Aeration Control System Design

Preface xi Acknowledgments xiii List of Figures xv List of Tables xxi 1 Introduction 1 1.1 Basic Concepts and Objectives 2 1.2 Safety 9 1.3 The Importance of an Integrated Approach 10 1.4 Importance of Operator Involvement 13 1.5 The Benefits of Successful Aeration Process Automation 14 Example Problems 19 2 Initial System Assessment 21 2.1 Define Current Operations 24 2.2 Evaluate Process and Equipment 37 2.3 Benchmark Performance 40 2.4 Estimate Potential Energy Savings and Performance Improvement 42 2.5 Prepare Report 45 Example Problems 47 3 Aeration Processes 49 3.1 Process Fundamentals 49 3.2 Loading Variations and Their Implications 68 3.3 Process Limitations and Their Impact on Control Systems 70 Example Problems 74 4 Mechanical and Diffused Aeration Systems 77 4.1 Oxygen Transfer Basics 78 4.2 Types of Aerators 87 4.3 Savings Determinations 106 Example Problems 111 5 Blowers and Blower Control 113 5.1 Common Application and Selection Concerns 114 5.2 Positive Displacement Blowers and Control Characteristics 134 5.3 Dynamic Blowers 143 Example Problems 157 6 Piping Systems 161 6.1 Design Considerations 162 6.2 Pressure Drop 178 6.3 Control Valve Selection 182 Example Problems 187 7 Instrumentation 191 7.1 Common Characteristics and Electrical Design Considerations 192 7.2 Pressure 202 7.3 Temperature 205 7.4 Flow 209 7.5 Analytic Instruments 216 7.6 Motor Monitoring and Electrical Measurements 224 7.7 Miscellaneous 226 Example Problems 230 8 Final Control Elements 233 8.1 Valve Operators 234 8.2 Guide Vanes 238 8.3 Motor Basics 239 8.4 Motor Control 247 8.5 Variable Frequency Drives 251 Example Problems 259 9 Control Loops and Algorithms 261 9.1 Control Fundamentals 264 9.2 Dissolved Oxygen Control 280 9.3 Aeration Basin Air Flow Control 287 9.4 Pressure Control 288 9.5 Most-Open-Valve Control 291 9.6 Blower Control and Coordination 293 9.7 Control Loop Timing Considerations 302 9.8 Miscellaneous Controls 303 Example Problems 305 10 Control Components 309 10.1 Programmable Logic Controllers 310 10.2 Distributed Control Systems 323 10.3 Human Machine Interfaces 323 10.4 Control Panel Design Considerations 328 Example Problems 330 11 Documentation 333 11.1 Specification Considerations 335 11.2 Data Lists 338 11.3 Process and Instrumentation Diagrams 341 11.4 Ladder and Loop Diagrams 342 11.5 One-Line Diagrams 344 11.6 Installation Drawings 345 11.7 Loop Descriptions 347 11.8 Operation and Maintenance Manuals 348 Example Problems 349 12 Commissioning 351 12.1 Inspection 354 12.2 Testing 357 12.3 Tuning 361 12.4 Training 365 12.5 Measurement and Verification of Results 368 Example Problems 369 13 Summary 371 13.1 Review of Integrated Design Procedure 371 13.2 Potential Problem Areas 374 13.3 Benefits 375 Example Problems 375 Appendix A: Example Problem Solutions 377 Appendix B: List of Equations and Variables 447 Bibliography 485 Index 487