1、Mass Measurement of Natural Gas LiquidsGPA Standard 818212API Manual of Petroleum Measurement Standards Chapter 14.7FOURTH EDITION, APRIL 2012ADOPTED AS TENTATIVE STANDARD, 1982REVISED 1984, 1995, 2003, 2012GAS PROCESSORS ASSOCIATION6526 EAST 60TH STREETTULSA, OKLAHOMA 74145AMERICAN PETROLEUM INSTIT
2、UTE1220 L STREET, NWWASHINGTON, D.C. 20005Mass Measurement of Natural Gas LiquidsGPA Standard 818212API Manual of Petroleum Measurement Standards Chapter 14.7Measurement CoordinationFOURTH EDITION, APRIL 2012ADOPTED AS TENTATIVE STANDARD, 1982REVISED 1984, 1995, 2003, 2012GAS PROCESSORS ASSOCIATION6
3、526 EAST 60TH STREETTULSA, OKLAHOMA 74145AMERICAN PETROLEUM INSTITUTE1220 L STREET, NWWASHINGTON, D.C. 20005Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed.Neit
4、her API nor any of APIs employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for
5、any use, or the results of such use, of any information or process disclosed in this publication. Neither API nor any of APIs employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights.API publications may be used
6、by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or re
7、sponsibility for loss or damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict.API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are
8、 not intended to obviate the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices.Any manufacturer marking equipment
9、 or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard.Users of this St
10、andard should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein.All rights reserved. No part of this work may be reproduced, translated, stored in a retrieval s
11、ystem, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, NW, Washington, DC 20005.Copyright 2012 American Petroleum InstituteForewordMeasureme
12、nt by mass is often preferred for chemical reactions and various processes where the mass ratios of components are of primary interest in effecting control of the operation. Since the 1970s, the gas processing industry has recognized the importance of measuring mixed natural gas liquid (NGL) streams
13、 using mass measurement techniques. The volume at standard conditions of each component of an NGL mixture may be accurately derived from the mass measurement process because, unlike volumetric measurement, the mass measurement process is not sensitive to the effect pressure, temperature, intermolecu
14、lar adhesion and solution mixing have on the measured stream.Solution mixing and intermolecular adhesion occurs when smaller molecules fill in the spaces between the larger molecules in the solution. Temperature and pressure also affect the amount of shrinkage caused by solution mixing and intermole
15、cular adhesion. Due to these behaviors, the sum of the volumes of individual components in their pure state is greater than the volume of the mixture. Today, mass measurement systems are commonly used to measure NGL mixtures like raw make and ethane-propane mixes as well as specification ethane prod
16、uct. On the other hand, many propane, isobutane, normal butane and natural gasoline streams are measured using volumetric techniques. A number of industry-developed standards address the design, construction, operation and maintenance aspects of mass and volumetric measurement systems. Volumetric me
17、asurement depends on tables and correlations to correct the volume measured at flowing conditions to a volume at base conditions. The actual stream composition is important to both mass and volumetric techniques.The Gas Processors Association (GPA) publishes specifications for some of the products r
18、esulting from natural gas processing and fractionation including commercial propane, HD-5 propane, commercial butane, and others. Many companies also have specifications describing, among other things, the compositional requirements of a particular product. Mass measurement is the recommended method
19、 of measurement for these mixtures.These specification products rarely, if ever, are comprised of a single component. Instead, specification products are themselves a mixture of several components and the actual composition may vary somewhat over time as a function of plant operation. Solution mixin
20、g therefore occurs in specification products as well as in raw make. Industry developed tables and correlations address physical properties of certain specification products, within the limits of the research database. Volumetrically measured streams are then adjusted using these tables and correlat
21、ions for temperature, pressure and density effects. Errors may result when performing these volumetric measurement adjustments if the composition of the stream does not match the compositions for which the volume correction tables and correlations were derived or due to uncertainties in the correlat
22、ions themselves.This standard was developed jointly by GPA Section H, Measurement and Product Handling, and the API Committee on Gas Fluids Measurement (COGFM). It is referenced by API as Chapter 14, Section 7 (14.7) of the API Manual of Petroleum Measurement Standards (MPMS). The participation of C
23、OGFM in developing this standard is gratefully appreciated and acknowledged.Throughout this publication, the latest appropriate API and GPA Standards are referenced.Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sa
24、le, or use of any method, apparatus, or product covered by letters patent. Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent.This document was produced under API standardization procedures that ensure appropriate
25、 notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which this publication was developed should be directed in writing t
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27、rmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually by API,
28、 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standardsapi.org.ivContentsPage1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Normative References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Terms, Definitions, and Abbreviations . . . . . . . . . . . .
30、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.2 Abbreviations. . . . . . . . . . .
31、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Mass vs Volumetric MeasurementAccuracy and Precision Implications . . . . . . . . . . . . . . . . . . . . . . . . . 35 Mass Determination . . . . . . . . . . . . . . .
32、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.1 Direct Mass Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.2 Inferred Mass Measurement
33、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.3 Orifice Meters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
34、6 Density Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35、 . . . . . . . . . . . . . . . . . 46.2 Measured Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.3 Empirical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.4 Application in Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Volumetric Measurement for Inferred Mass Determination
37、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.2 Displacement Meters. . . . . . . . . . . . .
38、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.3 Turbine Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.4 Ultrasonic
39、 Meters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.5 Coriolis Meters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40、 . . . . . . . . . . . 67.6 Meter Proving. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77.7 Measurement By Orifice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41、 . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Sample Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . .
42、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 710 Conversion of Measured Mass to Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Bibliography . . . . . . . . . . . . . . . . . . . . . . . . .
43、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8v1Standard for Mass Measurement of Natural Gas Liquids1 ScopeThis standard serves as a reference for the selection, design, installation, operation and maintenance of single-phase dynamic
44、 liquid mass measurement systems that operate in the 351.7 kg/m3to 687.8 kg/m3(0.350 to 0.688 relative density at 60 F) density range. The mass measurement systems within the scope of this document include inferred mass measurement, where volume at flowing conditions is combined with density at simi
45、lar conditions to result in measured mass, as well as Coriolis mass measurement. Liquids with density below 351.7 kg/m3and above 687.8 kg/m3(below 0.350 and above 0.688 relative density at 60 F) and cryogenic fluids (colder than approximately 50.8 F) are excluded from the scope of this document, but
46、 the principles described herein may apply to such streams. NGL product should be analyzed to determine the mixture composition and the composition should be considered in determining the measurement methods and equipment to be used. It is especially important to use mass measurement whenever the ra
47、nge of molecular sizes is great, such as in high ethane content (more than 2 % to 5 % ethane) raw make, and when mixture composition is variable during the measurement period. It is less critical when the sizes of molecules in the mixture are similar, such as in the case of mixed butanes. Sampling e
48、quipment and techniques are covered including standards for analytical methods used to determine the composition of the sampled product. Equations of state and correlations used to calculate the density of the product are discussed. The standard used to convert mass to equivalent liquid volumes of c
49、omponents is also discussed.Equipment exists which uses diverse principles for measuring volume, sampling the product, and determining the composition and density of the product. This standard does not advocate the preferential use of any particular type of equipment. It is not the intention of this standard to restrict future development or improvement of equipment. The contracting parties to any agreement should mutually agree on the equipment to be used.2 Normative ReferencesThe following referenced documents are indispensable for the application of this document, or provide ad
