High temperature air combustion: from energy conservation to pollution reduction

Description

Maximize efficiency and minimize pollution: the breakthrough technology of high temperature air combustion (HiTAC) holds the potential to overcome the limitations of conventional combustion and allow engineers to finally meet this long-standing imperative. Research has shown that HiTAC technology can provide simultaneous reduction of CO2 and nitric oxide emissions and reduce energy consumption for a specific process or requirement.High Temperature Air Combustion: From Energy Conservation to Pollution Reduction provides the first comprehensive exposition of the principles and practice of HiTAC. With a careful balance of theory and practice, it reviews the historical background, clearly describes HiTAC combustion phenomena, and shows how to simulate and apply the technology for significant energy savings, reduced equipment size, and lower emissions. It offers design guidelines for high performance industrial furnaces, presents field trials of practical furnaces, and explores potential applications of HiTAC in other fields, including the conversion of solid waste fuels to cleaner fuels, stationary gas turbine engines, internal combustion engines, and other advanced energy-to-power conversion systems.Developed through an intensive research project sponsored by the Japanese government, HiTAC now promises to revolutionize our paradigm for using all kinds of fossil, alternative, waste, and derived fuels for energy conversion and utilization in industry. This book is your opportunity to understand its principles, learn about the technology, and begin to use it to the benefit of your application, your company, and the environment. High Temperature Air Combustion From Energy Conservation to Pollution Reduction......Page 1 Dedication......Page 5 Foreword......Page 7 Preface......Page 9 The Authors......Page 12 Acknowledgments......Page 13 Table of Contents......Page 15 1.1.1 Environment and Energy Conservation......Page 22 Contents......Page 0 1.1.2 Reduction of Pollutant Emissions and Energy Crisis......Page 23 1.1.3 Panorama of High Temperature Air Combustion Technology......Page 25 1.2.1.1 Heat Recirculating Combustion......Page 27 1.2.1.3 Heat Recirculation and Exhaust Gas Recirculation......Page 31 1.2.2.1 Carbon Dioxide......Page 34 1.2.2.2 Nitric Oxides......Page 36 1.2.3 Heat Transfer in High Temperature Air Combustion......Page 38 1.2.3.1 Convection Heat Transfer of High Temperature Air Combustion......Page 39 1.2.3.2 Radiant Heat Transfer of High Temperature Air Combustion......Page 41 1.2.3.3 Effect of Wall as Wavelength Conversion Body in High Temperature Air Combustion......Page 42 1.2.4 Thermodynamics of High Temperature Air Combustion......Page 44 References......Page 49 2.1 Introduction......Page 50 2.2.1 Flame Stability......Page 51 2.2.1.1 Temperature Profiles......Page 53 2.2.2.2 Cold Flow Model Test......Page 55 2.2.2.3 Temperature Profiles......Page 57 2.2.2.4 Flow Patterns......Page 59 2.2.3.2 Combustion Conditions......Page 60 2.2.3.3 Optical Measurement Results......Page 63 2.2.3.4 Summary......Page 69 2.2.4.1 Improved Heating Method......Page 70 2.2.4.2.1 Gross Heat Input......Page 71 2.2.4.2.2 Heat Transfer in Furnace......Page 72 2.2.4.3.1 Effect of Gas Recirculation......Page 74 2.2.4.3.2 Heat and Gas Recirculation......Page 75 2.2.4.4 Discussion......Page 78 2.3.1 Extinction Limit and NOx in Laminar Diffusion Flame......Page 81 2.3.1.1 Experimental Apparatus......Page 82 2.3.1.2 Velocity Field and Temperature Field......Page 83 2.3.1.3 Extinction and Re-ignition Temperatures of Laminar Diffusion Flame......Page 85 2.3.1.4 Distributions of Temperature and Concentrations of Species......Page 87 2.3.1.5 Effect of Flame Temperature on NOx Formation......Page 89 2.3.1.6 Relationship between Flame Temperature and the Critical Velocity Gradient......Page 90 2.3.1.7 Summary......Page 91 2.3.2.1 Simulation Model......Page 92 2.3.2.2 Simulation Results and Discussion......Page 93 2.3.2.2.2 Preheated and Diluted Premixed Flames......Page 94 2.3.2.2.3 Fuel Flux......Page 95 2.3.2.2.4 NO Formation......Page 96 2.3.2.3 Summary......Page 99 2.3.3.1 Jet Mixing......Page 100 2.3.3.2 Unmixedness......Page 104 2.3.3.3 Well-Stirred Reactor......Page 106 2.3.4 Pollutant Formation......Page 107 2.3.5 Pollutant Formation and Emission......Page 111 2.3.5.2 Results and Discussion......Page 112 Summary......Page 122 2.3.6 Radiation......Page 123 2.4.1.1 Experimental Apparatus......Page 129 2.4.1.1.3 Spray Nozzle......Page 130 2.4.1.2.1 Air Preheating......Page 132 2.4.1.2.3 Spraying Method......Page 133 2.4.1.2.4 Measurement of Flame......Page 134 2.4.1.3.1 Temperature of Blowout......Page 135 2.4.1.3.2 Flame Form and Flame Color......Page 136 2.4.1.4.1 Blowout of Flame......Page 138 2.4.1.5 Summary......Page 139 2.4.2 Emissions in Liquid Fuel Flame......Page 140 2.5.1 Solid Fuel Flame Characteristics......Page 142 2.5.2 Combustion Process of Coal......Page 144 2.5.2.2 Combustion Phenomena around Particles......Page 145 2.5.2.3 Combustion Phenomena inside a Particle......Page 148 2.5.2.4 Final Stage of Combustion......Page 149 2.5.2.5 Combustion Behavior of Coal at Synthetic Air Condition of High Temperature......Page 150 2.5.2.6 Summary......Page 153 2.5.3.1 The Furnace Setup......Page 154 2.5.3.3 Experimental Program......Page 155 2.5.3.4 In-Flame Measurements......Page 157 2.5.3.4.1 Heat and Mass Balance......Page 158 2.5.3.4.2 Gas Composition......Page 159 2.5.3.4.3 Temperature Measurements......Page 161 2.5.3.4.4 Velocity Measurements......Page 162 2.5.3.4.5 Burnout......Page 164 2.5.3.4.6 Solid Concentration......Page 166 2.5.3.4.7 Total Radiative Heat Flux......Page 167 2.5.3.4.8 Total Radiance......Page 168 2.5.3.5 Input/Output Measurements......Page 172 2.5.3.5.1 Coal Gun Position......Page 173 2.5.3.5.2 Coal Transport Air Mass Flow......Page 175 2.5.3.5.3 Precombustor NOx Level......Page 177 2.5.3.6 Summary......Page 179 2.5.4.1 Combustion Field and Solid Carbon Specimens......Page 180 2.5.4.2 Experimental Results......Page 181 2.5.4.4 Combustion Rate in High Temperature Airflow......Page 182 2.5.4.5 Dynamic Analysis of Reactive Gas......Page 183 2.5.4.6 Lower Limit of Oxygen Concentration......Page 187 2.5.4.7 Surface Temperature When a CO Flame Is Formed......Page 189 2.5.4.9 Summary......Page 190 References......Page 191 3.1.1 Introduction......Page 194 3.1.2.1 Arrhenius Type One-Step Global Reaction Model......Page 195 3.1.2.2 Mixing-Is-Reacted Model......Page 196 3.1.2.3 Eddy-Break-Up Model......Page 197 3.2.1 Characteristics of High Temperature Air Combustion......Page 199 3.2.2 Proposed Improvements......Page 200 3.2.3 Temperature Correction for Thermal Dissociation......Page 201 3.2.4.1 One-Step Global Reaction Model (Coffee)......Page 205 3.2.4.2 Four-Step Reaction Model (Jones and Lindstedt)......Page 206 3.2.4.3 Four-Step Reaction Model (Srivatsa)......Page 207 3.2.5.1 Comparison of Flame Lifted Height by Different Reaction Models......Page 209 3.2.5.2 Comparison of Maximum Flame Temperature by Different Reaction Models......Page 210 3.2.5.3 Influence of Jet Velocity on Flame Lift Height......Page 211 3.3.1.1 Gray Model......Page 213 3.3.1.2 Weighted-Sum-of-Gray-Gases Model......Page 215 3.3.1.3 Nongray Models......Page 216 3.3.2 Radiative Heat Transfer Using Nongray Property of Radiation......Page 218 3.4 Examples of Practical Application......Page 220 3.4.1.1 Thermal NO......Page 221 3.4.1.3 NO Reduction Mechanism (Reburning)......Page 222 3.4.1.4 Results and Discussion......Page 224 3.4.2.1 Fluid Dynamics Model......Page 225 3.4.2.2 Radiation Heat Transfer Model......Page 226 3.4.2.3 Combustion Model......Page 227 3.4.2.4 Temperature Distribution during Fuel Changeover......Page 228 3.4.2.5 Comparison with Measured Temperatures by Suction Pyrometer......Page 229 3.4.2.6 Calculation on Wide Regenerative Furnace......Page 230 References......Page 231 4.1.1 Energy Technologies Discussed at COP3......Page 233 4.1.2 Conventional Technologies of Energy Saving and Combustion Control for Industrial Furnaces......Page 237 4.1.3 Development of High Performance Industrial Furnaces......Page 241 4.2.2 Effect of Improvement......Page 252 4.3 Pollution Reduction......Page 257 4.3.2 Results of the Test......Page 259 4.3.3 Pollution Reduction......Page 260 References......Page 263 5.1.2 Optimal Design for Furnace Length and Height......Page 264 5.1.3.2 Partition Wall......Page 269 5.1.3.3 Analytical Study of the Effect of a Partition Wall......Page 270 5.1.3.4 Lower Part of Furnace......Page 272 5.1.3.5 Furnace Width and Maximum Combustion Capacity......Page 283 5.2.1 Outline of Simulation Program......Page 284 5.2.2 Basic Functions of the Simulator......Page 286 5.2.2.2 Calculation Method of the Internal Temperature of the Semifinished Steel......Page 287 5.2.4 Radiation Heat from the Furnace Body and Heat Loss by Cooling Water......Page 290 5.2.6 Comparison of Calculation and Measurement......Page 292 5.2.7 Effect of Fuel Calorific Value on the Fuel Consumption of Reheating Furnaces......Page 293 5.3 Combustion Control System......Page 301 5.3.1 Basic Combustion Control System for Stable Operation......Page 303 5.3.2 Signal Processing Method......Page 308 5.3.3 Disturbance Suppression Control of Door Open and Close......Page 313 5.3.4 Future Trends of Combustion Control Technology Using High Temperature Air Combustion......Page 316 5.4.1 Reheating Furnace......Page 317 5.4.1.1 Specifications and Performance of Facility......Page 318 5.4.1.2 Detailed Specifications of Facility......Page 322 5.4.1.3 Attachments......Page 323 5.4.2 Billet Reheating......Page 326 5.4.3 Heat Treatment Furnace......Page 328 5.4.3.1 Heat Balance and Evaluation Method of Furnace Performance......Page 329 5.4.3.2 Furnace Scale-Up for Commercial Production......Page 333 5.4.3.3 Test Design of Heat Treatment Furnace......Page 335 5.4.4.1 Energy Savings and Exhaust Gas Regulation......Page 341 5.4.4.2 Size Reduction......Page 343 5.4.4.3 Method of Improving the Heat Transfer Efficiency inside the Furnace......Page 345 5.4.4.4 A Design Example of High Performance Aluminum- Melting Furnace......Page 346 5.5 Field Trials and Experiences Obtained Through Field Test Demonstration Project......Page 348 5.5.2 Applications for the Field Test in Fiscal Years 1998 and 1999......Page 349 5.5.3 Characteristic Aspects of the 1998 Field Test Project......Page 354 5.5.4 Effects of Modifications in the Field Tests......Page 355 References......Page 360 6.1 Introduction......Page 361 6.2 Combustion of Wastes and Solid Fuels......Page 364 6.2.1.1 Refuse (or Waste) Derived Fuel......Page 370 6.2.1.3 Changes in the Calorific Value of Municipal Wastes......Page 371 6.2.1.4 Problems with Waste Derived Fuel Production and Combustion......Page 372 6.3 Burning of Coals and Lowgrade Coals......Page 373 6.5 Ash Melting......Page 374 6.7 Gas Turbine Combustion, Micro Gas Turbines, and Independent Power Production......Page 375 6.9 Fuel Cells......Page 376 References......Page 379 A.2 Items and Methods of Investigation......Page 381 A.3.2 Results of Interview with Users......Page 382 A.3.3 Results of Estimate of Number of Installed Industrial Furnaces and Energy Consumption......Page 384 A.4.1 Evaluation of Estimated Number of Industrial Furnaces......Page 388 A.4.3 Consideration of the Results of Interviews - Efficiency of Industrial Furnaces......Page 391 A.5.1 Assumptions of Calculations......Page 393 A.5.2 Results of the Calculation......Page 396 A.6 Summary......Page 397 References......Page 398 B.1 Universal Constants and Conversion Factors......Page 399 B.2 Nondimensional Parameters......Page 401 B.3 Nomenclature......Page 402