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BRITISH STANDARDBS EN 12953-7:2002Shell boilers Part 7:Requirements for firing systems for liquid and gaseous fuels for the boilersThe European Standard EN 12953-7:2002 has the status of a British StandardICS 27.060.30;27.100NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWLicensed Copy:Institute Of Technology Tallaght,Institute of Technology,Tue May 15 11:08:32 GMT+00:00 2007,Uncontrolled Copy,(c)BSIBS EN 12953-7:2002This British Standard,having been prepared under the direction of the Engineering Sector Policy and Strategy Committee,was published under the authority of the Standards Policy and Strategy Committee on 14 June 2002 BSI 14 June 2002ISBN 0 580 39847 1National forewordThis British Standard is the official English language version of EN 12953-7:2002.When the reference to this European Standard has been published in the Official Journal of the European Communities(OJ),compliance with it will confer a presumption of conformity with the essential requirements covered by the standard in respect of the Pressure Equipment Directive.The UK participation in its preparation was entrusted to Technical Committee PVE/16,Shell boilers,which has the responsibility to:A list of organizations represented on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled“International Standards Correspondence Index”,or by using the“Search”facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract.Users of this publication are responsible for their correct application.Compliance with a British Standard does not of itself confer immunity from legal obligations.aid enquirers to understand the text;present to the responsible international/European committee any enquiries on the interpretation,or proposals for change,and keep the UK interests informed;monitor related international and European developments and promulgate them in the UK.Summary of pagesThis document comprises a front cover,an inside front cover,the EN title page,pages 2 to 10,an inside back cover and a back cover.The BSI copyright date displayed in this document indicates when thedocument was last issued.Amendments issued since publicationAmd.No.DateCommentsLicensed Copy:Institute Of Technology Tallaght,Institute of Technology,Tue May 15 11:08:32 GMT+00:00 2007,Uncontrolled Copy,(c)BSIEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 12953-7May 2002ICS 27.060.30;27.100English versionShell boilers-Part 7:Requirements for firing systems for liquidand gaseous fuels for the boilersChaudires tubes de fume-Partie 7:Exigences pourles quipements de chauffe pour combustibles gazeux etliquides de la chaudireGrowasserraumkessel-Teil 7:Anforderungen anFeuerungsanlagen fr flssige und gasfrmige Brennstoffefr den KesselThis European Standard was approved by CEN on 15 May 2002.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration.Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions(English,French,German).A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria,Belgium,Czech Republic,Denmark,Finland,France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain,Sweden,Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre:rue de Stassart,36 B-1050 Brussels 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref.No.EN 12953-7:2002 ELicensed Copy:Institute Of Technology Tallaght,Institute of Technology,Tue May 15 11:08:32 GMT+00:00 2007,Uncontrolled Copy,(c)BSIEN 12953-7:2002(E)2ContentspageForeword.31Scope.42Normative references.43Terms and definitions.44Fuel supply.64.1Fuel transfer and preparation.64.2Fuel lines.64.3Safety shut-off devices(Safety trip valves).75Air supply,air/fuel ratio.76Firing system.86.1Burners.86.2Inspection openings.86.3Purging,start-up and shutdown.86.4Common stack for several firing systems.86.5Fuels.8Annex ZA(informative)Clauses of this European Standard addressing essential requirements or otherprovisions of EU Directives.9Bibliography.10Licensed Copy:Institute Of Technology Tallaght,Institute of Technology,Tue May 15 11:08:32 GMT+00:00 2007,Uncontrolled Copy,(c)BSIEN 12953-7:2002(E)3ForewordThis document(EN 12953-7:2002)has been prepared by Technical Committee CEN/TC 269 Shell and water-tubeboilers,the secretariat of which is held by DIN.This European Standard has been prepared under a mandate given to CEN by the European Commission and theEuropean Free Trade Association,and supports essential requirements of EU Directive(s).For relationship with EU Directive(s),see informative Annex ZA,which is an integral part of this standard.This European Standard shall be given the status of a national standard,either by publication of an identical text orby endorsement,at the latest by November 2002,and conflicting national standards shall be withdrawn at the latestby November 2002.The European Standard EN 12953 concerning shell boilers consists of the following Parts:?Part 1:General.?Part 2:Materials for pressure parts of boilers and accessories.?Part 3:Design and calculation for pressure parts.?Part 4:Workmanship and construction of pressure parts of the boiler.?Part 5:Inspection during construction,documentation and marking of pressure parts of the boiler.?Part 6:Requirements for equipment for the boiler.?Part 7:Requirements for firing systems for liquid and gaseous fuels for the boiler.?Part 8:Requirements for safeguards against excessive pressure.?Part 9:Requirements for limiting devices of the boiler and accessories.?Part 10:Requirements for boiler feedwater and boiler water quality.?Part 11:Acceptance tests.?Part 12:Requirements for firing systems for solid fuels for the boiler.?Part 13:Operating instructions.CR 12953-14:Guidelines for the involvement of an inspection body independent of the manufacturer.Although these Parts can be obtained separately,it should be recognized that the Parts are inter-dependent.Assuch,the design and manufacture of shell boilers requires the application of more than one Part in order for therequirements of the standard to be satisfactorily fulfilled.According to the CEN/CENELEC Internal Regulations,the national standards organizations of the followingcountries are bound to implement this European Standard:Austria,Belgium,Czech Republic,Denmark,Finland,France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain,Sweden,Switzerland and the United Kingdom.Licensed Copy:Institute Of Technology Tallaght,Institute of Technology,Tue May 15 11:08:32 GMT+00:00 2007,Uncontrolled Copy,(c)BSIEN 12953-7:2002(E)41 ScopeThis Part of this European Standard specifies requirements for firing systems for oil and gaseous fuels applicable toshell boilers,as defined in EN 12953-1,irrespective of the degree of supervision.For multifuel firing systems usingseparate or combined burners,these requirements apply to the oil and/or gas firing part involved.This Part of this European Standard specifies the improved safety measures required when several fuels are burntsimultaneously.2 Normative referencesThis European Standard incorporates,by dated or undated reference,provisions from other publications.Thesenormative references are cited at the appropriate places in the text and the publications are listed hereafter.Fordated references,subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision.For undated references,the latest edition of thepublication referred to applies(including amendments).EN 267,Forced draught oil burners-Definitions,requirements,testing,marking.EN 676,Automatic forced draught burners for gaseous fuels.EN 12953-1,?General.3 Terms and definitionsFor the purposes of this Part of this European Standard,the following terms and definitions apply.3.1liquid fuelslight fuel oils,and heavy fuel oils which need preheating for proper atomisation3.2gaseous fuelsstandardized quality differentiated mainly by their relative density3.2.1light gaseswith relative density below 1,3 e.g.natural gas,coke-oven gas,blast-furnace gasNOTENatural gas in accordance with ISO 6976.3.2.2heavy gaseswith relative densities exceeding 1,3 e.g.liquefied petroleum gases,the main components of which are propaneand butane3.3burnersdevices for the introduction of fuel and air into a combustion chamber at required velocities,turbulence and localfuel concentration to establish and maintain proper ignition and stable combustion of the fuel3.4burner management systemperforms a predetermined sequence of actions and always operates in conjunction with a flame monitor that reactsto signals from control and safety devices,gives control commands,controls the start-up sequence,supervises theburner operation,and causes controlled shutdown and lockoutLicensed Copy:Institute Of Technology Tallaght,Institute of Technology,Tue May 15 11:08:32 GMT+00:00 2007,Uncontrolled Copy,(c)BSIEN 12953-7:2002(E)53.5firing systemtotal equipment required for the combustion of fuels including the installations for the storage,preparation,andsupply of fuels,the combustion air supply,the burner(s),the flue gas discharge,and all related control and moni-toring devicesNOTEA flue gas re-circulation system can be installed as an integral part of the firing system.3.6firing system heat inputheat input into the combustion chamber,including the reserve required for load control at which the boiler can besafely operatedNOTEThe mass flow of the fuel supplied multiplied by the net calorific value.3.7flame monitordevice which detects the presence or absence or break-away of the flame and transmits a signal to the control de-vice,and generally,consists of a sensing device(if necessary with amplifier)and switching equipment3.8flue gas re-circulationreturn of flue gas from downstream of the flame zone or from the flue gas exit by hydrodynamic pressure differenceor a separate fan into the air register of the burner or directly into the combustion chamber3.9limitersdevice that,on reaching a fixed value(e.g.pressure,temperature,flow,water level)is used to interrupt and lock-outthe energy supply and requires manual unlocking before restart3.10lock-outisolation of energy supply which requires a manual intervention to reinstateNOTESee EN 676 for definition of non-volatile lock-out.3.11master fuel tripdevice for rapid automatic shut-off of all fuel supplies to the boiler area in the event of danger which may act byautomatic,manual or emergency switch initiation even if a possible electrical or mechanical fault occurs3.12firing rate of the burnerrate at which the burner may be operated3.13multi-fuel burnersburners in which more than one fuel is burned either simultaneously or separately3.14purging of the flue gas passesforced flow of air through the combustion chamber,flue gas passes,and associated ducts which effectively re-moves any combustible products and replaces them with air3.16relative densityratio of the density of the gas to the density of dry air under equal conditions of pressure and temperatureLicensed Copy:Institute Of Technology Tallaght,Institute of Technology,Tue May 15 11:08:32 GMT+00:00 2007,Uncontrolled Copy,(c)BSIEN 12953-7:2002(E)63.17return-flow atomizeroil burners where a portion of the quantity of oil supplied to the burner via the flow line does not flow from a burnergun into the combustion chamber,but flows backwards into the storage tank or the suction side of the pump via aseparate return line,the output being adjusted by a control device in the return line4 Fuel supply4.1 Fuel transfer and preparation4.1.1The fuel supply line shall be equipped with a master fuel trip which shall be positioned in a safe location.Itshall cut off the fuel supply to the boiler room or the boiler area and can be operated manually or by remote control,or by an emergency switch.4.1.2Some liquid fuels such as heavy fuel oil shall be preheating to achieve the viscosity required for proper at-omisation.Any heat source that can be cut off immediately if required,and the rating of which can be automatically controlled,can be used for oil preheating.Open flames shall not be permitted.The fuel oil temperature shall not attain the fueloil flash point at atmosphere pressure.Each fuel oil preheating system shall be automatically temperature controlled.A temperature indicator shall be fitteddownstream of the preheating system.A suitable cut-out for the heating source shall be provided to preventoverheating of the oil.In addition,a minimum temperature limiting device shall also be provided to ensure adequateatomisation.For pressurized preheaters,the requirements for pressure vessels shall be applied,including overpressureprotection.Any escaping oil shall be safely discharged.4.2 Fuel lines4.2.1Fuel lines,including gaskets and valves shall be designed and laid out to withstand the mechanical,chemi-cal and thermal loads to which they are exposed in service.Only fire resistant piping material shall be permitted.Isolation valves shall be provided between the burner and the fuel lines.4.2.2The fuel lines shall be tight and properly fixed.In systems subjected to vibrations the resulting stressesshall be minimized to avoid leakage.4.2.3Flexible lines may be used for connecting the burner to the fixed piping.For fuel oil in the preheated state,only jacketed metallic hoses shall be permitted.Isolated valves shall be installed.Flexible lines may be used instead of compensators at protected locations.For oil,these lines should be jacketedmetallic hoses,otherwise they need a protective device consisting of e.g.a double line with an oil monitor whichswitches off the oil supply pump in case of an oil leakage.For gas,these lines shall be corrugated steel pipes.All flexible lines shall be as short as possible and be installed with adequate bending radii.The flexible lines and theconnections shall carry the manufacturers symbols and indication of the nominal carry pressure.The designpressure shall be at least 1,5 times the maximum allowable pressure.The lines shall be protected againstunacceptable external heating.4.2.4To protect fuel lines against unaccept