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

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

Carey Merritt

ISBN: 978-1-119-08545-4

Oct 2015

336 pages

Description

Comprehensively describes the equipment used in process steam systems, good operational and maintenance practices, and techniques used to troubleshoot system problems

  • Explains how an entire steam system should be properly designed, operated and maintained
  • Includes chapters on commissioning and troubleshooting various process systems and problems
  • Presents basic thermodynamics and heat transfer principles as they apply to good process steam system design
  • Covers Steam System Efficiency Upgrades; useful for operations and maintenance personnel responsible for modifying their systems

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 (ΔTm) 33

ΔTm for a Steam Boiler 34

ΔTm 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