Table of Contents. Chapter 1. Introduction. Chapter 2. Hydrodynamics

Transcription

1

2 Table of Contents Chapter 1 Introduction 1.1 Background 1.2 Fluidized Bed Equipment Applications Fluidized Bed Gasifiers Fluidized Bed Boilers Application in Cement Industries 1.3 Features of Fluidized Beds Advantages of Fluidized Bed Boilers Features Specific to CFB Boiler 1.4 Fluidized Bed and Other Technology Options Technological Options for Generation of Power from Solid Fuels Improved Firing Combined-Cycle Plants Cost Implications Chapter 2 Hydrodynamics 2.1 Regimes of Fluidization Packed Beds Bubbling Fluidized Beds Slugging Turbulent Beds Bubbling to Turbulent Transition Terminal Velocity of a Particle Freeboard and Furnace Heights 2.2 Fast Fluidized Bed Characteristics of Fast Beds Transition to Fast Fluidization Dense Suspension Up-Flow 2.3 Hydrodynamic Regimes in a CFB Difference in Operating Regimes of CFB Boilers and Reactors 2.4 Hydrodynamic Structure of Fast Beds Axial Voidage Profile Lateral Distribution of Voidage in a Fast Bed 2.5 Gas Solid Mixing Gas Solid Slip Velocity Dispersion 2.6 Scale-Up Circulating Fluidized Bed Bubbling Fluidized Bed Cyclone

3 Dimensionless Numbers Chapter 3 Fluidized Bed Gasification 3.1 Types of Gasifiers Entrained Bed Fluidized Bed Spouted Bed Fixed/Moving Bed 3.2 Theory Pyrolysis or Devolatilization Combustion Gasification Composition of Gas Yield 3.3 Effect of Operating Parameters on Gasification Boudouard Reaction Water Gas Methanation 3.4 Effect of Feed Properties on Gasification Fuel Reactivity Volatile Matter Ash Moisture 3.5 Fluidized Bed Gasification Comparison of Bubbling and Circulating Fluidized Bed Gasifiers Types of Fluidized Bed Gasifiers 3.6 Examples of Some Fluidized Bed Gasifiers Winkler Gasifier KRW Gasifier Spouted Bed Partial Gasifier Foster Wheeler Atmospheric CFB Gasifier Battelle/Columbus Indirect Gasifier Halliburton KBR Transport Reactor Carbon Dioxide Acceptor Process 3.7 Gas Cleaning Sulfur and Other Chemical Contaminants Removal Tar Removal Particulate Removal 3.8 Design Considerations Gasifier Efficiency Equivalence Ratio Gas Composition Energy and Mass Balance Bed Materials Gasifier Sizing Alternative Design Approach 3.9 Modeling of Fluidized Bed Gasification Appendix 3A Estimating Equilibrium Gas Composition

4 Appendix 3B An Example of a Fluidized Bed Biomass Gasifier Chapter 4 Combustion 4.1 Stages of Combustion Heating and Drying Devolatilization Volatile Combustion Char Combustion Burning Rate of Char in Fluidized Beds Communition Phenomena during Combustion 4.2 Factors Affecting Combustion Efficiency Feed Stock Operating Conditions 4.3 Combustion in Bubbling Fluidized Bed Boilers Recirculation of Fly Ash Effect of Design Parameters on Combustion Efficiency 4.4 Combustion in Circulating Fluidized Bed Boilers Combustion of Char Particles Effect of Cyclone Design on Combustion Efficiency Some Combustion Design Considerations Performance Modeling 4.5 Biomass Combustion Agglomeration Fouling Corrosion Potential in Biomass Firing Dimensionless Numbers Chapter 5 Emissions 5.1 Air Pollution Pollutants Emission Standards 5.2 Sulfur Dioxide Emission Chemical Reactions Reactions on Single Sorbent Particles Reactivity of Sorbents Sulfur Capture in Fluidized Beds Simple Model for Sulfur Capture in CFB Boilers Selection of Sorbent 5.3 Nitrogen Oxide Emission Sources of NO x Methods of Reduction of NO x Emissions NO x Emission from CFB

5 5.4 Nitrous Oxide Emission Mechanism of Formation of N 2 O in CFB Effects of Operating Parameters on N 2 O Reduction of N 2 O 5.5 Mercury Emission Sorbent Injection Electro-Catalytic Oxidation Precombustion Technologies 5.6 Carbon Monoxide Emission 5.7 Carbon Dioxide Emission 5.8 Emission of Trace Organics 5.9 Particulate Emission Ash Characteristics Chapter 6 Heat Transfer 6.1 Gas-to-Particle Heat Transfer Gas-to-Particle Heat Transfer Equations Heating of Gas and Solids in the Fast Bed 6.2 Heat Transfer in Circulating Fluidized Beds Mechanism of Heat Transfer Theory Experimental Observations in a CFB Boiler Effect of Vertical Fins on the Walls 6.3 Heat Transfer in Bubbling Fluidized Bed Mechanistic Model Experimental Observations in Bubbling Fluidized Beds Heat-Transfer Correlation in Bubbling Beds Use of Design Graphs Calculation Based on Tables 6.4 Freeboard Heat Transfer in Bubbling Fluidized Beds 6.5 Heat Transfer in Commercial-Size CFB Boilers Heat Transfer to the Walls of Commercial CFB Boilers Wing Walls Heat-Transfer Variation along the Furnace Height Circumferential Distribution of Heat-Transfer Coefficient Dimensionless Numbers Chapter 7 Bubbling Fluidized Bed Boiler 7.1 Description of a BFB Boiler Feedstock Preparation and Feeding Air and Gas Handling Ash and Emission Systems Steam Generation System Combustion Chamber

6 7.2 Features of BFB Boilers Advantages Limitations 7.3 Thermal Design of Bubbling Fluidized Bed Boilers Overall Heat Balance of the Boiler Boiler Efficiency Energy Balance in Dense Bubbling Bed Heat Balance of Boiler Components Mass Flow Rates of Fuel and Air Gas-Side Heat Balance 7.4 Combustion in Bubbling Fluidized Bed Coal Combustion in BFB Boilers Minimization of Combustible Losses in BFB Combustors 7.5 Furnace Design Basic Design of Furnace Part-Load Operations Other Operating Conditions 7.6 Start-Up Procedure and Control Start-Up Procedure Control of BFB Boiler 7.7 Some Operational Problems and Remedies Erosion of In-Bed Components 7.8 Design of Feed Systems for BFB Bed Boiler Chapter 8 Circulating Fluidized Bed Boiler 8.1 General Arrangement Air System Flue Gas Stream Solid Stream Water Steam Circuit 8.2 Types of CFB Boilers Boilers without Bubbling Bed Heat Exchangers Boilers with Bubbling Fluidized Bed Heat Exchanger Boilers with Inertial or Impact Separators Boilers with Vertical, Noncircular Cyclones Other Types 8.3 Non-CFB Solid Circulation Boilers Circo-Fluid Boilers Low-Solid Circulation Boiler Circulating Moving Bed Boiler 8.4 Combustion in a Circulating Fluidized Bed Furnace 8.5 Design of CFB Boilers Combustion Calculations Heat Balance Mass Balance Flow Split Control of Bed Inventory Some Operating Issues

7 8.6 Furnace Design Furnace Cross-Section Width and Breadth Ratio Furnace Openings 8.7 Design of Heating Surfaces Effect of Fuel Type on Furnace Heat Load Heat Absorption in the External Heat Exchanger Heat Absorption in the Furnace and Rest of the Boiler Heat Balance around a CFB Loop 8.8 Auxiliary Power Consumption 8.9 Control of CFB Boilers Part-Load Operation Load Control Options 8.10 Supercritical CFB Boiler Supercritical Operation Vertical vs. Wrapped Tube Arrangement Low Heat Flux Cost Advantage Chapter 9 Material Issues 9.1 Material Selection Criteria Structural Requirements Heat-Transfer Duty 9.2 Erosion Potential Basics of Erosion Types of Erosion Erosion in Bubbling Fluidized Beds Options for Reduction of Erosion in Bubbling Beds Erosion in CFB Boilers 9.3 Corrosion Potentials Corrosion Mechanisms Examples of Fire-Side Corrosion Chemistry of Fire-Side Corrosion of Heating Surfaces Chlorine Corrosion Vanadium Corrosion Prevention of High-Temperature Corrosion Erosion Corrosion Fouling and Deposit Formation 9.4 Steels Used in Fluidized Bed Boilers Carbon and Alloy Steels 9.5 Refractory and Insulations Importance of Lining Properties of Refractory Types of Refractory Types of Insulation Anchors Design Considerations of Lining Areas of Refractory Use in Fluidized Bed Boilers

8 9.5.8 Failure Analysis Refractory Maintenance 9.6 Expansion Joints Chapter 10 Solid Handling Systems for Fluidized Beds 10.1 Solid Handling Systems Fossil Fuel Plants Municipal Solid Waste 10.2 Biomass Handling Systems Feeding of Harvested Fuels Feeding of Nonharvested Fuels 10.3 Feed System for Bubbling Beds Types of Feeders Mode of Feeding in Bubbling Beds Feed Point Allocation 10.4 Feed System for Circulating Fluidized Beds Fuel Feed Ports Limestone Feed System 10.5 Design of Pneumatic Transport Lines for Solids Pressure Drop in a Pneumatic Transport Line Design of a Pneumatic Injection System Fuel Splitter Chapter 11 Air Distribution Grate 11.1 Distributor Plates Plate-Type Distributor Nozzle-Type Distributor Sparge Pipe Distributor Distributor Grids for CFB Distributor Grids for Bubbling Beds 11.2 Operation of Distributors What Causes Nonuniform Fluidization 11.3 Design Methods Design Procedure for Bubbling Fluidized Beds Design Procedure for Circulating Fluidized Beds 11.4 Practical Considerations Plenum or Air Box Sealing of Distributor Attrition Back-Flow of Solid Opening and Closing of Nozzles Erosion and Corrosion of Nozzles

9 Chapter 12 Gas Solid Separators 12.1 Cyclones Types of Cyclone Theory Critical Size of Particles Working of Cyclones for CFB Combustors or Gasifiers Pressure Drop through a Cyclone Cyclone Collection Efficiency Reentrainment of Solids Cyclone Geometry Effect of the Vortex Finder Practical Considerations for CFB Cyclones 12.2 Impact Separator Features and Types Separation through Impaction Separation through Interception Grade Efficiency of Impingement Collectors Some Types of Impact Separators 12.3 Inertial Separators Separation through Gravity Settling Cavity Separator Design Steps Chapter 13 Solid Recycle Systems 13.1 Types of Nonmechanical Valves Loop- Seal L-Valve V-Valve 13.2 Principles of Operation Solid Flow from Standpipe to Recycle Chamber Flow of Solids through Recycle Chamber 13.3 Design of Loop-Seal Pressure Balance Size of Loop- Seal Air-Flow through Loop- Seal 13.4 Design of L-Valve Maximum Solid Flow Rate Additional Design Considerations 13.5 Practical Considerations Plugging of Loop-Seal Pressure Surge Avoiding Loop-Seal Plugging

10 Appendix 1 Characteristics of Solid Particles A1.1 Solid Particles A1.1.1 Equivalent Diameters A1.1.2 Sphericity (f) A1.1.3 Mean Particle Size and Its Measurement A1.2 Packing Characteristics A1.3 Particle Classification A1.3.1 Group C A1.3.2 Group A A1.3.3 Group B A1.3.4 Group D Appendix 2 Stoichiometric Calculations A2.1 Chemical Reactions A2.2 Air Required A2.3 Sorbent Requirement A2.4 Solid Waste Produced A2.5 Gaseous Waste Products A2.5.1 Carbon Dioxide A2.5.2 Water Vapor A2.5.3 Nitrogen A2.5.4 Oxygen A2.5.5 Sulfur Dioxide A2.5.6 Fly Ash A2.6 Heating Value of Fuels Reference Appendix 3 Simplified Model for Sulfur Capture Appendix 4 Tables of Design Data