SIST EN 12952-16:2003

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserrohrkessel und Anlagenkomponenten - Teil 16: Anforderungen an Rost- und Wirbelschichtfeuerungsanlagen für feste Brennstoffe für den KesselChaudieres a tubes d'eau et installations auxiliaires - Partie 16: Exigences pour les équipements de chauffe a lit fluidisé et a grille pour combustibles solides de la chaudiereWater-tube boilers and auxiliary installations - Part 16: Requirements for grate and fluidized-bed firing systems for solid fuels for the boiler27.060.30Grelniki vode in prenosniki toploteBoilers and heat exchangersICS:Ta slovenski standard je istoveten z:EN 12952-16:2002SIST EN 12952-16:2003en01-december-2003SIST EN 12952-16:2003SLOVENSKI
STANDARD



SIST EN 12952-16:2003



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12952-16December 2002ICS 27.040English versionWater-tube boilers and auxiliary installations - Part 16:Requirements for grate and fluidized-bed firing systems for solidfuels for the boilerChaudières à tubes d'eau et installations auxiliaires - Partie16: Exigences pour les équipements de chauffe à lit fluidiséet à grille pour combustibles solides de la chaudièreWasserrohrkessel und Anlagenkomponenten - Teil 16:Anforderungen an Rost- undWirbelschichtfeuerungsanlagen für feste Brennstoffe fürden KesselThis European Standard was approved by CEN on 4 November 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 12952-16:2002 ESIST EN 12952-16:2003



EN 12952-16:2002 (E)2ContentspageForeword.31Scope.41.1Firing systems.41.2Fuels.41.3Operation.42Normative references.53Terms and definitions.54Fuel storage facilities with conveying plant.74.1General.74.2Conveying plant.74.3Fuel bunkers.84.4Fuel bins.85Fuel treatment.85.1General.85.2Size reduction of the fuel.95.3Drying of the fuel.96Fuel feeding.97Explosion prevention measures.108Equipment for combustion air supply and flue gas discharge.108.1Air supply.108.2Combustion air/fuel ratio.118.3Flue gas discharge.119Firing system.129.1General.129.2Monitoring and control.129.3Electrical equipment.129.4Safety precautions.129.5Common stack for several firing systems.1410Ash handling and extraction.1411Operating manual.15Annex A (informative)
Operational requirements for permanently supervised firing systems for solidfuels for fluidized-bed and grate firing systems.16Annex ZA (informative)
Clauses of this European Standard addressing essential requirements orother provisions of EU Directives.18Bibliography.19SIST EN 12952-16:2003



EN 12952-16:2002 (E)3ForewordThis document (EN 12952-16:2002) has been prepared by Technical Committee CEN/TC 269 "Shell and water-tube boilers", 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 orby endorsement, at the latest by June 2003, and conflicting national standards shall be withdrawn at the latest byJune 2003.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 EU Directive 97/23/EC [1].For relationship with EU Directive 97/23/EC, see informative Annex ZA, which is an integral part of this document.The European Standard EN 12952 concerning water-tube boilers and auxiliary installations consists of the followingparts:¾ Part 1: General¾ Part 2: Materials for pressure parts of boilers and accessories¾ Part 3: Design and calculation for pressure parts¾ Part 4: In-service boiler life expectancy calculations¾ Part 5: Workmanship and construction of pressure parts of the boiler¾ Part 6: Inspection during construction, documentation and marking of pressure parts of the boiler¾ Part 7: Requirements for equipment for the boiler¾ Part 8: Requirements for firing systems for liquid and gaseous fuels for the boiler¾ Part 9: Requirements for firing systems for pulverized solid fuels for the boiler¾ Part 10: Requirements for safeguards against excessive pressure¾ Part 11: Requirements for limiting devices of the boiler and accessories¾ Part 12: Requirements for feedwater and boiler water quality¾ Part 13: Requirements for flue gas cleaning systems¾ Part 14: Requirements for flue gas DENOX-systems¾ Part 15: Acceptance tests¾ Part 16: Requirements for grate and fluidized-bed firing systems for solid fuels for the boilerCR 12952-17, Water-tube boilers and auxiliary installations — Part 17: Guideline for the involvement of an inspec-tion body independent of the manufacturer.Although these parts may be obtained separately, it should be recognized that the parts are inter-dependent. Assuch, the design and manufacture of water-tube boilers requires the application of more than one part in order forthe requirements of the European Standard to be satisfactorily fulfilled.NOTEParts 4 and 15 are not applicable during the design, construction and installation stages.Annex A of this European Standard is informative.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following coun-tries 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, Swe-den, Switzerland and the United Kingdom.SIST EN 12952-16:2003



EN 12952-16:2002 (E)41 Scope1.1 Firing systemsThis Part of this European Standard applies to atmospheric fluidized-bed and grate firing systems of steam boilersand hot water generators. These systems commence at the fuel bunkers and end at the ash extraction plant. Forcombination of various firing systems, the individual requirements of each system apply, especially those includedin EN 12952-8 and EN 12952-9.If several fuels are burnt simultaneously or if a fuel quality varies considerably (e.g. moisture content), additionalsafety measures may be necessary, especially with respect to limitation of the fuel flow into the firing system andensuring proper air supply to the individual fuels.Pressurized firing systems may require enhanced safety measures, which are not given in this European Standard.1.2 FuelsThis European Standard covers the use of solid fuels. Pulverized fuel fired in an entrained air flow (burner) systemis covered by EN 12952-9.Solid fuels covered are:¾ all coal qualities, e.g. lignite or brown coal, sub-bituminous or hard brown coal, bituminous coal or hard coal,pitch coal, anthracite, coke, coal culm, coal sludge;¾ other fossil solid fuels (e.g. peat, oil shale);¾ biomass solid fuels (e.g. wood, wood wastes [bark], pellets, energy plants [miscanthus], harvest wastes [straw]and briquettes);¾ municipal waste solid fuels (e. g. garbage, sewage sludge, refuse derived fuels [RDF]);¾ industrial waste solid fuels (e. g. petrol coke, soot, tyres, paper wastes, coated wood chips, spent wood, animalproduct wastes).Fuel blends from two or more groups, or fuels of unconventional or unknown quality may require special safetymeasures which can be proved either by practical experience gained from comparable fuels, or by suitable tests,e.g. in accordance with EN 26184-1. Such measures specified and documented by the manufacturer.Fuels on which the design is documented in the operating instructions (see 11.2). This include the fuel data for100 % input of the basic fuel and the data for any supplementary fuels together with their maximum thermal inputpercentage.1.3 OperationThe requirements for operational equipment in clauses 4 to 11 apply to steam boilers and hot water generators withpermanent supervision by properly trained personnel familiar with the special conditions of the firing systems andthe type of fuel.SIST EN 12952-16:2003



EN 12952-16:2002 (E)52 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 12952-8:2002, Water-tube boilers and auxiliary installations - Part 8: Requirements for firing systems for liquidand gaseous fuels for the boiler.EN 12952-9:2002, Water-tube boilers and auxiliary installations - Part 9: Requirements for firing systems for pul-verized solid fuel for the boiler.prEN 50156-1, Electrical equipment for furnaces and ancillary equipment — Part 1: Requirements for application,design and installation.3 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply.3.1annunciatordevice to sense a non-standard or abnormal condition and initiate a visual and/or audible signal3.2back-up firing systemseparate firing system to maintain safe ignition and stable combustion3.3basic firein the case of grate firing systems the layer of glowing fuel, fire bed, or flame of the fed fuelNOTEThe basic fire ensures safe ignition.3.4carrier gastransport medium for pneumatic conveying3.5combustion airtotal air supplied to the firing system for combustion3.6combustion process monitoring devicedevice which detects the presence of the fire, or the conditions required for a stable combustion process3.7firing system heat inputheat input into the combustion chamber. This normally is calculated as the mass flow of the fuel multiplied by its netcalorific value3.8firing systemsthe total equipment required for the combustion of fuels, including the installations for the storage in the boilerhouse, preparation and supply of fuels, the combustion air supply, the grate or fluidized bed, the flue gas dis-charge, and all related control and monitoring devicesSIST EN 12952-16:2003



EN 12952-16:2002 (E)63.9fluidized-bed combustion firing systems (FBC)fuel is burnt in its fluidized state together with an inert component3.10fuel binsilodust-tight and air-tight container for storage of fuels3.11fuel bunkercontainer for the storage of solid fuel3.12fuel feeding systemdevice to transport fuel into the combustion chamberNOTEThis can be effected e.g. by feeders through ports in the furnace walls, by means of chutes or lances, through thebottom grate or fluidizing gas distributor, or indirectly into the ash recirculation or combustion air supply.3.13fuel handling plantinstallation for conveying, mixing and distributing solid fuels to the individual fuel bunkers or fuel bins3.14grate firing systemfuel is burnt in a layer supported by a system e.g. firebars, which can have a cooling system3.15indicatormeasuring instrument which indicates a variable value (e. g. pressure, temperature, flow, level)NOTEIt can be equipped with an annunciator.3.16lighting-up equipmentfacility to achieve safe ignition of the feed fuel3.17limitertransducer, which, on reaching a fixed limit value (e. g. pressure, temperature, flow, level) is used to interrupt andlock-out the energy supply. It requires manual unlocking before restart3.18lockoutinterruption of the energy supply. Manual unlocking is required before restart3.19minimum fluidized-bed temperaturelowest temperature of the fluidized material at which it can be safely burnt3.20minimum heat input of the firing systemminimum heat input at which the firing system can be safely operated3.21monitortransducer which on reaching of a fixed limit value and initiates an alarm and/or a cut-out. The output signal onlyreverses if the causing value has changed at a defined rangeSIST EN 12952-16:2003



EN 12952-16:2002 (E)73.22purging of the flue gas passesflow including air through the combustion chamber, flue gas passes, treatment systems and associated ducts whicheffectively removes any gaseous combustibles3.23cold start-up conditionplant started when the temperature of ceramic lining and bed material is at ambient value4 Fuel storage facilities with conveying plant4.1 General4.1.1All facilities shall be designed so as to withstand mechanical and thermal stresses. Fuel shall not be heatedto an unacceptable level. Sites where fuel may accumulate shall be avoided.4.1.2Conveyance, temporary storage, and extraction of fuel shall be arranged such that blockage is avoided.4.1.3Fuels liable to volatise or pyrolysis in the absence of external heating require measures to prevent fire, ex-plosion and injuries to personnel.NOTEWet sludges can have an inherent explosion risk due to the release of volatiles (e.g. methane) when stored. Driedsludges have a fire and dust explosion risk comparable to that of pulverized fuels. Sludge storage in bins is preferable to bunkerstorage (see 4.4.1).4.1.4The storage of fuels supplied in small grain sized particles or fibres which can be stirred up and becomeairborne shall only be permitted in bins (silos).4.1.5If different types of fuels are used, dangerous operating conditions due to blending shall be excluded, e.g.by the use of separate bunkers or bins and separate feeding systems.4.1.6If there is a risk of blockage of conveying systems or firing systems by coarse fuel lumps, foreign matter,and tramp metal, it shall be removed, preferably before entering the bunker.4.2 Conveying plant4.2.1Several continuous conveyors arranged in series to form one conveying line shall be interlocked such thatthe normal operation of any conveyor is possible only if the downstream conveyors are in operation and the storagefacility is ready to accept the fuel.4.2.2Automatic facilities for open mechanical conveyance and distribution of fuel shall only start after visualand/or audible warning signals have been given.Precautions shall be taken for the protection of personnel against injury from moving components. Sufficient timeshall be provided between a warning signal and starting of the plant.4.2.3If the type and format of the fuel requires bins (silos) for temporary storage in accordance with 4.1.3 or4.1.4, subsequent conveyance shall be performed in a closed system, which shall be air-tight if operated underinternal pressure.4.2.4For pneumatic conveyance of fuel in closed pipes, deposition shall be prevented by sufficient velocity of thecarrier gas depending on the type and format of the fuel.4.2.5All piping system components of a pneumatic conveying system shall be capable of being purged of fuel.4.2.6Feeding of fuel into the pneumatic conveying line shall be interlocked in such a way that feeding is possibleonly if sufficient carrier gas is supplied. Suitable monitoring devices, e.g. monitors for flow or pressure of the carriergas shall be provided.SIST EN 12952-16:2003



EN 12952-16:2002 (E)84.2.7If the carrier gas is exhausted to the atmosphere via a dust separator, the outlet shall be protected againstcontact with ignition sources, or sparks.4.2.8If multiple lines are installed, devices shall be provided to isolate idle conveying lines from the downstreamstorage facility or the furnace.4.2.9If fuels are conveyed hydraulically by pumps, 4.2.3 to 4.2.5 shall apply.4.3 Fuel bunkers4.3.1With exception of bunkers emptied by cranes, fuel bunkers shall be built to achieve uniform discharge bythe selection of proper shape and design, in order to ensure a continuous uniform fuel flow and to avoid segrega-tion.4.3.2To avoid ingress of hot air/gas into the bunker, a minimum fuel level shall be maintained and monitored inthe bunker, or other suitable measures shall be taken.4.3.3The inner surface of the fuel bunker roof shall be designed to prevent the accumulation of dust and gas indead pockets.4.3.4Bunker charging openings shall be guarded to prevent personnel from falling in.4.3.5Fuel bunkers shall be equipped with fire fighting or fire prevention equipment. Coal bunkers may beemptied by use of emergency chutes.4.4 Fuel bins4.4.1Some fuels according to their type and format shall be stored in dust-tight bins (silos). The requirements forpulverized fuel bins defined in EN 12952-9:2002, 5.4 and 6.2.2 shall apply.4.4.2The permissible maximum storage temperature shall be specified for each single fuel and fuel blends andshall be monitored during the storage, if there is a risk of self ignition.4.4.3If emanation of combustible gas from the fuel cannot be prevented, bins shall be equipped with suitablegas monitoring and safe venting devices, or an explosion-proof bin or inertgas protection shall be provided.4.4.4Fuels described in 4.1.4 shall be stored in bins equipped with a stationary non-freezing fire extinguishingsystem to enable fire to be fought without opening access doors. The extinguishing compound shall be evenlysprayed across the entire cross sectional area of the bin. Spray nozzles shall be protected against blockage by theingress of dust. Where stationary spray-type extinguishing systems are operated automatically, manual initiationshall be possible.4.4.5Outdoor bins and fuel bearing components as well as buildings for indoor installation shall be equippedwith a lightning protective system (according to relevant standards e.g. prEN 61024-1).5 Fuel treatment5.1 General5.1.1The equipment shall be designed to withstand mechanical and thermal stresses. It shall be so arranged asto be readily accessible to enable cleaning operations to be carried out. The total system shall be gas tight if oper-ated under internal pressure.5.1.2Practicable steps shall be taken to avoid sites in the plant where combustible dust or fuel may becomelodged.SIST EN 12952-16:2003



EN 12952-16:2002 (E)95.1.3If there is a possibility of settlement of combustible dust on components that have become hot during op-eration, facilities shall be provided for purging and cleaning after shut-down.5.1.4Mechanical equipment for fuel treatment shall be designed and operated such that no unacceptable heat-ing of the fuel occurs.5.1.5The system shall include indicators and annunciators which will provide the operator with adequate infor-mation about significant operating conditions, both normal and abnormal.5.1.6To avoid the build up of electrostatic charges, all components shall be earthed unless forced and faultlessearthing is inherent in the design.5.2 Size reduction of the fuelIf size reduction of the fuel is performed by mills or crushers in the boiler house with the application of hot gas asthe carrier gas for combined grinding and drying process, the requirements for mills and the necessary explosionprevention measures given in EN 12952-9:2002, 5.3, clause 6, and 8.7.4 shall apply.5.3 Drying of the fuelWhen drying fuel prior to combustion, the permissible maximum temperature in accordance with 4.4.2 shall bemonitored. The vapours shall be discharged in order to prevent the risk of explosion. For combined grinding anddrying process see 5.2.6 Fuel feeding6.1Fuel feeding systems shall be designed to withstand mechanical and thermal stresses.6.2Fuel feeders shall be designed to provide a continuous fuel flow.6.3A shut-off device shall be installed within the fuel feeding system. This shut-off device shall be closed auto-matically:¾ if the minimum fuel level is lost when mechanical feeding;¾ if the minimum supply pressure is lost when pneumatic or hydraulic feeding.Shut-off devices need not to be installed if a rotary vane feeder is installed or if it can be ensured that negativepressure is maintained in the fuel feeding system or a minimum fuel level (see 4.3.2) is maintained in the fuel bun-ker.6.4It shall be ensured that after shut-off of the firing system and during outage, no fuel can enter the furnace.6.5The feeding of fuel shall be cut off in the event of control power loss (see 9.2.4), under the start-up conditionsin accordance with 9.4.4.1 a), or under shutting-down conditions in accordance with 9.4.5.1 a).6.6Fuel feeding systems shall be made such that flash-back by flame, or flying sparks and backfire, or egress ofhot gases is prevented.6.7Depending on the type of fuel, fire fighting equipment shall be installed. An alarm shall be activated, when aset value has been exceeded in the fuel supply equipment. Equipment for monitoring and fire fighting shall beplaced in such a way that a fire can be extinguished quickly. The equipment shall be easy to test.6.8Pneumatic fuel feeding shall be performed either indirectly by carrier gas separation (see 4.2.8), or directlyinto the furnace.If the carrier gas fails to be supplied (see 4.2.7) the shutoff device in the carrier gas supply line shall close. The po-sition of the shutoff device shall be visible from outside the supply system.SIST EN 12952-16:2003



EN 12952-16:2002 (E)10The shut-off of fuel shall be effected by first stopping the feeding of fuel into the pneumatic line, and subsequentlystopping the carrier gas supply.6.9Hydraulic feeding devices shall be designed such that they form a seal between the furnace and the feedlines (see 6.3).6.10For manual fuel feeding, double sealing shall be applied. The outer sealing shall be opened/closed duringoperation for feeding the fuel to the furnace.For firing systems not exceeding a thermal capacity of 50 kW and with assured negative pressure of the flue gas,single sealing may be used for manual fuel feeding.7 Explosion prevention measuresCombustible dusts have different propensities to ignite and can form explosive mixtures with air.The hazard of combustible dust explosion exists, if the dust is dispersed in a confined space containing air or oxy-gen in concentrations within the upper and lower explosion limits, and an ignition source shall be present. For pri-mary prevention of explosions, at least one of these conditions shall be safely excluded at all times.Individual components of a firing system require specific protective measures. For preference, explosion protectivemeasures shall be inherent in the design of the components, e.g. the avoidance of leakages, the prevention of de-posits, and the exclusion of external heating. For easy reference, an overview of important prevention measures forthe different operational areas shall be in accordance with Table 1.Table 1 — Overview of important prevention measures for different operational areasOperational areaFor explosion prevention measures see clause(s)Fuel properties1.2 (see EN 26184-1), 4.1.3 to 4.1.5Pneumatic fuel supply4.2.5 to 4.2.8Fuel bunkers4.3.3Fuel binsEN 12952-9:2002, 5.4.2, 5.4.5, 5.4.6, 6.2.2 and 4.4.3Fuel treatment plant5.1.2 to 5.1.4Size reduction of fuelEN 12952-9:2002, 5.3, 6, 8.7.2.2 and 8.7.4Drying of fuel5.3Fuel feeding6.3 to 6.7Combustion monitoring9.2Purging9.4.2Start-up, operation, and shutting down of the com-bustion process9.4.3 to 9.4.5All operating areasA.68 Equipment for combustion air supply and flue gas discharge8.1 Air supply8.1.1Air ducts shall be capable of withstanding the mechanical and thermal stresses occurring during operation,e.g. gauge and vacuum pressures resulting from closed dampers, implosions and rapid temperature changes.SIST EN 12952-16:2003



EN 12952-16:2002 (E)118.1.2Air ducts shall be gas-tight.8.1.3For firing systems with both controlled underbed and overfire air supply, the air distribution shall be indi-cated.8.1.4For fluidized-bed firing systems, a limiter shall be required which responds when the value of the air pres-sure drops to the lowest permissible value of fluidizing gas flow.8.1.5The combustion air supply system shall be established such that the combustion air influx can be stopped.This shall be achieved by cutting off the fans or, in the case of branched systems, by shut-off devices in the corre-sponding ducts. Shut-off devices in the air ducts shall be protected against unintentional maladjustment. Open,start-up and minimum flow positions shall be capable of being recognized, checked and monitored.8.1.6The combustion air, or forced draught fan shall be monitored by the combustion air flow and one of the fol-lowing criteria:a) speed of the forced draught fan;b) pressure downstream of the forced draught fan;c) differential pressure at the forced draught fan;d) power input of the forced draught fan motor;e) power circuit breaker of the forced draught fan motor.8.2 Combustion air/fuel ratio8.2.1Fuel flow and combustion air flow shall be controlled automatically or manually in mutual dependence.8.2.2Allowable values, including their ratio and corresponding safety margins, shall be given in the operatinginstructio
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