《BS-ISO-20765-1-2005.pdf》由会员分享，可在线阅读，更多相关《BS-ISO-20765-1-2005.pdf（54页珍藏版）》请在三一文库上搜索。
1、BS ISO 20765-1:2005 ICS 75.060 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Natural gas Calculation of thermodynamic properties Part 1: Gas phase properties for transmission and distribution applications Licensed CopyChinese University of Hong Kong, 11/04/2
2、009 08:46, Uncontrolled Copy, (c) BSI This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2009 BSI 2009 ISBN 978 0 580 66761 9 Amendments/corrigenda issued since publication DateComments BS ISO 20765-1:2005 National foreword This Brit
3、ish Standard is the UK implementation of ISO 20765-1:2005. The UK participation in its preparation was entrusted to Technical Committee PTI/15, Natural gas and gas analysis. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not p
4、urport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Licensed CopyChinese University of Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1
5、:2005 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: P
6、roprits de la phase gazeuse utilise pour des applications de transport et de distribution Licensed CopyChinese University of Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2005 ISO 20765-1:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with
7、 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 computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing po
8、licy. 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 create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every
9、 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 the Central Secretariat at the address given below. ISO 2005 All rights reserved. Unless otherwise specified, no part of this publication
10、 may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either 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 T
11、el. + 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 Licensed CopyChinese University of Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2005 ISO 20765-1:2005(E) ISO 2005 All rights reserved
12、 iii Contents Page Foreword 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 calc
13、ulation8 5.1 Input variables8 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
14、 8 Reporting of results.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) Assign
15、ment of trace components.30 Annex F (informative) Implementation of the method.32 Annex G (informative) Examples .35 Bibliography42 Licensed CopyChinese University of Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2005 ISO 20765-1:2005(E) iv ISO 2005 All rights reserved Forew
16、ord 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 subject for which a techni
17、cal 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 (IEC) on all matters of e
18、lectrotechnical 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 to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to
19、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 possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for i
20、dentifying 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 of the following parts, under the general title Natural gas Calculation of thermodynamic properties: Part 1: Gas phase pro
21、perties for transmission and distribution applications The following parts are under preparation: Part 2: Single phase properties (gas, liquid and dense-fluid) for extended ranges of application Part 3: Two-phase properties (vapour-liquid equilibria) Licensed CopyChinese University of Hong Kong, 11/
22、04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2005 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.
23、 This part of ISO 20765 has four normative annexes and three informative annexes. Licensed CopyChinese University of Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2005 Licensed CopyChinese University of Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2
24、005 INTERNATIONAL STANDARD ISO 20765-1:2005(E) ISO 2005 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 calori
25、c properties of natural gases, natural gases containing 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 o
26、perations normally take place. For volumetric properties (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
27、 is usually greater. 2 Normative references The following 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 3
28、1-3, Quantities and units Part 3: Mechanics ISO 31-4, 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
29、purposes of this document, the terms and definitions 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 f
30、rom a fundamental equation of state NOTE The caloric 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. Licensed CopyChinese University o
31、f Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2005 ISO 20765-1:2005(E) 2 ISO 2005 All rights reserved 3.2 equation of state mathematical relationship between state variables of a gas or homogeneous gas mixture NOTE In this part of ISO 20765, it is useful to distinguish bet
32、ween 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, and (2) fundamental equation of state, in which the relationship is between the density
33、, 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 difference between a thermodynamic property of a real gas or gas mixture and the same thermodyn
34、amic 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 characteristic of a gas or homogeneous gas mixture that can be calculated from a volumetric equ
35、ation 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 on the concept that pipeline-quality natural gas is completely characterized for the calc
36、ulation 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 state variables available as input data are more usually temperature and pressure and, in
37、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, from which all of the thermodynamic properties can be obtained in terms of the Helmholtz fre
38、e 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 ppm 1) should be represented. For a typical natural gas, this might include alkane hydrocar
39、bons 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 some natural gases, it may be necessary to take into consideration additional components
40、 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 all of the major and minor components of natural gas are included (see 6.2). Any trace comp
41、onent 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. Licensed CopyChinese University of Hong Kong, 11/04/2009 08:46, Uncontrolled Copy, (c) BSI BS ISO 20765-1:2005 ISO 20765-1:2005(E) ISO 2005 Al
42、l rights reserved 3 4.2 The fundamental equation of Helmholtz free energy 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 compressi
43、on factor. In this respect, it is already the subject of ISO 12213-2. 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. I
44、n order for the AGA8 equation to become useful for the calculation of 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 Hel
45、mholtz free energy. In fact, although not published as such, the original 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
46、 its derivatives with respect to the state conditions of temperature 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 th
47、e isobaric heat capacity and so, again, the chosen formulation 3, 4 has 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 a
48、nd residual parts of the Helmholtz free energy is that the derivatives 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,
49、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 gas transmission and distribution applications. 4.2.2 The Helmholtz free energy The Helmholtz free energy, f, of a homogeneous gas mixture at uniform pressure and temperature can be expressed as the sum of a part f o describing the ideal gas behaviour and a part fr describing the