Boiler (power generation)

Abstract: 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

Abstract: Introduction Basic concepts Corrosion kinetics Types of corrosion: materials and environments Cathodic protection Corrosion control by inhibition Coatings Corrosion prevention by design Selection of materials for corrosive environments Atmospheric corrosion Boiler corrosion Concrete corrosion Index

Abstract: The efficiency of conventional boiler/steam turbine fossil power plants is a strong function of the steam temperature and pressure. Research to increase both has been pursued worldwide, since the energy crisis in the 1970s. The need to reduce CO2 emission has recently provided an additional incentive to increase efficiency. Thus, steam temperatures of the most efficient fossil power plants are now in the 600 °C (1112 °F) range, which represents an increase of about 60 °C (108 °F) in 30 years. It is expected that steam temperatures will rise another 50 to 100 °C (90 to 180 °F) in the next 30 years. The main enabling technology is the development of stronger high-temperature materials, capable of operating under high stresses at ever-increasing temperatures. Recently, the EPRI performed a state-of-the-art review of materials technology for advanced boiler/steam turbine power plants (ultrasupercritical power plants). The results of the review show that with respect to boilers, high-strength ferritic 9–12Cr steels for use in thick section components are now commercially available for temperatures up to 620 °C (1150 °F). Initial data on two experimental 12Cr ferritic steels indicate that they may be capable of long-term service up to 650 °C (1112 °F), but more data are required to confirm this. For higher temperatures, austenitic steels and Ni-based alloys are needed. Advanced austenitic stainless steels for use as super and reheater tubing are available for service temperatures up to 650 °C (1112 °F) and possibly 700 °C (1292 °F). Ni-based superalloys would be needed for higher temperatures. None of these steels have been approved by the ASME Boiler Code Group so far. Higher-strength materials are needed for upper water walls of boilers with steam pressure above 24 MPa (3400 psi). A high-strength 2-1/2%Cr steel recently ASME code approved as T-23 is the preferred candidate material for this application. Field trials are in progress. This paper will present the results of the EPRI review in detail, relating to boiler material. Results relating to turbine materials are presented in a companion paper as Part 2.

Abstract: During the last fifty years steam pressure and temperature in fossil-fired power plants have been continuously raised to improve thermal efficiency. Recent efforts for raising steam conditions are in response to the social demand for environmental protection as well as energy conservation concerns. Today the steam temperature of 600°C for modern power plants equipped with swing load or sliding pressure demand functions has already been realized, and a goal for the future is the 630°C to 650°C class with ferritic steels.However the 600°C to 630°C class is possible for current construction, based on already developed materials that include ferritic steels for pipework and rotors. Numerous studies on heat resistant steels actively conducted since the early 1970s have allowed great progress in both 9–12% Cr steels and austenitic steels. This paper presents a historical view of developments in steam pressure and temperature of fossil-fired power plants and alloy design for heat resistant steels in the 20th century, particularly over the last severaldecades, as well as a survey of the current status of steel development for power plants, mainly with regard to creep strengthening and enhancement of corrosion resistance.