Water-tube boilers and auxiliary installations - Part 9: Requirements for firing systems for pulverized solid fuels for the boiler

1.1   Firing systems
This document applies to pulverized fuel firing systems of steam boilers and hot water generators and commences at the filling equipment for the boiler bunkers or for the pulverized fuel storage system and ends at the ash extraction plant. For multifuel firing systems using separate or combined burners, these requirements apply to the pulverized fuel firing part involved. For other fuels or firing systems used in combination, other requirements apply, e.g. EN 12952-8:2022.
1.2   Fuels
These requirements cover the use of pulverized fuels (e.g. coke, anthracite, bituminous coal or hard coal, lignite or brown coal, petrol coke, oil shale and pulverized bio mass) ranging from low to high volatile matter content.
1.3   Operation
Requirements for operational equipment apply for steam boilers and hot water generators with permanent supervision by properly trained persons.
As firing systems using pulverized fuel can be designed either as direct-firing or as indirect-firing systems, operational requirements have to be differentiated. Annex A summarizes the operational requirements for firing systems including the pulverizing system.

Wasserrohrkessel und Anlagenkomponenten - Teil 9: Anforderungen an Staubfeuerungsanlagen für den Kessel

1.1   Feuerungsanlagen
Das Dokument gilt für Kohlenstaubfeuerungen an Dampf- und Heißwassererzeugern (Dampfkessel). Es umfasst Beschickungseinrichtungen für die Brennstoffbunker oder für die Kohlenstaub-Lagerungsanlage bis hin zu Entaschungsanlagen. Bei Mehrstoff-Feuerungen mit getrennten oder Kombinationsbrennern gelten diese Anforderungen für den entsprechenden Kohlenstaubfeuerungsteil. Für andere in Kombination eingesetzte Brennstoffe oder Feuerungsanlagen gelten andere Anforderungen, z. B. EN 12952 8:2022.
1.2   Brennstoffe
Diese Anforderungen behandeln Brennstoffstäube (z. B. Koks, Anthrazit, Steinkohle, Braunkohle, Petrolkoks, Ölschiefer und Biomassestaub) mit niedrigem bis hohem Gehalt an flüchtigen Bestandteilen.
1.3   Betrieb
Die Anforderungen für Betriebseinrichtungen gelten für Dampfkessel und Heißwassererzeuger mit ständiger Beaufsichtigung durch entsprechend ausgebildete Personen.
Da Kohlenstaubfeuerungsanlagen als Anlagen mit Direktfeuerung oder indirekter Feuerung ausgelegt sein können, ist zwischen den betrieblichen Anforderungen zu unterscheiden. Anhang A enthält die betrieblichen Anforderungen für Feuerungsanlagen einschließlich der Mahlanlage.

Chaudières à tubes d’eau et installations auxiliaires - Partie 9: Exigences pour les équipements de chauffe pour combustibles solides de la chaudière

1.1   Équipements de chauffe
Le présent document s'applique aux équipements de chauffe pour combustibles pulvérisés de générateurs de vapeur et d'eau surchauffée et commence aux appareils d’alimentation des trémies de stockage des combustibles de la chaudière ou du système de stockage des combustibles pulvérisés et se termine avec l'installation d'extraction des cendres. En ce qui concerne les équipements de chauffe polycombustibles utilisant des brûleurs séparés ou combinés, ces prescriptions s'appliquent à l'élément de chauffe pour combustibles pulvérisés impliqué. Pour d'autres combustibles ou équipements de chauffe utilisés conjointement, d'autres exigences doivent s'appliquer, par exemple l’EN 12952 8:2022.
1.2   Combustibles
Ces prescriptions couvrent l'utilisation de combustibles pulvérisés (par exemple, le coke, l'anthracite, le charbon bitumineux ou la houille, la lignite ou « brown coal », le coke de pétrole, le schiste bitumineux et biomasse pulvérisée) dont la teneur en matière volatile s'étend de faible à forte.
1.3   Mode opératoire
Les exigences relatives aux équipements d'exploitation s'appliquent aux générateurs de vapeur et d'eau surchauffée sous surveillance permanente par du personnel disposant d'une formation appropriée.
Du fait que les équipements de chauffe peuvent être conçus à chauffe directe ou indirecte, les exigences opérationnelles sont à différencier. L'annexe A résume les exigences opérationnelles pour les équipements de chauffe y compris les systèmes de pulvérisation.

Vodocevni kotli in pomožne napeljave - 9. del: Zahteve za gorilnike kotlov na prašnata goriva

General Information

Status
Published
Publication Date
18-Oct-2022
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
19-Oct-2022
Due Date
26-Aug-2021
Completion Date
19-Oct-2022

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SLOVENSKI STANDARD
SIST EN 12952-9:2022
01-december-2022
Nadomešča:
SIST EN 12952-9:2003
Vodocevni kotli in pomožne napeljave - 9. del: Zahteve za gorilnike kotlov na
prašnata goriva

Water-tube boilers and auxiliary installations - Part 9: Requirements for firing systems for

pulverized solid fuels for the boiler
Wasserrohrkessel und Anlagenkomponenten - Teil 9: Anforderungen an
Staubfeuerungsanlagen für den Kessel

Chaudières à tubes d’eau et installations auxiliaires - Partie 9: Exigences pour les

équipements de chauffe pour combustibles solides de la chaudière
Ta slovenski standard je istoveten z: EN 12952-9:2022
ICS:
27.060.30 Grelniki vode in prenosniki Boilers and heat exchangers
toplote
SIST EN 12952-9:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 12952-9:2022
---------------------- Page: 2 ----------------------
SIST EN 12952-9:2022
EN 12952-9
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 27.040 Supersedes EN 12952-9:2002
English Version
Water-tube boilers and auxiliary installations - Part 9:
Requirements for firing systems for pulverized solid fuels
for the boiler

Chaudières à tubes d'eau et installations auxiliaires - Wasserrohrkessel und Anlagenkomponenten - Teil 9:

Partie 9: Exigences pour les équipements de chauffe Anforderungen an Staubfeuerungsanlagen für den

pour combustibles solides de la chaudière Kessel
This European Standard was approved by CEN on 15 August 2022.

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. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC 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

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12952-9:2022 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 12952-9:2022
EN 12952-9:2022 (E)
Contents Page

European foreword ............................................................................................................................................ 4

1 Scope .......................................................................................................................................................... 6

1.1 Firing systems ........................................................................................................................................ 6

1.2 Fuels ........................................................................................................................................................... 6

1.3 Operation ................................................................................................................................................. 6

2 Normative references .......................................................................................................................... 6

3 Terms and definitions ......................................................................................................................... 7

4 Fuel bunkers and conveying plant ................................................................................................ 11

4.1 General.................................................................................................................................................... 11

4.2 Conveying plant ................................................................................................................................... 11

4.3 Solid fuel bunkers ............................................................................................................................... 11

5 Pulverizing system and pulverized fuel system ...................................................................... 12

5.1 Introduction .......................................................................................................................................... 12

5.2 Solid fuel feeders ................................................................................................................................. 12

5.3 Mills .......................................................................................................................................................... 12

5.4 Pulverized fuel bins ........................................................................................................................... 13

5.5 Pulverized fuel supply pipes and shut-off devices .................................................................. 13

6 Explosion prevention measures for pulverizing systems and pulverized fuel systems

................................................................................................................................................................... 14

6.1 General.................................................................................................................................................... 14

6.2 Plants operated without inert gas protection .......................................................................... 15

6.3 Plants operated with inert gas protection ................................................................................. 15

7 Equipment for air supply and flue gas discharge .................................................................... 16

7.1 Air supply ............................................................................................................................................... 16

7.2 Air/fuel ratio ........................................................................................................................................ 17

7.3 Flue gas discharge ............................................................................................................................... 17

8 Firing system ........................................................................................................................................ 17

8.1 General.................................................................................................................................................... 17

8.2 Burners for pulverized fuel ............................................................................................................. 18

8.3 Flue gas recirculation ........................................................................................................................ 18

8.4 Monitoring and control ..................................................................................................................... 18

8.5 Electrical equipment.......................................................................................................................... 19

8.6 Safety precautions .............................................................................................................................. 19

8.6.1 Purging of the flue gas passes and lighting-up ......................................................................... 19

8.6.2 Start-up ................................................................................................................................................... 20

8.6.3 Operation ............................................................................................................................................... 20

8.6.4 Shutting down of direct-firing systems ....................................................................................... 20

8.6.5 Shutting down of indirect-firing systems ................................................................................... 22

9 Ash extraction plant ........................................................................................................................... 23

10 Operation and maintenance ........................................................................................................... 23

10.1 General.................................................................................................................................................... 23

10.2 Operating instructions ...................................................................................................................... 23

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SIST EN 12952-9:2022
EN 12952-9:2022 (E)

Annex A (informative) Operational requirements for permanently supervised firing system

for pulverized fuel .............................................................................................................................. 24

A.1 General ................................................................................................................................................... 24

A.2 Operation ............................................................................................................................................... 24

A.3 Mills ......................................................................................................................................................... 24

A.4 Air/fuel ratio ........................................................................................................................................ 24

A.5 Firing system ........................................................................................................................................ 24

A.5.1 Combustion residues ......................................................................................................................... 24

A.5.2 Modification of the firing system setting ................................................................................... 24

A.5.3 Safety precautions .............................................................................................................................. 24

A.5.4 Operation ............................................................................................................................................... 25

A.6 Operating and maintenance ........................................................................................................... 25

Annex B (informative) Significant technical changes between this document and the

previous edition .................................................................................................................................. 26

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Directive 2014/68/EU aimed to be covered ........................................... 27

Bibliography ....................................................................................................................................................... 28

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SIST EN 12952-9:2022
EN 12952-9:2022 (E)
European foreword

This document (EN 12952-9:2022) 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 or by endorsement, at the latest by April 2023, and conflicting national standards shall be

withdrawn at the latest by April 2023.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 12952-9:2002.

The technical modifications in comparison with the previous edition are listed in Annex B.

The EN 12952 series concerning water-tube boilers and auxiliary installations 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: 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 using liquefied pressurized ammonia and ammonia

water solution;
• Part 15: Acceptance tests;

• Part 16: Requirements for grate and fluidized-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.
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SIST EN 12952-9:2022
EN 12952-9:2022 (E)
• Part 18: Operating instructions

Although these parts can be obtained separately, it should be recognized that the parts are inter-

dependent. As such, the design and manufacture of water-tube boilers requires the application of more

than one part in order for the requirements of the document to be satisfactorily fulfilled.

This document has been prepared under a Standardization Request given to CEN by the European

Commission and the European Free Trade Association, and supports essential requirements of EU

Directive(s) / Regulation(s).

For relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, which is an integral part

of this document.

Any feedback and questions on this document should be directed to the users’ national standards body.

A complete listing of these bodies can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,

Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,

Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North

Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United

Kingdom.
---------------------- Page: 7 ----------------------
SIST EN 12952-9:2022
EN 12952-9:2022 (E)
1 Scope
1.1 Firing systems

This document applies to pulverized fuel firing systems of steam boilers and hot water generators and

commences at the filling equipment for the boiler bunkers or for the pulverized fuel storage system and

ends at the ash extraction plant. For multifuel firing systems using separate or combined burners, these

requirements apply to the pulverized fuel firing part involved. For other fuels or firing systems used in

combination, other requirements apply, e.g. EN 12952-8:2022.
1.2 Fuels

These requirements cover the use of pulverized fuels (e.g. coke, anthracite, bituminous coal or hard coal,

lignite or brown coal, petrol coke, oil shale and pulverized bio mass) ranging from low to high volatile

matter content.
1.3 Operation

Requirements for operational equipment apply for steam boilers and hot water generators with

permanent supervision by properly trained persons.

As firing systems using pulverized fuel can be designed either as direct-firing or as indirect-firing

systems, operational requirements have to be differentiated. Annex A summarizes the operational

requirements for firing systems including the pulverizing system.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1127-1:2019, Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and

methodology

EN ISO 4126-1:2013, Safety devices for protection against excessive pressure - Part 1: Safety valves

(ISO 4126-1:2013)

EN 12952-8:2022, Water-tube boilers and auxiliary installations — Part 8: Requirements for firing systems

for liquid and gaseous fuels for the boiler

EN 12952-18:2012, Water-tube boilers and auxiliary installations - Part 18: Operating instructions

As impacted by EN ISO 4126-1:2013/A1:2016 and EN ISO 4126-1:2013/A2:2019.
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SIST EN 12952-9:2022
EN 12952-9:2022 (E)
3 Terms and definitions

For the purposes of this document the terms and definitions given in EN 12952-8:2022 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
back-up firing system

separate firing system to maintain safe ignition and stable combustion of the pulverized fuel

3.2
burner group

burners operated in forced unison and controlled jointly and the burners supplied by the same mill or

the same pulverized fuel feeder
3.3
burner management system

system which performs a predetermined sequence of actions and always operates in conjunction with a

flame monitor

Note 1 to entry: It reacts to signals from control and safety devices, gives control commands, controls the start-up

sequence, supervises the burner operation, and causes controlled shutdown and lock-out.

3.4
carrier gas

transport medium for pulverized fuel through mill, classifier, and pulverized fuel lines

Note 1 to entry: It can consist of primary air and/or inert gas.
3.5
clearing

removal of accumulation or settlement of pulverized fuel in the case of insufficient purging of the

pulverizing system
3.6
bunker
bunker for the storage of raw fuel for an individual mill
3.7
fuel feeder

installation for the extraction of fuel from the fuel bunker and the controlled feeding of fuel into the mill

3.8
combustion air
total air supplied to the firing system for combustion
3.9
conveying plant (fuel handling plant)

installation for conveying and distributing raw fuel to the individual fuel bunkers

---------------------- Page: 9 ----------------------
SIST EN 12952-9:2022
EN 12952-9:2022 (E)
3.10
direct-firing system

system where the fuel is ground and dried in the mill and then is fed directly to the burners

3.11
explosion

unintentional instantaneous combustion phenomenon occurring in a confined space with considerable

pressure build-up
Note 1 to entry: A weak explosion is called puffing.
3.12
explosion pressure resistant design

installation that is dimensioned so as to withstand the maximum explosion pressure without substaining

permanent deformation
3.13
explosion pressure shock resistant design

installation that is dimensioned so as to withstand the pressure surge occurring during an explosion

without rupture although permanent deformation can occur
3.14
firing rate during start-up

firing rate of a burner or a burner group forming part of a pulverizing system of a direct-fired system

during start-up
3.15
firing system

equipment for the combustion of fuels, including the installations for the storage in the boiler house,

preparation and supply of fuels, the combustion air supply, the burner(s), the flue gas discharge, and all

related control and monitoring devices

Note 1 to entry: A flue gas recirculation system can be installed as an integral part of the firing system.

3.16
firing system heat input
heat input into the combustion chamber

Note 1 to entry: Firing system heat input is normally calculated as the mass flow of the fuel supplied multiplied by

its net calorific value
3.17
flame monitor

device that detects the presence or absence of the flame and transmits a signal to the control device

Note 1 to entry: For a pulverized fuel firing system the flame can be defined as:

• an individual flame of a single burner,

• the flame of a burner group for instance all burners connected to a pulverizing system,

• the flame of all burners in one combustion chamber.
---------------------- Page: 10 ----------------------
SIST EN 12952-9:2022
EN 12952-9:2022 (E)
3.18
flame-resistant material

combustible only when subjected to a continual supply of heat energy and extinguishes upon removal of

the ignition source
3.19
flue gas recirculation
return of flue gas from downstream of the flame zone or from the flue gas exit

Note 1 to entry: This can be achieved by pressure difference or the use of a separate fan or fans into the pulverizing

system, the air register of the burner, or directly into the combustion chamber.
3.20
implosion
unintentional instantaneous negative pressure build-up

Note 1 to entry: This can occur as a consequence of an explosion in a confined space, by rapid closing of dampers,

or by rapid reduction in temperature, e.g. flame out.
3.21
indirect-firing system

system where the fuel that has been ground and dried in the mill is intermediately stored in bins and the

vapours are separated

Note 1 to entry: The pulverized fuel is extracted from the bin and fed to the burners.

3.22
inerting

dilution of the oxygen content of an air/fuel mixture by the addition of an inert gas or steam to a level

where it is no longer ignitable
3.23
lighting-up equipment
facility to achieve safe ignition of pulverized fuel at the burner

Note 1 to entry: It may also be used for the provision of heat to initiate the drying process during start-up of a mill

in a direct-firing system.
3.24
limiter

transducer, which, on reaching a fixed value (e.g. pressure, temperature, flow, water level) is used to

interrupt and lockout the energy supply and requires manual unlocking before restart

3.25
lockout
interruption of the energy supply
Note 1 to entry: Manual unlocking is required before restart.
3.26
master fuel trip

device for rapid automatic shutoff of all fuel supplies to the boiler area and power to the electrical igniters

in the event of danger
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SIST EN 12952-9:2022
EN 12952-9:2022 (E)
3.27
maximum heat input of the firing system

maximum heat input including the reserves required for load control at which the firing system can be

safely operated including all reserves
3.28
mill

installation for grinding and drying the raw coal or bio mass and for classifying and conveying the

pulverized fuel
3.29
minimum heat input of the firing system
minimum heat input at which the firing system can be safely operated
3.30
monitor

limit transducer that senses the reaching of a fixed limit value and initiates an alarm and/or a cut out

Note 1 to entry: The output signal is only cancelled if the cause of the alarm has been removed and the value has

returned to within its fixed limits.
3.31
multi-fuel burner

burner in which more than one fuel is burned either simultaneously or alternately

3.32
multi-fuel firing system

firing system where, in a common combustion chamber, more than one fuel can be burned

simultaneously or alternately by separate or multi-fuel burners
3.33
primary air

part of the combustion air flow fed to the mill for the drying and conveying of pulverized fuel. This

primary air may be mixed with flue gas
3.34
pulverized fuel bin
bin (silo) for the intermediate storage of pulverized fuel
3.35
pulverized fuel burner

device for the introduction of fuel and air into a combustion chamber at required velocities, turbulence,

and local fuel concentration in order to establish and maintain proper ignition and stable combustion of

the fuel
3.36
pulverized fuel feeder

device for the controlled feeding of pulverized fuel from the pulverized fuel bin into the pulverized fuel

supply lines to the burners or other equipment
3.37
pulverizing system heat input

firing system heat input is the sum of the heat input from the single pulverizing systems

---------------------- Page: 12 ----------------------
SIST EN 12952-9:2022
EN 12952-9:2022 (E)
3.38
purging of the flue gas passes

flow of air through the combustion chamber, flue gas passes and associated ducts, which effectively

removes any gaseous combustibles and replaces them with air
3.39
purging of the pulverizing system

removal of any accumulation or settlement of pulverized fuel from inside the pulverizing system

3.40
safety time

time period during which the effectiveness of the safety device may be inhibited without a hazardous

condition occurring
4 Fuel bunkers and conveying plant
4.1 General

4.1.1 The conveyance of solid fuels, temporary storage in bunkers, and extraction shall be arranged

such that the flow of the fuel is ensured as far as possible.

4.1.2 Coarse solid fuel lumps, foreign matter, and tramp metal shall be removed to avoid damage or

blockage of the pulverizing system.

4.1.3 Dangerous areas of the fuel handling plant shall be marked by warning signs.

4.2 Conveying plant

4.2.1 Automatic facilities for the conveyance and distribution of solid fuel into the bunkers shall only

be started if visual and/or audible warning signals have been given beforehand. Precautions necessary

for the protection of personnel against injury by moving components shall be taken. Sufficient waiting

time between warning signal and start-up shall be provided (see A.4).

4.2.2 Several continuous conveyors arranged in series to form one conveying line shall be interlocked

such that the normal operation of any conveyor is possible only if the downstream conveyors are in

operation and the storage facility is ready to accept the fuel.
4.3 Solid fuel bunkers

4.3.1 The solid fuel bunkers shall be built to achieve uniform discharge by the selection of proper shape

and design in order to ensure a continuous uniform flow of the fuel and to avoid segregation.

4.3.2 To avoid ingress of hot air/gas into the bunker or the suction of leakage air into the pulverizing

system, a minimum fuel level shall be maintained in the bunker, unless other suitable measures are taken.

Monodisperse solid fuels like pelletized bio mass or biomass shells have very poor sealing behaviour. The

minimum fuel level is several times higher compared to coal. A decoupling element like a rotary gate

valve in the fuel down pipe between feeder and mill is recommended.

4.3.3 The minimum filling level of solid fuel bunkers shall be monitored and the feeder downstream of

the bunker shall be automatically stopped if the level falls below the predetermined level.

4.3.4 The inner surface of the solid fuel bunker roof shall be designed so as to avoid the accumulation

of dust and gas in dead pockets.
---------------------- Page: 13 ----------------------
SIST EN 12952-9:2022
EN 12952-9:2022 (E)

4.3.5 Bunker charging openings shall be guarded to prevent personnel from falling in (see A.5).

4.3.6 Fuel bunkers shall be equipped with fire fighting or fire prevention equipment.

5 Pulverizing system and pulverized fuel system
5.1 Introduction

5.1.1 The pulverizing system shall be readily accessible to enable cleaning operations to be carried out.

Pressurized systems shall be dust-tight and gas-tight.

5.1.2 All practicable steps should be taken to eliminate sites in the pulverizing system where pulverized

fuel and raw fuel can become lodged.

5.1.3 If there is a possibility of settlement of pulverized fuel on components that have become hot

during operation, facilities shall be provided for purging and clearing after shut-down.

5.1.4 To avoid the build up of electrostatic charges, all components shall be earthed unless forced and

faultless earthing is inherent in the design.
5.2 Solid fuel feeders

5.2.1 Solid fuel feeders and chutes shall be designed to provide a uniform flow of fuel into the mill.

5.2.2 Means shall be provided for monitoring the flow of fuel. In the event of loss of flow the conveyor

shall be automatically stopped (if necessary time delayed).
5.3 Mills

5.3.1 Mills shall be designed to withstand the mechanical and thermal loadings which occur during

operation.

Manufacturers of pulverised fuel systems shall follow the requirements of EN 1127-1:2019, where

applicable to ensure that the risks from dust explosions are eliminated or properly controlled.

5.3.2 The temperature downstream of the mill or classifier shall be continuously measured. If the

allowable operating tem
...

SLOVENSKI STANDARD
oSIST prEN 12952-9:2020
01-marec-2020
Vodocevni kotli in pomožne napeljave - 9. del: Zahteve za gorilnike kotlov na
premogov prah

Water-tube boilers and auxiliary installations - Part 9: Requirements for firing systems for

pulverized solid fuels for the boiler
Wasserrohrkessel und Anlagenkomponenten - Teil 9: Anforderungen an
Staubfeuerungsanlagen für den Kessel

Chaudières à tubes d’eau et installations auxiliaires - Partie 9: Exigences pour les

équipement de chauffe pour combustibles solides de la chaudière
Ta slovenski standard je istoveten z: prEN 12952-9
ICS:
27.060.30 Grelniki vode in prenosniki Boilers and heat exchangers
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oSIST prEN 12952-9:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 12952-9:2020
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oSIST prEN 12952-9:2020
DRAFT
EUROPEAN STANDARD
prEN 12952-9
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2020
ICS 27.040 Will supersede EN 12952-9:2002
English Version
Water-tube boilers and auxiliary installations - Part 9:
Requirements for firing systems for pulverized solid fuels
for the boiler

Chaudières à tubes d'eau et installations auxiliaires - Wasserrohrkessel und Anlagenkomponenten - Teil 9:

Partie 9: Exigences pour les équipement de chauffe Anforderungen an Staubfeuerungsanlagen für den

pour combustibles solides de la chaudière Kessel

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

CEN/TC 269.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, 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: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12952-9:2020 E

worldwide for CEN national Members.
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Contents Page

European foreword ...................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 6

1.1 Firing systems .................................................................................................................................................. 6

1.2 Fuels ..................................................................................................................................................................... 6

1.3 Operation ........................................................................................................................................................... 6

2 Normative references .................................................................................................................................... 6

3 Terms and definitions ................................................................................................................................... 7

4 Symbols and abbreviations ....................................................................................................................... 11

4.1 General.............................................................................................................................................................. 11

4.2 Conveying plant ............................................................................................................................................. 11

4.3 Solid fuel bunkers ......................................................................................................................................... 12

5 General.............................................................................................................................................................. 12

5.1 General............................................................................................................ Error! Bookmark not defined.

5.2 Solid fuel feeders ........................................................................................................................................... 12

5.3 Mills .................................................................................................................................................................... 12

5.4 Pulverized fuel bins ..................................................................................................................................... 13

5.5 Pulverized fuel supply pipes and shutoff devices ............................................................................. 14

6 Explosion prevention measures for pulverizing systems and pulverized fuel systems ..... 14

6.1 General.............................................................................................................................................................. 14

6.2 Plants operated without inert gas protection .................................................................................... 15

6.3 Plants operated with inert gas protection ........................................................................................... 15

7 Equipment for air supply and flue gas discharge .............................................................................. 16

7.1 Air supply ......................................................................................................................................................... 16

7.2 Air/fuel ratio .................................................................................................................................................. 17

7.3 Flue gas discharge ......................................................................................................................................... 17

8 Firing system .................................................................................................................................................. 17

8.1 General.............................................................................................................................................................. 17

8.2 Burners for pulverized fuel ....................................................................................................................... 18

8.3 Flue gas recirculation .................................................................................................................................. 18

8.4 Modification of the firing system setting .............................................................................................. 18

8.5 Monitoring and control ............................................................................................................................... 18

8.6 Electrical equipment.................................................................................................................................... 19

8.7 Safety precautions ........................................................................................................................................ 19

8.7.1 Purging of the flue gas passes and lighting-up ................................................................................... 19

8.7.2 Start-up ............................................................................................................................................................. 19

8.7.3 Operation ......................................................................................................................................................... 20

8.7.4 Shutting down of direct-firing systems ................................................................................................. 20

8.7.5 Shutting down of indirect-firing systems ............................................................................................. 22

9 Ash extraction plant ..................................................................................................................................... 23

10 Operation and maintenance ..................................................................................................................... 23

10.1 General.............................................................................................................................................................. 23

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10.2 Operating instructions ................................................................................................................................ 23

Annex A (informative) Operational requirements for permanently supervised firing system

for pulverized fuel ........................................................................................................................................ 24

A.1 General ............................................................................................................................................................. 24

A.2 Operation ......................................................................................................................................................... 24

A.3 Mills ................................................................................................................................................................... 24

A.4 Air/fuel ratio .................................................................................................................................................. 24

A.5 Firing system .................................................................................................................................................. 24

A.5.1 Combustion residues ................................................................................................................................... 24

A.5.2 Modification of the firing system setting ............................................................................................. 24

A.5.3 Safety precautions ........................................................................................................................................ 24

A.5.4 Operation ......................................................................................................................................................... 25

A.6 Operating and maintenance ..................................................................................................................... 25

A.6.1 General ............................................................................................................................................................. 25

Annex B (informative) Significant technical changes between this document and the

previous edition ............................................................................................................................................ 26

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Directive 2014/68/EU aimed to be covered ..................................................... 27

Bibliography ................................................................................................................................................................. 28

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prEN 12952-9:2020 (E)
European foreword

This document (prEN 12952-9:2020) has been prepared by Technical Committee CEN/TC 269 “Shell

and water-tube boilers”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 12952-9:2002.

EN 12952 series concerning water-tube boilers and auxiliary installations 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: 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 using liquefied pressurized ammonia and ammonia

water solution;
• Part 15: Acceptance tests;

• Part 16: Requirements for grate and fluidized-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 may be obtained separately, it should be recognized that the parts are inter-

dependent. As such, the design and manufacture of water-tube boilers requires the application of more

than one part in order for the requirements of the document to be satisfactorily fulfilled.

NOTE Parts 4 and 15 are not applicable during the design, construction and installation stages.

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This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association, and supports essential requirements of EU Directive 2014/68/EU.

For relationship with EU Directive 2014/68/EU, see informative Annex ZA, which is an integral part of

this document.
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1 Scope
1.1 Firing systems

This document applies to pulverized fuel firing systems of steam boilers and hot water generators and

commences at the filling equipment for the boiler bunkers or for the pulverized fuel storage system and

ends at the ash extraction plant. For multifuel firing systems using separate or combined burners, these

requirements apply to the pulverized fuel firing part involved. For other fuels or firing systems used in

combination, other requirements apply e.g. prEN 12952-8:2020.
1.2 Fuels

These requirements cover the use of pulverized fuels (e.g. coke, anthracite, bituminous coal or hard

coal, lignite or brown coal, petrol coke, oil shale and pulverized bio mass) ranging from low to high

volatile matter content.
1.3 Operation

Requirements for operational equipment apply for steam boilers and hot water generators with

permanent supervision by properly trained persons.

As firing systems using pulverized fuel may be designed either as direct-firing or as indirect-firing

systems, operational requirements have to be differentiated. Annex A summarizes the operational

requirements for firing systems including the pulverizing system.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1127-1:2019, Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts

and methodology

prEN 12952-8:2020, Water-tube boilers and auxiliary installations — Part 8: Requirements for firing

systems for liquid and gaseous fuels for the boiler

EN 12952-18:2012, Water-tube boilers and auxiliary installations - Part 18: Operating instructions

EN 50156-1:2015, Electrical equipment for furnaces and ancillary equipment - Part 1: Requirements for

application design and installation
Under preparation
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3 Terms and definitions

For the purposes of this document the terms and definitions given in prEN 12952-8:2020 and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
back-up firing system

separate firing system to maintain safe ignition and stable combustion of the pulverized fuel

3.2
burner group

burners operated in forced unison and controlled jointly and the burners supplied by the same mill or

the same pulverized fuel feeder
3.3
burner management system

burner management system performs a predetermined sequence of actions and always operates in

conjunction with a flame monitor

Note 1 to entry: It reacts to signals from control and safety devices, gives control commands, controls the start-up

sequence, supervises the burner operation, and causes controlled shutdown and lock-out.

3.4
carrier gas

transport medium for pulverized fuel through mill, classifier, and pulverized fuel lines

Note 1 to entry: It may consist of primary air and/or inert gas.
3.5
clearing

removal of accumulation or settlement of pulverized fuel in the case of insufficient purging of the

pulverizing system
3.6
coal bunker
bunker for the storage of raw coal for an individual mill
3.7
fuel feeder

installation for the extraction of fuel from the fuel bunker and the controlled feeding of fuel into the mill

3.8
combustion air
total air supplied to the firing system for combustion
3.9
conveying plant (coal handling plant)

installation for conveying and distributing raw coal to the individual coal bunkers

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3.10
direct-firing system

system where the fuel is ground and dried in the mill and then is fed directly to the burners

3.11
explosion

unintentional instantaneous combustion phenomenon occurring in a confined space with considerable

pressure build-up
Note 1 to entry: A weak explosion is called puffing.
3.12
explosion pressure resistant design

installations that are dimensioned so as to withstand the maximum explosion pressure without

substaining permanent deformation
3.13
explosion pressure shock resistant design

installations that are dimensioned so as to withstand the pressure surge occurring during an explosion

without rupture although permanent deformation may occur
3.14
firing rate during start-up

firing rate of a burner or a burner group forming part of a pulverizing system of a direct-fired system

during start-up
3.15
firing system

equipment for the combustion of fuels, including the installations for the storage in the boiler house,

preparation and supply of fuels, the combustion air supply, the burner(s), the flue gas discharge, and all

related control and monitoring devices

Note 1 to entry: A flue gas recirculation system can be installed as an integral part of the firing system.

3.16
firing system heat input

heat input into the combustion chamber, normally calculated as the mass flow of the fuel supplied

multiplied by its net calorific value
3.17
flame monitor

device that detects the presence or absence of the flame and transmits a signal to the control device

Note 1 to entry: For a pulverized fuel firing system the flame can be defined as:

• an individual flame of a single burner,

• the flame of a burner group for instance all burners connected to a pulverizing system,

• the flame of all burners in one combustion chamber.
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3.18
flame-resistant material

flame-resistant material that is combustible only when subjected to a continual supply of heat energy

and extinguishes upon removal of the ignition source
3.19
flue gas recirculation
return of flue gas from downstream of the flame zone or from the flue gas exit

Note 1 to entry: This can be achieved by pressure difference or the use of a separate fan or fans into the

pulverizing system, the air register of the burner, or directly into the combustion chamber.

3.20
implosion
unintentional instantaneous negative pressure build-up

Note 1 to entry: This can occur as a consequence of an explosion in a confined space, by rapid closing of dampers,

or by rapid reduction in temperature, e.g. flame out.
3.21
indirect-firing system

system where the fuel that has been ground and dried in the mill is intermediately stored in bins and

the vapours are separated

Note 1 to entry: The pulverized fuel is extracted from the bin and fed to the burners.

3.22
inerting

dilution of the oxygen content of an air/fuel mixture by the addition of an inert gas or steam to a level

where it is no longer ignitable
3.23
lighting-up equipment
facility to achieve safe ignition of pulverized fuel at the burner

Note 1 to entry: It may also be used for the provision of heat to initiate the drying process during start-up of a mill

in a direct-firing system.
3.24
limiter

transducer, which, on reaching a fixed value (e.g. pressure, temperature, flow, water level) is used to

interrupt and lockout the energy supply and requires manual unlocking before restart

3.25
lockout
interruption of the energy supply
Note 1 to entry: Manual unlocking is required before restart.
3.26
master fuel trip

device for rapid automatic shutoff of all fuel supplies to the boiler area and power to the electrical

igniters in the event of danger
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3.27
maximum heat input of the firing system

maximum heat input including the reserves required for load control at which the firing system can be

safely operated including all reserves
3.28
mill

installation for grinding and drying the raw coal and for classifying and conveying the pulverized fuel

3.29
minimum heat input of the firing system
minimum heat input at which the firing system can be safely operated
3.30
monitor

limit transducer that senses the reaching of a fixed limit value and initiates an alarm and/or a cut out

Note 1 to entry: The output signal is only cancelled if the cause of the alarm has been removed and the value has

returned to within its fixed limits.
3.31
multi-fuel burners

burners in which more than one fuel is burned either simultaneously or alternately

3.32
multi-fuel firing system

firing system where, in a common combustion chamber, more than one fuel can be burned

simultaneously or alternately by separate or multi-fuel burners
3.33
primary air

part of the combustion air flow fed to the mill for the drying and conveying of pulverized fuel. This

primary air may be mixed with flue gas
3.34
pulverized fuel bin
bin (silo) for the intermediate storage of pulverized fuel
3.35
pulverized fuel burner

device for the introduction of fuel and air into a combustion chamber at required velocities, turbulence,

and local fuel concentration in order to establish and maintain proper ignition and stable combustion of

the fuel
3.36
pulverized fuel feeder

device for the controlled feeding of pulverized fuel from the pulverized fuel bin into the pulverized fuel

supply lines to the burners or other equipment
3.37
pulverizing system heat input

firing system heat input of a direct-fired system divided by the number of pulverizing systems in

operation
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3.38
purging of the flue gas passes

flow of air through the combustion chamber, flue gas passes and associated ducts, which effectively

removes any gaseous combustibles and replaces them with air
3.39
purging of the pulverizing system

removal of any accumulation or settlement of pulverized fuel from inside the pulverizing system

3.40
safety time

time period during which the effectiveness of the safety device may be inhibited without a hazardous

condition occurring
3.41
boundary of pulverizing system
a pulverizing system is bounded by:
• the outlet of the fuel bunkers feeding the mill;
• the outlet of the burners fed from that mill;

• the points at which the hot air or flue gas and tempering air or flue gas leave their main supply

ducts including the primary air fan if associated individually with the mill
4 Symbols and abbreviations
4.1 General

4.1.1 The conveyance of solid fuels, temporary storage in bunkers, and extraction shall be arranged

such that the flow of the fuel is ensured as far as possible.

4.1.2 Coarse solid fuel lumps, foreign matter, and tramp metal shall be removed to avoid damage or

blockage of the pulverizing system.

4.1.3 Dangerous areas of the coal handling plant shall be marked by warning signs.

4.2 Conveying plant

4.2.1 Automatic facilities for the conveyance and distribution of solid fuel into the bunkers shall only

be started if visual and/or audible warning signals have been given beforehand. Precautions necessary

for the protection of personnel against injury by moving components shall be taken. Sufficient waiting

time between warning signal and start-up shall be provided (see A.4).

4.2.2 Several continuous conveyors arranged in series to form one conveying line shall be interlocked

such that the normal operation of any conveyor is possible only if the downstream conveyors are in

operation and the storage facility is ready to accept the coal.
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4.3 Solid fuel bunkers

4.3.1 The solid fuel bunkers shall be built to achieve uniform discharge by the selection of proper

shape and design in order to ensure a continuous uniform flow of the fuel and to avoid segregation.

4.3.2 To avoid ingress of hot air/gas into the bunker or the suction of leakage air into the pulverizing

system, a minimum fuel level shall be maintained in the bunker, unless other suitable measures are

taken.

4.3.3 The minimum filling level of solid fuel bunkers shall be monitored and the feeder downstream

of the bunker shall be automatically stopped if the level falls below the predetermined level.

4.3.4 The inner surface of the solid fuel bunker roof shall be designed so as to avoid the accumulation

of dust and gas in dead pockets.

4.3.5 Bunker charging openings shall be guarded to prevent personnel from falling in (see A.5).

4.3.6 Fuel bunkers shall be equipped with fire fighting or fire prevention equipment.

5 General
5.1 Introduction

5.1.1 The pulverizing system shall be readily accessible to enable cleaning operations to be carried

out. Pressurized systems shall be dust-tight and gas-tight.

5.1.2 All practicable steps should be taken to eliminate sites in the pulverizing system where

pulverized fuel and raw coal may become lodged.

5.1.3 If there is a possibility of settlement of pulverized fuel on components that have become hot

during operation, facilities shall be provided for purging and clearing after shut-down.

5.1.4 To avoid the build up of electrostatic charges, all components shall be earthed unless forced and

faultless earthing is inherent in the design.
5.2 Solid fuel feeders

5.2.1 Solid fuel feeders and chutes shall be designed to provide a uniform flow of fuel into the mill.

5.2.2 Means shall be provided for monitoring the flow of fuel. In the event of loss of flow the conveyor

shall be automatically stopped (if necessary time delayed).
5.3 Mills

5.3.1 Mills shall be designed to withstand the mechanical and thermal loadings which occur during

operation.

Manufacturers of pulverised fuel systems shall follow the requirements of EN 1127-1:2019, where

applicable to ensure that the risks from coal dust explosions are eliminated or properly controlled.

5.3.2 The temperature downstream of the mill or classifier shall be continuously measured. If the

allowable operating temperature is exceeded, this shall
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