Title Page
Abstract
Contents
Chapter 1. Overall Introduction 19
1-1. Current Status of Korean Electric Supply 19
1-2. Current Status of Various Thermoelectric Power Plants in Korea 21
1-3. Problems of The National Coal-fired Power Plants 26
1-4. Literature Review 28
References 29
Chapter 2. Design Study to Enhance Performance and Wear Resistance of the PA Nozzle for CFBC Boiler 30
2.1. Introduction 30
2.2. Literature Review 34
2-2-1. Working Principle of CFBC Boiler 34
2-2-2. Pros and Cons of CFBC Boiler 35
2-2-3. Operational elements of CFBC Boiler 37
2-2-4. PA nozzles in CFBC Boiler 39
2-2-5. Pressure Drop of PA Nozzle 41
2-2-6. Abrasive Behavior of PA nozzle 42
2.3. Methodology 46
2-3-1. Modeling Bottom Airflow Part of CFBC Boiler 46
2-3-2. Shape Selection and Design Optimization of PA Nozzle 46
2-3-3. Initial and Boundary Conditions of the Bottom Airflow Part of CFBC Boiler for CFD Analysis 47
2-3-4. Analysis and Evaluation 47
2.4. Results 49
2-4-1. Macroscopic Turbulence Behavior in CFBC Boiler 49
2-4-2. Shape and Flow Analysis of PA Nozzle 50
2-4-3. Flow Analysis After Outlet Area Expansion of PA Nozzle 54
2-4-4. Flow Change Depending on Vanes in PA Nozzle 56
2-4-5. Flow Visualization of PA Nozzle with Vanes 61
2.5. Conclusions 65
References 66
Chapter 3. Wear Properties of PA Nozzle for CFBC Boiler for Different Materials 67
3.1. Introduction 67
3.2. Literature Review 67
3-2-1. Types and Classifications of Cast Steel 67
3-2-2. Effect of the Other Additional Elements Rather Than Ni and Cr on Cast Steel 70
3-2-3. Types and Characteristics of Heat Resistant Steel 74
3-2-4. Casting Process of Heat Resistant Steel 76
3.3. Methodology 79
3-3-1. Alloy Design Methods 79
3-3-2. Casting Samples 80
3-3-3. Mechanical Property Analysis 81
3-3-4. Manufacturing a Sample for Verification Test, and Performing Verification Experiment 86
3.4. Results 90
3-4-1. Result of Phase Fraction Analysis Using J-Mat Pro 90
3-4-2. Hardness and High-temperature Strength Simulation for Different Compositions by J-Mat Pro 92
3-4-3. Simulating High-temperature Strength for Different Compositions Using J-Mat Pro 98
3-4-4. Material Selection and Analysis through J-Mat Pro 101
3-4-5. Result of Verification Test 104
3.5. Conclusions 115
References 117
Chapter 4. Antiseizing Solution: Resonance Frequency Generator to Impede Coal Adhesion to Coal Conveyor Chute 119
4.1. Introduction 119
4.2. Literature Review 125
4-2-1. Concept and Examples of Resonance 125
4-2-2. Mathematics of Resonance 129
4-2-3. A Method for Coal Desorption 130
4.3. Methodology 132
4-3-1. Modeling Coal Chute #5-6 in Dangjin Coal-fired Power Plant and Boundary Conditions for Analysis 132
4-3-2. Manufacturing Test Module of Coal Chute #5-6 in Dangjin Coal-fired Power Plant 134
4-3-3. Coal Property Analysis 135
4-3-4. Design and Manufacturing Rotary woofer for Vibration Control 137
4-3-5. Coal Desorption Test at Different Frequencies 138
4.4. Results 139
4-4-1. Results of Modeling and Modal Analysis Result of Chute 139
4-4-2. Characteristics and Resonance Frequency of Compressed Coal 145
4-4-3. Design and Manufacturing Rotary Woofer 146
4-4-4. Measuring Resonance Frequency of Experimental Coal Chute 157
4-4-5. Coal Desorption Rate of Experimental Coal Chute for Different Frequencies 172
4.5. Conclusions 176
References 177
Chapter 5. Overall Conclusions 178
5.1. Study on the Shape of PA Nozzles in CFBC Boiler for Improvement of Efficiency and Abrasion Resistance 178
5.2. Material Improvement of PA Nozzles in CFBC Boiler for High Abrasion Resistance 179
5.3. Vibrational Solution to Antiseize Coal Inside Coal Conveying Chute 180
References 182
Table 1-1. Current Status of 500MW Coal-fired Power Plant Operation 25
Table 1-2. Current Status of 800MW Coal-fired Power Plant Operation 25
Table 1-3. Current Status of 1000MW Coal-fired Power Plant Operation 25
Table 2-1. Pros and Cons of CFBC Boiler 35
Table 2-2. Major Operational Elements of CFBC Boiler 38
Table 3-1. Cast Steel Classifications for Different Workable Temperatures 68
Table 3-2. Cast Steel Classifications for Different Chemical Compositions 69
Table 3-3. Classifications of Heat Resistant Steel for Different Cr and Ni Contents 74
Table 3-4. Heat Resistant Steel Classification by ACI 75
Table 3-5. Compositions of the Existing PA Nozzle 79
Table 3-6. Compositions of the Five Samples 80
Table 3-7. Compositions of the Sand Cast Samples 101
Table 3-8. Hardness Test Result of the New Samples 102
Table 3-9. Tensile Test of the New Samples with 12mm of Thickness 102
Table 3-10. High-temperature Tensile Properties of the New Samples 103
Table 3-11. Wear Test Result of the New Samples 103
Table 3-12. Selection Index of the New Samples for Material Selection 104
Table 3-13. Weight Change of the Existing PA Nozzles 106
Table 3-14. Weight Change of the New PA Nozzles with V-Type Vanes 107
Table 3-15. Measurement of the Flowing Back Fluid Sand through the Existing PA Nozzles 114
Table 3-16. Measurement of the Flowing Back Fluid Sand through the PA Nozzles with V-type Vanes 114
Table 4-1. Desorption Rate and Weight of Coal in Different Frequencies 173
Fig 1-1. National Electricity Generation for Different Power Sources 20
Fig 1-2. National Power Plants for Different Power Sources 21
Fig 1-3. Diagram and Principle of Steam Power Plant 23
Fig 1-4. Diagram and Principle of Combined Cycle Power Plant 24
Fig 2-1. Diagram of CFBC Boiler 31
Fig 2-2. Structure of CFBC Boiler and Installation Location of PA Nozzles 32
Fig 2-3. PA Nozzles Installed in CFBC Boiler 33
Fig 2-4. Fluidization in Combustion Chamber of CFBC Boiler 35
Fig 2-5. Different shapes of PA Nozzles 40
Fig 2-6. Shape of PA nozzle(Drawing) 42
Fig 2-7. Wear patters of PA nozzle 45
Fig 2-8. Drawing and 3D model of the CFBC Boiler 46
Fig 2-9. Design and Appearance of the System for Flow Visualization Experiment of CFBC Boiler 48
Fig 2-10. Turbulence in the Furnace Using Macroscopic CFD Analysis 49
Fig 2-11. CFD of 4OT PA Nozzle for Different Inlet Air Velocity 50
Fig 2-12. Pressure Distribution inside of 4OT PA Nozzle in CFBC Boiler 51
Fig 2-13. Air Flows at Inlet and Outlets of 4OT PA Nozzle with 4m/s Inlet Air Velocity 52
Fig 2-14. Air Flows at Inlet and Outlets of 4OT PA Nozzle with 8m/s Inlet Air Velocity 53
Fig 2-15. Air Flows at Inlet and Outlets of 4OT PA Nozzle with 20m/s nlet Air Velocity 53
Fig 2-16. Air Flows at Inlet and Outlets of 4OT PA Nozzle with the enlarged outlets at 4m/s Inlet Air Velocity 55
Fig 2-17. Air Flows at Inlet and Outlets of 4OT PA Nozzle with the enlarged outlets at 8m/s Inlet Air Velocity 55
Fig 2-18. Air Flows at Inlet and Outlets of 4OT PA Nozzle with the enlarged outlets at 20m/s Inlet Air Velocity 56
Fig 2-19. Air Flows at Inlet and Outlets of 4OT PA Nozzle with U-type Vanes at 4m/s Inlet Air Velocity 58
Fig 2-20. Air Flows at Inlet and Outlets of 4OT PA Nozzle with U-type Vanes at 8m/s Inlet Air Velocity 59
Fig 2-21. Air Flows at Inlet and Outlets of 4OT PA Nozzle with U-type Vanes at 20m/s Inlet Air Velocity 59
Fig 2-22. Air Flows at Inlet and Outlets of 4OT PA Nozzle with V-type Vanes at 20m/s Inlet Air Velocity 60
Fig 2-23. Stagnation Flow of 4OT PA Nozzle with V-type Vanes at Different Air Velocities 61
Fig 2-24. Result of Flow Visualization Experiment of PA Nozzle with Enlarged Outlets 63
Fig 2-25. Result of Flow Visualization Experiment of PA Nozzle with V-type Vanes 64
Fig 3-1. Matrix Structural Change for Different Ni and Cr Contents 70
Fig 3-2. Sand Casting Diagrams 77
Fig 3-3. Investment Casting Process Diagrams 78
Fig 3-4. Design and Appearance of Wooden Model for Samples 80
Fig 3-5. Shape of Sand Mold 81
Fig 3-6. Casting Process and a Casted Sample 81
Fig 3-7. Micro-hardness Testing Machine 83
Fig 3-8. Drawing of Standard Test Specimen for tensile test(ASTM E8) 84
Fig 3-9. Shape of tensile test Specimens 84
Fig 3-10. tensile testing Machine 85
Fig 3-11. Cast Molds and Their Assemble Process 86
Fig 3-12. Manufacturing Testing Products by Casting 87
Fig 3-13. Installation Location of PA nozzle for Verification Test 88
Fig 3-14. Weight of the PA Nozzles before Installation 88
Fig 3-15. Appearance of Basket to Measure Backflow Amount of Fluid Sand 89
Fig 3-16. Fracture Changes of Austenite and Ferrite for Different Compositions 92
Fig 3-17. Changes of Material Properties of Sample #1 at High Temperature for Different Si Contents 94
Fig 3-18. Changes of Material Properties of Sample #2 at High Temperature for Different Si Contents 94
Fig 3-19. Changes of Material Properties of Sample #3 at High Temperature for Different Si Contents 95
Fig 3-20. Changes of Material Properties of Sample #4 at High Temperature for Different Si Contents 95
Fig 3-21. Changes of Material Properties of Sample #5 at High Temperature for Different Si Contents 96
Fig 3-22. Change of High-temperature Strength in Different Si Contents for Compositions 97
Fig 3-23. High-temperature Strength Change of Sample #1 for Different Si Content 98
Fig 3-24. High-temperature Strength Change of Sample #2 for Different Si Content 99
Fig 3-25. High-temperature Strength Change of Sample #3 for Different Si Content 99
Fig 3-26. High-temperature Strength Change of Sample #4 for Different Si Content 100
Fig 3-27. High-temperature Strength Change of Sample #5 for Different Si Content 100
Fig 3-28. PA Nozzle for Verification 105
Fig 3-29. Wears at the Outlets of the Existing and New PA Nozzles 111
Fig 3-30. Measurement Process of the Backflow Rate of the Fluid Sand 113
Fig 4-1. Concept and Diagram of Coal Unloading and Conveying Systems of Coal-fired Power Plant 119
Fig 4-2. Concept and Appearance of Coal Unloader 120
Fig 4-3. Coal Yards(Outdoor and Indoor) 121
Fig 4-4. Appearance of Coal Conveyor Chute(Dangjin Power Plant) 122
Fig 4-5. Accumulated Coal in Coal Chute 123
Fig 4-6. Vibration Change at Natural Frequency 125
Fig 4-7. Vibration Change nearby Natural Frequency 128
Fig 4-8. Coal Antiseizing Technologies for Conveyor Belt 130
Fig 4-9. Inner Cleaning Methods by Electromagnetic hammer and Water Jet Cleaner 131
Fig 4-10. Chute Drawings Provided by Dangjin Coal-fired Power Plant 133
Fig 4-11. Site Visiting and Meausring Coal Chute in Dangjin Coal-fired Power Plant 134
Fig 4-12. Experimental Coal Chute 135
Fig 4-13. Provided Coals and Evaporation Test 136
Fig 4-14. Customized Chladni Plate in Dustproof Container 137
Fig 4-15. Concept of Rotary Woofer Installed on Coal Chute 138
Fig 4-16. 3D Model of Coal Chute #5-6 in Dangjin Coal-fired Power Plant 139
Fig 4-17. Contact and Restraint Conditions of Coal Chute 140
Fig 4-18. Materials of Coal Chute; SS275(Grey), Rubber(Yellow) 141
Fig 4-19. Modal Analysis Result of Coal Chute 142
Fig 4-20. FRF Result of Coal Chute(X-axis) 143
Fig 4-21. FRF Result of Coal Chute(Y-axis) 144
Fig 4-22. FRF Result of Coal Chute(Z-axis) 144
Fig 4-23. Destruction of Compressed Coal by Resonance 145
Fig 4-24. Vibration Acceleration Change of Compressed Coal at Different Frequencies 146
Fig 4-25. Concept and Mounting Arrangement of Vibrator 147
Fig 4-26. Explosion View of Rotary Woofer 147
Fig 4-27. Inner Connections Between Parts of Rotary Woofer 148
Fig 4-28. Woofer Modification 149
Fig 4-29. DC Motor and Inverter for Propeller Rotation 149
Fig 4-30. Design Optimization and FEA Results of the Shaft Design Variations 150
Fig 4-31. Manufacturing Shaft and Assembly of Shaft and DC Motor 151
Fig 4-32. Diagram and Principle of Rotor Head 151
Fig 4-33. Design and Manufacturing Rotor Head 152
Fig 4-34. Modeling and FEA Result of Blades for Rotor Head 152
Fig 4-35. Design and FEA Result of Propeller Blades(Continued) 153
Fig 4-36. Design Optimization and FEA Result of Airfoil Blades 155
Fig 4-37. Assembly of Airfoil Blades and Rotor Head 155
Fig 4-38. Rotary Woofer 156
Fig 4-39. Experimental Coal Chute for Coal Desorption Test 157
Fig 4-40. Measuring Vibration Acceleration for Different Frequencies 158
Fig 4-41. Vibration Accleration of Experimential Coal Chute for Different Frequencies 158
Fig 4-42. FFT Result of Vibration Acceleration for Different Frequencies(1~70Hz)(Continued) 159
Fig 4-43. Coal Chute Experiment Process 172
Fig 4-44. Desorption Rate Change at Different Frequencies 174
Fig 4-45. Change in the Amount of the Adhesive Coal Before and After Applying the 30Hz Vibration 175