Process Steam Systems – A Practical Guide for Operators, Maintainers, and Designers

Carey Merritt has over 25 years experience designing, operating and maintaining process steam systems. He has designed over 200 process steam systems for almost every imaginable industry. He has traveled to Europe, Australia, Canada, Central America and China to oversee the installation of these steam systems and train system operators Other notable achievements include Certified Energy Manager, CEM, Association of Energy Engineers, since 2008 and Certified Trainer in Steam System Design for Professional Engineers, The Practicing Institute for Professional Engineers, since 2007.

Preface xi Acknowledgements xiii List of Examples xv List of Tables xvii 1 Steam: A Heat Transfer Fluid 1 What is Steam? 1 Steam Is Safe and Flexible 2 Steam Is Easy to Control 2 Steam System Types 3 The Process Steam System 6 2 Steam Formation, Accumulation, and Condensation 9 The Formation of Steam; Boiling 9 Pressure and Boiling 11 The Ideal Gas Law 11 The Boiling Process 13 Steaming 14 Latent and Sensible Heat versus Pressure 16 The Formation of Flash Steam 16 Steam Accumulation and Storage 18 Condensation of Steam 20 3 Understanding Heat Transfer 23 Radiation Type Heat Transfer 23 Conduction Type Heat Transfer 26 Convection ]Type Heat Transfer 29 The Heat Transfer Equations 31 The Overall Heat Transfer Coefficient (U) 31 Mean Temperature Difference ( Tm) 33 Tm for a Steam Boiler 34 Tm for a Steam to Process Fluid Heat Exchanger 35 Surface Area (m) 35 Heat Flux 37 4 Steam Quality: It Matters 39 Why Steam Quality is Important 40 Poor Steam Quality Cause and Cures 40 Steam Classifications 43 Measuring Steam Quality 45 Superheated Steam 46 5 Boiler Room Considerations 49 Steam Generator Selection 49 Codes and Standards 49 Steam System Performance Considerations 53 Environmental Considerations 55 Boiler Room Utilities 60 6 The Steam Generator 67 The Ideal Steam Generator 68 Steam Generator Types 70 Fossil Fuel ]Fired Boilers 70 Solid Fuel ]Fired Boilers 76 Electric Boilers 78 Unfired Steam Generators 81 7 Boiler Trim, Fuel Delivery, and Combustion Control System 83 The Packaged Boiler Concept 83 Fuel Delivery and Combustion Systems 91 Low Emissions 98 8 The Steam Delivery System 103 Steam Flow 103 Steam Distribution Piping 104 Control Valves 115 Steam Accumulators 121 Steam Filtration 124 Sensing Equipment 126 Stop and Safety Valves 127 9 The Condensate Recovery System 131 Condensate Line Sizing 133 Steam Trap Applications 136 Thermostatic Group 136 Mechanical Group 136 Thermodynamic Group 136 Thermostatic Steam Trap Group 136 Mechanical Group 138 Thermodynamic Group 141 Flash Steam Utilization 144 How to Size Flash Tanks and Vent Lines 145 Condensate Collection 147 Electric Condensate Return System 148 Pressure Motive Condensate Pump 150 Pressure Motive Pump Installation Requirements 150 Pumped Condensate Return Line Installation 153 Surge Tank Application 153 10 The Feed Water System 155 Feed Water Deaeration 155 The Elimination of Dissolved Gases 156 Feed Water Tanks 158 Feed Water Tank Sizing 160 Feed Water Pumps 162 Feed Water Pump Sizing 166 Feed Water Piping 167 11 Steam System Chemistry Control 171 Basic Water Chemistry 171 Scale Control 172 Fouling Control 176 Corrosion Control 177 Boiler Blowdown (BD) 180 Best Operating Practices for Boiler BD 181 Automatic versus Manual BD Controls 181 Determining BD Rate 181 Chemical Feed Systems 183 Chemistry Limits 186 12 Steam System Applications 187 High ]Pressure Steam with High Condensate Returns 189 Low ]Pressure Steam with High Condensate Returns 190 High ] or Low ]Pressure Steam with Little or No Returns 192 High ]Pressure or Superheated Steam with Condensate Returns 195 Multiple Boiler Installations 195 Specialized Steam Equipment 197 Back Pressure Turbine or BPT 197 Steam Hydro Heater 198 Steam Superheaters 200 Steam Discharge Mufflers 202 13 Steam System Efficiency 205 The System Heat Balance 205 Boiler Heat Balance 207 Boiler Efficiency 207 Steam System Efficiency 213 Boiler Internal Cleanliness 216 Steam Delivery System Efficiency 217 Condensate and Feed Water System Efficiency 217 Biomass Fuel Water Content Reduction 219 14 Shutdown, Startup, Inspection, and Maintenance 223 Shutdown and Startup Practices 223 Boiler Safety Checks 225 Maintenance and Inspection Practices 227 Inspections 228 Boil Out and Layup Practices 231 15 Troubleshooting and Commissioning Basics 235 Startup versus Commissioning 235 Approach to Troubleshooting 236 Don t Play the Blame Game 236 Precommissioning 237 16 Commissioning and Troubleshooting the Steam Generator 239 Determining Boiler Input, Output, and Efficiency 239 Boiler Performance Test 241 Commissioning the Boiler/Burner Controls 243 Commissioning the Boiler Pressure Control System 243 Commissioning the Boiler Level Control System 244 Commissioning the Boiler Blowdown Controls 244 Steam Boiler Troubleshooting 244 17 Commissioning and Troubleshooting the Steam Delivery System 253 Steam Distribution Piping 253 Control Valves 254 Steam Piping Venting 255 Condensate Trapping/Draining 255 Troubleshooting the Steam Delivery System 255 18 Commissioning and Troubleshooting the Condensate and Feed Water System 257 Condensate Collection 257 Feed Water System 258 Troubleshooting the Condensate and Feed Water Systems 259 19 Commissioning and Troubleshooting the Water Treatment Equipment 263 Setting Up the Water Treatment Systems 263 Troubleshooting Water Treatment System Problems 264 Appendix A References and Reference Information 267 Appendix B Operations, Maintenance, and Inspection Guidance 283 Appendix C Steam System Design and Commissioning Guidance 293 Index 301