Combustion and Gasification in Fluidized Beds

Presenting a snapshot of the current state of the field, this is the most practical book available on fluidized bed gasification. It provides comprehensive insight into the working principles of fluidized bed boilers and gasifiers, covering how the equipment works, the basic principles of thermodynamics and fluid mechanics, planning new projects, and the troubleshooting or operating of fluidized bed boilers or gasification plants. In 13 chapters with four appendices and several tables that are useful in designing fluidized bed boilers and gasifiers, Combustion and Gasification in Fluidized Beds gives planners a better appreciation of the process along with its capabilities and its limitations.

Besides being one of the best Clean Coal Technologies, fluidized beds are also proving to be the most practical option for biomass conversion. Although the technology is well established, the field lacks a comprehensive guide to the design and operating principles of fluidized bed boilers and gasifiers. With more than 30 years of research and industrial experience, Prabir Basu answers this pressing need with Combustion and Gasification in Fluidized Beds. This book is a versatile resource that explains how fluidized bed equipment works and how to use the basic principles of thermodynamics and fluid mechanics in design while providing insight into planning new projects, troubleshooting existing equipment, and appreciating the capabilities and limitations of the process. From hydrodynamics to construction and maintenance, the author covers all of the essential information needed to understand, design, operate, and maintain a complete fluidized bed system. It is a must for clean coal technology as well as for biomass power generation. Beginning with a general introduction to fossil or biofuel conversion choices, the book surveys hydrodynamics, fundamentals of gasification, combustion of solid fuels, pollution aspects including climate change mitigation, heat transfer in fluidized beds, the design and operation of bubbling and circulating fluidized bed boilers, and various supporting components such as distributor grates, feeding systems, and gas-solid separators.

INTRODUCTION Background Fluidized Bed Equipment Features of Fluidized Beds Fluidized Bed and Other Clean Coal Options HYDRODYNAMICS Regimes of Fluidization Fast Fluidized Bed Hydrodynamic Regimes in a CFB Hydrodynamic Structure of Fast Beds Gas–Solid Mixing Scale-Up FLUIDIZED BED GASIFICATION Types of Gasifiers Theory Effect of Operating Parameters on Gasification Effect of Feed Properties on Gasification Fluidized Bed Gasification Examples of Some Fluidized Bed Gasifiers Gas Cleaning Design Methods Modeling of Fluidized Bed Gasification Appendix 3A: Estimating Equilibrium Gas Composition Appendix 3B: An Example of a Fluidized Bed Biomass Gasifier COMBUSTION Stages of Combustion Factors Affecting Combustion Efficiency Combustion in Bubbling Fluidized Bed Boilers Combustion in Circulating Fluidized Bed Boilers Biomass Combustion EMISSIONS Air Pollution Sulfur Dioxide Emission Nitrogen Oxide Emission Nitrous Oxide Emission Mercury Emission Carbon Monoxide Emission Carbon Dioxide Emission Emission of Trace Organics Particulate Emission HEAT TRANSFER Gas-to-Particle Heat Transfer Heat Transfer in Circulating Fluidized Beds Heat Transfer in Bubbling Fluidized Bed Freeboard Heat Transfer in Bubbling Fluidized Beds Heat Transfer in Commercial-Size CFB Boilers BUBBLING FLUIDIZED BED BOILER Description of a BFB Boiler Features of BFB Boilers Thermal Design of Bubbling Fluidized Bed Boilers Combustion in Bubbling Fluidized Bed Furnace Design Start-Up Procedure and Control Some Operational Problems and Remedies Design of Feed Systems for BFB Bed Boiler CIRCULATING FLUIDIZED BED BOILER General Arrangement Types of CFB Boilers Non-CFB Solid Circulation Boilers Combustion in a Circulating Fluidized Bed Furnace Design of CFB Boilers Furnace Design Design of Heating Surfaces Auxiliary Power Consumption Control of CFB Boilers Supercritical CFB Boiler MATERIAL ISSUES Material Selection Criteria Erosion Potential Corrosion Potentials Steels Used in Fluidized Bed Boilers Refractory and Insulations Expansion Joints SOLID HANDLING SYSTEMS FOR FLUIDIZED BEDS Solid Handling Systems Biomass Handling Systems Feed System for Bubbling Beds Feed System for Circulating Fluidized Beds Design of Pneumatic Transport Lines for Solids AIR DISTRIBUTION GRATE Distributor Plates Operation of Distributors Design Methods Practical Considerations GAS–SOLID SEPARATORS Cyclones Impact Separator Inertial Separators SOLID RECYCLE SYSTEMS Types of Non-mechanical Valves Principles of Operation Design of Loop-Seal Design of L-Valve Practical Considerations Nomenclature References APPENDIX 1: CHARACTERISTICS OF SOLID PARTICLES APPENDIX 2: STOICHIOMETRIC CALCULATIONS APPENDIX 3: SIMPLIFIED MODEL FOR SULFUR CAPTURE APPENDIX 4: TABLES OF DESIGN DATA

Prabir Basu