Front Cover -- Biomass Gasification, Pyrolysis, and Torrefaction -- Copyright Page -- Dedication -- Contents -- Preface -- Acknowledgments -- About the Author -- 1 Introduction -- 1.1 Biomass and its Products -- 1.1.1 Products of Biomass -- 1.1.1.1 Chemicals Industries -- 1.1.1.2 Energy Industries -- 1.1.1.3 Transport Industries -- 1.1.1.4 Environmental Industries -- 1.2 Biomass Conversion -- 1.2.1 Biochemical Conversion -- 1.2.2 Thermochemical Conversion -- 1.2.2.1 Combustion -- 1.2.2.2 Pyrolysis -- 1.2.2.3 Torrefaction -- 1.2.2.4 Gasification -- 1.2.2.5 Liquefaction -- 1.3 Motivation for Biomass Conversion -- 1.3.1 Renewability Benefits -- 1.3.2 Environmental Benefits -- 1.3.2.1 Carbon-Neutral Feature of Biomass -- 1.3.2.2 Sulfur Removal -- 1.3.2.3 Nitrogen Removal -- 1.3.2.4 Dust and Hazardous Gases -- 1.3.3 Sociopolitical Benefits -- 1.4 Historical Background -- 1.5 Commercial Attraction of Gasification -- 1.5.1 Comparison of Gasification and Combustion -- 1.6 Brief Description of Some Biomass Conversion Processes -- 1.6.1 Torrefaction -- 1.6.2 Pyrolysis -- 1.6.3 Combustion of Carbon -- 1.6.4 Gasification of Carbon -- 1.6.5 Syngas Production -- 1.6.6 Methanol Synthesis -- 1.6.7 Ammonia Synthesis -- 1.6.8 Fischer-Tropsch Reaction -- 1.6.9 Methanation Reaction -- Symbols and Nomenclature -- 2 Economic Issues of Biomass Energy Conversion -- 2.1 Introduction -- 2.2 Biomass Availability and Products -- 2.2.1 Availability Assessment -- 2.2.1.1 Energy Crop -- 2.2.1.2 Biomass Cost -- 2.2.2 Product Revenue from Biomass Conversion -- 2.2.2.1 Energy Revenue -- 2.2.2.2 Revenue from Chemicals -- 2.2.2.3 Revenue from Secondary Fuel Production -- 2.3 Biomass Conversion Process Plant Equipment and Cost -- 2.3.1 Biomass Collection System -- 2.3.2 Preprocessing -- 2.3.3 Gasifier Cost -- 2.3.4 Torrefier Cost -- 2.3.5 Pyrolyzer Cost.

2.3.6 Comparison of Capital Costs -- 2.4 Financial Analysis -- 2.4.1 Capital Cost Adjustment for Size and Time -- 2.4.1.1 Scale-Up with Size -- 2.4.1.2 Scale-Up with Time -- 2.4.2 Capital Requirement -- 2.4.3 Operation and Maintenance Cost -- 2.4.3.1 Carrying Charge -- 2.4.3.2 Revenue Requirement -- Symbols and Nomenclature -- 3 Biomass Characteristics -- 3.1 Introduction -- 3.2 What Is Biomass? -- 3.2.1 Biomass Formation -- 3.2.2 Types of Biomass -- 3.2.2.1 Lignocellulosic Biomass -- 3.2.2.2 Crops and Vegetables -- 3.2.2.3 Waste Biomass -- 3.3 Structure of Biomass -- 3.3.1 Structure of Wood -- 3.3.2 Constituents of Biomass Cells -- 3.3.2.1 Cellulose -- 3.3.2.2 Hemicellulose -- 3.3.2.3 Lignin -- 3.4 General Classification of Fuels -- 3.4.1 Atomic Ratio -- 3.4.2 Relative Proportions of Lignocellulosic Components -- 3.4.3 Ternary Diagram -- 3.5 Properties of Biomass -- 3.5.1 Physical Properties -- 3.5.1.1 Densities -- True Density -- Apparent Density -- Bulk Density -- Biomass (Growth) Density -- 3.5.2 Thermodynamic Properties -- 3.5.2.1 Thermal Conductivity -- 3.5.2.2 Specific Heat -- 3.5.2.3 Heat of Formation -- 3.5.2.4 Heat of Combustion (Reaction) -- 3.5.2.5 Heating Value -- 3.5.2.6 Ignition Temperature -- 3.6 Composition of Biomass -- 3.6.1 Ultimate Analysis -- 3.6.2 Proximate Analysis -- 3.6.2.1 Volatile Matter -- 3.6.2.2 Ash -- 3.6.2.3 Moisture -- Basis of Expressing Moisture -- Fixed Carbon -- Char -- 3.6.3 Thermogravimetric Analysis -- 3.6.4 Bases of Expressing Biomass Composition -- 3.6.4.1 As-Received Basis -- 3.6.4.2 Air-Dry Basis -- 3.6.4.3 Total Dry Basis -- 3.6.4.4 Dry Ash-Free Basis -- 3.6.5 Heating Value of Fuel -- 3.6.5.1 Higher Heating Value (HHV) -- 3.6.5.2 Lower Heating Value (LHV) -- 3.6.5.3 Bases for Expressing Heating Values -- 3.6.5.4 Estimation of Biomass Heating Values.

3.6.6 Stoichiometric Calculations for Complete Combustion -- 3.6.6.1 Amount of Product Gas of Complete Combustion -- 3.6.6.2 Composition of the Product of Combustion -- 3.6.7 Composition of the Product Gas of Gasification -- Symbols and Nomenclature -- Subscripts -- 4 Torrefaction -- 4.1 Introduction -- 4.2 What Is Torrefaction? -- 4.2.1 Pyrolysis, Carbonization, and Torrefaction -- 4.2.1.1 Difference Between Carbonization, Pyrolysis, and Torrefaction -- 4.3 Carbonization -- 4.3.1 Charcoal Fuel -- 4.3.2 Activated Charcoal -- 4.3.3 Biocoke -- 4.3.4 Biochar -- 4.4 Torrefaction Process -- 4.4.1 Heating Stages -- 4.4.1.1 Predrying -- 4.4.1.2 Drying -- 4.4.1.3 Postdrying Heating -- 4.4.1.4 Torrefaction -- 4.4.1.5 Cooling -- 4.4.2 Mechanism of Torrefaction -- 4.4.3 Effect of Design Parameters on Torrefaction -- 4.4.3.1 Temperature -- Core Temperature Rise -- 4.4.3.2 Residence Time -- 4.4.3.3 Biomass Type -- 4.4.3.4 Feed Size -- 4.5 Degree of Torrefaction -- 4.5.1 Mass Yield -- 4.5.2 Energy Density -- 4.5.3 Energy Yield -- 4.6 Physical Properties of Torrefied Biomass -- 4.6.1 Density and Volume -- 4.6.2 Grindability -- 4.6.2.1 Effect of Torrefaction Parameters on Grinding -- 4.6.3 Hydrophobicity of Torrefied Biomass -- 4.6.3.1 Why Biomass Becomes Hydrophobic after Torrefaction? -- 4.6.4 Explosion Potential of Torrefied Dust -- 4.6.5 Densification or Pelletization -- 4.7 Torrefaction Technologies -- 4.7.1 Classification of Torrefaction Reactors -- 4.7.1.1 Classification on Mode of Heating -- Directly Heated Reactors -- Convective Reactor (Moving/Fixed/Entrained Bed) -- Fluidized Bed -- Hydrothermal Reactor -- Indirectly Heated Reactors -- Rotating Drum -- Screw or Stationary Shaft -- Microwave -- 4.7.1.2 Classification on Mode of Gas-Solid Mixing -- 4.8 Design Methods -- 4.8.1 Design of Torrefaction Plant -- 4.8.1.1 Choice of Reactor Type.

4.8.1.2 Design Approach -- Design Input -- Mass and Energy Balance -- Dryer -- Torrefier -- Cooler -- Burner -- Unit Sizing -- Predrying Section -- Drying and Postdrying Sections -- Torrefier Section -- Burner Design -- Symbols and Nomenclature -- Subscripts -- Greek symbol -- Appendix: Mass and Energy Balance of Torrefier -- Assumptions -- Mass Balance -- Torrefier -- Oil Burner -- Energy Balance -- Torrefier: Control Volume of Torrefaction Zone -- Oil Burner: Control Volume of Oil Burner -- 5 Pyrolysis -- 5.1 Introduction -- 5.1.1 Historical Background -- 5.2 Pyrolysis -- 5.2.1 Pyrolysis Products -- 5.2.1.1 Liquid -- 5.2.1.2 Solid -- 5.2.1.3 Gas -- 5.2.2 Types of Pyrolysis -- 5.2.2.1 Slow Pyrolysis -- 5.2.2.2 Fast Pyrolysis -- 5.2.2.3 Flash Pyrolysis -- 5.2.2.4 Ultrarapid Pyrolysis -- 5.2.2.5 Pyrolysis in the Presence of a Medium -- 5.3 Pyrolysis Product Yield -- 5.3.1 Effect of Biomass Composition -- 5.3.2 Effect of Pyrolysis Temperature -- 5.3.3 Effect of Heating Rate -- 5.3.4 Effect of Particle Size -- 5.4 Pyrolysis Kinetics -- 5.4.1 Physical Aspects -- 5.4.2 Chemical Aspects -- 5.4.2.1 Cellulose -- 5.4.2.2 Hemicellulose -- 5.4.2.3 Lignin -- 5.4.3 Kinetic Models of Pyrolysis -- 5.4.3.1 One-Stage Global Single-Reaction Model -- 5.5 Heat Transfer in a Pyrolyzer -- 5.5.1 Mass Transfer Effect -- 5.5.2 Is Pyrolysis Autothermal? -- 5.6 Pyrolyzer Types -- 5.6.1 Fixed-Bed Pyrolyzer -- 5.6.2 Bubbling-Bed Pyrolyzer -- 5.6.3 CFB Pyrolyzer -- 5.6.4 Ultrarapid Pyrolyzer -- 5.6.5 Ablative Pyrolyzer -- 5.6.6 Rotating-Cone Pyrolyzer -- 5.6.7 Vacuum Pyrolyzer -- 5.7 Pyrolyzer Design Considerations -- 5.7.1 Production of Liquid Through Pyrolysis -- 5.8 Biochar -- 5.8.1 Potential Benefits of Biochar -- Symbols and Nomenclature -- 6 Tar Production and Destruction -- 6.1 Introduction -- 6.2 Tar -- 6.2.1 Acceptable Limits for Tar -- 6.2.1.1 Level of Tar Production.

6.2.2 Tar Formation -- 6.2.3 Tar Composition -- 6.2.3.1 Primary Tar -- 6.2.3.2 Secondary Tar -- 6.2.3.3 Tertiary Tar -- 6.3 Tar Reduction -- 6.3.1 In Situ Tar Primary Reduction -- 6.3.1.1 Reduction Reactions -- 6.3.1.2 Operating Conditions -- Temperature -- Reactor Pressure -- Residence Time -- Gasification Medium -- 6.3.1.3 Tar Reduction by Catalysts in Fluidized-Bed Gasifiers -- Dolomite -- Olivine -- Alkali -- Nickel -- Char -- 6.3.1.4 Gasifier Design -- Updraft Gasifier -- Downdraft Gasifier -- Fluidized-Bed Gasifier -- Entrained-Flow Gasifier -- 6.3.1.5 Design Modifications for Tar Removal -- 6.3.2 Postgasification-Secondary Reduction of Tar -- 6.3.2.1 Physical Tar Removal -- Cyclones -- Barrier Filters -- Wet Electrostatic Precipitators -- Wet Scrubbers -- Alkali Remover -- Disposal of Collected Tar -- 6.3.2.2 Cracking -- 7 Gasification Theory -- 7.1 Introduction -- 7.2 Gasification Reactions and Steps -- 7.2.1 Gasifying Medium -- 7.3 The Gasification Process -- 7.3.1 Drying -- 7.3.2 Pyrolysis -- 7.3.3 Char Gasification Reactions -- 7.3.3.1 Speed of Char Reactions -- 7.3.3.2 Boudouard Reaction -- 7.3.3.3 Water-Gas Reaction -- 7.3.3.4 Shift Reaction -- 7.3.3.5 Hydrogasification Reaction -- 7.3.4 Char Combustion Reactions -- 7.3.5 Catalytic Gasification -- 7.3.5.1 Catalyst Selection -- 7.3.6 Gasification Processes in Reactors -- 7.3.6.1 Moving-Bed Reactor -- 7.3.6.2 Fluidized-Bed Reactor -- 7.3.6.3 Entrained-Flow Reactor -- 7.4 Kinetics of Gasification -- 7.4.1 Chemical Equilibrium -- 7.4.1.1 Reaction Rate Constant -- 7.4.1.2 Gibbs Free Energy -- 7.4.1.3 Kinetics of Gas-Solid Reactions -- 7.4.1.4 Boudouard Reaction -- 7.4.1.5 Water-Gas Reaction -- 7.4.1.6 Hydrogasification Reaction -- 7.4.1.7 Steam Reforming of Hydrocarbon -- 7.4.1.8 Kinetics of Gas-Phase Reactions -- 7.4.2 Char Reactivity -- 7.4.2.1 Effect of Pyrolysis Conditions.

7.4.2.2 Effect of Mineral Matter in Biomass.