1、GEOP Gas Engineering and Operating Practices A Series by the Operating Section The American Gas Association Volume II TRANSMISSION Book T4 Gas Control The American Gas Association Arlington, Virginia Legal Notice The Gas Engineering and Operating Practices Series was prepared by the American Gas. As
2、sociation (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 com-panies, employees, nor any person acting on their behalf: a. Makes any warranty or representation, express or implied, with respect to the accuracy, c
3、ompleteness, 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 personal injuries resulting from the
4、 use of any information apparatus, methods, 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 this series does not represent
5、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 manufac-ture, sale, or use in connection
6、with any method, apparatus, or product covered by letters patent, nor as insuring anyone against liability for infringement of letters patent. Copyright 1992 by the American Gas Association, A.G.A. All rights reserved. Library of Congress Catalog Card Number: 85 70460 ISBN 0 872570088 A.G.A. Catalog
7、 Number XY9205 1M11.929849 Printed in the United States of America CONTENTS FIGURES . xiii PREFACE xv GEOP TASK GROUPS . xvii ACKNOWLEDGMENTS xxi CHAPTER 1. KNOWLEDGE REQUIRED BY GAS CONTROLLERS . 1 Summary . 1 The Role of Gas Control 1 The Round-the-Clock Function . 1 Monitoring Critical Areas and
8、Applications . 1 Emergency Communication . 2 Safety in System Operation . 2 Support for Non-24-hour Company Operations 2 Outage Coordination 3 The Daily Function 3 Demand Forecasting 3 Facility Control . 5 Data Acquisition, Recordkeeping, and Reporting . 5 The Seasonal Function 6 Monthly Supply/Dema
9、nd Balancing . 6 Inventory Management 6 The Annual Function . 6 Input Into Long-Range Plans 6 Knowledge Requirements . 7 iii iv GAS CONTROL Facilities 7 Company 7 Receipt Points 7 Delivery Points 8 Procedures . 8 Emergency . 8 Operating Philosophy . 8 Recordkeeping Routines . 8 Contractual Requireme
10、nts . 9 Tariffs . 9 Firm Supply . 9 Interruptible Supply . 9 Firm Transportation . 9 Interruptible Transportation 10 Interruptible Demand . 10 Profile of the Candidate for Gas Control Work 10 Company Experience 10 Field Operations 10 Rotating Shift 10 Computer Literacy 11 Technical Skills . 11 Forma
11、l Training 11 On the Job Experience 11 Mathematical Aptitude . 11 Communications Skills . 12 Verbal . 12 Written . 12 Team Player 12 Managerial Skills . 12 Teacher 12 Delegator . 12 Planner 12 Training 13 Checklist . 13 General Industry Training . 13 Engineering Principles . 13 Regulatory Requiremen
12、ts . 13 Site-Specific Training 13 Facility Locations 13 Company Relationships 14 Operating Parameters 14 Individual Responsibilities . 14 Formal Classroom Training . 14 CONTENTS v In-house Programs . 14 Outside Organizations . 14 Simulators 15 CHAPTER 2. FUNDAMENTALS OF NATURAL GAS FLOW 17 Units of
13、Measurement 18 Pressure 18 Pressure Relationship 18 Pressure Base . 18 Temperature . 19 Temperature Relationships . 19 Temperature Base 20 Calculations 20 Flow 20 Properties of Natural Gas . 23 Components of Natural Gas 23 Molecular Weight . 23 Compressibility 24 Density . 25 Specific Gravity 25 Hea
14、ting Value 25 Calculations 26 Pressure, Volume, and Temperature Relationships . 28 Fluid Dynamics 28 Gas Laws 28 Boyles Law . 28 Charles Law . 28 Pipeline Flow Equations 29 Conclusion . 31 CHAPTER 3. GAS MEASUREMENT AND QUALITY . 33 Summary . 33 Primary Measurement Devices 33 Inferential Meters 33 O
15、rifice Meters . 33 Turbine Meters . 35 Pitot Tube . 36 Ultrasonic Metering . 37 Positive Displacement Meters . 38 Diaphragm Meters . 39 Rotary Meters . 41 Ancillary Measurement Devices . 42 vi GAS CONTROL Transducers 42 Gravitometers . 42 Calorimeters . 43 Chromatograps . 44 Calculation of Total Vol
16、ume 45 Circular Charts . 46 Electronic Flow Computer . 47 Gas Quality 48 Heating Value . 48 Interchangeability 48 Dew Point 48 Impurities . 49 Carbon Dioxide 49 Hydrogen Sulfide . 49 Particulates . 49 Hydrates 49 Typical Contract Language 50 Odorization . 50 Philosophy . 50 Odorant . 51 Odorizing Eq
17、uipment . 51 CHAPTER 4. GAS TRANSPORTATION . 53 Summary 53 Contractual Arrangements 53 Entities 54 Transactions . 54 The Sale/Purchase Transaction 54 The Ship/Transport Transaction 55 The Physical Exchange Transaction . 55 Types of Transportation . 56 Firm Transportation . 56 Interruptible Transport
18、ation 56 The Nomination/Allocation Process 57 Placing Nominations 57 Why Nominate? . 57 Who Places Nominations? . 57 Who Accepts Nominations? 58 What Information Is Required to Nominate? 58 When Are Nominations Placed? . 58 How Are Nominations Transmitted? . 61 Confirmation of Nominations 61 CONTENT
19、S vii Who Confirms Nominations? . 62 What Conditions Must Be Met? . 62 The Allocation Process . 62 Pro-Rata Allocation Based on Confirmed Nominations . 62 Swing Based on Confirmed Nominations . 63 Suspense Allocation Based on Confirmed Nominations 63 Balancing Agreement Allocation Based on Confirmed
20、 Nomination 63 Allocations Based on Entitlement . 63 Managing Imbalances . 64 Description of Imbalance . 64 Types of Imbalances 64 The Sale/Purchase Imbalance 64 The Ship/Transport Imbalance 64 The Custody Transfer Imbalance 64 Conclusion . 65 CHAPTER 5. DAILY PLANNING . 67 Summary . 67 Weather . 67
21、 Pertinent Elements 68 Temperature . 68 Wind 68 Cloud Cover 68 Percipitation . 69 Severe-Storm Warning or Watch . 70 Weather Forecasts . 70 National Weather Service 70 Private Forecasts 70 Demand Analysis 71 Customer Classifications . 71 Residential Customers . 71 Commercial Customers 72 Industrial
22、Customers . 72 Interruptible Customers 73 Consumption Patterns . 73 Base Load 73 Variable Load . 73 Conservation Effects 74 Sendout Forecasting 74 Forecasting Daily Sendout 75 Graphical Method . 75 viii GAS CONTROL Previous-Day Method 76 Monitoring Revising Daily Sendout Forecasts . 76 Similar-Day M
23、odel 77 Supply Scheduling . 79 Types of Supplies 79 Contractual Obligations . 80 Daily/Seasonal Supply Strategy 80 Economics 80 Conclusion 80 CHAPTER 6. SYSTEM FACILITIES AND OPERATIONS . 83 Summary 83 Pipelines . 83 Facilities 83 Gathering Systems 83 Transmission Systems 84 Distribution Systems 86
24、Custody Transfer 87 Metering Facilities 87 Regulating Facilities . 87 Operating Considerations 88 Maximum Allowable Operating Pressure 88 Linepack 88 Supply/Demand Balancing . 89 Maintenance/Construction Scheduling 90 Pigging . 90 Compressor Stations 91 Equipment . 91 Reciprocating Engines/Compresso
25、rs 91 Turbines and Centrifugal Compressors . 92 Operating Philosophy . 92 Unmanned Operations 92 Manned Operations . 92 Storage Facilities . 93 Aquifers . 93 Reservoir Mechanics . 94 Injection Operation . 95 Withdrawal Operation 95 Depleted Gas Fields 95 Reservoir Mechanics . 95 Injection Operation
26、. 96 Withdrawal Operation 96 CONTENTS ix Depleted Oil Fields 97 Reservoir Mechanics 97 Injection Operation . 98 Withdrawal Operation . 98 Salt Domes . 98 Peak Shaving Facilities 99 Storage of Liquified Natural Gas 99 Supply/LiquefactionOperation . 100 Vaporization (Regasification) Operation . 100 Pr
27、opane Peak Shaving . 101 Supply Operations 102 Vaporization Operations 102 Supplemental Natural Gas Facilities 103 Production from Liquid Hydrocarbons . 103 Production from Coal . 104 Other Production . 104 Gas Treatment Facilities 105 Gas-Cleaning Equipment 105 Water Removal . 105 Carbon Dioxide an
28、d Hydrogen Sulfide Removal 106 Conclusion . 107 CHAPTER 7. SUPERVISORY CONTROL AND DATA ACQUISITION . 109 Summary . 109 Equipment . 110 The Control Center 110 The Gas Controllers Console . 110 Data Printer 111 Event/Alarm Logger . 111 Mapboard 111 Strip Charts 113 Overhead Projectors . 113 Video Cop
29、iers 113 The Back-up Gas Control Center 114 Remote Locations . 114 RTU Functions . 114 Transducers 114 Digital Status Transmitters 114 Communications 116 The Control Function . 116 Field Control Systems 116 x GAS CONTROL Open-Loop Control 117 Closed-Loop Control 117 Remote Control Setpoint Validatio
30、n 119 The Data Acquisition Function . 119 Real-Time Data . 119 Alarms . 120 Scheduled Functions 120 Unscheduled Functions 122 Trending 122 Daily Activity 123 Monthly Activity . 123 Pipeline Modeling 123 Steady-State Models . 123 Off-Line Transient Models . 124 On-Line Modeling Systems 124 Pipeline S
31、imulation Training Systems . 124 Optimization of Compression/Pipeline Facilities 125 Conclusion 125 CHAPTER 8. EMERGENCY PLANNING . 127 Summary 127 Planning Elements . 128 Communications Coordination 128 Rerouting Supplies . 128 Curtailing Demand . 128 Relocation of the Gas Control Center 129 Round-
32、the-Clock Responsibilities . 129 Monitoring System Integrity . 129 Monitoring Sensitive Areas 129 Customer Contact . 130 Service Dispatching 130 One-Call Notices . 130 Notifications 130 Conclusion 130 APPENDIX A. TRAINING CHECKLIST FOR GAS CONTROLLERS 131 General Training 131 Terms and Definitions 1
33、31 Equipment . 131 Communication Skills 132 Natural Gas Laws, Properties, and Fundamentals 132 CONTENTS xi Market Demand Profiles/Weather 132 Transportation . 132 Gas Quality Problems and Solutions . 132 Supply/Inventory Management . 133 Underground Storage 133 Operational Constraints 133 Constructi
34、on and Maintenance . 133 SCADA Fundamentals 133 Odorization . 133 Contracts and Tariffs . 134 Pipeline Control Strategy 134 Site-Specific Training 134 Office Equipment . 134 SCADA System 134 Supply Scheduling . 134 Other Gas Control Tools and Aids 134 APPENDIX B. REGRESSION ANALYSIS IN FORECASTING S
35、ENDOUT 137 Summary . 137 Guidelines 137 Selection of Variables 138 Base-Load Component . 138 Weather Component 138 Ambient Temperature 139 Wind Velocity 139 Sunshine 139 Temperature Lag 139 Known-load Component 139 Statistical Analysis 139 Gathering and Organizing Data 140 Correlation 140 Other Conc
36、erns 141 Application of the Equation 141 References 142 Key Terms 143 GLOSSARY 145 INDEX . 147 FIGURES 1. Pressure reference point. . 19 2. Temperature scales. . 21 3. Typical natural gas analyses. 23 4. Molecular structure of aliphatic hydrocarbons. . 24 5. Regulator-station pressures and temperatu
37、res. . 30 6. Primary element of an orifice meter. 34 7. Primary element of a turbine meter. 35 8. Primary element of a pitot tube meter. 36 9. Primary element of an ultrasonic meter. 38 10. Operation of a diaphragm meter. 40 11. Primary element of a rotary meter. 41 12. Schematic diagram of a gravit
38、ometer. 43 13. Basic calorimeter. . 44 14. Gas chromatograph. . 45 15. Circular chart installation. 46 16. Pump-type odorizer. . 52 17. Relationships among gas transportation organizations. . 54 18. Typical form for sale/purchase transaction. . 59 19. Typical form for ship/transport transaction. 59
39、20. Typical form for custody transfer transaction #1. 60 21. Typical form for custody transfer transaction #2. 60 22. Typical form for custody transfer transaction #3. 61 23. Relationship of sendout to temperature. 68 24. Sendout adjustment vs. wind speed. . 69 25. Sendout adjustment vs. cloud cover
40、. . 69 26. National Weather Service forecast. . 71 27. Private weather service forecast. 72 28. Effect of conservation on sendout. . 75 xiii xiv GAS CONTROL 29. Sendout adjustment vs. daily temperature change. . 76 30. Previous-day-forecast method. . 77 31. Similar-day model. 78 32. Flow diagram of
41、gas processing plant. . 85 33. Liquid storage facilities. . 85 34. Gas compressor. 86 35. Pressure regulators. 87 36. Guidelines for linepack vs. delivery. 89 37. Electronic “smart” pig. 91 38. Cross section of aquifer storage field. 94 39. LNG facility. 100 40. Low-pressure propane storage tanks. 1
42、01 41. Propane vaporizers. 102 42. SNG production process. 104 43. Filter separator. 105 44. Diagram of a water removal facility. . 106 45. Diagram of a typical SCADA system. 109 46. Typical gas control center. 110 47. Gas controllers console. 111 48. Data printer and alarm logger. 112 49. Mapboard.
43、 112 50. Strip-chart recorders. 113 51. Remote terminal unit. . 115 52. Typical transducer installation. . 115 53. Open-loop control system. 117 54. Closed-loop control system. 118 55. Alarm log. 121 56. Sendout report. 121 57. Hourly-trend report. . 122 PREFACE Arlington, Virginia September 1992 Th
44、is is one of four books that comprise the Transmission volume in the Gas Engineering and Operating Practices (GEOP) series pub-lished by the American Gas Association (A.G.A.); the other three books are Pipelines/Planning and Economics, Compressor Station Operations , and Automation and Telecommunica
45、tions. This book was written by members of the A.G.A. Operating Sections Gas Control Committee to provide a basic knowledge of the role that the gas-control department referred to simply as gas control plays in moving gas from the producer to the end user in the natural gas in-dustry. The equipment,
46、 practices, and procedures discussed represent a typical gas control operation. With this understanding, the authors have refrained from repetitious use of the words “typically,” “usually,” etc. They realize that some facilities will be better equipped and staffed than the “typical” facility and tha
47、t some will be operating effectively with less resources. It will be the readers responsibility to apply the information appropriately. This publication is not intended to be a “how-to” procedures manual. Rather, it is a reference manual for help in understanding the scope and operating practices of gas control. It describes the gas-control res- ponsibilities of pipeline companies (pipelines), who perform primarily the transmission function, and local distribution companies (LDCs), who perform primarily the distribution function. The reader should recognize this dis
