Torrefaction and Pelletization of Different Forms of Biomass of Ontario by Bimal Acharya A Thesis

168 Pages·2013·4.77 MB·English

by  Bimal Acharya

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
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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