1、 GEOP Gas Engineering and Operating Practices A Series by the Operating Section The American Gas Association Volume IV MEASUREMENT Book M-1 Transmission and Distribution Measurement The American Gas Association Arlington, Virginia Legal Notice The Gas Engineering and Operating Practices Series was p
2、repared by the American Gas Association (A.G.A.), its member companies and other individuals and groups with an interest in the natural gas industry. Neither A.G.A., its member companies, employees, nor any person acting on their behalf: a. Makes any warranty or representation, express or implied, w
3、ith respect to the accuracy, completeness, or usefulness of the information contained in this series, or that the use of any apparatus, method, or process disclosed in this series may not infringe privately owned rights; or b. Assumes any liability with respect to the use of, or for damages or perso
4、nal injuries resulting from the use of any information, apparatus, method, or process disclosed in this series, or for violation of any federal, state or municipal regulation with which it may conflict. c. Reference to trade names or specific commercial products, methods, commodities or services in
5、this series does not represent or constitute an endorsement, recommendation or favoring by A.G.A. or any other person of the specific commercial product, commodity or service. d. Nothing contained in this series is to be construed as granting any right, by implication or otherwise, for the manufactu
6、re, sale, or use in connection with any method, apparatus, or product covered by letters patent, nor as insuring anyone against liability for infringement of letters patent. Copyright 1993 by the American Gas Association, A.G.A All rights reserved. Library of Congress Catalog Card Number: 85-70460 I
7、SBN 0-87257-009-6 A.G.A. Catalog Number XY9208 1M11.93-158-79 Printed in the United States of America CONTENTS FIGURERS AND TABLES xv PREFACE xxi ACKNOWLEDGEMENTS xxiii PART ONE: TRANSMISSION CHAPTER 1. INTRODUCTION 3 Organization 3 Principles of Gas Measurement 4 Units of Measurements 4 Gas Laws as
8、 Applied to Measurement 7 Other Factors That Affect Gas Measurement 8 Contract Measurement Specification 13 CHAPTER 2. ORIFICE METERING 19 Elements of the Orifice Meter 19 Primary Element-Design 21 General 21 Symbols 22 Definitions 22 Orifice-plate Specifications 25 Orifice Flanges 36 Orifice Fittin
9、gs 37 Straightening Vanes 40 Primary Element-Installation 41 iii iv TRANSMISSION AND DISTRIBUTION MEASUREMENT Orifice Plate 41 Meter Tube 44 Thermometer Wells 51 Insulation 51 Secondary Element Design 51 Differential Gage Devices 51 Pressure Element 54 Temperature Element 54 Gage Lines 55 Charts 55
10、Chart Drives 58 Pens 58 Ink 58 Secondary Element Installation 59 Location 59 Leveling 59 Housing 59 Gage Piping 59 Prevention of Freezing 60 Installation Records 60 Testing 61 Pulsations 62 Effect on Orifice Meters 63 Detection Devices 65 Corrective Measures 66 Orifice Meter Selection 70 Appendices
11、Flow Computation and Application Guidelines . 70 Appendix A-Computation Procedures 71 Appendix B-Application Guidelines 86 CHAPTER 3. TURBINE METERING 105 History 105 Principle of Operation 106 Typical Construction 107 Performance Characteristics 107 Accuracy 107 Repeatability 108 Meter Capacity 109
12、 Rangeability 110 Pressure Loss 110 Volume Flow Measurement 111 Mass Flow Measurement 112 CONTENTS v Installation 113 Recommended Installation For In-Line Meters 116 Optional Installations for In-Line Meters 116 Recommended Installation For Angle-Body Meters 116 Additional Installation Requirements
13、117 Calibration and Field Checking 117 Calibration Methods 117 Bell Prover 118 Transfer Prover 118 Sonic Nozzles 119 Field Checking 119 Visual Inspection 119 Spin-Time Test 119 Module Interchange 120 Maintenance and Inspection Frequency 120 CHAPTER 4. SONIC NOZZLE METERING 123 History and Characteri
14、stic 123 Advantages and Disadvantages 126 Advantages 126 Disadvantages 126 Accuracy Verification and Certification 127 Qualified Testing Laboratories 127 Precision Throat Measurement 127 Bell Prover Transfer Proving 127 Sample Calculations of Prover Preset Frequency 129 Test Configuration and Proced
15、ure 130 General Configuration 130 General Procedure 131 A Simple Prover Operating at Line Pressure 131 On-Site Sonic-Nozzle Provers 133 Shop Test Configurations 134 Operating Precautions 135 Summary 138 Instrumentation 138 Manual Testing 138 Automatic Testing 138 Maintenance 138 Manual Testing 139 A
16、utomatic Testing 139 Training 140 vi TRANSMISSION AND DISTRIBUTION MEASUREMENT CHAPTER 5. PRESSURE REGULATION and OVERPRESSURE PROTECTION 141 Definitions 141 Pressure Regulation 142 Physical Principles 142 Basic Construction 143 Classes of Regulators 145 Performance Characteristics 160 Inspection an
17、d Testing 166 Overpressure Protection 167 Design Requirements 167 Selection of Overpressure Devices 168 Types of Devices 169 Inspection and Testing 174 CHAPTER 6. GATE STATIONS 175 Design Considerations 175 Metering Capacity 175 Metering Pressure 176 Piping Configuration 176 Pulsation 176 Electronic
18、 Flow Measurement 177 Determination of Gas Composition 177 Design Standardization 177 Rotary-Meter Installations 178 Meter Isolation Valves 178 Strainer 178 Meter 180 Thermowell 180 Check Valve 180 Overspeed Protection 180 Sample Gas 180 Fuel Gas 180 Meter Bypass 180 Turbine-Meter Installations 181
19、Meter-Run-Isolation Valves 181 Strainer 181 Fuel Gas 181 Straining Vanes 182 Meter 182 Overspeed Protection 182 Thermowell 182 CONTENTS vii Sample Gas 182 Check Valve 182 Blowdown 183 Differential-Pressure Taps 183 Meter-Run Bypass 183 Orifice-Meter Installations 183 Meter-Run-Isolation Valves 183 S
20、traightening Vanes 183 Meter 184 Thermowell 184 Fuel Gases 184 Sample Gas 185 Check Valve 185 Blowdown 185 Regulate-Meter-Odorize Installations 185 In-Line Heater 185 Alcohol Injector 185 First-Stage Regulator 185 First-Stage Overpressure Protection 186 Second-Stage Regulator 186 Second-Stage Overpr
21、essure Protection 186 Meter 187 Odorant System 187 Delivery Outlet 187 PART TWO: DISTRIBUTION CHAPTER 7. DIAPHRAGM METERS 191 Background 191 History 191 Present Status 191 National Standards 192 Coverage 192 Small Diaphragm Meters 192 Large Diaphragm Meters 193 Operation and Theory 193 Principles of
22、 Operation 193 Theoretical Considerations 194 Practical Considerations 195 Design and Construction 196 Basic Designs 196 Construction Materials 199 viii TRANSMISSION AND DISTRIBUTION MEASUREMENT Capacity Rating and Sizing 203 Capacity Rating 203 Sizing for Loads 204 Effect of Elevated Pressure 204 T
23、est Methods 205 Types of Provers and Tests 205 Special Tests and Adjustments 209 Accuracy and Performance 214 Accuracy Testing 214 Out-Testing 214 In-Testing 214 Performance-Evaluation Programs 214 Instrumentation 214 General 215 Handling 215 Storage 215 Installation 215 CHAPTER 8. ROTARY METERS 217
24、 Summary 217 History 217 Principles of Operation 218 General 218 Construction 220 Standard Materials 220 Special Construction-Production-Gas Meters 222 Manufacturers Standard Specifications 222 Applications 222 Performance Characteristics 222 Sizing 226 Installation Requirements 226 Testing 228 Fact
25、ory Proof 228 Differential Tests 228 Accuracy Tests 228 Test Periods 228 Maintenance and Repair 229 Inspections 229 Oil Changes 229 Repairs 229 Accessories 229 Changing Technology 230 CONTENTS ix CHAPTER 9. PRESSURE REGULATION AND CONTROL 231 Introduction 231 Principle of Operation 232 Basic Constru
26、ction 232 Restricting Element 232 Loading Element 233 Sensing Element 233 Classes of Regulators 234 Self-Operated Regulators 235 Relay-Operated Regulators 240 Instrument-Operated Regulators 246 Performance Characteristics 250 Diaphragm Effect 250 Spring Effect 251 Inlet Pressure Fluctuations 251 Hys
27、teresis 253 Valve Configuration 253 Valve Plug Forces 254 Shutoff or Lockup 254 Selection and Sizing 255 Operating Conditions 255 Regulator Characteristics 256 Applications 261 Selection Summary 266 CHAPTER 10. REGULATOR INSTALLATION AND MAINTENANCE 267 Design of Installations 267 Station Design 267
28、 Installation Guidelines 272 Overpressure Protection 274 General Requirements 274 Design Considerations 276 Selection 277 Types of Overpressure Devices 277 Inspection and Testing 282 Maintenance 282 Controlling Factors 283 Procedures 284 Typical Problems 286 x TRANSMISSION AND DISTRIBUTION MEASUREME
29、NT CHAPTER 11. CORRECTING METERED VOLUMES FOR BASE CONDITIONS 289 Introduction 289 Basic Gas Laws 290 Boyles Law 290 Charles Law 290 The Law of Perfect Gases 291 Supercompressibility (Compressibility) 291 Correction Methods 292 Pressure Compensating Indexes 292 Fixed-Pressure Factors 294 Integrating
30、 Instruments 295 Chart Recorders 301 CHAPTER 12. FIXED-PRESSURE-FACTOR MEASUREMENT 307 Justification for Using FPFM 307 Low Capital Investment 307 Low Operating and Maintenance Costs 308 Basic Conditions 308 Formulas 308 Accuracy Consideration 308 The Basic Equation 309 The Variables 309 The FPFM Eq
31、uation 310 Examples 310 Special Considerations 311 Selection of Regulators 312 Direct-Acting Spring-Loaded Regulators 312 Constant-Pressure-Loaded Regulators 313 Pilot-Loaded Regulators 314 Additional Considerations 314 Installation Considerations 315 Use of Pressure-Compensated Indexes 316 Discrepa
32、ncy Correction 317 Inspection, Calibration, and Maintenance 319 Policies and Procedures 319 Equipment 319 Records 319 Acceptability of Pressure Regulation 320 Maintenance 320 CONTENTS xi Verification of Accounts 321 Precautions 322 CHAPTER 13. BELL PROVERS 325 Introduction 325 The Proving Room 325 A
33、ir Conditioning Equipment 327 Prover Air Supply 328 Operation of the Bell Prover Set Up 328 Balancing 329 Testing for Leaks 330 Calibration 330 Bottling 331 Strapping 334 Read-Out Devices 335 Maintenance 336 Proving Techniques 336 Pressure Proving 336 Vacuum Proving 337 Pulse Proving 338 Test Stands
34、 340 Manual Operation 340 Automatic Operation 341 CHAPTER 14. TRANSFER PROVERS 349 Operating Principle 349 Theory of Operation 349 Design 351 CHAPTER 15. SONIC NOZZLE PROVERS 355 Introduction 355 History 355 Theory of Operation 356 Advantages 357 Disadvantages 358 Accuracy Verification and Certifica
35、tion 358 Manufacturer Method 358 Bell-Prover Method 358 Commercial-Laboratory Method 361 Testing Procedures 361 xii TRANSMISSION AND DISTRIBUTION MEASUREMENT General Test Configuration 361 General Test Procedures 362 A Simple Line-Pressure Sonic-Nozzle Prover 362 A Vacuum Sonic-Nozzle Prover 363 Sho
36、p Test Configurations 366 Operating Precautions 366 Instrumentation Requirements 367 Manual Testing 367 Automatic Testing 367 Maintenance Requirements 368 Training Suggestions 369 CHAPTER 16. METER REPAIR CLASSIFICATIONS 371 Introduction 371 Standard Classifications 371 O.K. Repair 371 Readjust Repa
37、ir 372 Partial Repair 372 General Repair 372 Diaphragm Repair 372 Conversion Rebuild 372 Condemn 372 Repair Operations 373 CHAPTER 17 METER HISTORY AND PERFORMANCE RECORDS 375 Introduction 375 History 375 Identification 375 Service 376 External History Sources 376 Performance 377 Conclusion 381 CHAP
38、TER 18. TESTING INTERVALS 383 Introduction 383 Types of Testing Plans 383 Mileage Testing 383 Periodic-Interval Testing 383 Statistical-Sampling Testing 383 CONTENTS xiii Variable-Interval Testing 384 CHAPTER 19 REMOTE AND AUTOMATIC METER READING 385 Summary 385 Introduction 385 Traditional Meter-Re
39、ading Process 385 Problems with Manual Meter Reading 386 Advances in Meter-Reading Systems 388 Remote Indexes 388 General 388 Adaptability to Existing Equipment 389 Special Requirements 390 Data Collection 390 Advantages 390 Disadvantages 390 Enhanced Data-Collection Systems 391 General 391 Adaptabi
40、lity to Existing Equipment 392 Data Collection 393 System Characteristics 394 Advantages 394 Disadvantages 395 Automatic Meter-Reading Systems 396 General 396 Cable-Television Links 397 Radio Data Links 398 Telephone Links 399 Future Direction 400 Meter Construction 400 Alternative Communications Sy
41、stems 400 PART THREE REFERENCES 403 INDEX 409 TABLES AND FIGURES PART ONE: TRANSMISSION TABLES 1. Effect of Elevation on Pressure 6 2. Orifice-Plate Flatness Tolerance 26 3. Roundness Tolerance for Orifice-Plate Bore Diameter 28 4. Linear Coefficient of Thermal Expansion 28 5. Orifice-Plate Dimensio
42、ns 30, 31 6. Example Meter Tube Internal Diameter Roundness Tolerances: Within First Mean Meter Tube Diameter Upstream of Orifice Plate 35 7. Example Meter Tube Internal Diameter Roundness Tolerances: All Upstream Meter Tube Individual Internal Diameter Measurements 35 8. Maximum Orifice-Plate Bore
43、Eccentricity Tolerances (Inches) 42 9. Typical Chart Ranges 56 10. Table of Humidity Factors 129 11. Sections of DOT Standards Pertaining to Overpressure Protection 168 12. Advantages and Disadvantages of Various Meter Types 179 13. Typical Parameters for Various Meter Types 179 FIGURES 1. Water-vap
44、or content of compressed natural gas 9 xv xvi TRANSMISSION AND DISTRIBUTION MEASUREMENT 2. Symbols for orifice-plate dimensions 25 3. Allowable variations in locations of pressure-tap holes 39 4. Tube-bundle type flow straightener 40 5. Eccentricity measurement (sample method) 43 6. Partly closed va
45、lve upstream of the meter tube 45 7. Two ells not in the same plane upstream of meter tube 46 8. Less than 10 pipe diameters between two ells in same plane upstream of meter tube 47 9. More than 10 pipe diameters between two ells in same plane upstream of meter tube 48 10. Reducer or expander upstre
46、am of meter tube 49 11. Mercury differential-pressure gage 52 12. Bellows type differential-pressure gage 53 13. Typical uniform-scale direct-reading chart 56 14. Typical square-root chart 57 15. Amount of Pulsation 63 16. Square-root averaging error 64 17. Pulsation dampeners 67 18. High-speed osci
47、llograph recording of effect of installing a pulsation dampener 68 19. Orifice-meter gage recording before and after installation of an in-line pulsation dampener 69 20. Two schematic-drawing versions of the axial flow gas turbine meter 106 21. Accuracy of a gas-turbine meter vs. actual flow rate at
48、 atmospheric pressure 108 22. Accuracy of a gas-turbine meter vs. base flow rate at various pressures 108 23. Recommended installation of in-line gas-turbine meter 114 24. Short-coupled installation of in-line gas-turbine meter 115 25. Close-coupled installation of an in-line gas tubine meter with i
49、ntegral straightening vanes 115 26. Recommended installation of an angle body gas turbine meter (minimum lengths) 115 27. Schematic of a sonic nozzle 125 28. Sonic nozzle test set up 128 29. Vacuum sonic-nozzle prover 132 30. Low-pressure vacuum sonic-nozzle provet 132 31. Configuration with three valves for testing several meters 133 32. Configuration for a permanently installed sonic prover 134 33. Installation with two sonic nozzles permanently in place 134 TABLES AND FIGURES xvii 34. Automated sonic-nozzle prover system for smaller meters 135 35. Schematic of sonic-nozzle system f
