SIST EN 16726:2016
(Main)Gas infrastructure - Quality of gas - Group H
Gas infrastructure - Quality of gas - Group H
This draft European standard specifies characteristics and requirements for gases entering networks intended for conveyance of gases of group H of the second family, as defined by EN 437, and is intended to be applicable at cross border points and eventually also on networks and infrastructure conveying such gases.
Specific requirements for biomethane are not included as they are given in prEN…. (CEN/TC 408)
NOTE: It is recognised that some specifications, while acceptable in the general case, may lead to technical or operational problems for some stakeholders. Those impacts have been identified in the standard and their mitigation should be agreed upon by the interested parties in agreement with the regulatory agency.
Gasinfrastruktur - Beschaffenheit von Gas - Gruppe H
Diese Europäische Norm legt die Kenngrößen und Parameter, sowie die zugehörigen Grenzwerte für die Beschaffenheit von als Gruppe H eingeteilten Gasen fest, die zu transportieren, in Speicher ein und aus Speichern auszuspeisen, zu verteilen und zu verbrauchen sind.
ANMERKUNG Für Informationen zu Gasfamilien und Gasgruppen, siehe EN 437.
Diese Norm umfasst keine Gase, die in isolierten Netzen befördert werden.
Für Biomethan gelten die zusätzlichen Anforderungen nach prEN 16723 1.
Infrastructure gazière - Qualité du gaz - Groupe H
La présente Norme européenne spécifie les caractéristiques et les paramètres de qualité des gaz ainsi que leurs limites, pour des gaz classés dans le groupe H qui sont destinés à être transportés, injectés dans et depuis les stockages, distribués et utilisés.
NOTE Pour toute information sur les familles de gaz et groupes de gaz, voir l'EN 437.
La présente norme ne couvre pas les gaz transportés par des réseaux isolés.
Pour le biométhane, les exigences complémentaires indiquées dans l’EN 16723-1 s’appliquent.
Infrastruktura za plin - Kakovost plina - Skupina H
Ta osnutek evropskega standarda določa lastnosti in zahteve za pline, ki vstopajo v omrežja za prenos plinov skupine H druge družine, kot so opredeljeni v standardu EN 437, in je namenjen uporabi na mejnih točkah ter sčasoma tudi za omrežja in infrastrukturo za prenos takih plinov. Posebne zahteve za biometan niso vključene, ker so podane v standardu prEN ... (CEN/TC 408) OPOMBA: Znano je, da lahko nekatere specifikacije nekaterim deležnikom povzročijo tehnične ali operativne težave, čeprav so v splošnem sprejemljive. Taki vplivi so opredeljeni v standardu in zainteresirane stranke naj bi se skladno z zakonodajnimi organi dogovorile, kako zmanjšati njihov obseg.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Infrastruktura za plin - Kakovost plina - Skupina HGasinfrastruktur - Beschaffenheit von Gas - Gruppe HInfrastructure gazière - Qualité du gaz - Groupe HGas infrastructure - Quality of gas - Group H75.060Zemeljski plinNatural gasICS:Ta slovenski standard je istoveten z:EN 16726:2015SIST EN 16726:2016en,fr,de01-marec-2016SIST EN 16726:2016SLOVENSKI
STANDARD
SIST EN 16726:2016
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16726
December
t r s w ICS
y wä r x r English Version
Gas infrastructure æ Quality of gas æ Group H Infrastructure gazière æ Qualité du gaz æ Groupe H
Gasinfrastruktur æ Beschaffenheit von Gas æ Gruppe HThis European Standard was approved by CEN on
t v October
t r s wä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
9
t r s w CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
s x y t xã t r s w ESIST EN 16726:2016
EN 16726:2015 (E) 2 Contents Page European foreword . 3 Introduction . 4 1 Scope . 5 2 Normative references . 5 3 Terms and definitions . 5 4 Reference conditions and pressure units . 6 5 Requirements . 6 Annex A (normative)
Calculation of methane number of gaseous fuels for engines . 9 A.1 Introduction . 9 A.2 Calculation of methane number . 9 A.3 Example 1: 2H-gas . 10 A.4 Example 2: enriched biomethane . 16 A.5 Example 3: 2H-gas with hydrogen addition . 17 Annex B (informative)
Sulfur . 31 B.1 General . 31 B.2 Total sulfur from Odorants . 31 Annex C (informative)
Water dew point and hydrocarbon dew point . 35 C.1 Water dew point . 35 C.2 Hydrocarbon dew point . 35 Annex D (informative)
Background for not including a Wobbe Index range into this standard . 36 D.1 General . 36 D.2 A common European Wobbe index range . 38 Annex E (informative)
Hydrogen - Admissible Concentrations in natural gas systems . 39 Annex F (informative)
Sampling . 40 Annex G (informative)
A–deviations . 41 Bibliography . 46 SIST EN 16726:2016
EN 16726:2015 (E) 3 European foreword This document (EN 16726:2015) has been prepared by Technical Committee CEN/TC 234 “Gas infrastructure”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2016, and conflicting national standards shall be withdrawn at the latest by June 2016. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. The need for a European Standard concerning the specification of the quality of gases of group H is derived from the mandate M/400 issued to CEN by the European Commission. According to this mandate the goal is to define specifications that are as wide as possible within reasonable costs. This means that the specifications enhance the free flow of gas within the internal EU market, in order to promote competition and security of supply minimizing the negative effects on gas infrastructure and gas networks, efficiency and the environment and allow appliances to be used without compromising safety. Some requirements specified in this European Standard, Clause 5, cannot be applied in Germany, Hungary and the Netherlands due to existing conflicting national legislation. The related A-Deviations are listed in Annex G. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16726:2016
EN 16726:2015 (E) 4 Introduction This European standard sets requirements for gas quality with the aim to allow the free flow of gas between the CEN member states and to enable the security of supply taking into account the impact on the whole value chain from gas production and supply to end uses. However, at the moment of publication of this European standard, a common Wobbe Index range cannot be defined because of different regulations in CEN Member States and limited knowledge of the influence of broadening Wobbe Index range on integrity, efficiency and safe use of appliances in some countries (see Annex D). In order to find a common Wobbe Index range, further studies, such as the Gas Quality Harmonization Implementation Pilot, are necessary. The Wobbe Index should be defined when the pending results of these studies are available. The common Wobbe Index range should be implemented in a revised standard in due time. For hydrogen, at present it is not possible to specify a limiting value which would generally be valid for all parts of the European gas infrastructure (see Annex E). Responsibility and liability issues in the context of this European standard are subject to European or national regulations. SIST EN 16726:2016
EN 16726:2015 (E) 5 1 Scope This European standard specifies gas quality characteristics, parameters and their limits, for gases classified as group H that are to be transmitted, injected into and from storages, distributed and utilized. NOTE For information on gas families and gas groups see EN 437. This European standard does not cover gases conveyed on isolated networks. For biomethane, additional requirements indicated in prEN 16723-1 apply. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO 13443, Natural gas - Standard reference conditions (ISO 13443) EN ISO 14532, Natural gas - Vocabulary (ISO 14532) ISO 14912, Gas analysis — Conversion of gas mixture composition data 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN ISO 14532 and the following apply. 3.1 isolated network network where transmission, distribution and utilization of gas are combined and which is physically unconnected to other networks 3.2 entry point point at which gas enters a gas distribution or gas transmission system 3.3 interconnection point physical point connecting adjacent entry-exit systems or connecting an entry-exit system with an interconnector [SOURCE: Commission Regulation (EU) No 984/2013, modified] 3.4 maximum operating pressure maximum pressure at which a network can be operated continuously under normal conditions expressed as absolute pressure Note 1 to entry: Normal conditions are: no fault in any device or stream. [SOURCE: EN 1594:2013, 3.23, modified] SIST EN 16726:2016
EN 16726:2015 (E) 6 3.5 application equipment that utilizes the transported and distributed gas Note 1 to entry: Some examples of gas applications are: gas appliances (domestic or commercial), processes (chemical or industrial), power plants, vehicles, greenhouses etc. 4 Reference conditions and pressure units Unless stated otherwise all volumes are given for the real dry gas at ISO standard reference conditions of 15 °C (288,15 K) and 1013,25 mbar (101,325 kPa). Unless otherwise stated all pressures are absolute pressures. Whenever data on the volume, gross calorific value (GCV), energy and Wobbe Index are communicated, it shall be specified under which reference conditions these values were calculated. In assessing compliance with this European standard parameters should be determined directly at ISO standard reference conditions. If the properties are only available at other reference conditions and the actual gas composition is not known then conversion to ISO standard reference conditions shall be carried out using the procedure described in EN ISO 13443. NOTE Besides the ISO standard reference conditions, particular in gas transmission, normal reference conditions (25/0 °C) are used according to the Network Code Interoperability and Data exchange. These are indicated in Table 1 for information. 5 Requirements Gas shall comply with the requirements given in Table 1 and shall be accepted for conveyance. Table 1 — Requirements Parameter Unit Limits based on standard reference condition 15 °C/15°C Limits
based on normal reference condition 25°C /0°C (for information) Reference standards for test methodsd (informative) Min. Max. Min. Max. Relative density no unit 0,555 0,700 0,555 0,700 EN ISO 6976,
EN ISO 15970 Total sulfur without odorant mg/m3 not applicable 20a not applicable 21a EN ISO 6326-5,
EN ISO 19739 For sulfur in high pressure networks and on interconnection points the maximum acceptable sulfur content for conveyance is 20 mg/m3, where in high pressure networks non-odorized gas is current practice. However, for existing practices with respect to transmission of odorized gas between high pressure networks higher sulfur content value up to 30 mg/m3 may be accepted. NOTE On distribution networks the odorization is considered as a national safety issue. Some information about sulfur odorant content is given in Annex B. Hydrogen sulphide + Carbonyl sulphide
(as sulfur) mg/m3 not applicable 5a not applicable 5a EN ISO 6326-1,
EN ISO 6326-3,
EN ISO 19739 SIST EN 16726:2016
EN 16726:2015 (E) 7 Parameter Unit Limits based on standard reference condition 15 °C/15°C Limits
based on normal reference condition 25°C /0°C (for information) Reference standards for test methodsd (informative) Min. Max. Min. Max. Mercaptan sulfur without odorant (as sulfur) mg/m3 not applicable 6a not applicable 6a EN ISO 6326-3,
EN ISO 19739 Oxygen mol/mol not applicable 0,001 % or 1 %
(see below) not applicable 0,001 % or 1 %
(see below) EN ISO 6974-3,
EN ISO 6974-6,
EN ISO 6975 At network entry points and interconnection points the mole fraction of oxygen shall be no more than 0,001 %, expressed as a moving 24 hour average. However, where the gas can be demonstrated not to flow to installations sensitive to higher levels of oxygen, e.g. underground storage systems, a higher limit of up to 1 % may be applied. Carbon dioxide mol/mol not applicable 2,5 % or 4 %
see below not applicable 2,5 % or 4 %
see below EN ISO 6974 parts 1 to 6, EN ISO 6975 At network entry points and interconnection points the mole fraction of carbon dioxide shall be no more than 2,5 %. However, where the gas can be demonstrated not to flow to installations sensitive to higher levels of carbon dioxide, e.g. underground storage systems, a higher limit of up to 4 % may be applied. Hydro carbon dew pointb,c °C not applicable
«2 not applicable
«2 ISO 23874,
ISO/TR 12148 at any pressure from 0,1 to 7 MPa (70 bar) absolute pressure Water dew pointb,c at 7 MPa (70 bar) or, if less than 7 MPa (70 bar), at maximum operating pressure of the system in which the gas flows °C not applicable
«8 not applicable
«8 EN ISO 6327,
EN ISO 18453,
EN ISO 10101 parts 1 to 3 Methane number no unit 65 not applicable 65 not applicable see normative
Annex A Contaminants The gas shall not contain constituents other than listed in Table 1 at levels that prevent its transportation, storage and/or utilization without quality adjustment or treatment. a Figures are indicated without post-comma digits due to analytical uncertainty. b Under given climatic conditions, a higher water dew point and hydrocarbon dew point may be accepted at national level. c For further information on water dew point and hydrocarbon dew point see Annex C. d Test methods other than those listed in the reference standards indicated in Table 1 may be applied, provided their fitness for purpose can be demonstrated. SIST EN 16726:2016
EN 16726:2015 (E) 8 Gas quality shall not impede safety of gas appliances and operations of end users. Appropriate measures shall be taken. NOTE Applications are sensitive towards variations of the gas quality depending on the type of application and the degree of variation. For sampling, reference is made to Annex F. SIST EN 16726:2016
EN 16726:2015 (E) 9 Annex A (normative)
Calculation of methane number of gaseous fuels for engines A.1 Introduction The methane number of a gaseous fuel can be calculated from its composition according to several different methods, all of which can give different results. For the purposes of compliance with this European standard the methodology described in this Annex shall be employed. The method is based on the original data of the research program performed by AVL Deutschland GmbH /1/ for FVV (the Research Association for Combustion Engines) but employs amendments implemented in 2005 and 2011 by MWM GmbH. These amendments have been unpublished until the publication of this European standard. The method requires input of composition in the form of volume fractions at reference conditions of 0 °C and 101,325 kPa and expressed as a percentage. Composition is more likely to be available either as mole fraction (e.g. in the natural gas transmission and distribution industry) or as mass fraction (e.g. in the automotive fuel industry) and conversion to volume fraction shall be performed using the methods in ISO 14912. Numerical examples are provided so as to enable software developers to validate implementations of the methodology described in this annex. As an aid to validation a relatively large number of decimal places has been retained. For expression of the final result rounding to zero decimal points is recommended. A.2 Calculation of methane number A.2.1 Applicability The method described in this European Standard is applicable to gaseous fuels comprising the following gases: carbon monoxide; butadiene; butylene; ethylene; propylene; hydrogen sulphide; hydrogen; propane; ethane; butane; methane; nitrogen and carbon dioxide. The method treats hydrocarbons other than those specified as butane and is therefore applicable to gaseous fuels containing such higher hydrocarbons. The numerical examples provided in this annex are appropriate to gases of the second family and hence consider mixtures comprising methane, ethane, propane, butane, nitrogen and carbon dioxide. Hydrogen is also included in one example because of the growing interest in injection of hydrogen into gas pipelines. During the preparation of this standard MWM GmbH has confirmed that the method is applicable to both 2H and 2L gases. Oxygen and water vapour shall be ignored and the fuel gas composition shall be calculated on a dry, oxygen-free basis. A.2.2 General approach The methane number of a gaseous fuel is calculated from its composition in five steps. The steps are outlined below and discussed more fully in turn in A.3. Additional examples are discussed in A.4 and A.5. Table A.10 provides results of calculations for further software validation purposes. SIST EN 16726:2016
EN 16726:2015 (E) 10 a) The composition of the gaseous fuel is simplified by converting it into an inert-free mixture comprising the combustible compounds carbon monoxide, ethylene, propylene, hydrogen sulphide, hydrogen, propane, ethane, butane and methane. For gases of the second family conveyed in pipeline systems carbon monoxide, ethylene, propylene, hydrogen sulphide are unlikely to be present at concentrations that would impact on methane number and can be ignored. b) The simplified mixture is sub-divided further into a number of partial ternary mixtures. The number and particular partial ternary mixtures chosen is decided by inspection of available ternary systems in a given order, including those systems that contain the relevant combustible compounds. Selection is ceased when all combustible compounds are contained in at least two ternary systems. c) The composition and fraction of the selected partial mixtures is adjusted iteratively so as to minimize the difference between the methane numbers of each partial mixture. d) The methane number of the simplified mixture is determined from the weighted average of the methane number of the selected partial mixtures. e) Finally, the methane number of the gaseous fuel is calculated by correcting the methane number of the simplified mixture to allow for the presence of inerts in the original fuel gas. A.3 Example 1: 2H-gas A.3.1 Simplification of the composition of the gaseous fuel The description of the calculation is illustrated by reference to a 2H-gas of composition shown in Table A.1. The composition of the gas (column 1) is simplified by increasing the quantity of butanes to allow for the presence of butadiene, butylene, pentanes and hydrocarbons of carbon number greater than 5. The adjustment made is as follows: — Butadiene and butylene are replaced with an equivalent amount of butanes by multiplying their quantities by 1. — Pentanes are replaced with an equivalent amount of butanes by multiplying the quantity of pentanes by 2,3. — Hydrocarbons of carbon number greater than 5 (“hexanes+”) are replaced with an equivalent amount of butanes by multiplying the quantity of hexanes+ by 5,3. In the case of example 1 the quantity of butanes
= 0,2100 + 0,1900 + (0,0400 + 0,0500) × 2,3 + 0,0600 × 5,3
= 0,9250 (Column 2) The simplified mixture is then re-normalized to 100 % (Column 3). SIST EN 16726:2016
EN 16726:2015 (E) 11 A.3.2 Selection of the ternary systems A.3.2.1 Ternary mixtures The ternary mixtures are chosen from the following list: — A1:
Methane – Hydrogen – Ethane — A2:
Propane – Ethane – Butane — A3: Hydrogen – Propane - Propylene — A4: Methane – Ethane – Propane — A5: Methane – Hydrogen – Propane — A6: Methane – Hydrogen – Butane — A7: Methane – Propane – Butane — A8: Methane – Ethane – Butane — A9: Methane – Ethylene – Butane — A10: Methane – Hydrogen Sulphide – Butane — A11: Methane – Ethane – Hydrogen Sulphide — A12: Methane – Propylene — A13: Ethane – Propylene — A14: Carbon Monoxide – Hydrogen — A15: Ethane – Ethylene — A16: Propane – Ethylene — A17: Butadiene — A18: Butylene NOTE Mixtures A12 – A16 are clearly not ternary systems; however, for ease of mathematical treatment the coefficients have been adjusted so as to allow the expression of the methane number using a single equation. A.3.2.2 Range of applicability of ternary mixture data The range of applicability of most ternary systems is wide (each component can vary from 0 to 100 %). However, for some ternary systems there is a reduced range of applicability. This is a major issue when selecting ternary mixtures. The range of applicability of each ternary system is specified in Table A.2, expressed as maximum and minimum content of each component. SIST EN 16726:2016
EN 16726:2015 (E) 12 A.3.2.3 Factors affecting the ternary system selection process The ternary systems are selected in accordance with three main considerations: a) The number of gases in the ternary system that are present in the simplified mixture. Priority is always given to ternary systems that have all three of their components present in the simplified mixture. Systems with two of their components present in the simplified mixture are acceptable if insufficient systems with three components present in the simplified mixture are available. b) Where there is a choice of ternary systems, the system with the highest fitness, Wj, takes priority. c) Each component in the simplified mixture shall be represented in at least two ternary systems. Fitness of a system is calculated from the following formula: ()()==+=∑1100,15inii,jjiiV,minVmaxWVsum (A.1) where n is the number of components in the simplified mixture Vi is the volume fraction of component i in the simplified mixture Vmaxi,j is the maximum content of component i for the range of applicability of system j Vsumi is the sum of all maximum contents of component i for the range of applicability of all systems, i.e. ()()===+∑18,1100,15jiijiVsumminVmax (A.2) Values of Vsumi are independent of the composition of the simplified mixture. However, Wj is dependent upon the composition of the simplified mixture and so shall be calculated prior to selection. Note that this also means that the choice of ternary mixtures may be different for mixtures containing the same components, but in different proportions. In the case of example 1, the calculation of Vsumi and Wj is shown in Tables A.3 and A.4. A.3.2.4 Description of the ternary system selection process The aim is to identify the optimum number of ternary systems that meet the three criteria described in A.3.2.3 and this is achieved by consideration of each component present in the simplified mixture in the following sequence: 1) Carbon Monoxide 2) Butadiene 3) Butylene 4) Ethylene 5) Propylene 6) Hydrogen Sulphide 7) Hydrogen SIST EN 16726:2016
EN 16726:2015 (E) 13 8) Propane 9) Ethane 10) Butane 11) Methane Step 1: For the first component in the simplified mixture, one ternary system that contains that component is selected. The priority of selection is as follows: a) Ternary systems with all three components present in the simplified mixture have priority over systems having one or two components present. b) The ternary mixture with the highest fitness has priority. Step 2: Consideration is then given to the second component in the simplified mixture. If this component is not present in the ternary system selected for the first component, then a ternary system is selected for this component using the same priority of selection as in step 1. If, however, the ternary system selected for the first component contains the second component, then the selection proceeds for the third component (step 3). Step 3: Consideration is then given to third, fourth, fifth, etc. components in the same manner as Steps 1-2. Step 4: When all components in the simplified mixture have been examined once, steps 1-3 are repeated in the same component order. If any component is represented in only one selected ternary mixture, then an additional ternary mixture is selected, again using the same priority of selection as in step 1. The selection process ends when all components in the simplified mixture are represented in at least two ternary systems. In the case of example 1: — The first component in the simplified mixture is propane and this is present in four ternary systems that have all their components present in the simplified mixture – A2, A4, A7 and A8. In this case, A4 is selected because it has the largest value of fitness (i.e. 10,3138). — The second component in the simplified mixture is ethane and this is already represented in system A4, so no ternary mixture is selected. — The third component of the simplified mixture, butane, is not represented in system A4, so system selection continues and system A8 is selected because it has the highest value of fitness (10,2859). — The fourth component in the simplified mixture is methane and this is already represented in systems A4 and A8, so no ternary mixture is selected. — Selection is repeated with the first component in the simplified mixture, propane, and ternary system A7 is selected because it has the next highest value of fitness (9,6263; system A4 has already been selected). All components in the simplified mixture are now represented in at least two of the ternary systems selected and the selection process ends. The systems selected are therefore: A4, A7 and A8. SIST EN 16726:2016
EN 16726:2015 (E) 14 A.3.3 Sub-division of the inert-free mixture into the selected partial mixtures The simplified mixture is divided into the selected partial ternary mixtures. A preliminary division of the simplified mixture is made by assigning each component equally between the ternary systems in which it is represented. In the case of example 1, three ternary systems – A4, A7 and A8 – are selected. The preliminary division is made by assigning: methane equally between A4, A7 and A8; ethane equally between A4 and A8; propane equally between A4 and A7; and butanes equally between A7 and A8 (Columns 4, 6 and 8). A.3.4 Calculation of the methane number of the partial mixtures The methane number of each partial mixture is calculated from the general formula ()=====∑∑67,00jiijtijijMNaxy (A.3) Where x and y are the volume fractions of the first and second components in each partial ternary mixture, expressed as a percentage. In order to calculate the methane number of each partial mixture, therefore, the composition of each is normalized to 100 %. In the case of example 1 the composition of each partial mixture is calculated by renormalizing to 100 % (Columns 5, 7 and 9). Table A.2 lists the values of coefficients ai,j for the partial ternary systems A1–A18. In the case of example 1 application of Formula (A.3) for each preliminary composition of partial mixture results in calculated methane numbers of 76,2489, 77,3777 and 71,9706 for A4, A7 and A8 respectively (Columns 5, 7 and 9). A.3.5 Adjustment of the composition and fraction of the partial mixtures The composition and fraction (Ft) of each partial mixture is adjusted iteratively by varying the quantity of each component in each partial mixture so as to minimize the difference between the methane numbers of each partial mixture. The value to be minimised is therefore: (MNmax
« MNmin), where MNmax and MNmin are the maximum and minimum methane numbers for the selected partial mixtures. In the case of example 1, three ternary partial mixtures are selected and hence there are nine quantities to
...
SLOVENSKI STANDARD
oSIST prEN 16726:2014
01-julij-2014
Infrastruktura za plin - Kakovost zemeljskega plina - Skupina H
Gas infrastructure - Quality of natural gas - Group H
Gasinfrastruktur - Beschaffenheit von Erdgas - Gruppe H
Infrastructures gazières - Qualité du gaz naturel - Groupe H
Ta slovenski standard je istoveten z: prEN 16726
ICS:
75.060 Zemeljski plin Natural gas
oSIST prEN 16726:2014 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 16726:2014
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oSIST prEN 16726:2014
EUROPEAN STANDARD
DRAFT
prEN 16726
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2014
ICS 75.060
English Version
Gas infrastructure - Quality of gas - Group H
Infrastructure gazière - Qualité du gaz - Groupe H Gasinfrastruktur - Beschaffenheit von Gas - Gruppe H
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 234.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
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 supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16726:2014 E
worldwide for CEN national Members.
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oSIST prEN 16726:2014
prEN 16726:2014 (E)
Contents
Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms and definitions .5
4 Reference conditions .7
5 Requirements .7
Annex A (normative) Calculation of methane number of gaseous fuels for engines . 10
A.1 Introduction . 10
A.2 Calculation of methane number . 10
A.2.1 Applicability . 10
A.2.2 General approach . 10
A.3 Example 1: H-gas . 11
A.3.1 Simplification of the composition of the gaseous fuel . 11
A.3.2 Selection of the ternary systems . 11
A.3.3 Sub-division of the inert-free component into the selected partial mixtures . 14
A.3.4 Calculation of the methane number of the partial mixtures . 14
A.3.5 Adjustment of the composition and fraction of the partial mixtures . 14
A.3.6 Calculation of the methane number of the inert-free mixture . 15
A.3.7 Calculation of the methane number of the gaseous fuel . 16
A.4 Example 2: enriched biomethane. 16
A.4.1 Simplification of the composition of the gaseous fuel . 16
A.4.2 Calculation of fitness of the ternary systems . 16
A.4.3 Selection of ternary mixtures . 16
A.4.4 Calculation of the methane number. 17
A.5 Example 3: H-gas with hydrogen addition . 17
A.5.1 Calculation of fitness of the ternary systems . 17
A.5.2 Selection of ternary mixtures . 17
A.5.3 Calculation of the methane number. 18
A.6 Additional numerical examples . 18
A.7 Bibliography . 31
Annex B (informative) Sulfur . 32
B.1 General . 32
B.2 Total sulfur from Odorants . 32
Annex C (informative) Water dew point and hydrocarbon dew point . 43
C.1 Water dew point . 43
C.2 Hydrocarbon dew point . 43
Annex D (informative) Hydrogen - Admissible Concentrations in natural gas systems . 44
Annex E (informative) Sampling . 45
Bibliography . 46
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Foreword
This document (prEN 16726:2014) has been prepared by Technical Committee CEN/TC 234 “Gas
infrastructure”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
The need for a European Standard concerning the specification of the quality of gases of group H of the
second family as classified in EN 437 is derived from the mandate M/400 issued to CEN by the European
Commission.
According to this mandate the goal is to define standards that are as wide as possible within reasonable costs.
This means that the standards enhance the free flow of gas within the internal EU market, in order to promote
competition and security of supply minimizing the negative effects on gas infrastructure and gas networks,
efficiency and the environment and allow the maximum number of appliances to be used without
compromising safety.
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1 Scope
This European standard specifies gas quality characteristics, parameters and their limits, for gases classified
as group H, as in EN 437:2003+A1:2009.
This standard does not cover gases conveyed on isolated networks or gases prior to their entry in a
transmission network in Europe.
This European standard is applicable to gases that are to be transmitted, stored, distributed and used.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN ISO 6326-1, Natural gas — Determination of sulfur compounds — Part 1: General introduction
EN ISO 6326-3, Natural gas — Determination of sulfur compounds — Part 3: Determination of hydrogen
sulfide, mercaptan sulfur and carbonyl sulfide sulfur by potentiometry
EN ISO 6326-5, Natural gas — Determination of sulfur compounds — Part 5: Lingener combustion method
EN ISO 6327, Gas analysis — Determination of the water dew point of natural gas — Cooled surface
condensation hygrometers
EN ISO 6974-1, Natural gas — Determination of composition with defined uncertainty by gas
chromatography — Part 1: General guidelines and calculation of composition
EN ISO 6974-2, Natural gas — Determination of composition with defined uncertainty by gas
chromatography — Part 2: Uncertainty calculations
EN 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
hydrocarbons up to C using two packed columns
8
EN 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
EN ISO 6974-5, 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
EN ISO 6974-6, Natural gas — Determination of composition with defined uncertainty by gas
chromatography — Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and C to C
1 8
hydrocarbons using three capillary columns EN ISO 6975, Natural gas — Extended analysis — Gas-
chromatographic method
EN ISO 6976, Natural gas — Calculation of calorific values, density, relative density and Wobbe index from
composition
EN ISO 10101-1, Natural gas — Determination of water by the Karl Fischer method — Part 1: Introduction
EN ISO 10101-2, Natural gas — Determination of water by the Karl Fischer method — Part 2: Titration
procedure
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EN ISO 10101-3, Natural gas — Determination of water by the Karl Fischer method — Part 3: Coulometric
procedure
EN ISO 13443, Natural gas — Standard reference conditions
EN ISO 15970, Natural gas — Measurement of properties — Volumetric properties: density, pressure,
temperature and compression factor
EN ISO 15971, Natural gas — Measurement of properties — Calorific value and Wobbe index
EN ISO 18453, Natural gas — Correlation between water content and water dew point
EN ISO 19739, Natural gas — Determination of sulfur compounds using gas chromatography
ISO 23874, Natural gas — Gas chromatographic requirements for hydrocarbon dewpoint calculation
ISO/TR 12148, Natural gas — Calibration of chilled mirror type instruments for hydrocarbon dewpoint (liquid
formation)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
gas distribution network
pipeline network including piping above and below ground and all other equipment necessary to supply the
gas to the consumers
Note to entry: The terms of "system" and "network" are often interchanged and can therefore be considered synonymous.
[Source: EN 1594:2013, 3.11, modified]
3.2
gas transmission network
pipeline network including piping above and below ground and all other equipment necessary to supply the
gas to the gas distribution networks and some industrial consumers
Note 1 to entry: The terms of "system" and "network" are often interchanged and can therefore be considered
synonymous.
Note 2 to entry: The terms of "transportation" and "transmission" are often interchanged and can therefore be considered
synonymous.
[Source: EN 1594:2013, 3.13, modified]
3.3
isolated network
network where production, transmission, distribution and utilization of gas are combined
nd
[Source: EASEE-gas CBP 2005-001-02-3, Introduction 2 para, modified]
3.4
dry network
gas network in which no liquid water is present
3.5
entry point
point at which gas enters a gas distribution or gas transmission system
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3.6
cross-border point
point at which national obligations governing a gas transmission system change from one country to another
3.7
gas quality
attribute of gas defined by its composition and its physical properties
[Source: ISO 14532:2005, 2.1.1.14, modified]
3.8
gross calorific value
energy released as heat by the complete combustion in air of a specified quantity of gas, in such a way that
the pressure p1 at which the reaction takes place remains constant, and all the products of combustion are
returned to the same specified temperature t1 as that of the reactants, all of these products being in the
gaseous state except for water formed by combustion, which is condensed to the liquid state at t1
[Source: EN ISO 14532:2005, 2.6.4.1, modified]
3.9
relative density
quotient of the mass of a gas, contained within an arbitrary volume, and the mass of dry air of standard
composition (defined in EN ISO 6976[22]) which would be contained in the same volume at the same
reference conditions
[Source: EN ISO 14532:2005, 2.6.3.2]
3.10
wobbe index
calorific value, on a volumetric basis, at specified reference conditions, divided by the square root of the
relative density at the same specified metering reference conditions
Note to entry: In the absence of any qualifier, the term "Wobbe index" is taken to mean the gross Wobbe index.
[Source: EN ISO 14532:2005, 2.6.4.4, modified]
3.11
total sulfur
total concentration of sulfur in gas
[Source: Source: EN ISO 14532:2005, 2.5.3.3.17, modified]
3.12
mercaptan
organic sulfur compound with the general formula R-SH (where R is the alkyl group), either naturally present
or added as an odorant to gas
[Source: EN ISO 14532:2005, 2.5.3.3.9]
3.13
mercaptan sulfur
concentration of sulfur bonded in the form of a mercaptan in gas
[Source: EN ISO 14532:2005, 2.5.3.3.10, modified]
3.14
water dew point temperature
temperature above which no condensation of water occurs at a specified pressure
[Source: EN ISO 14532:2005, 2.6.5.1.1]
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3.15
hydrocarbon dew point temperature
temperature above which no condensation of hydrocarbons occurs at a specified pressure
[Source: EN ISO 14532:2005, 2.6.5.2.1]
3.16
maximum operating pressure
maximum pressure at which a network can be operated continuously under normal conditions
Note to entry: Normal conditions are: no fault in any device or stream.
(Source: EN 1594:2013, 3.2.3, modified)
3.17
Methane Number
MN
rating indicating the knocking characteristics of a fuel gas
[Source: EN ISO 14532:2005, 2.6.6.1]
3.18
odorisation
addition of odorants to gas (normally odourless) to allow gas leaks to be recognized by smell at trace levels
(before accumulating to dangerous concentrations in air)
[Source: ISO 14532:2005, 2.8.1, modified]
3.19
odorant
“strong” smelling organic chemical or combination of chemicals (e.g. sulfur compounds) added to fuel gases to
impart a characteristic and distinctive (usually disagreeable) warning odour so as to enable the detection of
gas leaks by smell
[Source: ISO 14532:2005, 2.8.2]
4 Reference conditions
°
Unless stated otherwise all volumes are for the real dry gas at ISO Standard Reference conditions of 15 C
and 101,325 kPa.
Unless stated otherwise all gross calorific values and gross Wobbe indices are for the real dry gas at ISO
° °
reference conditions of 15 C (combustion) and 15 C and 101,325 kPa (metering).
In assessing compliance with this European standard parameters should be determined directly at ISO
standard reference conditions. If the properties are only available at other reference conditions and the actual
gas composition is not known then conversion to ISO standard reference conditions shall be carried out using
the procedure described in EN ISO 13443.
5 Requirements
With the exception of Wobbe index, gas compliant with the requirements of Table 1 shall be considered
acceptable for conveyance, whilst gas not compliant with these requirements may not be considered
acceptable for conveyance.
For Wobbe index gas not compliant with the limit range in Table 1 may not be considered acceptable for
conveyance. However, gas that is compliant with the limit range could not be acceptable for conveyance in
some gas networks in some countries. Thus the implementation of this European standard shall be subject to
national assessment of the ability to accept all or part of the gases compliant with this European standard,
taking into account its end-use.
NOTE The Wobbe index range in Table 1 will not always allow gas flow throughout Europe due to local differences.
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Table 1 — Requirements
Limits
Parameter Unit Relevant standards
Min. Max.
EN ISO 6976,
3
Wobbe index MJ/m 46,44 54,00
EN ISO 15971
EN ISO 6976,
Relative density no unit 0,555 0,70
EN ISO 15970
EN ISO 6326-5,
3
Total sulfur without mg/m not applicable 20
EN ISO 19739
odorant
EN ISO 6326-1,
Hydrogen sulfide +
3
mg/m not applicable 5 EN ISO 6326−3,
Carbonyl sulfide
EN ISO 19739
(as sulfur)
EN ISO 6326-3,
3
Mercaptan sulphur mg/m not applicable 6
EN ISO 19739
without odorant
EN ISO 6974-3,
0,001 % or 1%
mol/mol not applicable EN ISO 6974−6,
(see below)
EN ISO 6975
At network entry points and cross border points between CEN member states the
Oxygen
maximum mole fraction of oxygen shall be no more than 0,001 % mol/mol. However,
at entry points where the gas entering will not flow to another member state’s
network through a cross border point, a higher National limit of up to 1 % mol/mol
may be applied, provided that the network is a dry network and not connected to
installations sensitive to higher levels of oxygen, e.g. underground storage systems.
2,5 % or 4% EN ISO 6974-1 to -6,
mol/mol not applicable
see below EN ISO 6975
At network entry points and cross border points between CEN member states the
maximum mole fraction of carbon dioxide shall be no more than 2,5 % mol/mol.
Carbon dioxide
However, at entry points where the gas entering will not flow to another member state’s
network through a cross border point, a higher National limit of up to 4 % mol/mol may
be applied, provided that the network is a dry network and not connected to
installations sensitive to higher levels of carbon dioxide, e.g. underground storage
systems.
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Table 1 (continued)
Limits
Parameter Unit Relevant standards
Min. Max.
Hydro carbon dew point
EN ISO 23874,
temperature °C not applicable -2
ISO 12148,
from 0,1 to 7 MPa absolute
pressure
Water dew point
temperature
EN ISO 6327,
at 7 MPa absolute
°C not applicable -8 EN ISO 18453,
pressure or
EN ISO 10101-1 to -3
at absolute maximum
operating pressure if less
than 7 MPa
Methane number no unit 65 not applicable see normative Annex A
The gas shall not contain constituents other than listed in Table 1 to the extent that it
Contaminants
cannot be transported, stored and/or utilized without quality adjustment or treatment
Test methods other than those listed in the relevant standards column in Table 1 may be applied, provided
their fitness for purpose can be demonstrated.
For sulfur, water and hydrocarbon dew point temperature, hydrogen as well as sampling reference additional
information is given in the dedicated Annexes B to E.
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Annex A
(normative)
Calculation of methane number of gaseous fuels for engines
A.1 Introduction
The methane number of a gaseous fuel can be calculated from its composition according to several different
methods, all of which can give different results. For the purposes of compliance with this European standard
the methodology described in this Annex shall be employed.
The method is based on the original data of the FVV research program performed by AVL /1/ but employs
amendments implemented in 2005 and 2011 by MWM. These amendments have been unpublished until the
publication of this European standard.
The method requires input of composition in the form of volume fractions at reference conditions of 0°C and
101.325 kPa and expressed as a percentage. Composition is more likely to be available either as mole
fraction (e.g., in the natural gas transmission and distribution industry) or as mass fraction (e.g., in the
automotive fuel industry) and conversion to volume fraction shall be performed using the methods in
EN ISO 14912 Gas analysis — Conversion of gas mixture composition data.
Numerical examples are provided so as to enable software developers to validate implementations of the
methodology described in this annex. As an aid to validation, a relatively large number of decimal places has
been retained. For expression of the final result rounding to zero decimal points is recommended.
A.2 Calculation of methane number
A.2.1 Applicability
The method described in this European Standard is applicable to gaseous fuels comprising the gases listed in
A.2.2 a), together with nitrogen and carbon dioxide. The numerical examples provided in this annex are
appropriate to gases of the second family and hence consider mixtures comprising methane, ethane, propane,
butane, nitrogen and carbon dioxide. Hydrogen is also included in one example because of the growing
interest in injection of hydrogen into gas pipelines.
Oxygen and water vapour shall be ignored and the fuel gas composition shall be calculated on a dry, oxygen-
free basis.
A.2.2 General approach
The methane number of a gaseous fuel is calculated from its composition in five steps. The steps are outlined
below and discussed more fully in turn in A.3. Additional examples are discussed in A.4 and A.5. A.6 provides
results of calculations for further software validation purposes.
a) The composition of the gaseous fuel is simplified by converting it into an inert-free mixture comprising the
combustible compounds carbon monoxide, ethylene, propylene, hydrogen sulphide, hydrogen, propane,
ethane, butane and methane.
For gases of the second family conveyed in pipeline systems carbon monoxide, ethylene, propylene,
hydrogen sulphide are unlikely to be present at concentrations that would impact on methane number and
can be ignored.
b) The simplified mixture is sub-divided further into a number of partial ternary mixtures. The number and
particular partial ternary mixtures chosen is decided by inspection of available ternary systems in a given
order, including those systems that contain the relevant combustible compounds. Selection is ceased
when all combustible compounds are contained in at least two ternary systems.
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c) The composition and fraction of the selected partial mixtures is adjusted iteratively so as to minimise the
difference between the methane numbers of each partial mixture.
d) The methane number of the simplified mixture is determined from the weighted average of the methane
number of the selected partial mixtures.
e) Finally, the methane number of the gaseous fuel is calculated by correcting the methane number of the
simplified mixture to allow for the presence of inerts in the original fuel gas.
A.3 Example 1: H-gas
A.3.1 Simplification of the composition of the gaseous fuel
The description of the calculation is illustrated by reference to an H-gas of composition shown in Table A.1.
The composition of the gas (Table A.1, Column 1) is simplified by increasing the quantity of butanes to allow
for the presence of butadiene, butylene, pentanes and hydrocarbons of carbon number greater than 5. The
adjustment made is as follows:
Butadiene and butylene are replaced with an equivalent amount of butanes by multiplying their quantities
by 1.
Pentanes are replaced with an equivalent amount of butanes by multiplying the quantity of pentanes by
2.3.
Hydrocarbons of carbon number greater than 5 (“hexanes+”) are replaced with an equivalent amount of
butanes by multiplying the quantity of hexanes+ by 5.3.
In the case of Example 1 the quantity of butanes is:
i) 0.2100 + 0.1900 + (0.0400 + 0.0500) x 2.3 + 0.0600 x 5.3
ii) 0.9250 (Table A.1, Column 2)
The simplified mixture is then re-normalised to 100% (Table A.1, Column 3).
A.3.2 Selection of the ternary systems
A.3.2.1 Ternary mixtures
The ternary mixtures are chosen from the following list:
A1: Methane – Hydrogen – Ethane
A2: Propane – Ethane – Butane
A3: Hydrogen – Propane - Propylene
A4: Methane – Ethane – Propane
A5: Methane – Hydrogen – Propane
A6: Methane – Hydrogen – Butane
A7: Methane – Propane – Butane
A8: Methane – Ethane – Butane
A9: Methane – Ethylene – Butane
A10: Methane – Hydrogen Sulphide – Butane
A11: Methane – Ethane – Hydrogen Sulphide
A12: Methane – Propylene
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A13: Ethane – Propylene
A14: Carbon Monoxide – Hydrogen
A15: Ethane – Ethylene
A16: Propane – Ethylene
A17: Butadiene
A18: Butylene
NOTE Mixtures A12 – A16 are clearly not ternary systems; however, for ease of mathematical treatment the
coefficients describing methane number (see A.3.4) have been adjusted so as to allow expression using a single equation.
A.3.2.2 Range of applicability of ternary mixture data
The range of applicability of most ternary systems is wide (each component can vary from 0 to 100 %).
However, for some ternary systems there is a reduced range of applicability. This is a major issue when
selecting ternary mixtures. The range of applicability of each ternary system is specified in Table A.2,
expressed as maximum and minimum content of each component.
A.3.2.3 Factors affecting the ternary system selection process
The ternary systems are selected in accordance with three main considerations:
a) The number of gases in the ternary system that are present in the simplified mixture. Priority is always
given to ternary systems that have all three of their components present in the simplified mixture.
Systems with two of their components present in the simplified mixture are acceptable if insufficient
systems with three components present in the simplified are available.
b) Where there is a choice of ternary systems, the system with the highest fitness, W , takes priority.
j
c) Each component in the simplified mixture must be represented in at least two ternary systems.
Fitness of a system is calculated from the following equation:
i=n
V .Vmax
i i,j
(A.1)
w=
i ∑
Vsum
i=1
i
where:
n is the number of components in the simplified mixture;
Vmax is the maximum content of component i for the range of applicability of system j;
i,j
Vsum is the sum of all maximum contents of component i for the range of applicability of al
...
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