Title Details

Contributors xvii

Preface xix

1 Introduction 1

Paul Stevenson

1.1 Gas–Liquid Foam in Products and Processes 1

1.2 Content of This Volume 2

1.3 A Personal View of Collaboration in Foam Research 3

Part I Fundamentals 5

2 Foam Morphology 7

D. Weaire, S.T. Tobin, A.J. Meagher and S. Hutzler

2.1 Introduction 7

2.2 Basic Rules of Foam Morphology 7

2.2.1 Foams, Wet and Dry 7

2.2.2 The Dry Limit 9

2.2.3 The Wet Limit 11

2.2.4 Between the Two Limits 11

2.3 Two-dimensional Foams 11

2.3.1 The Dry Limit in 2D 11

2.3.2 The Wet Limit in 2D 12

2.3.3 Between the Two Limits in 2D 12

2.4 Ordered Foams 15

2.4.1 Two Dimensions 15

2.4.1.1 The 2D Honeycomb Structure 15

2.4.1.2 2D Dry Cluster 15

2.4.1.3 2D Confinement 15

2.4.2 Three Dimensions 16

2.4.2.1 3D Dry Foam 16

2.4.2.2 3D Wet Foam 17

2.4.2.3 Ordered Columnar Foams 18

2.5 Disordered Foams 19

2.6 Statistics of 3D Foams 20

2.7 Structures in Transition: Instabilities and Topological Changes 21

2.8 Other Types of Foams 22

2.8.1 Emulsions 22

2.8.2 Biological Cells 22

2.8.3 Solid Foams 23

2.9 Conclusions 24

3 Foam Drainage 27

Stephan A. Koehler

3.1 Introduction 27

3.2 Geometric Considerations 29

3.3 A Drained Foam 33

3.4 The Continuity Equation 35

3.5 Interstitial Flow 36

3.6 Forced Drainage 38

3.7 Rigid Interfaces and Neglecting Nodes: The Original Foam Drainage Equation 41

3.8 Mobile Interfaces and Neglecting Nodes 43

3.9 Neglecting Channels: The Node-dominated Model 46

3.10 The Network Model: Combining Nodes and Channels 48

3.11 The Carman–Kozeny Approach 50

3.12 Interpreting Forced Drainage Experiments: A Detailed Look 51

3.13 Unresolved Issues 53

3.14 A Brief History of Foam Drainage 54

4 Foam Ripening 59

Olivier Pitois

4.1 Introduction 59

4.2 The Very Wet Limit 59

4.3 The Very Dry Limit 61

4.3.1 Inter-bubble Gas Diffusion through Thin Films 61

4.3.2 von Neumann Ripening for 2D Foams 62

4.3.3 3D Coarsening 64

4.4 Wet foams 65

4.5 Controlling the Coarsening Rate 69

4.5.1 Gas Solubility 69

4.5.2 Resistance to Gas Permeation 70

4.5.3 Shell Mechanical Strength 70

4.5.4 Bulk Modulus 71

5 Coalescence in Foams 75

Annie Colin

5.1 Introduction 75

5.2 Stability of Isolated Thin Films 76

5.2.1 Experimental Studies Dealing with Isolated Thin Liquid Films 76

5.2.2 Theoretical Description of the Rupture of an Isolated Thin Liquid Film 77

5.3 Structure and Dynamics of Foam Rupture 78

5.4 What Are the Key Parameters in the Coalescence Process? 81

5.5 How Do We Explain the Existence of a Critical Liquid Fraction? 86

5.6 Conclusion 89

6 Foam Rheology 91

Nikolai D. Denkov, Slavka S. Tcholakova, Reinhard Höhlerand Sylvie Cohen-Addad

6.1 Introduction 91

6.2 Main Experimental and Theoretical Approaches 93

6.3 Foam Visco-elasticity 95

6.3.1 Linear Elasticity 95

6.3.1.1 Monodisperse Dry Foam 95

6.3.1.2 Effects of Bubble Polydispersity and Liquid Content 96

6.3.2 Non-linear Elasticity 98

6.3.3 Linear Relaxations 99

6.3.3.1 Slow Relaxation 99

6.3.3.2 Fast Relaxation 101

6.3.4 Shear Modulus of Particle-laden Foams 102

6.4 Yielding 103

6.5 Plastic Flow 105

6.6 Viscous Dissipation in Steadily Sheared Foams 106

6.6.1 Predominant Viscous Friction in the Foam Films 108

6.6.2 Predominant Viscous Friction in the Surfactant Adsorption Layer 111

6.7 Foam–Wall Viscous Friction 112

6.8 Conclusions 114

7 Particle Stabilized Foams 121

G. Kaptay and N. Babcsán

7.1 Introduction 121

7.2 A Summary of Some Empirical Observations 123

7.3 On the Thermodynamic Stability of Particle Stabilized Foams 125

7.4 On the Ability of Particles to Stabilize Foams during Their Production 131

7.5 Design Rules for Particle Stabilized Foams 135

7.6 Conclusions 138

8 Pneumatic Foam 145

Paul Stevenson and Xueliang Li

8.1 Preamble 145

8.2 Vertical Pneumatic Foam 145

8.2.1 Introduction 145

8.2.2 The Hydrodynamics of Vertical Pneumatic Foam 147

8.2.2.1 Pneumatic Foam with Constant Bubble Size Distribution 148

8.2.2.2 The Introduction of Capillary Forces to Give a Liquid Fraction Profile 149

8.2.2.3 Liquid Fraction Profile with Changing Bubble Size Distribution with Height 150

8.2.2.4 Addition of Washwater to a Pneumatic Foam 151

8.2.3 The ‘Vertical Foam Misapprehension’ 152

8.2.4 Bubble Size Distributions in Foam 153

8.2.5 Non-overflowing Pneumatic Foam 153

8.2.6 The Influence of Humidity upon Pneumatic Foam with a Free Surface 155

8.2.7 Wet Pneumatic Foam and Flooding 155

8.2.8 Shear Stress Imparted by the Column Wall 157

8.2.9 Changes in Flow Cross-Sectional Area 158

8.3 Horizontal Flow of Pneumatic Foam 158

8.3.1 Introduction 158

8.3.2 Lemlich’s Observations 159

8.3.3 Wall-slip and Velocity Profiles 160

8.3.4 Horizontal Flow Regimes 161

8.4 Pneumatic Foam in Inclined Channels 162

8.5 Methods of Pneumatic Foam Production 162

9 Non-aqueous Foams: Formation and Stability 169

Lok Kumar Shrestha and Kenji Aramaki

9.1 Introduction 169

9.1.1 Foam Formation and Structures 169

9.1.2 Foam Stability 170

9.2 Phase Behavior of Diglycerol Fatty Acid Esters in Oils 173

9.3 Non-aqueous Foaming Properties 174

9.3.1 Effect of Solvent Molecular Structure 174

9.3.2 Effect of Surfactant Concentration 177

9.3.2.1 Particle Size Distribution 179

9.3.2.2 Rheological Properties of Particle Dispersion 179

9.3.2.3 Equilibrium Surface Tension 181

9.3.3 Effect of Hydrophobic Chain Length of Surfactant 181

9.3.3.1 Foaming of C12G2 in Liquid Paraffin, Squalene, and Squalane 182

9.3.3.2 Foaming of C12G2 in Olive Oil 182

9.3.4 Effect of Headgroup Size of Surfactant 187

9.3.5 Effect of Temperature 189

9.3.6 Effect of Water Addition 191

9.3.6.1 Effect of Water on Foamability 191

9.3.6.2 Effect of Water on Foam Stability 192

9.3.7 Non-aqueous Foam Stabilization Mechanism 201

9.4 Conclusion 203

10 Suprafroth: Ageless Two-dimensional Electronic Froth 207

Ruslan Prozorov and Paul C. Canfield

10.1 Introduction 207

10.2 The Intermediate State in Type-I Superconductors 208

10.3 Observation and Study of the Tubular Intermediate State Patterns 211

10.4 Structural Statistical Analysis of the Suprafroth 215

Part II Applications 227

11 Froth Phase Phenomena in Flotation 229

Paul Stevenson and Noel W.A. Lambert

11.1 Introduction 229

11.2 Froth Stability 233

11.3 Hydrodynamic Condition of the Froth 235

11.4 Detachment of Particles from Bubbles 236

11.5 Gangue Recovery 238

11.6 The Velocity Field of the Froth Bubbles 241

11.7 Plant Experience of Froth Flotation 242

11.7.1 Introduction 242

11.7.2 Frother-constrained Plant 242

11.7.3 Sampling, Data Manipulation and Data Presentation 244

11.7.4 Process Control 245

11.7.5 The Assessment of Newly Proposed Flotation Equipment 246

11.7.6 Conclusions about Froth Flotation Drawn from Plant Experience 246

12 Froth Flotation of Oil Sand Bitumen 251

Laurier L. Schramm and Randy J. Mikula

12.1 Introduction 251

12.2 Oil Sands 251

12.3 Mining and Slurrying 253

12.4 Froth Structure 265

12.5 Physical Properties of Froths 272

12.6 Froth Treatment 274

12.7 Conclusion 278

13 Foams in Enhancing Petroleum Recovery 283

Laurier L. Schramm and E. Eddy Isaacs

13.1 Introduction 283

13.2 Foam Applications for the Upstream Petroleum Industry 284

13.2.1 Selection of Foam-Forming Surfactants 284

13.3 Foam Applications in Wells and Near Wells 287

13.3.1 Drilling and Completion Foams 287

13.3.2 Well Stimulation Foams: Fracturing, Acidizing, and Unloading 288

13.4 Foam Applications in Reservoir Processes 289

13.4.1 Reservoir Recovery Background 289

13.4.1.1 Sweep Efficiency 290

13.4.1.2 Capillary Trapping 291

13.4.2 Foam Applications in Primary and Secondary Oil Recovery 292

13.4.3 Foam Applications in Enhanced (Tertiary) Oil Recovery 293

13.4.3.1 Foams in Carbon Dioxide Flooding 294

13.4.3.2 Foams in Hydrocarbon Flooding 294

13.4.3.3 Foams in Steam Flooding 297

13.5 Occurrences of Foams at the Surface and Downstream 298

13.6 Conclusion 299

14 Foam Fractionation 307

Xueliang Li and Paul Stevenson

14.1 Introduction 307

14.2 Adsorption in Foam Fractionation 310

14.2.1 Adsorption Kinetics at Quiescent Interface 311

14.2.2 Adsorption at Dynamic Interfaces 314

14.3 Foam Drainage 315

14.4 Coarsening and Foam Stability 316

14.5 Foam Fractionation Devices and Process Intensification 317

14.5.1 Limitations of Conventional Columns 317

14.5.2 Process Intensification Devices 319

14.5.2.1 Adsorption Enhancement Methods 319

14.5.2.2 Drainage Enhancement Methods 322

14.6 Concluding Remarks about Industrial Practice 324

15 Gas–Liquid Mass Transfer in Foam 331

Paul Stevenson

15.1 Introduction 331

15.2 Non-Overflowing Pneumatic Foam Devices 334

15.3 Overflowing Pneumatic Foam Devices 336

15.4 The Waldhof Fermentor 338

15.5 Induced Air Methods 340

15.6 Horizontal Foam Contacting 341

15.7 Calculation of Specific Interfacial Area in Foam 342

15.8 Hydrodynamics of Pneumatic Foam 343

15.9 Mass Transfer and Equilibrium Considerations 345

15.9.1 Gas–Liquid Equilibrium 345

15.9.2 Rate of Mass Transfer 345

15.9.3 Estimation of Mass Transfer Coefficient 346

15.10 Towards an Integrated Model of Foam Gas–Liquid Contactors 347

15.11 Discussion and Future Directions 349

16 Foams in Glass Manufacturing 355

Laurent Pilon

16.1 Introduction 355

16.1.1 The Glass Melting Process 356

16.1.2 Melting Chemistry and Refining 359

16.1.2.1 Redox State of Glass 359

16.1.2.2 Melting Chemistry 360

16.1.2.3 Refining Chemistry 360

16.1.2.4 Reduced-pressure Refining 362

16.1.3 Motivations 362

16.2 Glass Foams in Glass Melting Furnaces 363

16.2.1 Primary Foam 363

16.2.2 Secondary Foam 363

16.2.3 Reboil 364

16.2.4 Parameters Affecting Glass Foaming 365

16.3 Physical Phenomena 365

16.3.1 Glass Foam Physics 365

16.3.1.1 Mechanisms of Foam Formation 365

16.3.1.2 Glass Foam Morphology 367

16.3.2 Surface Active Agents and Surface Tension of Gas/Melt Interface 368

16.3.3 Drainage and Stability of a Single Molten Glass Film 369

16.3.4 Gas Bubbles in Molten Glass 370

16.3.4.1 Bubble Nucleation 370

16.3.4.2 Stability of a Single Bubble at the Glassmelt Surface 370

16.3.4.3 Bubble Rise through Molten Glass 371

16.4 Experimental Studies 373

16.4.1 Introduction 373

16.4.2 Transient Primary and Secondary Glass Foams 374

16.4.2.1 Experimental Apparatus and Procedure 374

16.4.2.2 Experimental Observations 375

16.4.3 Steady-state Glass Foaming by Gas Injection 383

16.4.3.1 Experimental Apparatus and Procedure 383

16.4.3.2 Experimental Observations and Foaming Regimes 383

16.4.3.3 Onset of Glass Foaming 384

16.4.3.4 Steady-state Foam Thickness 385

16.5 Modeling 386

16.5.1 Introduction 386

16.5.2 Dynamic Foam Growth and Decay 386

16.5.2.1 Foaming by Thermal Decomposition 386

16.5.2.2 Foaming by Gas Injection 387

16.5.3 Steady-State Glass Foams 389

16.5.3.1 Onset of Foaming 389

16.5.3.2 Steady-state Foam Thickness 390

16.5.4 Experiments and Model Limitations 394

16.6 Measures for Reducing Glass Foaming in Glass Melting Furnaces 395

16.6.1 Batch Composition 396

16.6.2 Batch Conditioning and Heating 397

16.6.3 Furnace Temperature 397

16.6.4 External and Temporary Actions 397

16.6.5 Atmosphere Composition and Flame Luminosity 398

16.6.6 Control Foaming in Reduced-Pressure Refining 399

16.7 Perspective and Future Research Directions 400

17 Fire-Fighting Foam Technology 411

Thomas J. Martin

17.1 Introduction 411

17.2 History 413

17.3 Applications 415

17.3.1 Foam Market 415

17.3.2 Hardware 415

17.4 Physical Properties 416

17.4.1 Mechanism of Action 417

17.4.2 Class A Foams 422

17.4.3 Class B Foams 422

17.5 Chemical Properties 430

17.5.1 Ingredients and Purpose 430

17.5.1.1 Water 431

17.5.1.2 Organic Solvents 431

17.5.1.3 Hydrocarbon Surfactants 433

17.5.1.4 Fluorosurfactants 439

17.5.1.5 Polymers 444

17.5.1.6 Salts, Buffers, Preservatives and Other Additives 446

17.5.2 Example Recipes 447

17.6 Testing 448

17.6.1 Lab Test Methods 449

17.6.1.1 Expansion and Quarter Drain Time 449

17.6.1.2 pH 450

17.6.1.3 Specific Gravity (SG) 450

17.6.1.4 Refractive Index (RI) 450

17.6.1.5 Brookfield Viscosity 450

17.6.1.6 Film Formation 451

17.6.1.7 Surface Tension (ST), Interfacial Tension (IFT), Spreading Coefficient (SC), and Critical Micelle

Concentration (CMC) 451

17.6.1.8 Proportioning Rate 451

17.6.1.9 Deluge-Resistance Time 451

17.6.1.10 Degree of Surfactant Retention in Foam 452

17.6.1.11 Drave’s Wetting Rate 452

17.6.2 Fire Test Standards 452

17.6.2.1 UL 162 Fire Tests 452

17.7 The Future 453

18 Foams in Consumer Products 459

Peter J. Martin

18.1 Introduction 459

18.1.1 Foams and Consumer Appeal 459

18.1.2 Market Descriptions and Directions 461

18.1.3 The Scope of This Chapter 463

18.2 Creation and Structure 463

18.2.1 Surfactants and Their Application 464

18.2.2 Creation 466

18.2.3 Growth 468

18.2.4 Application of structure 469

18.2.5 Maintenance of Structure 469

18.2.6 Summary 470

18.3 Sensory Appeal 470

18.3.1 Visual 471

18.3.2 Auditory 472

18.3.3 Mouth Feel 473

18.3.4 Summary 473

18.4 Conclusions 473

Index