Torrefaction and Pelletization of Different Forms of Biomass of Ontario by Bimal Acharya A Thesis Presented to The University of Guelph In partial fulfillment of requirements for the degree of Master of Applied Science in Engineering © Bimal Acharya, March, 2013 ii ABSTRACT Torrefaction and Pelletization of Different Forms of Biomass of Ontario Bimal Acharya Advisor University of Guelph, 2013 Dr. Animesh Dutta The purpose of this study is to investigate the torrefaction and pelletization behavior, hydrophobicity, storage behavior, ash analysis on three different biomasses: one (willow pellets) from wood products, one (oat pellets) from agricultural products and one (poultry litter) from the non-lignocellulosic biomass products during the processes. Four different torrefaction temperatures from 200°C-300°C, at 10-60 minute residence times, 0%-2.4% oxygen concentration, were considered. Of these, 285°C for willow pellets, 270°C for oat pellets and 275°C for poultry litter were found to be optimum for hydrophobicity. Studies of XRD and SEM of biomass ash at 800°C, 900°C and 1000°C were also carried out. The aforementioned results indicate that torrefaction is a feasible alternative to improve energy properties of ordinary biomass and prevent moisture re- absorption during storage. iii ACKNOWLEDGEMENTS I would firstly like to acknowledge my graduate advisor Dr. Animesh Dutta P.Eng., for his thoughtful insight and support throughout my graduate career. His mentorship extended beyond the walls of the University and his support allowed me to obtain several prestigious awards and compete in Biological Engineering. I would also like to extend my appreciation towards Dr. Shohel Mohmud who provided insight throughout the duration of my research. These acknowledgements would not be complete without naming the following individuals for their supports: Dr. Mathias Leon: thanks for English correction and guidance in the lab setup; John Whiteside, Joanne Ryks(School of Engineering): thanks for providing lab support; and to my colleagues: Idris Sule, Dr Poritosh Roy, Maxime Moisan, and Mohammad Tushar. I am glad our journeys have crossed paths and I hope this is just the beginning of a lasting friendship. I would lastly like to make personal acknowledgements to my family and friends. To my mother, father, brother and sister who throughout my life always encouraged higher education and a quest for knowledge. Special gratitude to my employer Nepal Telecom for granting me study leave to pursue graduate study from a Canadian University. Finally, to my wife and best friend Sushma Acharya, son Bibhu and daughter Suyasha, who has always wholeheartedly supported me throughout my scholarly achievements. iv TABLE OF CONTENTS ABSTRACT ....................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................... iii TABLE OF CONTENTS .................................................................................................. iv LIST OF TABLES ............................................................................................................. ix LIST OF FIGURES .............................................................................................................x NOMECLATURE .............................................................................................................xv Chapter I: Introduction ........................................................................................................1 1.1 Introduction ...................................................................................................... 1 1.2 Objectives ......................................................................................................... 4 1.3 Organization of the Thesis ................................................................................ 5 Chapter II: Literature Review ..............................................................................................6 2.1 Overview .......................................................................................................... 6 2.1.1 Fuel Characteristics of Biomass.................................................................... 7 2.1.2 Biomass Components.................................................................................... 8 2.2 Concept of Torrefaction .................................................................................. 11 2.3 Torrefaction Process Methods ........................................................................ 18 2.4 Classification of Reactors ............................................................................... 20 2.5 Commercial Application of Torrefaction in Canada ...................................... 26 2.6 Available Technologies for Torrefaction ....................................................... 29 2.7 Pelletization .................................................................................................... 31 2.8 Gasification ..................................................................................................... 36 v 2.9 Emission ......................................................................................................... 38 2.10 Storage Behavior ............................................................................................ 38 2.11 Economic Potential ......................................................................................... 40 2.12 Scanning Electron Microscopy (SEM) ........................................................... 43 2.13 X-ray Diffraction (XRD) ................................................................................ 45 2.14 Summary from Literature ............................................................................... 46 Chapter III: Methodology ..................................................................................................49 3.0 Problem Statement .......................................................................................... 49 3.1 Research Scope and Objectives ...................................................................... 50 3.2 Methodology ................................................................................................... 52 Chapter IV: Experiment Setup ...........................................................................................54 4.1 Biomass Characterization ............................................................................... 54 4.1.1 Proximate Analysis ......................................................................................... 54 4.1.2 Ultimate Analysis ........................................................................................... 54 4.1.3 Heating Value ................................................................................................. 54 4.2 Torrefaction .................................................................................................... 55 4.3 Hydrophobicity ............................................................................................... 58 4.4 Pelletization .................................................................................................... 58 4.5 Storage Behaviour .......................................................................................... 60 4.6 Scanning Electron Microscopy (SEM) ........................................................... 60 4.7 X-ray Diffraction (XRD) ................................................................................ 62 Chapter V: Results and Analysis .......................................................................................63 5.1 Poultry Litter Biomass .................................................................................... 63 vi 5.1.1 Biomass Characterization ........................................................................... 63 5.1.2 Torrefaction................................................................................................. 65 5.1.3 Hydrophobicity ........................................................................................... 68 5.1.4 Storage Behavior ......................................................................................... 69 5.1.5 Optimization by Box Behnken Model ........................................................ 70 5.1.6 Scanning Electron Microscopy (SEM) ....................................................... 74 5.1.8 Summary ..................................................................................................... 77 5.2 Willow Pellets................................................................................................. 78 5.2.1 Biomass Characterization ........................................................................... 78 5.2.2 Torrefaction................................................................................................. 81 5.2.4 Hydrophobicity ........................................................................................... 84 5.2.5 Storage Behavior ......................................................................................... 86 5.2.6 Pelletization................................................................................................. 88 5.2.7 Scanning Electron Microscope (SEM) ....................................................... 91 5.2.9 Summary ..................................................................................................... 95 5.3 Oat Pellets ....................................................................................................... 96 5.3.1 Biomass Characterization ........................................................................... 97 5.3.2 Torrefaction................................................................................................. 99 5.3.4 Hydrophobicity ......................................................................................... 102 5.3.5 Storage Behavior ....................................................................................... 104 vii 5.3.6 Pelletization............................................................................................... 105 5.3.7 Scanning Electron Microscope (SEM) ..................................................... 107 5.3.9 Summary ................................................................................................... 111 5.4 Comparative Analysis................................................................................... 112 5.4.1 Biomass Characterization ......................................................................... 112 5.4.2 Torrefaction............................................................................................... 116 5.4.3 Hydrophobicity ......................................................................................... 119 5.4.4 Storage Behavior and Moisture Uptake .................................................... 120 5.4.5 Ash Analysis ............................................................................................. 121 5.4.6 Summary ................................................................................................... 123 5.5 Errors and Repeatability Test ....................................................................... 124 Chapter VI: Conclusions and Recommendations ............................................................125 6.1 Conclusions .................................................................................................. 125 6.2 Recommendations ........................................................................................ 127 Chapter VII: References ..................................................................................................129 Chapter VIII: Appendix ...................................................................................................141 Appendix A: Photographs of Willow Pellets .............................................................. 141 Appendix B: Photographs of Oats Pellets ................................................................... 142 Appendix C: Methods and Equipment used in Characterizing Biomass .................... 143 Appendix D: Photograph of Experimental Setup for Torrefaction ............................. 144 Appendix E: Gas Analyzer ......................................................................................... 145 viii Appendix F: Ultimate Analysis, Ash Fusion Temp and Ash Elemental Analysis ..... 146 Appendix G: Error and Repeatibility Tests ................................................................ 148 ix LIST OF TABLES Table Page No. Table 2-1 Summary of Torrefied pellets Properties versus Coal 18 Table 2-2 Comparison of Potential Torrefaction Reactor Technologies 26 Table 2-3 Overview of Torrefaction Projects 30 Table 2-4 Summary of Specifications for Four Different Pelleting 33 Equipment Table 2-5 Comparison of BO2 Pellet Properties 36 Table 5-1 Proximate Analysis of Raw Biomass 112 Table 5-2 Ultimate Analysis and Heating Value of Raw Biomass 113 x LIST OF FIGURES Figures Page No. Figure1.1 Energy Density vs. Time and Temperature 3 Figure 2-1 Structure and Pretreatment effect on Biomass 9 Figure 2-2 Carbohydrate in the presence of Carbon Monoxide 10 Figure 2-3 Decomposition regimes of lignocellulosic material during 13 thermal treatment Figure 2-4 Basic principle of torrefaction Process 20 Figure 2-5 Pictures of raw and pelletized materials 34 Figure 2-6 Schematic Process Flow of the BO2-Technology 35 Figure 2-7 Delivery costs of pelletized biomass. (Numbers indicate 40 nominal capacity of system dry kilotons of raw biomass feedstock per year) Figure 2-8 SEM of Wood Ash from Gasifier 45 Figure 3-1 Schematic Block Diagram of Research Procedures 51 Figure 3-2 Flow chart of the methodology 53 Figure 4-1 Experimental Setup for Torrefaction and Weight loss 57 Figure 4-2 Experimental Setup for Pelletization 59 Figure 4-3 SEM Experimental Setup 62 Figure 5-1 Volatile Matter vs. Residence Time for Poultry Litter 64 Figure 5-2 Fixed Carbon vs. Residence Time for Poultry Litter 64 Figure 5-3 Ash Contents vs. Residence Time for Poultry Litter 65