Powders and bulk solids : behavior, characterization, storage and flow / Dietmar Schulze.

Format:

Book

Author/Creator:

Schulze, Dietmar, Dr.-Ing., author.

Language:

English

Subjects (All):

Bulk solids.

Physical Description:

1 online resource (632 pages)

Edition:

Second edition.

Place of Publication:

Cham, Switzerland : Springer, [2021]

Summary:

In the engineering community the handling of powders and bulk solids is called bulk solids technology being, at least in Germany, part of mecha- cal process engineering. Process engineering involves study of the change and transformation of material properties. If mechanical processes are used for this transformation, the engineering discipline is called mechanical process engineering. The best known unit operations of mechanical pr- ess engineering are grinding, agglomeration, mixing, and separation. Due to the mechanical treatment, the particles - either single particles or a c- lection of particles - increase in value. To profit from this value increase industry and academia perform research and development. When handling bulk solids, e. g. storing, dosing and conveying, no value increase can be achieved, because the material properties are not changed. What can be achieved is "at most" the elimination of problems which is less interesting research and development compared to the development of new products or processes with the chance to obtain a patent. A silo for the intermediate storage of bulk solids often seems to be only a single, unimportant element for the realization of a larger process. Bulk solid is filled into the silo continuously or discontinuously and discharged later at predetermined points of time in desired quantities. That is not - ways unproblematic. The known problems of arching and ratholing can lead to irregular discharge or complete blockage.

Contents:

Intro

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)

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

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

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

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

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

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

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

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

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

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

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

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

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.

Notes:

Includes bibliographical references and index.

Description based on print version record.

ISBN:

3-030-76720-5

OCLC:

1267299260