LLE 5: Phase Separation
     Part 1: Introduction
         1. PHASE SEPARTION
     Part 2: Coalescence in Liquid-Liquid Dispersions
         1. INTRODUCTION
             1.1 The Coalescence Process
             1.2 Film Drainage
                 1.2.1 Normal Forces
                 1.2.2 Viscous Forces.
             1.3 Gradients of Interfacial Tension
             1.4 Film Profiles
                 1.4.1 Small Drops
             1.5 Drainage Equations
             1.6 Coalescence Times
             1.7 Structure of Dispersions
             1.8 Steady State Dispersion
             1.9 Batch Dispersion
             1.10 Binary Coalescence
             1.11 Coalescence at the Disengaging Interface
             1.12 Prediction of Behaviour of Dispersions
             1.13 Effect of Hold-up
             1.14 Survey of Recent Literature
         2. COALESCENCE TIMES
             2.1 Introduction
             2.2 Single Drop Coalescence
             2.3 Distribution of Coalescence Times
             2.4 Factors Affecting Coalescence Times
                 2.4.1 Droplet Size
                 2.4.2 External Forces
                 2.4.3 Density Difference
                 2.4.4 Curvature of the Interface
                 2.4.5 Length of Fall to the Interface
                 2.4.6 Viscosity
                 2.4.7 Interfacial Tension
                 2.4.8 Presence of a Third Component
                 2.4.9 Mutual Solubility
                 2.4.10 Temperature and Temperature Gradient
                 2.4.11 Vibration
                 2.4.12 Electrical Effects
             2.5 Coalescence Time Correlations
             2.6 Theoretical Relationships
             2.7 Film Rupture
         3. FILM DRAINAGE
             3.1 Radial Drainage
                 3.1.1 Undeformable Surfaces
                 3.1.2 Dimpling
                 3.1.3 Non-Newtonian Fluids
                 3.1.4 Two-dimensional Drainage
             3.2 Effect of Gravity on Drainage of Films of Uniform Thickness
                 3.2.1 Inclined Planar Films
                 3.2.2 Cylindrical Films
                 3.2.3 Spherical Films
             3.3. Effect of Interfacial Mobility on Film Drainage
                 3.3.1 Planar films
                 3.3.2 Effect of Interfacial Tension Gradients
                 3.3.3 Dispersion stability
                 3.3.4 Spherical films
                 3.3.5 Sloping films
                 3.3.6 Approach of Deformable Spheres
             3.4 Binary Coalescence in Turbulent Field
                 3.4.1 Head-on Collision
                 3.4.2 Off-Centre Collision
             3.5 Gentle Collision of Drops
                 3.5.1 Off-Centre Collision
                 3.5.2 Gravitational field
                 3.5.3 Laminar Shear Field
             Appendix 3.1: Momentum Balances
         4. POPULATION BALANCE EQUATIONS
             4.1 Drop Breakage and Coalescence
             4.2 Variation in Average Quantities
                 4.2.1 Unsteady-State Batch System
                 4.2.2 Steady-State Flow System
             4.3 Batch Dispersions
                 4.3.1 Heights of Sedimentation and Dense-packed Zones
                 4.3.2 Relative Velocity of Drops in Sedimentation Zone
                 4.3.3 Volume Flux Balances
             4.4 Sedimentation
             4.5 Collision Frequency
                 4.5.1 Turbulent Flow
                 4.5.2 Simple Shear Flow
             4.6 Dense-Packed Dispersions
                 4.6.1 Binary Coalescence
                 4.6.2 Film Thickness and Foam Height
         5. DESIGN OF SETTLERS
             5.1 Coalescence in Spray Columns
             5.2 Vertical Settlers
             5.3 Horizontal Dispersions
             5.4 Factors Affecting the Performance of Mixer-Settlers
                 5.4.1 Mixer Design
                 5.4.2 Mixing Regime
                 5.4.3 Choice of Dispersed Phase
                 5.4.4 Feed Phase Ratio
                 5.4.5 Temperature
                 5.4.6 Electric Fields
                 5.4.7 Settler Design
         6. MODELS RELATING BATCH AND CONTINUOUS DISPERSIONS
             6.1 Derivation of General Equations
             6.2 Effect of Dispersion Height
                 6.2.1 Reference Conditions
                 6.2.2 Experimental
             6.3 Residence Times
                 6.3.1 Prediction of Steady-State Dispersion Height
                 6.3.2 Experimental Application
             6.4 Thickness of Sedimenting and Dense-Packed Zones
                 6.4.1 Sedimentation Height
                 6.4.2 Thickness of Dense-Packed Layer
                 6.4.3 Application
             6.5 Effect of Drop Size and Physical Properties
                 6.5.1 Experimental Results
             6.6 Turbulence and Power Dissipation
                 6.6.1 Turbulence
                 6.6.2 Power Dissipation
         7. SECONDARY DISPERSIONS
             7.1 Causes of Secondary Dispersion Formation
                 7.1.1 Partial Coalescence
                 7.1.2 Film Rupture
             7.2 Separation of Secondary Dispersions
                 7.2.1 Porous Media
                 7.2.2 Wetted Surfaces
                 7.2.3 Centrifugal Force
                 7.2.4 Electric Fields
                 7.2.5 Chemical Coagulants
                 7.2.6 Special Surfactants
         8. INDUSTRIAL COALESCERS
             8.1 Gravity Settlers
             8.2 Special Separators
             8.3 Types of Mixer-Settler
             8.4 Mixer-Settler Design
             8.5 Centrifugal Separators
             8.6 Extraction Columns
             8.7 Centrifugal Extractors
         9. CONCLUSIONS AND RECOMMENDATIONS
         10 NOTATION
         11 REFERENCES
     Part 3: The Application of Electric Fields to Phase Separation
         ABSTRACT
         1. INTRODUCTION
         2. ELECTRICAL PARAMETERS
             2.1 Electrical Terminology.
                 2.1.1 Electric field strength (see also 3.4)
                 2.1.2 Dielectric strength
                 2.1.3 RC time constant
                 2.1.4 Capacitative energy
             2.2 High Voltage Measurement Techniques
                 2.2.1 Measurement of potential difference
                 2.2.2 The use of probes
                 2.2.3 Current measurement
             2.3 High Voltage Generation
                 2.3.1 AC supply
                 2.3.2 DC supply
                 2.3.3 Pulsed DC
         3. ELECTRICAL EFFECTS IN INSULATING MATERIALS
             3.1 Ionic Conduction in Insulators
             3.2 Space Charge and Potential Distribution
             3.3 Dipoles
             3.4 Polarisation and Dielectric Constant
             3.5 Frequency Dependence of Relative Permittivity
             3.6 Relaxation Time
             3.7 Electrophoretic and Dielectrophoretic Forces
                 3.7.1 Dielectrophoresis
                 3.7.2 Electrophoresis
         4. AUGMENTED COALESCENCE FOR SINGLE DROPLETS
             4.1 Coalescence at a Plane Interface in an Electric Field
             4.2 Coalescence of a Pair of Droplets in an Electric Field
         5. ELECTRICAL TREATMENT OF CRUDE OIL-WATER EMULSIONS
             5.1 Historical Perspective
             5.2 Important Practical Developments
                 5.2.1 Electrofining
                 5.2.2 Distributors for emulsion feeding
                 5.2.3 The dual field approach
             5.3 Commercial Equipment
                 5.3.1 Crude oil dehydrator/desalter
                 5.3.2 DC treater
         6. PROSPECTIVE METHODS AND NEW APPLICATIONS
             6.1 Pulsed DC with Insulation Coated Electrodes
                 6.1.1 Effect of electrical parameters
                 6.1.2 Bailes' and Larkai's investigation into the effect of process and design variables
                 6.1.3 Other investigations
             6.2 AC with Insulation Coated Electrodes
                 6.2.1 Solvent extraction application
                 6.2.2 Liquid membrane applications
             6.3 Uncoated Electrodes
                 6.3.1 Solvent extraction applications
                 6.3.2 Liquid membrane applications
             6.4 Application of Electrostatic Coalescence to Liquid-liquid Contacting
                 6.4.1 Simple gravity liquid-liquid extraction columns
                 6.4.2 Applications to increase extraction column throughput
                 6.4.3 Enhancement of'liquid-liquid mixing
         7. THEORETICAL MODELLING OF ELECTRICAL COALESCENCE
             7.1 Mechanisms of Electrical Coalescence
                 7.1.1 Random collision
                 7.1.2 Induced-dipole coalescence
                 7.1.3 Dielectrophoresis
                 7.1.4 Electrophoresis
                 7.1.5 Chain formation
             7.2 Correlations for Electrical Coalescence of Emulsions
                 7.2.1 The work of Sjoblom and Goren
                 7.2.2 The correlation of Bailes and Larkai
                 7.2.3 Correlation of emulsion resolution times by Williams and Bailey
             7.3 Electrical Circuit Analogues for Modelling Electrostatic Coalescers
                 7.3.1 Polarisation as a factor in the electrical analysis
                 7.3.2 Dynamic response of an equivalent electrical network
         8. SAFETY ASPECTS
         9. CONCLUSIONS AND RECOMMENDATIONS
         10. NOMENCLATURE
         11. REFERENCES

Part 1 Introduction
Part 2 Coalescence in liquid-liquid dispersions
Part 3 The application of electric fields to phase separation in liquid-liquid dispersions

Volume SE V  Part 1 Introduction.

This part gives an overview of the volume and how to use it to best effect.

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Volume SE V  Part 2 Coalescence in liquid-liquid dispersions.

This report describes the qualitative aspects of coalescence and reviews the quantitative attempts to describe the drainage of thin films, coalescence times of single drops and the behaviour of drop dispersions. A comprehensive introductory chapter is followed by a detailed discussion of drop coalescence times and the influence of such factors as drop size, external forces, physical properties and geometry. Further chapters describe the limiting factor of the interdrop film drainage rate in well-defined drop assemblages and foams and secondary dispersions. Equations are derived relating the batch and continuous settling of a liquid-liquid dispersion and it is shown how parameters calculated from observations of batch coalescence can be used to predict continuous flow behaviour. Commercially available settler designs are described.

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Volume SE V  Part 3 The application of electric fields to phase separation in liquid-liquid dispersions.

The commercial use of electrostatic coalescence has until recently always been associated entirely with the oil industry. Recent developments in other industries involving the use of solvent extraction and liquid membrane technologies however, have led to a wider interest in the subject. This part shows the progressive practical developments that have made the more general application of electrostatic coalescence a real possibility for the future. Studies with single drops, theoretical assessments, laboratory experiments with dispersions and the patent literature are brought together with the aim of giving coherence to what is otherwise a rather wide-ranging topic. Many aspects of electrostatic coalescence lie at the interface between disciplines. To assist the reader, background material, for example, electrical parameters and electrical effects in insulating liquids, has been included.