UNIVERSITY OF CALGARY Emulsion Layer Growth in Asphaltene/Solids-Stabilized Water-in-Oil Emulsions by Michaela McGurn A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE GRADUATE PROGRAM IN CHEMICAL ENGINEERING CALGARY, ALBERTA AUGUST, 2017 © Michaela McGurn 2017 Abstract The effect of inorganic, coarse solids on emulsion layer stability and growth was investigated. Factors including solids type (kaolin and silica), size, concentration, and wettability were considered. Model asphaltene-stabilized water-in-oil emulsions were prepared from water and organic phase consisting of solids, asphaltenes, heptane, and toluene. In batch experiments, coalescence rates were determined from the change in emulsion height over time as the emulsion coalesced. In continuous experiments, emulsion layer growth was measured for emulsions in a continuous separator. A material balance/coalescence rate based model was developed and fit to the data. Coarse solids at low concentrations destabilized emulsions in batch separations but, above a threshold concentration, solids increased emulsion stability. In continuous separations, even at feed concentrations below the threshold, solids accumulated in the emulsion until the threshold was reached and stable emulsions were formed. The performance of continuous separations cannot be predicted from batch tests. ii Acknowledgements I would like to thank my supervisor Dr. Harvey Yarranton, lab manager Elaine Baydak, and my fellow members of the Asphaltene and Emulsion Research group for their continued support, guidance and encouragement throughout my M.Sc. studies. I am grateful to Suncor and Shell for providing bitumen samples for the experimental work. Special regards are extended to Dr. Danuta Sztukowski and Vieman Ali-Marcano for their valuable and insightful comments in the completion of this thesis. Lastly, I would like to extend my heartfelt thanks to my family, my parents Stephen and Karen McGurn and my sisters Leah and Tess, without whose support this thesis would not have been possible. Most importantly, I dedicate this thesis to my grandmother, Anne Morris, who passed away during my studies at the University of Calgary. May she always be loved and remembered. iii Table of Contents Abstract ............................................................................................................................... ii Acknowledgements ............................................................................................................ iii Table of Contents ............................................................................................................... iv List of Tables .................................................................................................................... vii List of Figures .................................................................................................................... ix List of Symbols, Abbreviations and Nomenclature ...........................................................xv CHAPTER 1: INTRODUCTION .....................................................................................1 1.1 Thesis Objectives .......................................................................................................3 1.2 Thesis Structure .........................................................................................................4 CHAPTER 2: LITERATURE REVIEW ........................................................................6 2.1 Emulsions ...................................................................................................................6 2.1.1 Emulsion Destabilization ...................................................................................7 Flocculation .........................................................................................................8 Sedimentation/Creaming .....................................................................................9 Coalescence .........................................................................................................9 Ostwald Ripening ...............................................................................................10 Phase Inversion ..................................................................................................11 2.1.2 Emulsion Stabilization .....................................................................................11 2.1.3 Emulsion Stabilizers: Surfactants ....................................................................12 2.1.4 Emulsion Stabilizers: Solids ............................................................................14 Effect of Solids Wettability .................................................................................14 Effect of Initial Particle Location ......................................................................16 Effect of Solids Size, Shape, and Concentration ................................................16 2.1.5 Emulsion Stabilizers in Crude Oils .................................................................18 2.1.5.1 Asphaltenes ............................................................................................19 2.1.5.2 Inorganic Solids .....................................................................................21 2.1.6 Other Factors in Emulsion Stability ................................................................24 Droplet Size Distribution ...................................................................................24 Dispersed Phase Volume Fraction ....................................................................24 2.1.7 Demulsification ...............................................................................................25 Chemical Treatment ...........................................................................................25 Thermal Treatment ............................................................................................26 Mechanical Treatment .......................................................................................26 Electrical Treatment ..........................................................................................26 2.2 Emulsion Layers in Water/Oil Separation Processes ..............................................27 2.2.1 Settling in Liquid-Liquid Dispersions .............................................................27 Batch Dispersions ..............................................................................................28 Continuous Dispersions .....................................................................................29 2.2.2 Mathematical Models ......................................................................................30 2.2.2.1 Hindered Settling and Coalescence Model ............................................30 2.2.2.2 Material Balance Model .........................................................................32 2.3 Rag Layers in Heavy Oil and Oil Sands Processes .................................................33 2.4 Chapter Summary ....................................................................................................37 iv CHAPTER 3: EXPERIMENTAL METHODS.............................................................39 3.1 Materials ..................................................................................................................39 3.1.1 Asphaltenes ......................................................................................................39 3.1.2 Solids ...............................................................................................................41 3.2 Emulsion Separation Experiments ...........................................................................41 3.2.1 Apparatus .........................................................................................................42 3.2.1.1 Apparatus Cleaning ................................................................................46 3.2.2 Preparation of Bulk Phases ..............................................................................47 3.2.3 Batch Experiment ............................................................................................47 3.2.4 Continuous Experiment ...................................................................................48 3.2.5 Decay Experiment ...........................................................................................49 3.2.6 Emulsion Layer Water Volume Fraction in Continuous Separation ...............50 3.2.7 Solids Content in Emulsion Layer from Continuous Separations ...................51 3.3 Property Measurements ...........................................................................................51 3.3.1 Particle Size Distribution .................................................................................51 3.3.2 Wettability of Solids ........................................................................................53 3.3.2.1 Contact Angle Measurement .................................................................53 3.3.2.2 Film Flotation Method ...........................................................................54 3.3.3 Drop Size Distribution .....................................................................................55 CHAPTER 4: MODELING ............................................................................................56 4.1 Batch Model .............................................................................................................56