1、Manual of PetroleumMeasurement StandardsChapter 14Natural Gas Fluids MeasurementSection 10Measurement of Flow to FlaresFIRST EDITION, JULY 2007REAFFIRMED, JUNE 2012Manual of PetroleumMeasurement StandardsChapter 14Natural Gas FluidsMeasurementSection 10Measurement of Flow to FlaresMeasurement Coordi
2、nationFIRST EDITION, JULY 2007REAFFIRMED, JUNE 2012SPECIAL NOTESAPI publications necessarily address problems of a general nature. With respect to particularcircumstances, local, state, and federal laws and regulations should be reviewed.Neither API nor any of APIs employees, subcontractors, consult
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14、 API standards are reviewed and revised, reaffirmed, or withdrawn at least everyfive years. A one-time extension of up to two years may be added to this review cycle. Statusof the publication can be ascertained from the API Standards Department, telephone (202)682-8000. A catalog of API publications
15、 and materials is published annually and updatedquarterly by API, 1220 L Street, N.W., Washington, D.C. 20005.Suggested revisions are invited and should be submitted to the Standards and PublicationsDepartment, API, 1220 L Street, NW, Washington, D.C. 20005, standardsapi.org.iiiCONTENTSPage1 INTRODU
16、CTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.2 Background . . . . . . . . . . . . . . . . . . . .
17、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.3 Field of Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.4 Flare Metering Technologies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . .22 REFERENCE PUBLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 TERMINOLOGY AND DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43.1 Definitions Consistent with Definitions in API MPMS Chapter 1. . . . . . .
19、 . . . . . .43.2 Definitions Unique to This Standard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44 APPLICATION CONSIDERATIONS FOR METERS IN FLARE SYSTEMS . . . . . .54.1 General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、. . . . . .54.2 Location of Flare Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64.3 Application-specific Factors Affecting Flow Meter Performance . . . . . . . . . . . . .74.4 Meter Sizing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、 . . . . . . . . . . . . . . . . . . . . . . . .84.5 Measurement Uncertainty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84.6 Flow Meter Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84.7 Specific Me
22、ter Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104.8 Secondary Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134.9 Codes and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . . . . . . .144.10 Maintenance Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144.11 Record-keeping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145 FACTORY CALIBRATIONS/VERIFI
24、CATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . .145.1 Flow Meter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145.2 Pressure and Temperature Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156
25、COMMISSIONING AND STARTUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156.1 Equipment Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156.2 FFMS Commissioning. . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . . . . . . . . . . .167 PERIODIC VERIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177.2 Periodic Verifi
27、cation MethodFlow Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177.3 Periodic Verification MethodSecondary Devices . . . . . . . . . . . . . . . . . . . . . . .188 RE-EVALUATION OF EXISTING FFMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .188.1 Re-evaluation
28、Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .189 PERFORMANCE TEST PROTOCOL SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .199.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29、. . . . . . . . . . .199.2 General Performance Test Protocol Requirements . . . . . . . . . . . . . . . . . . . . . . . .1910 UNCERTAINTY AND PROPAGATION OF ERROR . . . . . . . . . . . . . . . . . . . . . . . .1910.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30、 . . . . . . . . . . . . . . . . . . .1910.2 Uncertainty Analysis Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1910.3 Simplified Uncertainty Analysis Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20vPage10.4 Uncertainty Estimate for Flare
31、Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . .2110.5 Meter-specific Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2511 DOCUMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32、. . .3011.1 Procedural Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3011.2 Scaling Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3011.3 Other Documentation. . . . . . . . . . . . . . . . . .
33、. . . . . . . . . . . . . . . . . . . . . . . . . . . . .3011.4 Management of Change Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30APPENDIX A-1 EXAMPLE PROCESS STREAM DATA SHEET . . . . . . . . . . . . . . . .31APPENDIX A-2 FLARE METER CALCULATIONS . . . . . . . . . .
34、 . . . . . . . . . . . . . . . . .33APPENDIX A-3 COMPRESSIBILITY EFFECTS ON FLARE GAS MEASUREMENT UNCERTAINTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37APPENDIX A-4 GENERAL FLARE DESIGN CONSIDERATIONS . . . . . . . . . . . . . .39APPENDIX A-5 GUIDANCE ON MA
35、NAGEMENT OF CHANGE PROCESSFFMS SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49APPENDIX A-6 VELOCITY PROFILE AND VELOCITY INTEGRATION CONSIDERATIONS FOR FLARE GAS MEASUREMENT . . . . . . .51Figures1 Flare Flow Measurement System (FFMS) Graphic
36、al Representation ofan FFMS and its Relation to Other Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Measurement Error Caused by Gas Composi
37、tion Analysis Delay . . . . . . . . . . . . 234 Annulus Area vs. Distance from the Center of the Pipe . . . . . . . . . . . . . . . . . . . . 515 Point Velocity vs. Area Weighted Velocity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526 Predicted Velocity Contours through the Downstr
38、eam of the Single Bend. . . . . . 537 Comparison of Axial Velocity on the Horizontal Axis with NIST Dataat Various Axial Distances from the Bend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Tables1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
39、 . . . . . . . . . . . . . . . . . . . . . . . . .92 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40、. . . . . . . . . 134 Example Table of Combined Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Errors Related to Use of Fixed Composition for Different Meter andCalculations Types (Absolute Value of Error) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24A-2.1
41、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 Velocity/Pipe Bulk Average Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537 Table of Meter Errors Meter Using the Fully Developed P
42、rofile vs. 11.2D Profile . 548 Table of Meter Errors Meter Using the Fully Developed Profile vs. 2.7D Profile . . 541Chapter 14Natural Gas Fluids MeasurementSection 10Measurement of Flow to Flares1 Introduction1.1 SCOPEThe standard addresses measurement of flow to flares, and includes: Application c
43、onsiderations. Selection criteria and other considerations for flare meters and related instrumentation. Installation considerations. Limitations of flare measurement technologies.Calibration.Operation. Uncertainty and propagation of error. Calculations.The scope of this Standard does not include an
44、alytical instrumentation.1.2 BACKGROUNDMeasurement of flow to flares is important from accounting, mass balance, energy conservation, emissions reduction, and regula-tory perspectives. However, measurement of flow to flares remains distinctly different from traditional flow measurement foraccounting
45、 or custody transfer. Flares are safety relief systems which typically receive highly unpredictable rates of flow andvarying compositions, and for safety reasons do not often lend themselves to being taken out of service to accommodate measure-ment concerns, even for short periods. Therefore, some o
46、f the traditional paradigms applicable to custody transfer measurementsystems (reasonably predictable flow rates and composition, the use of in-line proving, capability to readily remove meters fromthe piping system, the use of by-pass connections, the use of master meters, etc.) must be abandoned a
47、ltogether or highly modi-fied in flare measurement applications. 1.3 FIELD OF APPLICATIONFor safety and other considerations, it is highly undesirable to directly flare multiphase mixtures of liquids and gases. Therefore,this Standard is primarily concerned with flare flow measurement in the gas or
48、vapor phase. However, considering that foulingsubstances (liquid droplets and or mist or other contaminants) may be present even in well designed flare systems, this Standardprovides appropriate cautionary detail as to the effects of such contaminants which may impact flare flow measurements.Most fl
49、are header applications are designed to operate during non-upset conditions at near atmospheric pressure and ambient temper-ature, where compressibility of the mixture is near unity. Extreme conditions have been noted to be between 3.4 kPa-g ( 0.5 psig)and 414 kPa-a (60 psia), and between 100C (148F) and 300C (572F). Flare gas compositions are highly variable, and canrange from average molecular weights approaching that of hydrogen to that of C5+ or higher. The uncertainty in flare gas densityassociated with varying pressure, temperature, and composition is discus
