester
		6.3.20 Torsional Shear Tester
		6.3.21 Ring Shear Tester
	6.4 Remarks on Reliability and Accuracy
	6.5 Measurement of Adhesive Forces
	6.6 Summary
	References
7 Properties Exhibited by Some Bulk Solids
	7.1 Effects in Flowing Bulk Solids
		7.1.1 Stick-Slip Behavior
		7.1.2 Variation of Wall Friction with Displacement and Position
	7.2 Parameters and Conditions Influencing Flow Behavior
		7.2.1 Particle Size Distribution
		7.2.2 Flow Agents
		7.2.3 Liquids, Moisture
		7.2.4 Gas Flow
		7.2.5 Particle Shape
		7.2.6 Formation of Agglomerates
	References
8 Examples of Measured Flow Properties
	8.1 Flow Agent
	8.2 Moisture Content
	8.3 Temperature
	8.4 Time Consolidation
	8.5 Particle Size
	8.6 Attrition
	8.7 Bulk Density
	8.8 Stress Dependency of Wall Friction
	8.9 Influence of Wall Material on Wall Friction Angle
	8.10 Direction-Dependent Wall Friction
	References
9 Calculation and Measurement of Stresses in Bins and Silos
	9.1 Stress States in Silos
		9.1.1 Ratio of Horizontal to Vertical Stress
		9.1.2 Stresses in Silos
	9.2 Assessment of Stresses
		9.2.1 Stresses in Vertical Channels (Janssen’s Approach)
		9.2.2 Further Application of Janssen’s Equation
		9.2.3 Bulk Solid Properties for Calculation of Stresses with Janssen’s Approach
		9.2.4 Calculation of Stresses in Hoppers
		9.2.5 Estimation of Stresses at an Outlet Opening
		9.2.6 Bulk Solid Properties for the Calculation of Hopper Stresses
		9.2.7 Assessment of the Stress Distribution in a Silo
	9.3 Loads on Feeders
		9.3.1 Vertical Stress at an Outlet Opening
		9.3.2 Estimation of Driving Forces
	9.4 Disturbances to the Stress Distribution
		9.4.1 Local Variations of the Cross-section
		9.4.2 Eccentric Flow
	9.5 Measurement of Stresses in Bulk Solids
	References
10 Silo Design for Flow
	10.1 Flow Profiles: Mass Flow and Funnel Flow
	10.2 Flow Problems in Silos
	10.3 Jenike’s Procedure for Silo Design
		10.3.1 Design of Mass Flow Silos
		10.3.2 Design of Funnel Flow Silos
	10.4 Other Approaches to Arch Formation
	10.5 Application of Results
	10.6 Design Diagrams
	References
11 Silo Configurations
	11.1 Influence of Flow Properties on Silo Configuration
	11.2 Hopper Configurations
		11.2.1 Hopper Shape
		11.2.2 Transitions and Inclined Walls
		11.2.3 Multiple Outlets
		11.2.4 Special Cases: Hoppers with Varying Steepness
	11.3 Inserts
		11.3.1 Inverted Cones and Wedges
		11.3.2 Cone-in-Cone Insert
		11.3.3 Discharge Tubes
	References
12 Discharge of Bulk Solids
	12.1 Maximum Discharge Rate
		12.1.1 Discharge Rate of Coarse-Grained Bulk Solids
		12.1.2 Discharge Rate of Fine-Grained Bulk Solids
	12.2 Discharge Aids
		12.2.1 Pneumatic Discharge Aids
		12.2.2 Mechanical Discharge Aids
		12.2.3 Application of Discharge Aids
	12.3 Feeders and Other Discharge Devices
		12.3.1 Rules for Design Regarding Mass Flow
		12.3.2 Types of Discharge Devices (Selection)
	12.4 Feeder Dimensions and Placement of Discharge Aids
	References
13 Segregation
	13.1 Segregation Mechanisms
		13.1.1 Sifting and Other Segregation Mechanisms on Inclined Surfaces
		13.1.2 Percolation in Particle Beds
		13.1.3 Effect of Air Resistance
	13.2 Techniques to Reduce Segregation
		13.2.1 Modification of the Bulk Solid
		13.2.2 Optimization of the Filling Process
		13.2.3 Remixing
	13.3 Mixing and Segregation
		13.3.1 Assessment of Mixtures
		13.3.2 Sampling
		13.3.3 Selected Applications
	13.4 Final Remarks
	References
14 Silo Quaking and Silo Honking
	14.1 Phenomenon
	14.2 Causes and Effects
		14.2.1 Shocks as a Result of Sudden Flow
		14.2.2 Sudden Flow and Pulsating Flow Caused by Stick-Slip Friction
		14.2.3 Shear Zones in Silos
		14.2.4 Acceleration and Deceleration Waves
	14.3 Silo Shocks Due to Flow of the Bulk Solid
		14.3.1 Shear Zones in Flowing Bulk Solid
		14.3.2 Unstable Stagnant Zones (Funnel Flow)
		14.3.3 Flow at the Silo Wall
		14.3.4 Combinations of Different Mechanisms
		14.3.5 Silo Honking
	14.4 Shocks and Vibrations Due to Other Reasons
		14.4.1 Large Discharge Rate with Respect to Outlet Size
		14.4.2 Cyclic Excitation by a Feeder
		14.4.3 Collapsing Arches and Ratholes
	14.5 Means for Reducing Silo Quaking and Silo Honking
		14.5.1 Reduction of the Accelerated Mass
		14.5.2 Regular Initiation of Small Shocks
		14.5.3 Increasing Roughness of the Vertical Section
		14.5.4 Reduction of Velocity Gradients
		14.5.5 Transforming Funnel Flow into Mass Flow
		14.5.6 Inserts
	References
15 Sample Problems and Solutions
	15.1 General Remarks
	15.2 Sample Problems
		15.2.1 Sample Problem 1: Stresses in the Vertical Section of a Silo
		15.2.2 Sample Problem 2: Maximum Stress in a Mass Flow Silo
		15.2.3 Sample Problem 3: Discharge Tube
		15.2.4 Sample Problem 4: Driving Force of a Feeder
		15.2.5 Sample Problem 5: Press
		15.2.6 Sample Problem 6: Stresses in Combined Bins
		15.2.7 Sample Problem 7: Stresses in FIBCs and Sacks on Pallets
		15.2.8 Sample Problem 8: Discharge Rate of a Coarse Bulk Solid
		15.2.9 Sample Problem 9: Selection of a Wall Material for Mass Flow
		15.2.10 Sample Problem 10: Design of a Mass Flow Silo
		15.2.11 Sample Problem 11: Design of a Funnel Flow Silo
		15.2.12 Sample Problem 12: Design of a Silo Under Consideration of Time Consolidation
	Reference
Symbols
Index