1、 Reference number ISO 14912:2003(E) ISO 2003INTERNATIONAL STANDARD ISO 14912 First edition 2003-03-15 Gas analysis Conversion of gas mixture composition data Analyse des gaz Conversion des donnes de composition de mlanges gazeux ISO 14912:2003(E) PDF disclaimer This PDF file may contain embedded typ
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6、ale 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 2003 All rights reservedISO 14912:2003(E) ISO 2003 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Terms and definitions .1 3 Symbo
7、ls and units 4 4 Basic principles.6 4.1 Expression of gas mixture composition.6 4.2 Conversion between different quantities8 4.3 Conversion between different state conditions.9 5 Main procedures10 5.1 Conversion between different quantities of composition.10 5.2 Conversion to reference conditions13
8、6 Practical implementation13 6.1 Conversion between quantities of composition 13 6.2 Conversion of single analyte contents .14 6.3 Conversion of complete compositions.15 6.4 Conversion between state conditions 15 6.5 Simple approximations applicable to conversion .15 7 Input quantities and their unc
9、ertainties16 7.1 Pure gas data.16 7.2 Gas mixture data .19 7.3 Rough uncertainty estimates.22 8 Conversion uncertainty 22 8.1 General considerations 22 8.2 Conversion of single analyte contents .23 8.3 Conversion of complete compositions.24 8.4 Uncertainty calculation using numerical differentiation
10、.26 8.5 Variances and covariances of input composition data.27 9 Application recommendations.29 Annex A (normative) Assessment of state conditions .30 Annex B (normative) Summation relations for the expression of mixture properties 33 Annex C (informative) Mixture component data 34 Annex D (informat
11、ive) Examples.40 Annex E (informative) Computer implementation of recommended methods.55 Bibliography57 ISO 14912:2003(E) iv ISO 2003 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The w
12、ork 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-govern
13、mental, 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. The
14、 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 vote.
15、 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 14912 was prepared by Technical Committee ISO/TC 158, Analysis of gases. ISO 14912:2003(E) ISO 2
16、003 All rights reserved vIntroduction The objective of gas analysis is to determine the composition of gas mixtures. Gas mixture composition is expressed qualitatively in terms of specified mixture components of interest, called analytes, and the complementary gas. Gas mixture composition is express
17、ed quantitatively by specifying the amount of every analyte in the mixture and the composition of the complementary gas. For the purpose of specifying the amount of an analyte in a gas mixture, different quantities are in use. This diversity is due to the fact that in different applications differen
18、t quantities have decisive advantages. Therefore procedures for conversion between different quantities are required. In cases where these quantities involve the volumes of the analytes or the gas mixture or both, they depend on the state conditions, i.e. pressure and temperature, of the gas mixture
19、. For each of these quantities, procedures for conversion between different state conditions are required. As a crude approximation, all of the conversions referred to above can be performed on the basis of the Ideal Gas Law. In most cases, however, an accurate conversion has to take into account th
20、e real gas volumetric behaviour of the analyte and of the gas mixture. In particular, many conversions require values of the compression factor (or of the density) of the gas mixture. This International Standard provides formally exact conversion procedures, based on fundamental principles, which fu
21、lly account for real gas behaviour of pure gases and gas mixtures. In addition to these, approximate procedures for practical applications are described, designed for different levels of accuracy and available data. These approximations are necessary because measured gas mixture compression factors
22、(or densities) are rarely available and therefore have to be estimated from component data. Uncertainty estimates are given which result from combining approximations in the conversion procedures with the uncertainties of the input data. Where conversions require real-gas volumetric data of pure gas
23、es or gas mixtures, these are expressed by compression factors. As equivalents, density data could be converted into compression factor data. INTERNATIONAL STANDARD ISO 14912:2003(E) ISO 2003 All rights reserved 1Gas analysis Conversion of gas mixture composition data 1 Scope This International Stan
24、dard defines the following quantities commonly used to express the composition of gas mixtures: mole fraction, mass fraction, volume fraction, and mole concentration, mass concentration, volume concentration. For these quantities of composition, this International Standard provides methods for conve
25、rsion between different quantities, and conversion between different state conditions. Conversion between different quantities means calculating the numerical value of an analyte content in terms of one of the quantities listed above from the numerical value of the same analyte content, at the same
26、pressure and temperature of the gas mixture, given in terms of another of these quantities. Conversion between different state conditions means calculating the numerical value of an analyte content, in terms of one of the quantities listed above, under one set of state conditions from the numerical
27、value of the same quantity under another set of state conditions, i.e. pressure and temperature, of the gas mixture. Gas mixture composition can be converted simultaneously between different quantities of composition and different state conditions by combination of the two types of conversion. This
28、International Standard is applicable only to homogeneous and stable gas mixtures. Therefore any state conditions (pressure and temperature) considered need to be well outside the condensation region of the gas mixture and that of each of the specified analytes (see Annex A). 2 Terms and definitions
29、For the purpose of this document, the following terms and definitions apply. NOTE See also References 1 and 2 in the Bibliography. 2.1 Quantities for the expression of gas mixture composition NOTE Further information concerning the terms defined in this subclause is given in 4.1. ISO 14912:2003(E) 2
30、 ISO 2003 All rights reserved2.1.1 mole fraction amount-of-substance fraction x quotient of the amount of substance of a specified component and the sum of the amounts of substance of all components of a gas mixture NOTE The mole fraction is independent of the pressure and the temperature of the gas
31、 mixture. 2.1.2 mass fraction w quotient of the mass of a specified component and the sum of the masses of all components of a gas mixture NOTE The mass fraction is independent of the pressure and the temperature of the gas mixture. 2.1.3 volume fraction quotient of the volume of a specified compone
32、nt and the sum of the volumes of all components of a gas mixture before mixing, all volumes referring to the pressure and the temperature of the gas mixture NOTE The volume fraction is not independent of the pressure and the temperature of the gas mixture. Therefore the pressure and the temperature
33、have to be specified. 2.1.4 mole concentration amount-of-substance concentration c quotient of the amount of substance of a specified component and the volume of a gas mixture NOTE The mole concentration is not independent of the pressure and the temperature of the gas mixture. Therefore the pressur
34、e and the temperature have to be specified. 2.1.5 mass concentration quotient of the mass of a specified component and the volume of a gas mixture NOTE The mass concentration is not independent of the pressure and the temperature of the gas mixture. Therefore the pressure and the temperature have to
35、 be specified. 2.1.6 volume concentration quotient of the volume of a specified component before mixing and the volume of a gas mixture, both volumes referring to the same pressure and the same temperature NOTE 1 The volume concentration is not independent of the pressure and the temperature of the
36、gas mixture. Therefore the pressure and the temperature have to be specified. NOTE 2 The volume fraction (2.1.3) and volume concentration (2.1.6) take the same value if, at the same state conditions, the sum of the component volumes before mixing and the volume of the mixture are equal. However, bec
37、ause the mixing of two or more gases at the same state conditions is usually accompanied by a slight contraction or, less frequently, a slight expansion, this is not generally the case. ISO 14912:2003(E) ISO 2003 All rights reserved 32.2 Additional quantities involved in conversions of gas mixture c
38、omposition 2.2.1 compression factor Z quotient of the volume of an arbitrary amount of gas at specified pressure and temperature and the volume of the same amount of gas, at the same state conditions, as calculated from the ideal gas law NOTE 1 This definition is applicable to pure gases and to gas
39、mixtures, therefore the term “gas” is used as a general term which covers pure gases as well as gas mixtures. NOTE 2 By definition, the compression factor of an ideal gas is 1. At room temperature and atmospheric pressure, for many gases the compression factor differs only moderately from 1. 2.2.2 m
40、ixing factor f quotient of the volume of an arbitrary amount of a gas mixture at specified pressure and temperature and the sum of the volumes of all mixture components, before mixing, at the same state conditions NOTE If the component volumes are strictly additive, i.e. if the sum of the component
41、volumes before mixing is the same as the volume after mixing, the mixing factor is 1. At room temperature and atmospheric pressure, for many gas mixtures the mixing factor differs only slightly from 1. 2.2.3 density quotient of the mass of an arbitrary amount of gas and its volume at specified press
42、ure and temperature NOTE This definition is applicable to pure gases and to gas mixtures, therefore the term “gas” is used as a general term which covers pure gases as well as gas mixtures. 2.2.4 molar volume V mol quotient of the volume of an arbitrary amount of gas at specified pressure and temper
43、ature and its amount of substance NOTE 1 This definition is applicable to pure gases and to gas mixtures, therefore the term “gas” is used as a general term which covers pure gases as well as gas mixtures. NOTE 2 The amount of substance of a mixture is given by the sum of the amounts of substance of
44、 the components. 2.2.5 virial coefficients coefficients in the expansion of the compression factor in terms of powers of a quantity of state NOTE In practice, only two virial expansions are used, where the quantity of state is either the pressure, p, or the inverse molar volume, 1/V mol , as follows
45、. () () () mol 2 mol mol ,1 . . . BT CT ZV T V V =+ + + (1) () () () 2 , 1 . ZpT BTpCTp =+ + + (2) ISO 14912:2003(E) 4 ISO 2003 All rights reserved2.2.5.1 second molar-volume virial coefficient B coefficient of 1/V molin the expansion of the compression factor in terms of inverse powers of the molar
46、 volume, V mol2.2.5.2 third molar-volume virial coefficient C coefficient of 1/ 2 mol V in the expansion of the compression factor in terms of inverse powers of the molar volume, V mol 2.2.5.3 second pressure virial coefficient B coefficient of p in the expansion of the compression factor in terms o
47、f powers of the pressure p 2.2.5.4 third pressure virial coefficient C coefficient of p 2in the expansion of the compression factor in terms of powers of the pressure p 3 Symbols and units Symbol Quantity SI unit abbreviation of p/(RT) mol/m 3B second molar-volume virial coefficient m 3 /mol B secon
48、d pressure virial coefficient 1/Pa mass concentration kg/m 3c mole concentration mol/m 3C third molar-volume virial coefficient m 6 /mol 2C third pressure virial coefficient 1/Pa 2D dilution factor 1 f mixing factor 1 volume fraction 1 i gas mixture components (i = 1, 2, , N) j, k gas mixture compon
49、ents (from 1 to N) (where needed in addition to symbol i) m mass kg M molar mass kg/mol n amount of substance mol ISO 14912:2003(E) ISO 2003 All rights reserved 5Symbol Quantity SI unit N number of gas mixture components p pressure Pa p vapsaturation vapour pressure Pa p dewdew pressure Pa R molar gas constant (8,314 510) J/(molK) density kg/m 3S (sample of) gas mixture volume concentration m 3 /m 3t Celsius temperature C T thermodynamic temperature K V volume m 3V molmolar volume m 3 /
