Foam Engineering

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.

• About the Editor xv Contributors xviiPreface xix1 Introduction 1Paul Stevenson1.1 Gas–Liquid Foam in Products and Processes 11.2 Content of This Volume 21.3 A Personal View of Collaboration in Foam Research 3Part I Fundamentals 52 Foam Morphology 7D. Weaire, S.T. Tobin, A.J. Meagher and S. Hutzler2.1 Introduction 72.2 Basic Rules of Foam Morphology 72.2.1 Foams, Wet and Dry 72.2.2 The Dry Limit 92.2.3 The Wet Limit 112.2.4 Between the Two Limits 112.3 Two-dimensional Foams 112.3.1 The Dry Limit in 2D 112.3.2 The Wet Limit in 2D 122.3.3 Between the Two Limits in 2D 122.4 Ordered Foams 152.4.1 Two Dimensions 152.4.1.1 The 2D Honeycomb Structure 152.4.1.2 2D Dry Cluster 152.4.1.3 2D Confinement 152.4.2 Three Dimensions 162.4.2.1 3D Dry Foam 162.4.2.2 3D Wet Foam 172.4.2.3 Ordered Columnar Foams 182.5 Disordered Foams 192.6 Statistics of 3D Foams 202.7 Structures in Transition: Instabilities and Topological Changes 212.8 Other Types of Foams 222.8.1 Emulsions 222.8.2 Biological Cells 222.8.3 Solid Foams 232.9 Conclusions 243 Foam Drainage 27Stephan A. Koehler3.1 Introduction 273.2 Geometric Considerations 293.3 A Drained Foam 333.4 The Continuity Equation 353.5 Interstitial Flow 363.6 Forced Drainage 383.7 Rigid Interfaces and Neglecting Nodes: The Original Foam Drainage Equation 413.8 Mobile Interfaces and Neglecting Nodes 433.9 Neglecting Channels: The Node-dominated Model 463.10 The Network Model: Combining Nodes and Channels 483.11 The Carman–Kozeny Approach 503.12 Interpreting Forced Drainage Experiments: A Detailed Look 513.13 Unresolved Issues 533.14 A Brief History of Foam Drainage 544 Foam Ripening 59Olivier Pitois4.1 Introduction 594.2 The Very Wet Limit 594.3 The Very Dry Limit 614.3.1 Inter-bubble Gas Diffusion through Thin Films 614.3.2 von Neumann Ripening for 2D Foams 624.3.3 3D Coarsening 644.4 Wet foams 654.5 Controlling the Coarsening Rate 694.5.1 Gas Solubility 694.5.2 Resistance to Gas Permeation 704.5.3 Shell Mechanical Strength 704.5.4 Bulk Modulus 715 Coalescence in Foams 75Annie Colin5.1 Introduction 755.2 Stability of Isolated Thin Films 765.2.1 Experimental Studies Dealing with Isolated Thin Liquid Films 765.2.2 Theoretical Description of the Rupture of an Isolated Thin Liquid Film 775.3 Structure and Dynamics of Foam Rupture 785.4 What Are the Key Parameters in the Coalescence Process? 815.5 How Do We Explain the Existence of a Critical Liquid Fraction? 865.6 Conclusion 896 Foam Rheology 91Nikolai D. Denkov, Slavka S. Tcholakova, Reinhard Höhler and Sylvie Cohen-Addad6.1 Introduction 916.2 Main Experimental and Theoretical Approaches 936.3 Foam Visco-elasticity 956.3.1 Linear Elasticity 956.3.1.1 Monodisperse Dry Foam 956.3.1.2 Effects of Bubble Polydispersity and Liquid Content 966.3.2 Non-linear Elasticity 986.3.3 Linear Relaxations 996.3.3.1 Slow Relaxation 996.3.3.2 Fast Relaxation 1016.3.4 Shear Modulus of Particle-laden Foams 1026.4 Yielding 1036.5 Plastic Flow 1056.6 Viscous Dissipation in Steadily Sheared Foams 1066.6.1 Predominant Viscous Friction in the Foam Films 1086.6.2 Predominant Viscous Friction in the Surfactant Adsorption Layer 1116.7 Foam–Wall Viscous Friction 1126.8 Conclusions 1147 Particle Stabilized Foams 121G. Kaptay and N. Babcsán7.1 Introduction 1217.2 A Summary of Some Empirical Observations 1237.3 On the Thermodynamic Stability of Particle Stabilized Foams 1257.4 On the Ability of Particles to Stabilize Foams during Their Production 1317.5 Design Rules for Particle Stabilized Foams 1357.6 Conclusions 1388 Pneumatic Foam 145Paul Stevenson and Xueliang Li8.1 Preamble 1458.2 Vertical Pneumatic Foam 1458.2.1 Introduction 1458.2.2 The Hydrodynamics of Vertical Pneumatic Foam 1478.2.2.1 Pneumatic Foam with Constant Bubble Size Distribution 1488.2.2.2 The Introduction of Capillary Forces to Give a Liquid Fraction Profile 1498.2.2.3 Liquid Fraction Profile with Changing Bubble Size Distribution with Height 1508.2.2.4 Addition of Washwater to a Pneumatic Foam 1518.2.3 The ‘Vertical Foam Misapprehension’ 1528.2.4 Bubble Size Distributions in Foam 1538.2.5 Non-overflowing Pneumatic Foam 1538.2.6 The Influence of Humidity upon Pneumatic Foam with a Free Surface 1558.2.7 Wet Pneumatic Foam and Flooding 1558.2.8 Shear Stress Imparted by the Column Wall 1578.2.9 Changes in Flow Cross-Sectional Area 1588.3 Horizontal Flow of Pneumatic Foam 1588.3.1 Introduction 1588.3.2 Lemlich’s Observations 1598.3.3 Wall-slip and Velocity Profiles 1608.3.4 Horizontal Flow Regimes 1618.4 Pneumatic Foam in Inclined Channels 1628.5 Methods of Pneumatic Foam Production 1629 Non-aqueous Foams: Formation and Stability 169Lok Kumar Shrestha and Kenji Aramaki9.1 Introduction 1699.1.1 Foam Formation and Structures 1699.1.2 Foam Stability 1709.2 Phase Behavior of Diglycerol Fatty Acid Esters in Oils 1739.3 Non-aqueous Foaming Properties 1749.3.1 Effect of Solvent Molecular Structure 1749.3.2 Effect of Surfactant Concentration 1779.3.2.1 Particle Size Distribution 1799.3.2.2 Rheological Properties of Particle Dispersion 1799.3.2.3 Equilibrium Surface Tension 1819.3.3 Effect of Hydrophobic Chain Length of Surfactant 1819.3.3.1 Foaming of C12G2 in Liquid Paraffin, Squalene, and Squalane 1829.3.3.2 Foaming of C12G2 in Olive Oil 1829.3.4 Effect of Headgroup Size of Surfactant 1879.3.5 Effect of Temperature 1899.3.6 Effect of Water Addition 1919.3.6.1 Effect of Water on Foamability 1919.3.6.2 Effect of Water on Foam Stability 1929.3.7 Non-aqueous Foam Stabilization Mechanism 2019.4 Conclusion 20310 Suprafroth: Ageless Two-dimensional Electronic Froth 207Ruslan Prozorov and Paul C. Canfield10.1 Introduction 20710.2 The Intermediate State in Type-I Superconductors 20810.3 Observation and Study of the Tubular Intermediate State Patterns 21110.4 Structural Statistical Analysis of the Suprafroth 215Part II Applications 22711 Froth Phase Phenomena in Flotation 229Paul Stevenson and Noel W.A. Lambert11.1 Introduction 22911.2 Froth Stability 23311.3 Hydrodynamic Condition of the Froth 23511.4 Detachment of Particles from Bubbles 23611.5 Gangue Recovery 23811.6 The Velocity Field of the Froth Bubbles 24111.7 Plant Experience of Froth Flotation 24211.7.1 Introduction 24211.7.2 Frother-constrained Plant 24211.7.3 Sampling, Data Manipulation and Data Presentation 24411.7.4 Process Control 24511.7.5 The Assessment of Newly Proposed Flotation Equipment 24611.7.6 Conclusions about Froth Flotation Drawn from Plant Experience 24612 Froth Flotation of Oil Sand Bitumen 251Laurier L. Schramm and Randy J. Mikula12.1 Introduction 25112.2 Oil Sands 25112.3 Mining and Slurrying 25312.4 Froth Structure 26512.5 Physical Properties of Froths 27212.6 Froth Treatment 27412.7 Conclusion 27813 Foams in Enhancing Petroleum Recovery 283Laurier L. Schramm and E. Eddy Isaacs13.1 Introduction 28313.2 Foam Applications for the Upstream Petroleum Industry 28413.2.1 Selection of Foam-Forming Surfactants 28413.3 Foam Applications in Wells and Near Wells 28713.3.1 Drilling and Completion Foams 28713.3.2 Well Stimulation Foams: Fracturing, Acidizing, and Unloading 28813.4 Foam Applications in Reservoir Processes 28913.4.1 Reservoir Recovery Background 28913.4.1.1 Sweep Efficiency 29013.4.1.2 Capillary Trapping 29113.4.2 Foam Applications in Primary and Secondary Oil Recovery 29213.4.3 Foam Applications in Enhanced (Tertiary) Oil Recovery 29313.4.3.1 Foams in Carbon Dioxide Flooding 29413.4.3.2 Foams in Hydrocarbon Flooding 29413.4.3.3 Foams in Steam Flooding 29713.5 Occurrences of Foams at the Surface and Downstream 29813.6 Conclusion 29914 Foam Fractionation 307Xueliang Li and Paul Stevenson14.1 Introduction 30714.2 Adsorption in Foam Fractionation 31014.2.1 Adsorption Kinetics at Quiescent Interface 31114.2.2 Adsorption at Dynamic Interfaces 31414.3 Foam Drainage 31514.4 Coarsening and Foam Stability 31614.5 Foam Fractionation Devices and Process Intensification 31714.5.1 Limitations of Conventional Columns 31714.5.2 Process Intensification Devices 31914.5.2.1 Adsorption Enhancement Methods 31914.5.2.2 Drainage Enhancement Methods 32214.6 Concluding Remarks about Industrial Practice 32415 Gas–Liquid Mass Transfer in Foam 331Paul Stevenson15.1 Introduction 33115.2 Non-Overflowing Pneumatic Foam Devices 33415.3 Overflowing Pneumatic Foam Devices 33615.4 The Waldhof Fermentor 33815.5 Induced Air Methods 34015.6 Horizontal Foam Contacting 34115.7 Calculation of Specific Interfacial Area in Foam 34215.8 Hydrodynamics of Pneumatic Foam 34315.9 Mass Transfer and Equilibrium Considerations 34515.9.1 Gas–Liquid Equilibrium 34515.9.2 Rate of Mass Transfer 34515.9.3 Estimation of Mass Transfer Coefficient 34615.10 Towards an Integrated Model of Foam Gas–Liquid Contactors 34715.11 Discussion and Future Directions 34916 Foams in Glass Manufacturing 355Laurent Pilon16.1 Introduction 35516.1.1 The Glass Melting Process 35616.1.2 Melting Chemistry and Refining 35916.1.2.1 Redox State of Glass 35916.1.2.2 Melting Chemistry 36016.1.2.3 Refining Chemistry 36016.1.2.4 Reduced-pressure Refining 36216.1.3 Motivations 36216.2 Glass Foams in Glass Melting Furnaces 36316.2.1 Primary Foam 36316.2.2 Secondary Foam 36316.2.3 Reboil 36416.2.4 Parameters Affecting Glass Foaming 36516.3 Physical Phenomena 36516.3.1 Glass Foam Physics 36516.3.1.1 Mechanisms of Foam Formation 36516.3.1.2 Glass Foam Morphology 36716.3.2 Surface Active Agents and Surface Tension of Gas/Melt Interface 36816.3.3 Drainage and Stability of a Single Molten Glass Film 36916.3.4 Gas Bubbles in Molten Glass 37016.3.4.1 Bubble Nucleation 37016.3.4.2 Stability of a Single Bubble at the Glassmelt Surface 37016.3.4.3 Bubble Rise through Molten Glass 37116.4 Experimental Studies 37316.4.1 Introduction 37316.4.2 Transient Primary and Secondary Glass Foams 37416.4.2.1 Experimental Apparatus and Procedure 37416.4.2.2 Experimental Observations 37516.4.3 Steady-state Glass Foaming by Gas Injection 38316.4.3.1 Experimental Apparatus and Procedure 38316.4.3.2 Experimental Observations and Foaming Regimes 38316.4.3.3 Onset of Glass Foaming 38416.4.3.4 Steady-state Foam Thickness 38516.5 Modeling 38616.5.1 Introduction 38616.5.2 Dynamic Foam Growth and Decay 38616.5.2.1 Foaming by Thermal Decomposition 38616.5.2.2 Foaming by Gas Injection 38716.5.3 Steady-State Glass Foams 38916.5.3.1 Onset of Foaming 38916.5.3.2 Steady-state Foam Thickness 39016.5.4 Experiments and Model Limitations 39416.6 Measures for Reducing Glass Foaming in Glass Melting Furnaces 39516.6.1 Batch Composition 39616.6.2 Batch Conditioning and Heating 39716.6.3 Furnace Temperature 39716.6.4 External and Temporary Actions 39716.6.5 Atmosphere Composition and Flame Luminosity 39816.6.6 Control Foaming in Reduced-Pressure Refining 39916.7 Perspective and Future Research Directions 40017 Fire-Fighting Foam Technology 411Thomas J. Martin17.1 Introduction 41117.2 History 41317.3 Applications 41517.3.1 Foam Market 41517.3.2 Hardware 41517.4 Physical Properties 41617.4.1 Mechanism of Action 41717.4.2 Class A Foams 42217.4.3 Class B Foams 42217.5 Chemical Properties 43017.5.1 Ingredients and Purpose 43017.5.1.1 Water 43117.5.1.2 Organic Solvents 43117.5.1.3 Hydrocarbon Surfactants 43317.5.1.4 Fluorosurfactants 43917.5.1.5 Polymers 44417.5.1.6 Salts, Buffers, Preservatives and Other Additives 44617.5.2 Example Recipes 44717.6 Testing 44817.6.1 Lab Test Methods 44917.6.1.1 Expansion and Quarter Drain Time 44917.6.1.2 pH 45017.6.1.3 Specific Gravity (SG) 45017.6.1.4 Refractive Index (RI) 45017.6.1.5 Brookfield Viscosity 45017.6.1.6 Film Formation 45117.6.1.7 Surface Tension (ST), Interfacial Tension (IFT), Spreading Coefficient (SC), and Critical MicelleConcentration (CMC) 45117.6.1.8 Proportioning Rate 45117.6.1.9 Deluge-Resistance Time 45117.6.1.10 Degree of Surfactant Retention in Foam 45217.6.1.11 Drave’s Wetting Rate 45217.6.2 Fire Test Standards 45217.6.2.1 UL 162 Fire Tests 45217.7 The Future 45318 Foams in Consumer Products 459Peter J. Martin18.1 Introduction 45918.1.1 Foams and Consumer Appeal 45918.1.2 Market Descriptions and Directions 46118.1.3 The Scope of This Chapter 46318.2 Creation and Structure 46318.2.1 Surfactants and Their Application 46418.2.2 Creation 46618.2.3 Growth 46818.2.4 Application of structure 46918.2.5 Maintenance of Structure 46918.2.6 Summary 47018.3 Sensory Appeal 47018.3.1 Visual 47118.3.2 Auditory 47218.3.3 Mouth Feel 47318.3.4 Summary 47318.4 Conclusions 473Index