SIST EN 12952-8:2002

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserrohrkessel und Anlagenkomponenten - Teil 8: Anforderungen an Feuerungsanlagen für flüssige und gasförmige für den KesselChaudieres a tubes d'eau et installations auxiliaires - Partie 8: Exigences pour les équipements de chauffe pour combustibles gazeux et liquides de la chaudiereWater-tube boilers and auxiliary installations - Part 8: Requirements for firing systems for liquid and gaseous fuels for the boiler27.060.30Grelniki vode in prenosniki toploteBoilers and heat exchangersICS:Ta slovenski standard je istoveten z:EN 12952-8:2002SIST EN 12952-8:2002en01-november-2002SIST EN 12952-8:2002SLOVENSKI
STANDARD



SIST EN 12952-8:2002



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12952-8May 2002ICS 27.040English versionWater-tube boilers and auxiliary installations - Part 8:Requirements for firing systems for liquid and gaseous fuels forthe boilerChaudières à tubes d'eau et installations auxiliaires - Partie8: Exigences pour les équipements de chauffe pourcombustibles gazeux et liquides de la chaudièreWasserrohrkessel und Anlagenkomponenten - Teil 8:Anforderungen an Feuerungsanlagen für flüssige undgasförmige für 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 STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR 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 12952-8:2002 ESIST EN 12952-8:2002



EN 12952-8:2002 (E)2ContentsPageForeword.31Scope.51.1Firing systems.51.2Fuels.51.3Operation.52Normative references.53Terms and definitions.64Fuel supply.104.1General.104.2Fuel transfer and preparation.104.3Fuel lines.104.4Safety shut-off devices (Safety trip valves).125Equipment for air supply and flue gas discharge.135.1Air supply.135.2Air/fuel ratio.145.3Flue gas discharge.146Firing system.156.1Burners.156.2Flue gas recirculation.156.3Control and monitoring.166.4Electrical equipment.176.5Safety precautions.176.6Common stack for several firing systems.187Operating manual.188Particular requirements for firing systems burning gaseous fuels with high relative
density.188.1Main firing systems.188.2Ignition burner systems.19Annex A (normative)
Chemical recovery boiler (black liquor boiler).20A.1General.20A.2Additional requirements for the firing system for black liquor in the chemical recovery boiler.20A.3Special requirements for oil- or gas firing for chemical recovery boilers.21Annex B (informative)
Operational requirements for permanent supervised firing systems for liquidand gaseous fuels.22B.1General.22B.2Operation.22B.3Fuel preparation.22B.4Safety shutoff devices.22B.5Air/fuel ratio.22B.6Modification of firing, burner or air/fuel ratio setting.22B.7Control and monitoring.23B.8Purging, start-up and shut down.23B.9Emergency operation.23B.10Operating and maintenance instructions.23B.11Firing systems burning gaseous fuels with high relative density.23Annex ZA (informative)
Clauses of this European Standard addressing essential safety requirementsor other provisions of the Pressure Equipment Directives.25Bibliography.26SIST EN 12952-8:2002



EN 12952-8:2002 (E)3ForewordThis document (EN 12952-8:2002) 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 12952 concerning “Water-tube boilers and auxiliary installations” consists of thefollowing Parts: Part 1: General. Part 2: Materials for pressure parts of boilers and accessories. Part 3: Design and calculation for pressure parts. Part 4: In-service boiler life expectancy calculations. Part 5: Workmanship and construction of pressure parts of the boiler. Part 6: Inspection during construction, documentation and marking of pressure parts of the boiler. Part 7: Requirements for equipment for the boiler. Part 8: Requirements for firing systems for liquid and gaseous fuels for the boiler. Part 9: Requirements for firing systems for pulverized solid fuels for the boiler. Part 10: Requirements for safeguards against excessive pressure. Part 11: Requirements for limiting devices of the boiler and accessories. Part 12: Requirements for boiler feedwater and boiler water quality. Part 13: Requirements for flue gas cleaning systems. Part 14: Requirements for flue gas DENOX-systems. Part 15: Acceptance tests. Part 16: Requirements for grate and fluidised bed firing systems for solid fuels for the boiler.CR 12952 Part 17: Guideline 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 interdependent. Assuch, the design and manufacture of water-tube boilers requires the application of more than one Part in order forthe requirements of the standard to be satisfactorily fulfilled.SIST EN 12952-8:2002



EN 12952-8:2002 (E)4NOTEParts 4 and 15 are not applicable during the design, construction and installation stages.Annex A of this European Standard is normative and Annex B is informative.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.SIST EN 12952-8:2002



EN 12952-8:2002 (E)51 Scope1.1 Firing systemsThis Part of this European Standard specifies requirements, for oil and gas firing systems of steam boilers and hotwater generators as defined in EN 12952-1.These requirements also apply to firing systems of chemical recovery boilers (black liquor boilers) with theadditions and amendments specified in Annex A of this standard.NOTE 1This standard is not applicable to coil type boilers (flash boilers/small boilers) that use burners in accordance withEN 12953-7 apply for single burner installations.1.2 NOTE 2This standard is not applicable to the storage of liquid fuels and to transferstations of long-distance gas pipelines. FuelsThis Part of this European Standard specifies requirements, which cover the use of liquid and gaseous fuels asdefined in this standard. Fuels deviating from standardized commercially available types may require additional oralternative safety measures. For black liquor these safety measures are given in Annex A.1.3 OperationThis Part of this European Standard specifies requirements for operational equipment in clauses 4 to 8 which applyto steam boilers and hot water generators with permanent supervision by properly trained personnel familiar withthe special conditions of the firing system and the type of fuel being fired.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 161,
Automatic shut-off valves for gas burners and gas appliances.EN 264,
Safety shut-off devices for combustion plants using liquid fuels — Safety requirements and testing.EN 287-1,
Approval testing of welders — Fusion welding — Part 1: Steels.EN 751-1,
Sealing materials for metallic threaded joints in contact with 1st, 2nd and 3rd family gases and hotwater — Part 1: Anaerobic jointing compounds.EN 751-2,
Sealing materials for metallic threaded joints in contact with 1st, 2nd and 3rd family gases and hotwater — Part 2: Non-hardening jointing compounds.EN 751-3,
Sealing materials for metallic threaded joints in contact with 1st, 2nd and 3rd family gases and hotwater — Part 3: Unsintered PTFE tapes.EN 1044,
Brazing — Filler metals.EN 12952-1,
1: General.EN 12952-5:2001,
Part 5: Workmanship and construction ofpressure parts of the boiler.EN 13480-2,
Metallic industrial piping — Part 2: Materials.SIST EN 12952-8:2002



EN 12952-8:2002 (E)6prEN 50156-1,
Electrical equipment for furnaces and ancillary equipment — Part 1: Requirements for applicationdesign and installation.EN ISO 3677,
Filler metal for soft soldering, brazing and braze welding — Designation (ISO 3677:1992).ISO 7-1,
Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances anddesignation. (ISO 7-1:1994)ISO 228-1,
Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions, tolerancesand designation (ISO 228-1:2000).3 Terms and definitionsFor the purposes of this Part of this European Standard and the following terms and definitions apply.3.1black liquorspent liquor from the pulp cook3.2black liquor gundevice for the introduction of the black liquor as a spray of droplets into the furnace. The black liquor gun is not aburner3.3high volume low concentration odorous gasmixtures of air and a low concentration of odorous gases collected from the pulp mill processes, where theconcentration of the combustible odorous gas is always kept below the lower explosion limit3.4burnersdevices (including main or igniter burners) for the introduction of fuel and air into a combustion chamber at requiredvelocities, turbulence and local fuel concentration to establish and maintain proper ignition and stable combustionof the fuel. Burners are differentiated by their mode of operation3.4.1automatic burnersburners equipped with automatic ignition, flame monitoring and safety control devices that control the firing ratewithout the intervention by operating personnel3.4.2semi-automatic burnersburners equipped with automatic ignition, flame monitoring and safety control devices which are started andstopped by the intervention of operating personnel3.4.3chemical recovery boiler start up burneroil- or gasfired burner mainly intended for the initiation of the black liquor combustion process. The chemicalrecovery boiler start up burners are located in and integrated with a combustion air register, like the primary or thesecondary air register of the furnace. Thus they have no individual air supply and no individual combustion aircontrol3.4.4multi-fuel burnersburners in which more than one fuel is burned either simultaneously or alternately3.4.5pilot burnerburner which maintains a proper permanent ignition source for one or a group of other non-monitored burnersSIST EN 12952-8:2002



EN 12952-8:2002 (E)73.5burner groupburners operated in unison and controlled jointly. One of the burners can be a master burner3.6burner management systemsystem that performs a predetermined sequence of actions and always operates in conjunction with a flamemonitor that reacts to signals from control and safety devices, gives control commands, controls the start-upsequence, supervises the burner operation, and manages controlled shutdown and lockout3.7firing 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 andmonitoring devices. A flue gas recirculation system can be an integral part of the firing system3.8firing system heat inputheat input into the combustion chamber according to the mass flow of the fuel supplied multiplied by the netcalorific value3.9flame monitordevice which detects the presence or absence or break-away of the flame and transmits a signal to the controldevice, and generally consists of a sensing device (with amplifier if necessary) and switching equipment3.10flue gas recirculationreturn 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 chamber3.11implosionunintentional instantaneous negative pressure build-up caused, for example, by an explosion in a confined space,by rapid closing of dampers, or by rapid reduction in temperature (flame out)3.12limiterstransducer, which, on reaching a fixed value (e.g. pressure, temperature, flow, water level) is used to interrupt andlock-out the energy supply, and requires manual unlocking before restart3.13lock-outisolation of energy supply which requires a manual intervention to reinstate3.14master fuel tripdevice for rapid automatic shut-off of all fuel supplies to the boiler area and electrical igniters in the event of dangerwhich may act by automatic, manual or emergency switch initiation even if a possible electrical or mechanical faultoccurs3.15maximum heat input of the
firing systemheat input including the reserve required for load control at which the boiler can be safely operated3.16maximum firing rate of the burnersfiring rate at which the burner may be operatedSIST EN 12952-8:2002



EN 12952-8:2002 (E)83.17monitorlimit transducer, which senses the reaching of a fixed limit value and initiates an alarm and/or a cut out. The outputsignal is only cancelled if the cause of the alarm has been removed and the value has returned to within its fixedlimits3.18multi-fuel firing systemfiring system where, in a common combustion chamber, more than one fuel can be burnt simultaneously oralternately by separate or multi-fuel burners3.19purge of burner gunscarried out after shutdown of a burner to ensure the removal of residual fuel by the introduction of steam orpressurized air into the fuel lines downstream of the shut-off devices3.20purging of the flue gas passesforced flow of air through the combustion chamber, flue gas passes, and associated ducts which effectivelyremoves any gaseous combustibles and replace them with air3.21quick-acting shut-off devicesafety trip valve which closes within 1 s3.22relative densityratio of the density of the gas to the density of dry air under equal conditions of pressure and temperature3.23liquid fuelsfuels include light fuel oils, and heavy fuel oils which need preheating for proper atomisation. For improvement ofatomisation, emulsions of heavy fuel oil with water may be used with appropriate precautions3.24gaseous fuelsstandardized quality differentiated mainly by their relative density3.24.1light gaseswith relative density below 1,3 e.g. natural gas, coke-oven gas, blast-furnace gasNOTENatural gas in accordance with ISO 6976.3.24.2heavy gaseswith relative densities exceeding 1,3 e.g. liquefied petroleum gases, the main components of which are propaneand butane3.25restartoperation where fuel supply shut-off is initiated within 1 s at the latest after extinction of the flame during operation,and a directly following attempt of re-ignition is automatically made in compliance with the start-up sequence. Thisoperation ends with the operating condition being reached or, if the flame is not ignited after expiration of theignition safety time, with the lock-outSIST EN 12952-8:2002



EN 12952-8:2002 (E)93.26return-fow atomizeroil burners, where a portion of the quantity of oil supplied to the burner via the flow line does not flow from a burnergun vortex chamber into the combustion chamber, but flows backwards into the storage tank or to the suction sideof the pump via a separate return line. Output is adjusted by a control device in the return line3.27safety shut-off devicesafety trip valvevalve which automatically and totally cuts off the fuel supply3.28safety timetolerance time during which the effectiveness of the safety device may be inhibited without a hazardous conditionoccurring3.28.1ignition time: When starting-up the burner, the period of time between the first fuel entering the combustionchamber and the first indication of the flame by the flame monitor3.28.2ignition safety time: When starting-up the burner, the period of time between the first fuel entering the combustionchamber and the de-energizing of the quick-acting shut-off device if the flame monitor does not indicate a flame3.28.3main burner safety time: When there is an ignition safety time applicable to an igniter burner only the period oftime between the first fuel of the main burner entering the combustion chamber and the de energizing of the quickacting shut-off device of the main burner if the flame monitor does not indicate a flame3.28.4extinction safety time: During operation of the burner the period of time between the extinction of the flame andthe de-energizing of the quick-acting shut-off device3.29transfer stationone or more lines each including a pressure control valve and a quick-acting shut-off device for the protection of thedownstream supply lines and the connected appliances against overpressure. The transfer station may comprise ofheating and filtering equipment for the gas supply, measuring equipment for flow and calorific value and noiseabatement devicesSIST EN 12952-8:2002



EN 12952-8:2002 (E)104 Fuel supply4.1 GeneralFor multifuel firing systems using separate or combined burners these requirements shall apply to the oil and/orgas firing part involved.Where several fuels are burnt simultaneously, improved safety measures can be necessary, especially in respectto limitation of heat input into the firing system and proper air supply to the individual fuels.4.2 Fuel transfer and preparation4.2.1The fuel supply line shall be equipped with a reliable quick-acting safety shut-off device (master fuel trip)which shall be positioned in a safe location. It shall reliably cut off the fuel supply to the boiler room or the boilerarea and shall be operable manually or by remote control or by an emergency switch (see 6.5).4.2.2Some liquid fuels, such as heavy fuel oil, require preheating to achieve the viscosity required for properatomisation. Where national oil quality standards are in existence, these shall be observed.Any heat source other than open flames, that can be cut off immediately if required, and the rating of which can beautomatically controlled, shall be used for oil preheating.In the unpressurized condition the fuel oil temperature shall not attain the fuel oil flash point and in any case shallnot exceed 90 C.To attain the temperature for the required atomisation viscosity, pressure type preheaters shall be used. Themaximum temperature shall be at least 5 C below the boiling temperature of water in the oil at the connectedpressure.Each fuel oil preheating system shall be automatically temperature controlled. A temperature indicator shall befitted downstream of the preheating system. Oil temperatures below the temperature prescribed upstream of eachburner or burner group shall shut off the burner or burner group.Oil temperatures above the temperature prescribed upstream of the burners shall shut off the heat supply of thepreheater or other suitable measures shall be taken.For pressurized preheaters, the requirements for pressure vessels shall be applied. Functioning of the necessaryoverpressure protection shall be ensured by suitable temperature control. Any escaping oil shall be safelydischarged.Where steam heating coils for oil preheating are installed and the condensate is returned to the boiler, the heatingcoils shall be safely dimensioned and tested to ensure that no oil can escape into the condensate. A means ofchecking the condensate for oil content shall be provided. When steam lines are connected to fuel oil lines forpurging purposes or for steam assisted atomisation, the line shall be protected against back flow from the higherpressured fluid.4.2.3For gaseous fuels, a pressure controller shall be provided in the supply line to each firing system unlessthis task is performed by the transfer station.The reliability of the gas pressure controller and its related safety device shall be proved by component testing oran individual test within the system acceptance test.4.3 Fuel lines4.3.1Fuel lines, including gaskets and valves shall be designed and laid out to withstand the mechanical,chemical and thermal loads to which they are exposed in service. Only fire resistant piping material shall bepermitted.4.3.2The fuel lines shall be tight and properly fixed. In systems subjected to vibrations the resulting stressesshall be minimized to avoid leakage.SIST EN 12952-8:2002



EN 12952-8:2002 (E)114.3.3Connections shall preferably be welded or brazed. Threaded joints or bolted flanges shall also be used.Welded joints shall only be made by welders approved to the appropriate standards (see EN 287-1).Brazed joints shall be permitted in oil lines for pipe diameters < DN 25 and/or operating pressure < 10 bar providedthe brazers shall be approved and the filler materials have been certified, e.g. by a certificate of a specializedmanufacturer (see EN ISO 3677 and EN 1044). They shall also be permitted in gas lines for pipe diameter < DN 80and/or operating pressure < 5 bar.For threaded joints the requirements of ISO 7-1 and ISO 228-1 shall apply. Thread joints shall be used up to DN 50and shall be sealed by metal to metal contact, or sealed by non-hardening sealing materials. Hemp shall only beused as a sealant support. The use of PTFE sealing materials shall be restricted as indicated in EN 751.Compression-type fittings in accordance with appropriate standards may be used up to DN 25, provided they shallbe not to be dismantled for maintenance purposes.Flanged connections on apparatus, equipment and valves shall be permitted for all diameters.Material shall be in accordance with
EN 13480-2.4.3.4Flexible lines shall be used for connecting the burner to the fixed piping. For fuel oil in the preheated stateonly jacketed metallic hoses shall be permitted.Furthermore, flexible lines may be used instead of expansion joints at protected locations. For oil, these linesshould be jacketed metallic hoses, otherwise they shall be provided with a protective device consisting of e.g. adouble line with an oil monitor which switches off the oil supply pump in case of an oil leakage. For gas, these linesshall be corrugated steel pipes.All flexible lines shall be as short as possible, be readily visible, and shall be installed with adequate bending radii.The flexible lines and the connections shall carry the manufacturer's symbols and indication of the nominalpressure. The design pressure shall be at least 1,5 times the maximum allowable pressure. The lines shall beprotected against unacceptable external heating.4.3.5To protect fuel lines against unacceptable high pressure, automatic control and safety devices shall beprovided. For oil lines, pressure relief valves shall be installed. Protection of oil pumps and the effect of pressurerise in lines between closed shut-off devices due to heating shall also be taken into consideration. For gas lines thenecessary protection against overpressure shall be performed by a safety shu
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