1、PD ISO/TR 29922:2017 Natural gas Supporting information on the calculation of physical properties according to ISO 6976 BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06PD ISO/TR 29922:2017 PUBLISHED DOCUMENT National foreword This Published Document is the UK implem
2、entation of ISO/TR 29922:2017. The UK participation in its preparation was entrusted to Technical Committee PTI/15, Natural Gas & Gas Analysis. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the nece
3、ssary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017. Published by BSI Standards Limited 2017 ISBN 978 0 580 90031 0 ICS 75.060 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard
4、 was published under the authority of the Standards Policy and Strategy Committee on 31 March 2017. Amendments/corrigenda issued since publication Date T e x t a f f e c t e dPD ISO/TR 29922:2017 ISO 2017 Natural gas Supporting information on the calculation of physical properties according to ISO 6
5、976 Gaz naturel Informations supplmentaires pour le calcul des proprits physiques selon lISO 6976 TECHNICAL REPORT ISO/TR 29922 Reference number ISO/TR 29922:2017(E) First edition 2017-03PD ISO/TR 29922:2017ISO/TR 29922:2017(E)ii ISO 2017 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2017, Pu
6、blished in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Perm
7、ission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.orgPD ISO/TR 29922:2017ISO/TR 299
8、22:2017(E)Foreword vi Introduction vii 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Symbols, units and abbreviated terms 1 4.1 Quantities 1 4.2 Subscripts 3 4.3 Superscripts . 3 4.4 Abbreviated terms . 3 5 Enthalpy of combustion of the ideal gas and its variation with temperat
9、ure .4 5.1 Preamble 4 5.2 Standard enthalpy of combustion at 25 C . 4 5.3 Standard enthalpy of combustion at other temperatures . 5 5.4 Formulation of the ideal-gas enthalpy 6 5.5 Illustrative examples 7 5.6 Uncertainty in enthalpy of combustion . 8 6 Non-ideality: Variation of real-gas enthalpy of
10、combustion with pressure 9 6.1 Preamble 9 6.2 Formulation of the enthalpic correction 10 6.3 Estimation of the enthalpic correction 12 6.4 Conclusion 13 7 Non-ideality: C ompr ession fact or effect on v olume-basis calorific v alues .13 7.1 Compression factor 13 7.2 Virial equation of state 14 7.3 E
11、stimation of mixture compression factor 15 7.4 Limitations of the modified IGT-32 method .17 7.5 Uncertainty in compression factor .18 8 Quantitation of volumetric non-ideality .18 8.1 Second virial coefficients of pure components 18 8.1.1 Preliminary procedures 18 8.1.2 Improved procedure 19 8.2 Su
12、mmation factors of pure components . .21 8.2.1 Overview 21 8.2.2 Major components of natural gas .21 8.2.3 Hydrogen and helium .22 8.3 Compression factors of the permanent gases .23 8.4 Pure component uncertainties .25 8.4.1 Uncertainty of second virial coefficients 25 8.4.2 Truncation error .25 8.4
13、.3 Linearization error . .27 8.4.4 Berlin versus Leiden 28 8.4.5 Hydrogen and helium .29 8.4.6 Water .30 8.4.7 Combination of uncertainties 31 8.5 Mixture uncertainty .31 9 Miscellaneous data 31 9.1 Atomic weights of the elements 31 9.1.1 Atomic weights 2007.31 9.1.2 Atomic weights 2009 and 2011 .32
14、 9.1.3 Discussion .34 ISO 2017 All rights reserved iii Contents PagePD ISO/TR 29922:2017ISO/TR 29922:2017(E)9.2 Composition and molecular weight of dry air 35 10 Effects of w at er v apour on calorific v alue .36 10.1 Preamble .36 10.2 Excluded volume effect .37 10.3 Latent heat (enthalpic) effect 3
15、8 10.4 Compression factor effect .39 10.5 Combination of effects .39 10.6 Spectator water .40 10.7 Effect of humid air .41 10.7.1 Preamble 41 10.7.2 Stoichiometric combustion with oxygen42 10.7.3 Combustion of dry gas with excess dry air.42 10.7.4 Combustion of wet gas with excess dry air 43 10.7.5
16、Combustion of wet gas with excess humid air 43 11 Summary , discussion and selection of the calorific v alue of methane 45 11.1 Standard enthalpy of combustion .45 11.1.1 Background45 11.1.2 Selection of data 45 11.1.3 Recalculation of Rossini values 46 11.1.4 Evaluation of selected data 48 11.1.5 S
17、elected value and uncertainty 52 11.2 Derived calorific values 52 11.3 Comparisons between calorimetric methodologies 54 12 Calorific v alues on a mass basis .56 12.1 Calorific values on a mass basis for components of natural gas .56 12.2 Alternative (non-normative) method of calculation for mass-ba
18、sis calorific values 57 13 Calorific v alues on a v olume basis 60 13.1 Calorific values on a volume basis for components of natural gas .60 13.2 Alternative (non-normative) method of calculation for volume-basis calorific values 60 14 Approximate conversion between reference conditions 63 14.1 Fact
19、ors for conversion between metric reference conditions 63 14.2 Equations for conversion between metric reference conditions65 14.3 Expression of non-SI reference (base) pressures in metric units 65 15 Mathematical and methodological issues relating to estimation of uncertainty.66 15.1 Principles 66
20、15.2 Input data .68 15.2.1 Preamble 68 15.2.2 Reference conditions .68 15.2.3 Composition data .68 15.2.4 Physical property data .69 15.3 Uncertainty of the calculational method .70 15.4 Evaluation of sensitivity coefficients 70 15.4.1 Preamble 70 15.4.2 Analytical method 71 15.4.3 Finite difference
21、 method 73 15.4.4 Monte Carlo method 73 16 Detailed derivation of uncertainty equations in ISO 6976:2016 73 16.1 Principles and assumptions 73 16.2 General formulation 74 16.3 Effects of correlations 75 16.3.1 Correlation between mole fractions 75 16.3.2 Correlation between molar masses 76 16.3.3 Co
22、rrelation between physical properties 78 16.4 Uncertainty equations for basic properties 78 16.4.1 Molar mass .78 iv ISO 2017 All rights reservedPD ISO/TR 29922:2017ISO/TR 29922:2017(E)16.4.2 Molar-basis gross calorific value .79 16.4.3 Molar-basis net calorific value 79 16.4.4 Summation factor .80
23、16.4.5 Compression factor .80 16.5 Uncertainty equations for compound properties 81 16.5.1 Mass-basis gross calorific value .81 16.5.2 Mass-basis net calorific value 82 16.5.3 Volume-basis gross calorific value 83 16.5.4 Volume-basis net calorific value 84 16.5.5 Density .86 16.5.6 Relative density
24、87 16.5.7 Gross Wobbe index88 16.5.8 Net Wobbe index .89 16.6 Repeatability and reproducibility91 17 Computer implementation of recommended methods .92 17.1 Compiled BASIC shareware program .92 17.2 Spreadsheet implementation 94 Bibliography .97 ISO 2017 All rights reserved vPD ISO/TR 29922:2017ISO/
25、TR 29922:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subj
26、ect for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IE
27、C) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be
28、 noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for iden
29、tifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents). Any trade name used in this document is information given for the con
30、venience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformit y assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) s
31、ee the following URL: www . i s o .org/ iso/ foreword .html. The committee responsible for this document is ISO/TC 193, Natural gas, Subcommittee SC 1, Analysis of natural gas.vi ISO 2017 All rights reservedPD ISO/TR 29922:2017ISO/TR 29922:2017(E) Introduction Both international and intranational cu
32、stody transfer of natural gas usually require precise determination of both the quantity and the quality of the gas to be traded. ISO 6976:2016, which cancels and replaces ISO 6976:1995, specifies methods for the calculation of those properties, often known as the combustion properties, which (in pa
33、rt) describe gas quality, namely gross (superior) and net (inferior) calorific value, density, relative density, gross and net Wobbe index. The methods provide the means of calculating the properties, including uncertainties, of any natural gas, natural gas substitute, or similar combustible gaseous
34、 fuel of known composition at commonly used reference conditions. Some 80-odd years ago, in the Introduction to Hyde and Mills classic text Gas Calorimetry, Sir Charles Vernon (CV) Boys wrote the words 109“ I hesitate to give the number of actual tests of the calorific value of gas which are made ev
35、ery year, but . it will be evident that any machinery set up to ascertain its value must be extensive . The fact is that no single commodity generally purchased by the public is so carefully watched and maintained of its guaranteed quality as gas ”. Since that time, the technology of gas calorimetry
36、 has changed beyond either recognition or imagination, but the truth of the sentiment expressed remains unchanged and refers every bit as much to 2017 as it did to 1932. This document acts as a repository for those manifold technical details which justify and explain the methods presented in the new
37、 third (2016) edition of ISO 6976 but which are not directly needed in its everyday routine implementation. In short, it is conceived and intended as a complete(ish) knowledge base which provides full and proper technical authentication of ISO 6976. ISO 2017 All rights reserved viiPD ISO/TR 29922:20
38、17PD ISO/TR 29922:2017Natural gas Supporting information on the calculation of physical properties according to ISO 6976 1 Scope This document acts as a repository for those manifold technical details which justify and explain the methods presented in the third edition of ISO 6976 but which are not
39、directly needed in the everyday routine implementation of the standard. Each main clause addresses a specific aspect of the calculational method described in ISO 6976:2016, and is intended to be self-sufficient and essentially independent of each other clause. For this reason, the user should not ex
40、pect the whole to be accessible to study as a sequentially coherent narrative. 2 Normative references There are no normative references in this document. 3 T erms a nd definiti ons For the purposes of this document, the terms and definitions given in ISO 6976 apply. ISO and IEC maintain terminologic
41、al databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp 4 Symbols, units and abbreviated terms 4.1 Quantities Symbol Meaning Unit a atomic index for
42、carbon in the generalized molecular species C a H b N c O d S e b atomic index for hydrogen in the generalized molecular species C a H b N c O d S e c atomic index for nitrogen in the generalized molecular species C a H b N c O d S e d atomic index for oxygen in the generalized molecular species C a
43、 H b N c O d S e e atomic index for sulfur in the generalized molecular species C a H b N c O d S e g coefficients in equation for B h molar enthalpy kJmol 1 k coverage factor m number of sets of values n number of determinations in a set of values p pressure (absolute) kPa q exact input quantity in
44、 calculation of Y (varies) r correlation coefficient s summation factor t Celsius temperature C u(Y) standard uncertainty of Y (varies) TECHNICAL REPORT ISO/TR 29922:2017(E) ISO 2017 All rights reserved 1PD ISO/TR 29922:2017ISO/TR 29922:2017(E) Symbol Meaning Unit u(Y,Y) covariance of Y and Y (varie
45、s) w repeatability or reproducibility (varies) x mole fraction y inexact input quantity in calculation of Y (varies) A atomic mass (atomic weight) kgkmol 1 B second virial coefficient m 3 mol -1 C third virial coefficient m 6 mol 2 Cp molar isobaric heat capacity kJmol 1 K 1 D (mass) density kgm 3 m
46、olar density molm 3 E non-random (systematic) bias from the true value of Hc kJmol 1 F function that generates property Y G relative density Hc molar-basis calorific value (negative enthalpy of combustion) kJmol 1 Hf enthalpy of formation kJmol 1 Hm mass-basis calorific value MJkg 1 Hv volume-basis
47、calorific value MJm 3 J j-th virial coefficient m 3( j-1) mol -(j-1) L molar enthalpy of vaporization of water kJmol 1 M molar mass (molecular weight) kgkmol 1 N number of components in a mixture number of input values of y Q amount of heat released kJmol 1 R molar gas constant Jmol 1 K 1 S sum of m
48、ole fractions (= 1) T thermodynamic (absolute) temperature K U(Y) expanded uncertainty of Y (varies) V molar volume m 3 mol 1 W Wobbe index MJm 3 Y general (unspecified) physical property (varies) Z compression factor mole fraction of nitrogen in dry combustion air mole fraction of oxygen in dry com
49、bustion air mole fraction of argon in dry combustion air mole fraction of water vapour in humid combustion air molar amount of air (including any excess) per mole of reactant zero-value parameter having non-zero uncertainty unity-value factor having non-zero uncertainty a + b/4 random contribution of offset from the true value of Hc kJmol 1 dipole moment debyes stoichiometric coefficient relative humidity
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