SIST EN ISO 22580:2022

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.

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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

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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
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
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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
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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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oSIST prEN ISO 22580:2021
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
2
DN Diameter of Nominal
H S Hydrogen Sulphide
2
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
3
— 99,99 % or less than 10 mg CH /Nm in flue gas at a reference of 15 vol % oxygen for enclosed high
4
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
2
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
...