1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels Metering of gas as fuel on LNG carriers during cargo transfer operationsBS ISO 19970:2017 ISO 2017Refrigerated hydrocarbon and non-petroleum based
2、 liquefied gaseous fuels Metering of gas as fuel on LNG carriers during cargo transfer operationsHydrocarbures rfrigrs et combustibles gazeux liqufis base non ptrolire Mesurage du gaz comme carburant sur les transporteurs de GNL pendant les opration de transfert de cargaisonINTERNATIONAL STANDARDISO
3、19970First edition2017-06Reference numberISO 19970:2017(E)National forewordThis British Standard is the UK implementation of ISO 19970:2017.The UK participation in its preparation was entrusted to Technical Committee PTI/12, Petroleum Measurement and Sampling.A list of organizations represented on t
4、his committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 88095 7IC
5、S 75.180.30Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2017.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS ISO 19
6、970:2017 ISO 2017Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels Metering of gas as fuel on LNG carriers during cargo transfer operationsHydrocarbures rfrigrs et combustibles gazeux liqufis base non ptrolire Mesurage du gaz comme carburant sur les transporteurs de GNL pendan
7、t les opration de transfert de cargaisonINTERNATIONAL STANDARDISO19970First edition2017-06Reference numberISO 19970:2017(E)BS ISO 19970:2017ISO 19970:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise specified,
8、no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs mem
9、ber body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 19970:2017ISO 19970:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and def
10、initions . 14 Design requirements 34.1 General . 34.2 Flowmeter . 34.3 Indicating device . 35 Accuracy requirement 36 Calibration and accuracy verification 46.1 General . 46.2 Calibration at laboratory or factory 46.3 Calibration and accuracy verification of indicating devices after installation . 4
11、6.4 Periodic accuracy verification of indicating devices 47 Metering and calculation . 57.1 General . 57.2 Metering 57.3 Calculation of heating value . 5Annex A (informative) Typical installation of fuel gas flowmeters 7Annex B (informative) Application of the energy of BOG consumed by LNG carriers
12、to custody transfer measurement . 8Bibliography 9 ISO 2017 All rights reserved iiiContents PageBS ISO 19970:2017ISO 19970:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Internat
13、ional 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-governmental, in liaison with I
14、SO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Pa
15、rt 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).Attention is drawn to the possibility that some of t
16、he 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. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations
17、received (see www .iso .org/ patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessm
18、ent, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.The committee responsible for this document is ISO/TC 28, Petroleum products and related products of sy
19、nthetic or biological origin, Subcommittee SC 5, Measurement of refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels.iv ISO 2017 All rights reservedBS ISO 19970:2017ISO 19970:2017(E)IntroductionConcerns over the emission of pollutants from ship exhausts prompted IMO to enact MARP
20、OL Annex VI to the IMO Protocol of 1997 which sets limits on sulfur oxide and nitrogen oxide emissions. As for sulfur, as from 1 January 2012, the annex specifies a global cap mass fraction of 3,5 % on the sulfur content of fuel oil and special SOx emission control areas (SECAs) where the sulfur con
21、tents shall not exceed a mass fraction of 1,0 %. In order to comply with these requirements, the ships in general need to fit special facilities to limit SOx emissions unless they use low sulfur fuel oil.However, liquefied natural gas (LNG) carrier is capable of utilizing BOG in ships and shore tank
22、s, and return gas during cargo transfer operation as fuel for their own power generation, if commercial value of such energy consumed on board is accountable as an element of custody transfer measurement.This document provides the procedures needed for metering gas and assessing its calorific value
23、and the requirements for metering devices.Aspects of safety are not dealt with in this document. It is the responsibility of the user to ensure that the system meets applicable safety regulations. ISO 2017 All rights reserved vBS ISO 19970:2017BS ISO 19970:2017Refrigerated hydrocarbon and non-petrol
24、eum based liquefied gaseous fuels Metering of gas as fuel on LNG carriers during cargo transfer operations1 ScopeThis document specifies minimum requirements to quantify the boil-off gas (BOG) consumed on liquefied natural gas (LNG) carriers for their own functions, notably for power generation, dur
25、ing cargo transfer operations. BOG in this document refers to the low molecular gas returned from shore tanks to ships tanks and the gas produced in ships cargo tanks.This document provides requirements for the metering of BOG and the subsequent calorific value calculations which can be taken into a
26、ccount when the energy transferred during cargo transfer is determined. This document also introduces performance requirements and calibration of the elements included in the BOG measurement system. A flowmeter of any type may be used to measure BOG as long as it meets the performance requirements s
27、pecified in this document.This document, with some modification, can also be applied to the measurement of BOG consumed by LNG carriers at sea.2 Normative referencesThere are no normative references in this document.3 Terms and definitionsFor the purposes of this document, the following terms and de
28、finitions apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp3.1boil offprocess of evaporation of a liquid
29、 resulting from heat ingress or a drop in pressureSOURCE: ISO 10976:2015, 3.1.63.2boil-off gasBOGvapour (3.14) produced by boil off (3.1)Note 1 to entry: BOG in this document refers to the low molecular gas returned from shore tanks to ships tanks and the gas produced in ships cargo tanks during car
30、go transfer operation.SOURCE: ISO 10976:2015, 3.1.7 Note 1 to entry has been added.3.3closing custody transfer measurementcustody transfer measurement (3.4) implemented after loading or discharging cargo from the tank(s)INTERNATIONAL STANDARD ISO 19970:2017(E) ISO 2017 All rights reserved 1BS ISO 19
31、970:2017ISO 19970:2017(E)3.4custody transfer measurementmeasurement of liquid level, liquid and vapour temperature, vapour pressure and analysis of the composition of LNG to be delivered to/from a tank, by which volumetric and other data are determined to be a basis of payment of cost or assessment
32、of duty3.5custody transfer measurement systemCTMSsystem that processes inputs from an ATG system, thermometers, pressure gauges, etc., and provides custody transfer measurement information on board, generating documents with regard to custody transfer of LNGSOURCE: ISO 18132-1:2011, 2.1.4, modified3
33、.6flowmeterflow measuring device which indicates the measured flowrate3.7gas dangerous space or zonespace or zone defined by the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code)3.8indicating devicedisplaying deviceset of components of a measu
34、ring instrument intended to indicate the measured value3.9intrinsic errorinherent errorerror of a measuring device when it is tested against a reference standard under controlled conditions as specified by the manufacturer3.10LNG carrierLNGCcargo ship specifically constructed and used for the carria
35、ge of LNG in bulk3.11maximum permissible errorMPEextreme value of measurement error, with respect to a known reference quantity value, permitted by specifications or regulations for a given measurement, measuring instrument, or measuring systemSOURCE: ISO/IEC Guide 99:2007, 4.26, modified3.12opening
36、 custody transfer measurementcustody transfer measurement (3.4) implemented before loading or discharging cargo from the tank(s)3.13uncertaintynon-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used3.14vapourfluid in
37、the gaseous state that is transferred to/from or contained within the cargo tank2 ISO 2017 All rights reservedBS ISO 19970:2017ISO 19970:2017(E)3.15verificationprocess of confirming the accuracy of an instrument by comparing to a source with known accuracy4 Design requirements4.1 GeneralFlowmeters s
38、hall be so constructed as not to leak gas in the atmosphere. In addition, all parts of a flowmeter in contact with BOG shall be chemically compatible with the product, to avoid both product contamination and corrosion of the flowmeter. Flowmeters installed in a gas dangerous space or zone shall be o
39、f gastight construction.All electric components of a flowmeter for use in electrically classified areas shall meet the electrical area classification. They shall conform to applicable sections of the national and/or international electrical safety standards. All flowmeters shall be maintained in saf
40、e operating condition and manufacturers maintenance instructions should be complied with.4.2 FlowmeterFlowmeters making use of any measurement principle may be used for the measurement of BOG. However, when selecting the flowmeter, consideration shall be given to the impact of the type of propulsion
41、 plant, constraints arising from the installation location and the nature of BOG flow on the meters performance.Regardless of the type of propulsion plant, flowmeters used for the measurement of BOG are always installed downstream of the low duty gas compressor and the gas heater on the fuel gas lin
42、e to the propulsion plant. Typical installation and instrument specifications of flowmeters used for the measurement of BOG are shown in Annex A.NOTE The consumption of BOG can be underestimated when the flow is below the minimum measureable flowrate.4.3 Indicating deviceResolution of indicating dev
43、ice (totalizer) shall be better than or equal to 1 m3or 1 kg.5 Accuracy requirementMaximum permissible error of a flowmeter at the time of calibration at laboratory or factory (see 6.2) shall be 2 % of reading throughout the expected operating range.Maximum permissible error of the indicating device
44、 determined in accordance with 6.3 and 6.4 shall be 1 % of the upper range limit of the expected operating range of the flowmeter. The accuracy of thermometers and pressure gauges associated with the flowmeters, if any, shall be better than or equal to 0,5 C and 1 % of the reading throughout the exp
45、ected operating range, respectively.NOTE Maximum permissible errors shown on Table 1 and Table 3-1 in OIML R 140 are referred to. ISO 2017 All rights reserved 3BS ISO 19970:2017ISO 19970:2017(E)6 Calibration and accuracy verification6.1 GeneralA flowmeter shall be calibrated and the uncertainty be e
46、stablished by the manufacturer before it is delivered for installation. The indicating device of the flowmeter shall be calibrated by the manufacturer or its authorized service representative after it is installed, and periodically, with the results verified.NOTE The accuracy of flow measurement is
47、affected by the inherent error of flowmeters, the error due to installation (e.g. stability, location, etc.) and the effect of changes in operating conditions.All flowmeter calibration records shall be documented. Calibration and verification records shall be available for the parties involved in cu
48、stody transfer of LNG. All adjustments to the flowmeters shall also be documented.6.2 Calibration at laboratory or factoryA flowmeter and associating measuring device shall be calibrated at the manufacturers factory or a laboratory against reference standards of which uncertainty is traceable to nat
49、ional standards. Uncertainty of a flowmeter may also be theoretically established in accordance with relevant international standards. In any case, the expanded uncertainty (k = 2) of the calibration shall not exceed 0,6 %.6.3 Calibration and accuracy verification of indicating devices after installationThe indicating devices shall be calibrated by the manufacturer against reference standard of which uncertainty is traceable to a national standard and their accuracy be verified after installation of
