Foam Engineering – Fundamentals and Applications

Containing contributions from leading academic and industrial researchers, this book provides a much needed update of foam science research. The first section of the book presents an accessible summary of the theory and fundamentals of foams. This includes chapters on morphology, drainage, Ostwald ripening, coalescence, rheology, and pneumatic foams. The second section demonstrates how this theory is used in a wide range of industrial applications, including foam fractionation, froth flotation and foam mitigation. It includes chapters on suprafroths, flotation of oil sands, foams in enhancing petroleum recovery, Gas-liquid Mass Transfer in foam, foams in glass manufacturing, fire-fighting foam technology and consumer product foams. Key features:* Foam fractionation is an exciting and emerging technology, starting to gain significant attention* Discusses a vital topic for many industries, especially mineral processing, petroleum engineering, bioengineering, consumer products and food sector* Links foam science theory to industrial applications, making it accessible to an engineering science audience* Summarizes the latest developments in this rapidly progressing area of research* Contains contributions from leading international researchers from academia and industry

Table of Contents:
About the Editor xv 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 Hohler and 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. Babcsan 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

About the Author :
Dr Paul Stevenson is Senior Lecturer at the Department of Chemical and Materials Engineering, University of Auckland, New Zealand. Paul has a First Class Chemical Engineering degree, and a PhD from the University of Cambridge. Paul has worked in the field of foam and its industrial applications for eight years, and has published extensively on the fundamentals of foam science and the use of foams in flotation and fractionation.