《ISO-20765-1-2005.pdf》由会员分享，可在线阅读，更多相关《ISO-20765-1-2005.pdf（50页珍藏版）》请在三一文库上搜索。
1、 Reference number ISO 20765-1:2005(E) ISO 2005 INTERNATIONAL STANDARD ISO 20765-1 First edition 2005-09-15 Natural gas Calculation of thermodynamic properties Part 1: Gas phase properties for transmission and distribution applications Gaz naturel Calcul des proprits thermodynamiques Partie 1: Propri
2、ts de la phase gazeuse utilise pour des applications de transport et de distribution Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo reproduction or networking per
3、mitted without license from IHS -,-,- ISO 20765-1:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the c
4、omputer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to c
5、reate this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform
6、the Central Secretariat at the address given below. ISO 2005 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from eith
7、er ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reserved Copyright Internationa
8、l Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20765-1:2005(E) ISO 2005 All rights reserved iii Contents Page Fo
9、reword iv Introduction v 1 Scope 1 2 Normative references1 3 Terms and definitions .1 4 Thermodynamic basis of the method2 4.1 Principle2 4.2 The fundamental equation of Helmholtz free energy.3 4.3 Thermodynamic properties derived from the Helmholtz free energy5 5 Method of calculation8 5.1 Input va
10、riables8 5.2 Conversion from pressure to reduced density.9 5.3 Implementation 9 6 Ranges of application .10 6.1 Pressure and temperature 10 6.2 Pipeline quality gas .10 7 Uncertainty.11 7.1 Uncertainty for pipeline quality gas.11 7.2 Impact of uncertainties of input variables 14 8 Reporting of resul
11、ts.14 Annex A (normative) Symbols and units16 Annex B (normative) The Helmholtz free energy of the ideal gas .19 Annex C (normative) The equation for the Helmholtz free energy 22 Annex D (normative) Detailed documentation for the equation of state.24 Annex E (informative) Assignment of trace compone
12、nts.30 Annex F (informative) Implementation of the method.32 Annex G (informative) Examples .35 Bibliography42 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo repr
13、oduction or networking permitted without license from IHS -,-,- ISO 20765-1:2005(E) iv ISO 2005 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standa
14、rds is normally carried out through ISO technical committees. Each member body interested in a subject 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 tak
15、e part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is
16、 to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibilit
17、y that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 20765-1 was prepared by Technical Committee ISO/TC 193, Natural gas, Subcommittee SC 1, Analysis of natural gas. ISO 20765 consists o
18、f the following parts, under the general title Natural gas Calculation of thermodynamic properties: Part 1: Gas phase properties for transmission and distribution applications The following parts are under preparation: Part 2: Single phase properties (gas, liquid and dense-fluid) for extended ranges
19、 of application Part 3: Two-phase properties (vapour-liquid equilibria) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo reproduction or networking permitted withou
20、t license from IHS -,-,- ISO 20765-1:2005(E) ISO 2005 All rights reserved v Introduction This part of ISO 20765 specifies methods for the calculation of thermodynamic properties of natural gases, natural gases containing synthetic admixture, and similar mixtures. This part of ISO 20765 has four norm
21、ative annexes and three informative annexes. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo reproduction or networking permitted without license from IHS -,-,- Co
22、pyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 20765-1:2005(E) ISO 20
23、05 All rights reserved 1 Natural gas Calculation of thermodynamic properties Part 1: Gas phase properties for transmission and distribution applications 1 Scope This part of ISO 20765 specifies a method of calculation for the volumetric and caloric properties of natural gases, natural gases containi
24、ng synthetic admixture and similar mixtures, at conditions where the mixture can exist only as a gas. The method is applicable to pipeline-quality gases within the ranges of pressure, p, and temperature, T, at which transmission and distribution operations normally take place. For volumetric propert
25、ies (compression factor and density), the uncertainty of calculation is about 0,1 % (95 % confidence interval). For caloric properties (for example enthalpy, heat capacity, Joule-Thomson coefficient, speed of sound), the uncertainty of calculation is usually greater. 2 Normative references The follo
26、wing referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 31-3, Quantities and units Part 3: Mechanics ISO 31-4,
27、 Quantities and units Part 4: Heat ISO 7504, Gas analysis Vocabulary ISO 12213-2, Natural gas Calculation of compression factor Part 2: Calculation using molar-composition analysis ISO 14532, Natural gas Vocabulary 3 Terms and definitions For the purposes of this document, the terms and definitions
28、given in ISO 31-4, ISO 7504 and ISO 14532 and the following apply. NOTE See Annex A for the list of symbols and units used in this part of ISO 20765. 3.1 caloric property characteristic of a gas or homogeneous gas mixture which can be calculated from a fundamental equation of state NOTE The caloric
29、properties to which this part of ISO 20765 can be applied are internal energy, enthalpy, entropy, isochoric heat capacity, isobaric heat capacity, Joule-Thomson coefficient, isentropic exponent and speed of sound. Copyright International Organization for Standardization Provided by IHS under license
30、 with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20765-1:2005(E) 2 ISO 2005 All rights reserved 3.2 equation of state mathematical relationship between state variables of a gas o
31、r homogeneous gas mixture NOTE In this part of ISO 20765, it is useful to distinguish between two types of equation of state, namely (1) volumetric equation of state, in which the relationship is between the state variables pressure, temperature and the volume occupied by a given amount of substance
32、, and (2) fundamental equation of state, in which the relationship is between the density, temperature and the Helmholtz free energy. 3.3 residual property that part of a thermodynamic property which results from the non-ideal (real-gas) behaviour of a gas or homogeneous gas mixture, i.e. the differ
33、ence between a thermodynamic property of a real gas or gas mixture and the same thermodynamic property for the same gas or gas mixture, in the ideal state, at the same state conditions of temperature and density 3.4 thermodynamic property volumetric or caloric property 3.5 volumetric property charac
34、teristic of a gas or homogeneous gas mixture that can be calculated from a volumetric equation of state NOTE The volumetric properties to which this part of ISO 20765 can be applied are compression factor and density. 4 Thermodynamic basis of the method 4.1 Principle The method recommended is based
35、on the concept that pipeline-quality natural gas is completely characterized for the calculation of its thermodynamic properties by component analysis. Such an analysis, together with the state variables of temperature and density, provides the necessary input data for the method. In practice, the s
36、tate variables available as input data are more usually temperature and pressure and, in this case, it is necessary first to convert these to temperature and density. Equations are presented which express the Helmholtz free energy of the gas as a function of density, temperature and composition, fro
37、m which all of the thermodynamic properties can be obtained in terms of the Helmholtz free energy and its derivatives with respect to temperature and density. The method uses a detailed molar composition analysis in which all components present in amounts exceeding 0,000 05 mole fraction 50 molar pp
38、m 1) should be represented. For a typical natural gas, this might include alkane hydrocarbons up to about C7 or C8, together with nitrogen, carbon dioxide and helium. Typically, isomers for alkanes above C5 may be lumped together by molecular weight and treated collectively as the normal isomer. For
39、 some natural gases, it may be necessary to take into consideration additional components such as C9 and C10 hydrocarbons, water vapour and hydrogen sulfide. For manufactured gases, hydrogen and carbon monoxide should be considered. More precisely, the method uses a 21-component analysis in which al
40、l of the major and minor components of natural gas are included (see 6.2). Any trace component present but not identified as one of the 21 specified components may be reassigned appropriately to a specified component. 1) ppm is a depredated unit. Copyright International Organization for Standardizat
41、ion Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:19:32 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20765-1:2005(E) ISO 2005 All rights reserved 3 4.2 The fundamental equation of Helmholtz free en
42、ergy 4.2.1 Background The AGA8 equation 1 was published in 1992 by the Transmission Measurements Committee of the American Gas Association, having been designed specifically as a means for the high accuracy calculation of compression factor. In this respect, it is already the subject of ISO 12213-2.
43、 Since then it has become increasingly apparent that the equation has excellent potential for use in the calculation of all thermodynamic properties of natural gas, even though the accuracy of calculation is less well documented. In order for the AGA8 equation to become useful for the calculation of
44、 all thermodynamic properties, there are two major requirements. a) The equation itself, published initially in a form explicit only for volumetric properties, has to be mathematically recast in a form explicit for the residual Helmholtz free energy. In fact, although not published as such, the orig
45、inal development of the equation was as a fundamental equation in the form of Helmholtz free energy. This formulation 2 is essential in that all residual thermodynamic properties can be calculated from the Helmholtz free energy and its derivatives with respect to the state conditions of temperature
46、and density. b) For the calculation of caloric properties, a formulation is required for the Helmholtz free energy of the ideal gas as a function of temperature. Most previous formulations for the ideal gas have been explicit in the isobaric heat capacity and so, again, the chosen formulation 3, 4 h
47、as to be recast so as to be explicit in the Helmholtz free energy. Again, derivatives of the Helmholtz free energy with respect to the state conditions are needed. An important aspect of the formulations chosen for both the ideal and residual parts of the Helmholtz free energy is that the derivative
48、s required for calculating the thermodynamic properties can be given in analytical form. Hence, there is no need for numerical differentiation or integration within any computer program that implements the procedures. As a result, numerical problems are avoided and calculation times are shorter. The method of calculation described is very suitable for use within process simulation programs and, in particular, within programs developed for use in natural ga