Flares for combustion of biogas (ISO 22580:2020)

This document applies to the design, manufacture, installation and operation of flares for the combustion of biogas. Test methods and performance requirements are also included.
Biogas systems are amongst others applied at industrial plants like food and beverage industries, waste water treatment plants, waste plants, landfill sites, small scale plants next to agricultural companies and small-scale household systems.

Fackeln für Biogasanlagen (ISO 22580:2020)

Dieses Dokument gilt für Auslegung, Herstellung, Aufbau und Betrieb von Fackeln für die Verbrennung von Biogas. Prüfverfahren und Leistungsanforderungen sind auch enthalten.
Biogasanlagen werden unter anderem in Industrieanlagen wie der Lebensmittel- und Getränkeindustrie, Abwasserbehandlungsanlagen, Abfallanlagen, Deponien, kleinen Anlagen neben landwirtschaftlichen Betrieben und kleinen häuslichen Anlagen eingesetzt.

Torchères pour la combustion du biogaz (ISO 22580:2020)

Le présent document s'applique à la conception, la fabrication, l'installation et l'exploitation de torchères pour la combustion du biogaz. Elle comprend également des méthodes d'essai et des exigences de performances.
Les installations de production de biogaz sont, entre autres, utilisées dans des installations industrielles, par exemple dans l'industrie des produits alimentaires et des boissons, les stations de traitement des eaux usées, les installations de traitement des déchets, les décharges, les installations agricoles de petite taille et les installations domestiques.

Naprave za sežig bioplina (ISO 22580:2020)

Ta dokument se uporablja za načrtovanje, proizvodnjo, vgradnjo in obratovanje naprav za sežig bioplina. Vključuje tudi preskusne metode in zahteve glede zmogljivosti.
Sistemi za bioplin se med drugim uporabljajo v industrijskih obratih, kot so živilska industrija in industrija pijač, čistilne naprave, obrati za predelavo odpadkov, odlagališča, manjši obrati ob kmetijskih podjetjih in manjši sistemi v gospodinjstvih.

General Information

Status
Published
Public Enquiry End Date
01-Oct-2021
Publication Date
12-Jan-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
21-Dec-2021
Due Date
25-Feb-2022
Completion Date
13-Jan-2022

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SLOVENSKI STANDARD
SIST EN ISO 22580:2022
01-februar-2022
Naprave za sežig bioplina (ISO 22580:2020)
Flares for combustion of biogas (ISO 22580:2020)
Fackeln für Biogasanlagen (ISO 22580:2020)
Torchères pour la combustion du biogaz (ISO 22580:2020)
Ta slovenski standard je istoveten z: EN ISO 22580:2021
ICS:
27.190 Biološki viri in drugi Biological sources and
alternativni viri energije alternative sources of energy
SIST EN ISO 22580:2022 en,fr,de

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

---------------------- Page: 1 ----------------------
SIST EN ISO 22580:2022
---------------------- Page: 2 ----------------------
SIST EN ISO 22580:2022
EN ISO 22580
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2021
EUROPÄISCHE NORM
ICS 27.190
English Version
Flares for combustion of biogas (ISO 22580:2020)

Torchères pour la combustion du biogaz (ISO Fackeln für Biogasanlagen (ISO 22580:2020)

22580:2020)
This European Standard was approved by CEN on 29 November 2021.

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, Turkey 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

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 22580:2021 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 22580:2022
EN ISO 22580:2021 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

---------------------- Page: 4 ----------------------
SIST EN ISO 22580:2022
EN ISO 22580:2021 (E)
European foreword

The text of ISO 22580:2020 has been prepared by Technical Committee ISO/TC 255 "Biogas” of the

International Organization for Standardization (ISO) and has been taken over as EN ISO 22580:2021 by

Technical Committee CEN/TC 408 “Natural gas and biomethane for use in transport and biomethane for

injection in the natural gas grid” the secretariat of which is held by AFNOR.

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 June 2022, and conflicting national standards shall be

withdrawn at the latest by June 2022.

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.

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 organizations 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, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 22580:2020 has been approved by CEN as EN ISO 22580:2021 without any modification.

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SIST EN ISO 22580:2022
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SIST EN ISO 22580:2022
INTERNATIONAL ISO
STANDARD 22580
First edition
2020-07
Flares for combustion of biogas
Torchères pour les installations de biogaz
Reference number
ISO 22580:2020(E)
ISO 2020
---------------------- Page: 7 ----------------------
SIST EN ISO 22580:2022
ISO 22580:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 22580:2022
ISO 22580:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Abbreviated terms .............................................................................................................................................................................................. 2

5 Classifications of flares for combustion of biogas.............................................................................................................. 3

6 Design and construction of flares for combustion of biogas .................................................................................. 4

6.1 Efficiency of the flare ......................................................................................................................................................................... 4

6.2 Pressure ........................................................................................................................................................................................................ 4

6.3 Air supply and gas flow.................................................................................................................................................................... 4

6.4 Pilot burner ................................................................................................................................................................................................ 5

6.5 Treatment of the gas .......................................................................................................................................................................... 5

6.6 Materials ....................................................................................................................................................................................................... 5

6.7 Flame arresters ....................................................................................................................................................................................... 6

6.8 Burner control unit, ignition transformer, flame monitoring device ....................................................... 6

6.9 Safety valves and other valves ................................................................................................................................................... 6

6.10 Control system......................................................................................................................................................................................... 7

6.11 Flow measuring and gas analysis ............................................................................................................................................ 7

6.12 Condensate removal ........................................................................................................................................................................... 8

6.13 Insulation and heating ...................................................................................................................................................................... 8

6.14 Heat protection ....................................................................................................................................................................................... 8

6.15 Buildings and cabinets ..................................................................................................................................................................... 8

6.16 Lightning protection and earthing ......................................................................................................................................... 8

6.17 Strength and stability calculations ........................................................................................................................................ 8

6.18 Distances to other objects ............................................................................................................................................................. 8

7 Operations and maintenance requirements ........................................................................................................................... 9

7.1 Operations and maintenance manual ................................................................................................................................. 9

7.2 Testing of the flare ............................................................................................................................................................................... 9

7.3 Operation of the flare .....................................................................................................................................................................10

7.4 Maintenance and inspection of the flare........................................................................................................................10

Bibliography .............................................................................................................................................................................................................................12

© ISO 2020 – All rights reserved iii
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SIST EN ISO 22580:2022
ISO 22580:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see

www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 255, Biogas.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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SIST EN ISO 22580:2022
ISO 22580:2020(E)
Introduction

Flares for combustion of biogas are amongst others applied at industrial plants like food and beverage

industries, waste water treatment plants, waste plants, landfill sites, small scale plants next to

agricultural companies and small-scale household systems.

Biogas is normally a by-product produced by amongst others wastewater treatment plants, food

& beverage plants, waste plants, landfill sites, small scale plants next to agricultural companies and

small-scale household systems. The main ingredients are approximately 50 ~ 65 volume % of methane

and approximately 30 ~ 50 volume % of carbon dioxide and also contains many other ingredients, such

as water vapor, hydrogen sulphide, ammonia, nitrogen, oxygen, siloxanes, and hydrocarbons. Methane

is one of the main initiators of the greenhouse effect. Biogas will not only pollute the environment, but

also causes serious potential safety hazards. Therefore, centralized processing of anaerobic methane

is needed. In case the biogas output cannot be used to generate energy or upgraded to biomethane,

because of economic reasons or in case the energy production installation does not work properly,

the biogas or biomethane is collected and combusted in a flare. The methane percentage of biogas or

biomethane to be combusted in a biogas flare can vary from 5 volume % to (almost) 100 volume %.

Biogas flares have the function of improving workplace safety, increasing the social identification,

reducing the odour pollution and reducing the greenhouse effect.

This document about flares for biogas plants is applicable for combustion of biogas as defined in

ISO 20675. The main purposes of this document are to ensure safe flares, to prevent health hazards

because of dangerous gases and explosive atmospheres and to reduce the emission of the strong

greenhouse gas methane.
The availability of a standard for biogas flares is necessary in order to:
— ensure that flares are built, operated and maintained safely;

— facilitate development of regional and national regulations and incentive programs to regulate

methane emissions;

— moderate communication between the different biogas parties through meaningful discussions;

— contribute to reinforcement of biogas flares’ safety and business competitiveness with recognized

terms and definitions that clarify actors’ expectations related to procurement;

— contracts and services as well as reporting on biogas related action plans, road maps, etc.;

— contribute to the use of standards by facilitating their development and furthering users’

understanding and application of standards.
© ISO 2020 – All rights reserved v
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SIST EN ISO 22580:2022
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SIST EN ISO 22580:2022
INTERNATIONAL STANDARD ISO 22580:2020(E)
Flares for combustion of biogas
1 Scope

This document applies to the design, manufacture, installation and operation of flares for the

combustion of biogas. Test methods and performance requirements are also included.

Biogas systems are amongst others applied at industrial plants like food and beverage industries, waste

water treatment plants, waste plants, landfill sites, small scale plants next to agricultural companies

and small-scale household systems.
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.

ISO 13577-2:2014, Industrial furnaces and associated processing equipment — Safety — Part 2: Combustion

and fuel handling systems

ISO 13577-4, Industrial furnace and associated processing equipment — Safety — Part 4: Protective systems

ISO 16852, Flame arresters — Performance requirements, test methods and limits for use

ISO 20675, Biogas — Biogas production, conditioning, upgrading and utilization — Terms, definitions and

classification scheme

ISO 23551-1, Safety and control devices for gas burners and gas-burning appliances — Particular

requirements

IEC 60730-2-5, Automatic electrical controls— Part 2-5: Particular requirements for automatic electrical

burner control systems

IEC 60730-2-6, Automatic electrical controls— Part 2-6: Particular requirements for automatic electrical

pressure sensing controls including mechanical requirements
IEC 62305-2, Protection against lightning — Part 2: Risk management

IEC 60079-10-1, Explosive atmospheres — Part 10-1: Classification of areas — Explosive gas atmospheres

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20675 and the following apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
open flare
biogas flare from which the burning flame is visible from outside
Note 1 to entry: This is also called external combustion flame burner.

Note 2 to entry: The flame burner combustion is not optimal, the combustion temperature is relatively low.

© ISO 2020 – All rights reserved 1
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SIST EN ISO 22580:2022
ISO 22580:2020(E)
3.2
enclosed flare

biogas flare which consists of an enclosed combustion chamber, where the flame is invisible from outside

Note 1 to entry: An enclosed flare is normally burning more efficiently with a relatively higher temperature than

an open flare (3.1), and the burning temperature is sometimes monitored, for example by a temperature sensor

such as a thermocouple.
3.3
ignition device

device for automatically igniting the flame in a biogas flare consisting of an ignition transformer,

ignition electrode, fuel gas source and its connecting cables, gas pipes, gas nozzle and valves

3.4
flame monitoring device

device consisting of an ultraviolet flame sensor, ionization sensor, similar and flame transmitter to

monitor the flame burning status of the biogas flare continuously
3.5
primary air coefficient

ratio of premixed air versus the total flow of air and biogas supplied to a flare

3.6
turn-down ratio

ratio of the maximum combustion flow where the flame is stable and not going outside the flare and the

minimum flow
3.7
burning residence time

retention time of biogas in the combustion chamber for an effective oxidation of hydrocarbons

3.8
burner control unit

stand-alone automatic safety system which includes an ignition transformer, ignition electrodes,

flame monitoring device, ignition or pilot solenoid valve, main gas valve and all other valves and safety

equipment needed to ignite the flame and to monitor the presence of the flame continuously

3.9
combustion yield
percentage of a substance which is combusted

Note 1 to entry: In this document the combustion yield refers to the percentage of methane which is combusted

in a biogas flare.
4 Abbreviated terms
AA Aluminum Alloy
AISI American Iron and Steel Institute
CO Carbon dioxide
DN Diameter of Nominal
H S Hydrogen Sulphide
IEC International Electrotechnical Commission
IP Ingress Protection
2 © ISO 2020 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 22580:2022
ISO 22580:2020(E)
ISO International Organization for Standardization
ppmv parts per million by volume
TBT Technical Barriers to Trade
URL Uniform Resource Locator
UV Ultraviolet
WD Working Draft
WG Working Group
WTO World Trade Organization
5 Classifications of flares for combustion of biogas

Biogas is produced by anaerobic digestion of organic matter, gasification of biomass or power to gas

from biomass sources.

Biogas mainly comprises methane (range from 15 volume % to 100 volume %), carbon dioxide, nitrogen,

oxygen, hydrogen sulphide and/or water and furthermore could contain hydrogen, carbon monoxide,

heavier hydrocarbons (including aromatic hydrocarbons), siloxanes and/or other substances.

Biogas can be treated in order to eliminate hydrogen sulphide, siloxanes, water and other substances

and be upgraded to a gas with higher methane content. Sometimes the biogas will be pressurized.

A biogas flare can be applied as a safety, environmental and/or process device.

A flare could be used if the biogas produced in biogas plants is not suitable for energy generation or the

biogas plant is not functioning properly. A flare can also be applied in case production of energy out of

biogas is not feasible and/or for landfill sites with a low percentage of methane.

A typical flare consists of e.g. an ignition system, flame and temperature detection system, flame

arrester, windscreen or windproof body and combustion chamber, biogas piping, valves, condensate

drainage, electrical control cabinet, installation fixtures, burner head, heat insulation and continuous

pilot or start-up ignition burner.

NOTE Direct ignition on the main burner increases the risks and is not allowed in most countries.

A flare can be classified into three main categories: open flare, enclosed flare and enclosed high

efficiency flare. The requirements for these categories are as follows:

— An open flare is classified as a flare from which the burning flame is visible from outside. This is

also called external combustion flame burner. The flame burner combustion is not optimal, the

combustion temperature is relatively low.

— An enclosed flare is classified as a flare which consists of an enclosed combustion chamber, where

the flame is invisible from outside. An enclosed flare burns more efficiently with a relatively higher

temperature than an open flare, and the burning temperature can be monitored.

— An enclosed high efficiency flare is classified as a flare which consists of an enclosed combustion

chamber, where the flame is invisible from outside and the biogas is combusted at a monitored and

automatically controlled temperature and retention time which has been scientifically proven to

result in the combustion yields mentioned in 6.1 Furthermore, other technologies, such as radiant

burner technologies or pre-mixed burners, exist to achieve the combustion yields mentioned in the

next chapter.

A flare can be operated continuously (more than 90 % of the hours per year) or in emergency situations.

An emergency flare is meant to combust biogas during exceptional situations when the biogas is not

© ISO 2020 – All rights reserved 3
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SIST EN ISO 22580:2022
ISO 22580:2020(E)

utilized. Emergency flares can be either an enclosed flare, enclosed high efficiency flare or open flare.

Continuously operated flares can be of the type enclosed flare or enclosed high efficiency flare.

In order to meet climate policy targets, enclosed high efficiency flares should be applied in case of

continuous operation.
6 Design and construction of flares for combustion of biogas

The minimum requirements for the design and construction of safe and minimized methane emission

flares for combustion of biogas are described in this Clause. Safety regulations on construction sites

during construction are not part of this document.
6.1 Efficiency of the flare
The combustion yield of the flare shall be at least:
— 99 % for enclosed flares, and

— 99,99 % or less than 10 mg CH /Nm in flue gas at a reference of 15 vol % oxygen for enclosed high

efficiency flares.

These yields need to be measured on a continuous or regular performance basis by an independent

party, using standardized or scientifically proven measurement methodologies which prove that the

measured values are representative for the operation of the flare. National standards might impose

additional requirements on combustion yields and/or additional protocols for measurement.

Measurement methods have to be scientifically supported (which often is the case for methods included

in National or International Standards), to prevent measurements which are not representative for the

operation of the flare. Scientifically proven combustion yields shall be proven by measurements.

The flare shall be able to combust the minimum and maximum flow and composition of biogas (or

biomethane) expected at the particular installation.
6.2 Pressure

The flare can use the biogas pressure system of the biogas plant to realize sufficient pressure of the

biogas if possible and to prevent the use of an additional compressor or blower. When the gas pressure

is very low (less than 1,0 kPa or 2,0 kPa) or not stable, an additional compressor or blower may be

needed. Generally, the minimum pressure is 1,0 kPa and the maximum pressure is depends on the

manufacturer.

The biogas main inlet pipe can be equipped with one or more pressure switches in order to realize

pressure sensing automatic ignition. The pressure shall be adjustable over a range reflecting the

actual operation of the system. When the pressure achieves the high limit, the flare turns on, when the

pressure reaches the low pressure limit the flare shuts down. The supplier of the flare shall determine

a safe operating shut-down point in order to prevent a vacuum drawing the flame into the digester.

Systems with constant pressure gas holders, such as dual membranes, shall use the gas holder level

signal and/or biogas pressure signal to determine the start and stop points of the flares.

Pressure detectors for safety shall comply with IEC 60730-2-6 and the function shall meet the

requirement of the protective system according to ISO 13577-4.
6.3 Air supply and gas flow

For the air supply natural draft may be used in order to avoid an additional combustion air blower

leading to additional operational requirements. High efficiency flares may utilize air injection for

pre-mixing. The flare should be designed in a way to realize sufficient air supply in relation to the gas

supplied via the gas burner (for example louvers can be used). The burner design shall enable pre-mixed

combustion. The air and the biogas are mixed in order to increase the combustion temperature and

4 © ISO 2020 – All rights reserved
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SIST EN ISO 22580:2022
ISO 22580:2020(E)

reduce the flame length. Alternative technologies to supply air can be used, as long as the applicable

combustion yields are achieved. When the flare stops working the gas supply shall be stopped before

the air supply is stopped.
6.4 Pilot burner

An ignition burner or pilot burner (next to the main burner) shall be used for auxiliary ignition to

prevent the potential explosion danger. The ignition device source can be biogas or bio methane itself

or other fuel gas. For safety reasons it is important the gas is combustible.

In some countries it is forbidden to use biogas as fuel for the pilot burner, for example because biogas

can be less reliable for a pilot burner, especially in the case of a cold climate or variable feedstocks.

In other countries other fuel gases might not be available, so biogas or biomethane is the only option.

National legislation shall be reviewed before choosing the type of fuel for the pilot burner.

6.5 Treatment of the gas

The biogas may be treated before combustion in the flare. This depends on the specification of the

biogas (composition o
...

SLOVENSKI STANDARD
oSIST prEN ISO 22580:2021
01-september-2021
Naprave za zgorevanje bioplina (ISO 22580:2020)
Flares for combustion of biogas (ISO 22580:2020)
Torchères pour la combustion du biogaz (ISO 22580:2020)
Ta slovenski standard je istoveten z: prEN ISO 22580
ICS:
27.190 Biološki viri in drugi Biological sources and
alternativni viri energije alternative sources of energy
oSIST prEN ISO 22580:2021 en,fr,de

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

---------------------- Page: 1 ----------------------
oSIST prEN ISO 22580:2021
---------------------- Page: 2 ----------------------
oSIST prEN ISO 22580:2021
INTERNATIONAL ISO
STANDARD 22580
First edition
2020-07
Flares for combustion of biogas
Torchères pour les installations de biogaz
Reference number
ISO 22580:2020(E)
ISO 2020
---------------------- Page: 3 ----------------------
oSIST prEN ISO 22580:2021
ISO 22580:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 22580:2021
ISO 22580:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Abbreviated terms .............................................................................................................................................................................................. 2

5 Classifications of flares for combustion of biogas.............................................................................................................. 3

6 Design and construction of flares for combustion of biogas .................................................................................. 4

6.1 Efficiency of the flare ......................................................................................................................................................................... 4

6.2 Pressure ........................................................................................................................................................................................................ 4

6.3 Air supply and gas flow.................................................................................................................................................................... 4

6.4 Pilot burner ................................................................................................................................................................................................ 5

6.5 Treatment of the gas .......................................................................................................................................................................... 5

6.6 Materials ....................................................................................................................................................................................................... 5

6.7 Flame arresters ....................................................................................................................................................................................... 6

6.8 Burner control unit, ignition transformer, flame monitoring device ....................................................... 6

6.9 Safety valves and other valves ................................................................................................................................................... 6

6.10 Control system......................................................................................................................................................................................... 7

6.11 Flow measuring and gas analysis ............................................................................................................................................ 7

6.12 Condensate removal ........................................................................................................................................................................... 8

6.13 Insulation and heating ...................................................................................................................................................................... 8

6.14 Heat protection ....................................................................................................................................................................................... 8

6.15 Buildings and cabinets ..................................................................................................................................................................... 8

6.16 Lightning protection and earthing ......................................................................................................................................... 8

6.17 Strength and stability calculations ........................................................................................................................................ 8

6.18 Distances to other objects ............................................................................................................................................................. 8

7 Operations and maintenance requirements ........................................................................................................................... 9

7.1 Operations and maintenance manual ................................................................................................................................. 9

7.2 Testing of the flare ............................................................................................................................................................................... 9

7.3 Operation of the flare .....................................................................................................................................................................10

7.4 Maintenance and inspection of the flare........................................................................................................................10

Bibliography .............................................................................................................................................................................................................................12

© ISO 2020 – All rights reserved iii
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oSIST prEN ISO 22580:2021
ISO 22580:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see

www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 255, Biogas.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
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Introduction

Flares for combustion of biogas are amongst others applied at industrial plants like food and beverage

industries, waste water treatment plants, waste plants, landfill sites, small scale plants next to

agricultural companies and small-scale household systems.

Biogas is normally a by-product produced by amongst others wastewater treatment plants, food

& beverage plants, waste plants, landfill sites, small scale plants next to agricultural companies and

small-scale household systems. The main ingredients are approximately 50 ~ 65 volume % of methane

and approximately 30 ~ 50 volume % of carbon dioxide and also contains many other ingredients, such

as water vapor, hydrogen sulphide, ammonia, nitrogen, oxygen, siloxanes, and hydrocarbons. Methane

is one of the main initiators of the greenhouse effect. Biogas will not only pollute the environment, but

also causes serious potential safety hazards. Therefore, centralized processing of anaerobic methane

is needed. In case the biogas output cannot be used to generate energy or upgraded to biomethane,

because of economic reasons or in case the energy production installation does not work properly,

the biogas or biomethane is collected and combusted in a flare. The methane percentage of biogas or

biomethane to be combusted in a biogas flare can vary from 5 volume % to (almost) 100 volume %.

Biogas flares have the function of improving workplace safety, increasing the social identification,

reducing the odour pollution and reducing the greenhouse effect.

This document about flares for biogas plants is applicable for combustion of biogas as defined in

ISO 20675. The main purposes of this document are to ensure safe flares, to prevent health hazards

because of dangerous gases and explosive atmospheres and to reduce the emission of the strong

greenhouse gas methane.
The availability of a standard for biogas flares is necessary in order to:
— ensure that flares are built, operated and maintained safely;

— facilitate development of regional and national regulations and incentive programs to regulate

methane emissions;

— moderate communication between the different biogas parties through meaningful discussions;

— contribute to reinforcement of biogas flares’ safety and business competitiveness with recognized

terms and definitions that clarify actors’ expectations related to procurement;

— contracts and services as well as reporting on biogas related action plans, road maps, etc.;

— contribute to the use of standards by facilitating their development and furthering users’

understanding and application of standards.
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INTERNATIONAL STANDARD ISO 22580:2020(E)
Flares for combustion of biogas
1 Scope

This document applies to the design, manufacture, installation and operation of flares for the

combustion of biogas. Test methods and performance requirements are also included.

Biogas systems are amongst others applied at industrial plants like food and beverage industries, waste

water treatment plants, waste plants, landfill sites, small scale plants next to agricultural companies

and small-scale household systems.
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.

ISO 13577-2:2014, Industrial furnaces and associated processing equipment — Safety — Part 2: Combustion

and fuel handling systems

ISO 13577-4, Industrial furnace and associated processing equipment — Safety — Part 4: Protective systems

ISO 16852, Flame arresters — Performance requirements, test methods and limits for use

ISO 20675, Biogas — Biogas production, conditioning, upgrading and utilization — Terms, definitions and

classification scheme

ISO 23551-1, Safety and control devices for gas burners and gas-burning appliances — Particular

requirements

IEC 60730-2-5, Automatic electrical controls— Part 2-5: Particular requirements for automatic electrical

burner control systems

IEC 60730-2-6, Automatic electrical controls— Part 2-6: Particular requirements for automatic electrical

pressure sensing controls including mechanical requirements
IEC 62305-2, Protection against lightning — Part 2: Risk management

IEC 60079-10-1, Explosive atmospheres — Part 10-1: Classification of areas — Explosive gas atmospheres

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20675 and the following apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
open flare
biogas flare from which the burning flame is visible from outside
Note 1 to entry: This is also called external combustion flame burner.

Note 2 to entry: The flame burner combustion is not optimal, the combustion temperature is relatively low.

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3.2
enclosed flare

biogas flare which consists of an enclosed combustion chamber, where the flame is invisible from outside

Note 1 to entry: An enclosed flare is normally burning more efficiently with a relatively higher temperature than

an open flare (3.1), and the burning temperature is sometimes monitored, for example by a temperature sensor

such as a thermocouple.
3.3
ignition device

device for automatically igniting the flame in a biogas flare consisting of an ignition transformer,

ignition electrode, fuel gas source and its connecting cables, gas pipes, gas nozzle and valves

3.4
flame monitoring device

device consisting of an ultraviolet flame sensor, ionization sensor, similar and flame transmitter to

monitor the flame burning status of the biogas flare continuously
3.5
primary air coefficient

ratio of premixed air versus the total flow of air and biogas supplied to a flare

3.6
turn-down ratio

ratio of the maximum combustion flow where the flame is stable and not going outside the flare and the

minimum flow
3.7
burning residence time

retention time of biogas in the combustion chamber for an effective oxidation of hydrocarbons

3.8
burner control unit

stand-alone automatic safety system which includes an ignition transformer, ignition electrodes,

flame monitoring device, ignition or pilot solenoid valve, main gas valve and all other valves and safety

equipment needed to ignite the flame and to monitor the presence of the flame continuously

3.9
combustion yield
percentage of a substance which is combusted

Note 1 to entry: In this document the combustion yield refers to the percentage of methane which is combusted

in a biogas flare.
4 Abbreviated terms
AA Aluminum Alloy
AISI American Iron and Steel Institute
CO Carbon dioxide
DN Diameter of Nominal
H S Hydrogen Sulphide
IEC International Electrotechnical Commission
IP Ingress Protection
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ISO International Organization for Standardization
ppmv parts per million by volume
TBT Technical Barriers to Trade
URL Uniform Resource Locator
UV Ultraviolet
WD Working Draft
WG Working Group
WTO World Trade Organization
5 Classifications of flares for combustion of biogas

Biogas is produced by anaerobic digestion of organic matter, gasification of biomass or power to gas

from biomass sources.

Biogas mainly comprises methane (range from 15 volume % to 100 volume %), carbon dioxide, nitrogen,

oxygen, hydrogen sulphide and/or water and furthermore could contain hydrogen, carbon monoxide,

heavier hydrocarbons (including aromatic hydrocarbons), siloxanes and/or other substances.

Biogas can be treated in order to eliminate hydrogen sulphide, siloxanes, water and other substances

and be upgraded to a gas with higher methane content. Sometimes the biogas will be pressurized.

A biogas flare can be applied as a safety, environmental and/or process device.

A flare could be used if the biogas produced in biogas plants is not suitable for energy generation or the

biogas plant is not functioning properly. A flare can also be applied in case production of energy out of

biogas is not feasible and/or for landfill sites with a low percentage of methane.

A typical flare consists of e.g. an ignition system, flame and temperature detection system, flame

arrester, windscreen or windproof body and combustion chamber, biogas piping, valves, condensate

drainage, electrical control cabinet, installation fixtures, burner head, heat insulation and continuous

pilot or start-up ignition burner.

NOTE Direct ignition on the main burner increases the risks and is not allowed in most countries.

A flare can be classified into three main categories: open flare, enclosed flare and enclosed high

efficiency flare. The requirements for these categories are as follows:

— An open flare is classified as a flare from which the burning flame is visible from outside. This is

also called external combustion flame burner. The flame burner combustion is not optimal, the

combustion temperature is relatively low.

— An enclosed flare is classified as a flare which consists of an enclosed combustion chamber, where

the flame is invisible from outside. An enclosed flare burns more efficiently with a relatively higher

temperature than an open flare, and the burning temperature can be monitored.

— An enclosed high efficiency flare is classified as a flare which consists of an enclosed combustion

chamber, where the flame is invisible from outside and the biogas is combusted at a monitored and

automatically controlled temperature and retention time which has been scientifically proven to

result in the combustion yields mentioned in 6.1 Furthermore, other technologies, such as radiant

burner technologies or pre-mixed burners, exist to achieve the combustion yields mentioned in the

next chapter.

A flare can be operated continuously (more than 90 % of the hours per year) or in emergency situations.

An emergency flare is meant to combust biogas during exceptional situations when the biogas is not

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utilized. Emergency flares can be either an enclosed flare, enclosed high efficiency flare or open flare.

Continuously operated flares can be of the type enclosed flare or enclosed high efficiency flare.

In order to meet climate policy targets, enclosed high efficiency flares should be applied in case of

continuous operation.
6 Design and construction of flares for combustion of biogas

The minimum requirements for the design and construction of safe and minimized methane emission

flares for combustion of biogas are described in this Clause. Safety regulations on construction sites

during construction are not part of this document.
6.1 Efficiency of the flare
The combustion yield of the flare shall be at least:
— 99 % for enclosed flares, and

— 99,99 % or less than 10 mg CH /Nm in flue gas at a reference of 15 vol % oxygen for enclosed high

efficiency flares.

These yields need to be measured on a continuous or regular performance basis by an independent

party, using standardized or scientifically proven measurement methodologies which prove that the

measured values are representative for the operation of the flare. National standards might impose

additional requirements on combustion yields and/or additional protocols for measurement.

Measurement methods have to be scientifically supported (which often is the case for methods included

in National or International Standards), to prevent measurements which are not representative for the

operation of the flare. Scientifically proven combustion yields shall be proven by measurements.

The flare shall be able to combust the minimum and maximum flow and composition of biogas (or

biomethane) expected at the particular installation.
6.2 Pressure

The flare can use the biogas pressure system of the biogas plant to realize sufficient pressure of the

biogas if possible and to prevent the use of an additional compressor or blower. When the gas pressure

is very low (less than 1,0 kPa or 2,0 kPa) or not stable, an additional compressor or blower may be

needed. Generally, the minimum pressure is 1,0 kPa and the maximum pressure is depends on the

manufacturer.

The biogas main inlet pipe can be equipped with one or more pressure switches in order to realize

pressure sensing automatic ignition. The pressure shall be adjustable over a range reflecting the

actual operation of the system. When the pressure achieves the high limit, the flare turns on, when the

pressure reaches the low pressure limit the flare shuts down. The supplier of the flare shall determine

a safe operating shut-down point in order to prevent a vacuum drawing the flame into the digester.

Systems with constant pressure gas holders, such as dual membranes, shall use the gas holder level

signal and/or biogas pressure signal to determine the start and stop points of the flares.

Pressure detectors for safety shall comply with IEC 60730-2-6 and the function shall meet the

requirement of the protective system according to ISO 13577-4.
6.3 Air supply and gas flow

For the air supply natural draft may be used in order to avoid an additional combustion air blower

leading to additional operational requirements. High efficiency flares may utilize air injection for

pre-mixing. The flare should be designed in a way to realize sufficient air supply in relation to the gas

supplied via the gas burner (for example louvers can be used). The burner design shall enable pre-mixed

combustion. The air and the biogas are mixed in order to increase the combustion temperature and

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reduce the flame length. Alternative technologies to supply air can be used, as long as the applicable

combustion yields are achieved. When the flare stops working the gas supply shall be stopped before

the air supply is stopped.
6.4 Pilot burner

An ignition burner or pilot burner (next to the main burner) shall be used for auxiliary ignition to

prevent the potential explosion danger. The ignition device source can be biogas or bio methane itself

or other fuel gas. For safety reasons it is important the gas is combustible.

In some countries it is forbidden to use biogas as fuel for the pilot burner, for example because biogas

can be less reliable for a pilot burner, especially in the case of a cold climate or variable feedstocks.

In other countries other fuel gases might not be available, so biogas or biomethane is the only option.

National legislation shall be reviewed before choosing the type of fuel for the pilot burner.

6.5 Treatment of the gas

The biogas may be treated before combustion in the flare. This depends on the specification of the

biogas (composition of the biogas) and the materials used.
The following treatments can be performed:
— desulfurization;
— dewatering;
— removal of siloxanes;
— removal of carbon dioxide (as part of possible biogas upgrading);
— pressurizing.

Flares designed specifically for biogas normally do not require treatment, although it may be required

by national emissions regulations, especially regarding sulphur.
6.6 Materials

Materials of construction should be designed to resist heat and corrosion that the particular portion of

the flare will see.

Materials in contact with the biogas, such as piping materials, shall be stainless steel AISI 304 or

AISI 316, at least AISI 304 when the H S concentration is lower than 300 ppmv and stainless steel

AISI 316 in case the H2S concentration is 300 ppmv or more. AISI 304 is allowed for materials in contact

with biogas with a H2S concentration between 300 ppmv and 600 ppmv in case an independent expert

can prove the material is resistant for such concentrations in the specific circumstances.

For valves, drip traps, and flame arresters in the line up to the flare, low copper aluminium (AA-356) is

an acceptable material.

Supporting structures should be made of hot dip galvanized steel or stainless steel AISI 304 or AISI 316.

The materials of the internally insulated combustion chamber can be AISI 304 or AISI 316.

The main body of the flame burner (directly in contact with the flames) should be high temperature

resistant stainless steel (anti-corrosion materials), AISI 309 or 310. An alternative for materials in

contact with combustion heat is AISI 347.

The main gas control valve material of flame burner should be made of corrosion resistant materials

or should have sufficient corrosion allowance (e.g. applicable for cast iron steel). For the seal fluorine

rubber or nitrile-base rubber are suitable for use. Except AISI 304 or AISI 316 also AA 356 is suitable as

corrosion resistant material.
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For enclosed flares when a lining or refractory ceramic fibre module is used, a top rain cover shall be

used to prevent erosion or corrosion of the material. When a stainless-steel body is used there is no

need to apply a rain cover. If the flare has a refractory lining, protection of rain ingress shall be applied

to protect the refractory.

The materials of the structure, the burner, the combustion chamber and the pipes shall be designed

with a life time of at least ten years based upon the composition of the gas for the specific location.

6.7 Flame arresters

The flare shall have a flame arrester placed between the main gas valve and the burner to prevent

propagation of the flames to the gas source and/or the gas storage. Flame arresters shall be in

accordance with ISO 16852.

The distance between the flame arrester and the gas burner shall not exceed the value specified by the

supplier of the flame arrester.

In order to prevent detrimental effects to the gas source and/or gas storage caused by possible sparks

from equipment such as compressors or blowers, it is recommended to place an additional flame

arrester upstream of this equipment.

One or more additional flame arresters are needed in cases where sparks from equipment can cause

risks to the gas source and/or gas storage. For example, this can be the case if the equipment is upstream

from the maximum distance between flame arrester and gas burner, as mentioned before.

Many types of flame arresters can only stop a flame for a prescribed period of time. The flame arresters

shall either be equipped with some means of thermal shut-off that is activated by a continuous burn on

the flame arrester or alternatively the burner nozzle pressure shall be monitored and switch off when

the flare burner pressure falls below a specified value to prevent back burning.
Flame arresters shall be maintained on
...

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