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1、 Please see the administrative notes on page iii RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE AND TO PROVIDE SUPPORT- ING DOCUMENTATION. IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECH
2、NO- LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STAN- DARDS TO WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS. Reference number ISO/FDIS 23874:2006(E) ISO 2006 FINAL DRAFT ISO/TC 193/SC 1 Se
3、cretariat: NEN Voting begins on: 2006-08-10 Voting terminates on: 2006-10-10 INTERNATIONAL STANDARD ISO/FDIS 23874 Natural gas Gas chromatographic requirements for hydrocarbon dewpoint calculation Gaz naturel Exigences relatives la chromatographie en phase gazeuse pour le calcul du point de rose hyd
4、rocarbures Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 20:48:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/FDIS 23874:2006(E) PDF disclaime
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8、is ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted under the applicable laws of the users country, neither this ISO draft nor any extract from it may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electron
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10、22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Reproduction may be subject to royalty payments or a licensing agreement. Violators may be prosecuted. ii ISO 2006 All rights reserved Copyright International Organization for Standardization Provided by IHS under license wit
11、h ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 20:48:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/FDIS 23874:2006(E) ISO 2006 All rights reserved iii In accordance with the provisions of Council Resolution 15/1993, this document is
12、 circulated in the English language only. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 20:48:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/F
13、DIS 23874:2006(E) iv ISO 2006 All rights reserved Contents Page Foreword.v 1 Scope1 2 Normative references .1 3 Principle.2 4 Materials.2 5 Apparatus.2 6 Performance requirements 3 7 Sampling3 8 Analytical procedure.4 9 Methods of test7 10 Uncertainty in composition9 11 Calculation of dewpoint tempe
14、rature9 12 Analytical uncertainty contribution to dewpoint temperature .9 Annex A (informative) Typical analytical conditions for C5 to C12 analysis10 Annex B (informative) Validation of fraction data.12 Annex C (informative) Precision of area ratio16 Annex D (informative) Recommendations on sample
15、calibration gas introduction20 Annex E (informative) Calculation of fraction quantities, boiling points and component uncertainties22 Bibliography .26 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not fo
16、r Resale, 04/12/2007 20:48:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/FDIS 23874:2006(E) ISO 2006 All rights reserved v Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies).
17、The work of preparing International Standards 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-g
18、overnmental, in liaison with ISO, also take 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
19、. The main task of technical committees is 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
20、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 identifying any or all such patent rights. ISO 23874 was prepared by Technical Committee ISO/TC 193, Natural gas, Subcommittee SC 1, Analy
21、sis of natural gas. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 20:48:41 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Org
22、anization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 20:48:41 MDTNo reproduction or networking permitted without license from IHS -,-,- FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23874:2006(E) ISO 2006 All rig
23、hts reserved 1 Natural gas Gas chromatographic requirements for hydrocarbon dewpoint calculation 1 Scope This International Standard describes the performance requirements for analysis of treated natural gas of transmission or pipeline quality in sufficient detail so that the hydrocarbon dewpoint te
24、mperature can be calculated using an appropriate equation of state. It can be applied to gases that have maximum dewpoint temperatures (cricondentherms) between 0 C and 50 C. The pressures at which these maximum dewpoint temperatures are calculated are in the range 2 MPa (20 bar) to 5 MPa (50 bar).
25、Major components are measured using ISO 6974 (all parts) and the ranges of components that can be measured are as defined in ISO 6974-1. The procedure given in this International Standard covers the measurement of hydrocarbons in the range C5 to C12. n-Pentane, which is quantitatively measured using
26、 ISO 6974 (all parts), is used as a bridge component and all C6 and higher hydrocarbons are measured relative to n-pentane. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For unda
27、ted references, the latest edition of the referenced document (including any amendments) applies. ISO 6974-1, Natural gas Determination of composition with defined uncertainty by gas chromatography Part 1: Guidelines for tailored analysis ISO 6974-2, Natural gas Determination of composition with def
28、ined uncertainty by gas chromatography Part 2: Measuring-system characteristics and statistics for processing of data ISO 6974-3, Natural gas Determination of composition with defined uncertainty by gas chromatography Part 3: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and hy
29、drocarbons up to C8 using two packed columns ISO 6974-4, Natural gas Determination of composition with defined uncertainty by gas chromatography Part 4: Determination of nitrogen, carbon dioxide and C1 to C5 and C6+ hydrocarbons for a laboratory and on- line measuring system using two columns ISO 69
30、74-5, Natural gas Determination of composition with defined uncertainty by gas chromatography Part 5: Determination of nitrogen, carbon dioxide and C1 to C5 and C6+ hydrocarbons for a laboratory and on- line process application using three columns ISO 6974-6, Natural gas Determination of composition
31、 with defined uncertainty by gas chromatography Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and C1 to C8 hydrocarbons using three capillary columns ISO 6975, Natural gas Extended analysis Gas-chromatographic method ISO 10715, Natural gas Sampling guidelines Copyright
32、International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 20:48:41 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/FDIS 23874:2006(E) 2 ISO 2006 All rights reserved 3 P
33、rinciple For hydrocarbon gas mixtures such as natural gas, the phase boundary or dewpoint line distinguishing single- phase gas from gas-liquid mixtures is a complex function of pressure, temperature and composition. For a given composition, the pressure at which the dewpoint temperature is at a max
34、imum is intermediate between those found in transmission and distribution operations. The analysis shall be comprehensive for inert components and for hydrocarbons up to C12. It is not necessary to measure helium, hydrogen, water and sulfur compounds unless any of these is present at greater than 0,
35、01 mole fraction. The analysis shall be performed in two parts. Major components (nitrogen, carbon dioxide and hydrocarbons from C1 to C5) shall be analysed according to ISO 6974 (all parts). Higher hydrocarbons (C5 to C12) shall be analysed to satisfy the requirements given in this International St
36、andard. This allows the traceability of measurements according to ISO 6974 (all parts) to be extended to the higher hydrocarbons. It is not possible to identify all the measured higher hydrocarbons, nor is it possible to obtain a reference gas mixture that contains more than a few representatives of
37、 the higher hydrocarbons. The analytical data are, therefore, handled with a number of simplifying assumptions. Unidentified components are allocated a carbon number or molar mass according to their positions in the chromatogram with respect to identified n-alkanes. Alkanes of carbon number 7 and ab
38、ove are summed by carbon number and treated as fractions for input to the dewpoint calculation. Average boiling points and densities of fractions are calculated from the individual boiling points and quantities of the components that comprise them; individual-component boiling points are calculated
39、by interpolation between the bracketing n-alkanes 1. Sample components are quantified by comparison with n-pentane, which has been measured according to ISO 6974 (all parts), using relative response factors based on their allocated carbon numbers. NOTE When using ISO 6974 (all parts), n-pentane can
40、be measured as a direct component that is also present in the calibration-gas mixture, or as an indirect component using a response factor relative to a different component (for example, n-butane) in the calibration gas mixture. In either case, the uncertainty on the quantity of n-pentane can be cal
41、culated according to ISO 6974-2. 4 Materials 4.1 Certified-reference gas mixture for major components (CRM1), such as is required for ISO 6974 (all parts). Depending upon the working range and the accuracy required, more than one CRM can be needed. 4.2 Certified-reference gas mixture, for higher hyd
42、rocarbons (CRM2), containing as a minimum, n- pentane, n-hexane, benzene, cyclohexane, n-heptane, toluene, methylcyclohexane and n-octane. Ideally, the CRM2 should also contain n-nonane, n-decane, n-undecane and n-dodecane in methane. The mole fractions of components in CRM2 shall be chosen to be ap
43、propriate for the application, provided that the mixture is stable and free from the possibility of condensation in transport, storage and in use. 5 Apparatus 5.1 Measurement system for major components, comprised of a sample introduction and transfer unit, a separation unit, a detection unit, an in
44、tegrator and a data reduction system, capable of meeting the analytical requirements described in 6.1. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 20:48:41 MDTNo reproduction
45、 or networking permitted without license from IHS -,-,- ISO/FDIS 23874:2006(E) ISO 2006 All rights reserved 3 ISO 6974 (all parts) describes equipment suitable for this part of the analysis. 5.2 Measurement system for higher hydrocarbons, comprised of a sample-introduction and transfer unit, a separ
46、ation unit, a detection unit, an integrator and a data-reduction system, capable of meeting the analytical requirements described in 6.2. Annex A describes a system that has been shown to be suitable. The user is responsible for demonstrating in each case that his/her chosen system is also suitable.
47、 6 Performance requirements 6.1 Major components The system for measurement of major components shall have performance as described in ISO 6974 (all parts). 6.2 Higher hydrocarbons The system for measurement of higher hydrocarbons shall satisfy the following requirements: be capable of measuring alk
48、anes up to and including n-dodecane; be capable of measuring individual alkanes at a concentration of 0,000 000 1 mole fraction (0,1 ppm 1) or less; be able to distinguish and measure benzene, toluene, cyclohexane and methylcyclohexane as individual components; use a detection system that can, at least in principle, measure all hydrocarbons in the range C5 to C12; use a detection system that has a predictable response to hydrocarbons based on