SIST EN ISO 20049-1:2020

SLOVENSKI STANDARD
oSIST prEN ISO 20049:2019
01-september-2019
Trdna biogoriva - Določevanje samosegrevanja peletiziranih biogoriv - 1. del:
Izotermalna kalorimetrija (ISO/DIS 20049-1:2019)
Solid biofuels - Determination of self-heating of pelletized biofuels - Part 1: Isothermal
calorimetry (ISO/DIS 20049-1:2019)
Biogene Festbrennstoffe - Bestimmung der Selbsterhitzung von Pellets aus biogenen
Brennstoffen - Teil 1: Isotherme Kalorimetrie (ISO/DIS 20049-1:2019)
Biocombustibles solides - Détermination de l'auto-échauffement des granulés de
biocombustibles - Partie 1: Détermination calorimétrique isotherme (ISO/DIS 20049-
1:2019)
Ta slovenski standard je istoveten z: prEN ISO 20049-1
ICS:
75.160.40 Biogoriva Biofuels
oSIST prEN ISO 20049:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 20049:2019

---------------------- Page: 2 ----------------------
oSIST prEN ISO 20049:2019
DRAFT INTERNATIONAL STANDARD
ISO/DIS 20049-1
ISO/TC 238 Secretariat: SIS
Voting begins on: Voting terminates on:
2019-06-14 2019-09-06
Solid biofuels — Determination of self-heating of pelletized
biofuels —
Part 1:
Isothermal calorimetry
Biocombustibles solides — Détermination de l'auto-chauffage des granulés de biocombustibles
ICS: 27.190; 75.160.40
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 20049-1:2019(E)
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. ISO 2019

---------------------- Page: 3 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

---------------------- Page: 4 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 3
6 Sample handling . 4
6.1 General . 4
6.2 Sampling . 4
6.3 Sample transport and storage . 4
6.4 Sample preparation . 4
7 Test procedure . 5
7.1 Temperature stabilisation . 5
7.2 Sample vial preparation . 5
7.2.1 Preparation procedure . 5
7.2.2 Procedure to find proper test portion mass in case of influence from
oxygen deficiency . 5
7.3 Reference vial preparation . 5
7.4 Measurement . 6
7.4.1 First baseline measurement . 6
7.4.2 Sample measurement . 6
7.4.3 Second baseline measurement . 6
7.4.4 Measurement data file . 6
8 Results . 7
8.1 Test data . 7
8.2 Reported data . 7
9 Test report . 7
10 Repeatability and reproducibility . 8
Annex A (normative) Calibration of the calorimeter. 9
Annex B (informative) Examples of screening data .11
Annex C (informative) Determination of reaction kinetics .13
Annex D (informative) Information on the Interlaboratory study (ILS) .20
Bibliography .26
© ISO 2019 – All rights reserved iii

---------------------- Page: 5 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(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 238, Solid biofuels.
A list of all parts in the ISO 20049 series can be found on the ISO website.
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 2019 – All rights reserved

---------------------- Page: 6 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

Introduction
There is a continuous global growth in production, storage, handling, bulk transport and use of solid
biofuels especially in the form of pelletized biofuels.
The specific physical and chemical characteristics of solid biofuels, their handling and storage can lead
to a risk of fire and/or explosion, as well as health risks such as intoxication due to exposure to carbon-
monoxide, asphyxiation due to oxygen depletion or allergic reactions.
Heat can be generated in solid biofuel by exothermic biological, chemical and physical processes.
Biological processes include the metabolism of fungus and bacteria and occur at lower temperatures;
the oxidation of wood constituents increases with temperature and dominates at higher temperatures;
the heat production from biological and chemical processes leads to transport of moisture in the bulk
material, with associated sorption and condensation of water, which both are exothermic processes. In,
e.g., a heap of stored forest fuel or a heap of moist wood chips, all of these processes can be present and
contribute to heat production.
[1]
Solid biofuels such as wood pellets, however, are intrinsically sterile due to the conditions during
manufacturing (exposure to severe heat during drying, fragmentation during hammermilling and
pressure during extrusion) but can attract microbes if becoming wet during handling and storage
resulting in metabolism and generation of heat. Leakage of water into a storage of wood pellets can
also lead to the physical processes mentioned above. Non-compressed wood like feedstock and chips
typically have a fauna of microbes which under certain circumstances will result in heating. All the
processes mentioned above contribute to what is called self-heating although oxidation is likely to be
one of the main contributing factors in the temperature range under which most biofuels are stored.
The heat build-up can be significant in large bulk stores as the heat conduction in the material is low.
Under certain conditions the heat generation can lead to thermal runaway and spontaneous ignition.
The potential for self-heating seems to vary considerably for different types of solid biofuel pellets. The
raw material used, and the properties of these raw materials have proven to influence the propensity
for self-heating of the produced wood pellets. However, the production process (e.g. the drying process)
also influences the potential for self-heating. It is therefore important to be able to identify solid biofuel
pellets with high heat generation potential to avoid fires in stored materials.
Two intrinsically different types of tests methods can be used to estimate the potential of self-heating;
— In the isothermal calorimetry method described in this document, the heat flow generated from the
test portion is measured directly.
— In basket heating tests, the temperature of the test portion is being monitored and the critical
ambient temperature (CAT), where the temperature of the test portion increases significantly due
to self-heating, is used for indirect assessment of self-heating.
These two methods are applied at different analysis temperature regimes. The operating temperature
for an isothermal calorimeter is normally in the range 5 °C to 90 °C whereas basket heating tests are
conducted at higher analysis (oven) temperatures. For basket heating tests with wood pellets, CATs are
found for a 1 l sample portion in the range 150 °C to 200 °C.
The application of the test data should thus be identified before selecting the appropriate analytical
method.
NOTE 1 It is likely that oxidation reactions taking place in the low- respective high temperature regimes for
solid biofuel pellets are of different character and thus have different reaction rates and heat production rates.
Extrapolation of the data from a high temperature test gives in such a case CATs with a large error; i.e., they are
predicted to be much higher than they actually are. In the general case of two reactions with different activation
energies, the high activation energy is “frozen out” at low temperatures and the low activation energy reaction is
[2]
“swamped” at higher temperatures .
NOTE 2 It has been shown for a limited number of different types of wood pellets that the reaction rates in the
lower temperature regime measured by isothermal calorimetry were higher compared to the reaction rate data
[3]
determined from basket heating tests in the higher temperature regime .
© ISO 2019 – All rights reserved v

---------------------- Page: 7 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

Isothermal calorimetry is used for determination of the thermal activity or heat flow of chemical,
physical and biological processes. The method described in this document is developed for the
measurement of heat flow from the self-heating of solid biofuel pellets, but the technique is most
[3-7]
commonly used in the fields of pharmaceuticals, energetic materials, and cement .
Data from the isothermal calorimetry screening test procedure included in this document is intended
for comparison of the spontaneous heat generation (self-heating) of solid biofuel pellets (Annex B).
Guidance is additionally given on the use of isothermal calorimetry test data for the calculation of for
the overall reaction rate of the heat producing reactions (Annex C).
vi © ISO 2019 – All rights reserved

---------------------- Page: 8 ----------------------
oSIST prEN ISO 20049:2019
DRAFT INTERNATIONAL STANDARD ISO/DIS 20049-1:2019(E)
Solid biofuels — Determination of self-heating of pelletized
biofuels —
Part 1:
Isothermal calorimetry
1 Scope
This document specifies a general test procedure for quantification of the spontaneous heat generation
from solid biofuel pellets using isothermal calorimetry.
This document further:
— specifies a screening test procedure for wood pellets using an instrument temperature of 60 °C,
— establishes procedures for sampling and sample handling of solid biofuel pellets prior to the analysis
of spontaneous heat generation, and
— gives guidance on the applicability and use of isothermal calorimetry for calculation of the net
reaction rate of the heat producing reactions of solid biofuel pellets.
The test procedure given in this document quantifies the thermal power (heat flow) of the sample
during the test, it does not identify the source of self-heating in the test portion analysed.
Data on spontaneous heat generation determined using this document is only associated with the
specific quality and age of the sample material. The results are product specific.
This document is applicable to solid biofuel pellets only.
The information derived using this document is for use in quality control and in hazard and risk
assessments related to the procedures given in ISO/DIS 20024:2019.
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 14780, Solid biofuels — Sample preparation
ISO 16559, Solid biofuels — Terminology, definitions and descriptions
ISO 18135, Solid Biofuels — Sampling
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16559 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/
© ISO 2019 – All rights reserved 1

---------------------- Page: 9 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

3.1
analysis temperature
temperature of the analysis environment, i.e. the calorimeter temperature
3.2
critical ambient temperature
CAT
ambient temperature (the analysis temperature (3.1) or the temperature of a storage) where the
internal temperature of the test portion (3.5) or the stored material increases significantly (due to self-
heating (3.3))
3.3
self-heating
rise in temperature in a material resulting from an exothermic reaction within the material
[SOURCE: ISO 13943:2017, definition 3.341. The definition has been modified for this document by
omitting “” in the beginning of the definition.]
3.4
spontaneous ignition
ignition caused by an internal exothermic reaction
[SOURCE: ISO 13943:2017, definition 3.24.]
Note 1 to entry: See definitions of ignition in ISO 13943.
3.5
test portion
sub-sample either of a laboratory sample (3.7) or a test sample (3.6)
[SOURCE: ISO 16559:2014, definition 4.202]
3.6
test sample
laboratory sample (3.7) after an appropriate preparation made by the laboratory
[SOURCE: ISO 16559:2014, definition 4.203. Given here for the convenience of the reader.]
Note 1 to entry: The test sample is here typically a representative sample from a batch of solid biofuel pellets.
3.7
laboratory sample
combined sample or a sub-sample of a combined sample for use in a laboratory
[SOURCE: ISO 16559:2014, definition 4.124]
3.8
thermal power
heat rate produced by the sample during the test and commonly expressed, with reference to the unit
-1 -1 -1
mass of pelletized biofuel, in W g or J s g .
[SOURCE: CEN/TR 16632:2014, definition 8.3 - The definition has been modified for this document by
substituting "cement" with " pelletized biofuel".]
4 Principle
Isothermal calorimetry is a sensitive technique for studying heat production or heat consumption from
samples of different kinds. It is non-destructive and non-invasive to the sample. When heat is produced
in a sample, an isothermal heat conduction calorimeter (here isothermal calorimeter) measures the
thermal power (heat flow). The sample is placed in an ampoule that is in contact with a heat flow
sensor that is also in contact with a heat sink. When heat is produced or consumed by any process, a
2 © ISO 2019 – All rights reserved

---------------------- Page: 10 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

temperature gradient is developed across the sensor. This will generate a voltage, which is measured.
The voltage is proportional to the heat flow across the sensor and to the rate of the process taking place
in the sample ampoule. This signal is recorded continuously and in real time.
NOTE 1 A commercial instrument for isothermal calorimetry normally has multiple channels and can thus be
used for measurements of several samples simultaneously.
For each sample (channel) there is an inert reference that is on a parallel heat flow sensor. During
the time that the heat flow is monitored, any temperature fluctuations entering the instrument will
influence both the sample and the reference sensors equally. This architecture allows a very accurate
determination of heat that is produced or consumed by the sample alone while other non-sample related
heat disturbances are efficiently removed. The measured heat flow is normalized against the weight of
the sample and the result is expressed in mW/g.
NOTE 2 The operating temperature for an isothermal calorimeter is normally in the range 5 °C to 90 °C.
However, there are calorimeters with somewhat higher span for operating temperature.
5 Apparatus
The usual laboratory apparatus and, in particular, the following.
5.1 Isothermal calorimeter, consisting of a sample holder for the sample vial and the reference vial,
each thermally connected to heat flow sensors, which are thermally connected to a constant temperature
sink. See example in Figure 1.
Key
1 thermostat 4 reference
2 heat sink 5 heat flow sensors
3 sample
Figure 1 — Schematic drawing of an isothermal calorimeter
The calorimeter shall be calibrated at the analysis temperature (see A.2 and A.3). The analysis
temperature for the screening test procedure shall be 60 °C.
The baseline shall exhibit a low random noise level and be stable against drift (see A.4).
The minimum sensitivity for measuring power output shall be 100 µW.
© ISO 2019 – All rights reserved 3

---------------------- Page: 11 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

The data acquisition equipment shall be capable of performing continues logging of the calorimeter
output measured at minimum time interval of 10 s.
5.2 Vials, made of glass with a minimum volume of 20 ml and provided with an air tight lid with an
inert seal.
NOTE Vials with volumes other than 20 ml can be used if the sample loading is scaled accordingly (see 7.2.1).
In such cases this deviation from the standard procedure shall be noted in the test report.
5.3 Balance, with a resolution of at least 10 mg.
6 Sample handling
6.1 General
Sample handling is important in maintaining the properties of solid biofuel pellets samples. The
transport and storage (see 6.3) are of special importance for self-heating properties as the reactivity
of the sample will be reduced from prolonged exposure to air oxygen. This is further accentuated at
exposure to elevated temperatures.
The sample history and the conditions for sample handling should be stated as thoroughly as possible
in the test report.
6.2 Sampling
Sampling of solid biofuel pellets shall be made according to procedures prescribed in ISO 18135.
The minimum size of the laboratory sample is 500 ml.
6.3 Sample transport and storage
The laboratory sample shall be transported in a closed airtight sample container.
NOTE 1 An airtight container is used to limit the amount of available oxygen in order to reduce oxidation
reactions with the sample.
The container shall be completely filled with sample.
NOTE 2 A completely filled container limits the amount of air in the container (i.e. the amount of oxygen) and
further reduces deteriorations of the sample from physical wear (i.e. reduces the amount of fine fraction).
The time between sampling and analysis shall be minimized and elevated temperatures shall be
avoided.
NOTE 3 It has been seen that a sample can be stored for several months without any significant changes in
reactivity if put in a freezer directly after received at the analysis lab.
6.4 Sample preparation
Any fine fraction shall be removed from the laboratory sample to create a test sample before extracting
test portions. The fine fraction can be removed by gentle hand sieving using sieve size 3,15 mm in
accordance with ISO 18846.
NOTE 1 Fine fraction are removed to avoid that fine fraction produced during the handling and transport is
included in the test portion.
The test portion shall be randomly taken from the test sample. Procedures from ISO 14780 shall be
followed.
4 © ISO 2019 – All rights reserved

---------------------- Page: 12 ----------------------
oSIST prEN ISO 20049:2019
ISO/DIS 20049-1:2019(E)

7 Test procedure
7.1 Temperature stabilisation
Set the instrument temperature to the selected analysis temperature. The analysis temperature for the
screening test procedure is 60 °C.
Follow the manufacturers procedure to ascertain the temperature stability.
NOTE The values for stability criterion vary for different calorimeters and are usually decided by the
software.
7.2 Sample vial preparation
7.2.1 Preparation procedure
The prepared sample vial shall not be pre-heated.
NOTE 1 Pre-heating of the sample vial is often used to reduce the disturbance in the measurement signal
from thermal imbalance between the sample and the calorimeter. However, pre-heating is not applied in this test
procedure as it was seen during a preliminary interlaboratory study (ILS) that pre-heating was not favourable
for measurement uncertainty in this application.
Handle the sample using a pair of tweezers or rubber gloves to avoid contamination of the sample.
Use whole pellets or larger pieces of pellets if possible.
Weigh into the sample vial (5.2) a test portion of 0,2 g pellets per ml volume of the glass vial used. For
example, use 4 ± 0,1 g pellets for a 20 ml glass vial.
NOTE 2 It has been shown for wood pellets that there is no significant difference in measured thermal power
[8]
for measurements made on whole pellets versus smaller parts of pellets (mixture from 2 mm particles and less) .
Tighten the lid of the sample vial properly after sample loading.
If oxygen deficiency which influences the test results is occurring in the closed ampoule during
measurement, follow the procedure in 7.2.2. A method to detect significant oxygen deficiency is
given in 8.1.
NOTE 4 It has been shown that oxygen deficiency in the closed vial normally does not influence the measured
heat production significantly in measurements with wood pellets using the screening test procedure prescribed
[8]
in this document . However, in certain cases with highly reactive pellets oxygen deficiency can influence the
test results and must be handled.
7.2.2 Procedure to find proper test portion mass in case of influence from oxygen deficiency
To find the proper sample mass for avoiding the influence of oxygen deficiency, first run tests with 4 g
and 2 g sample mass (in case of using a 20 ml sample vial). If the difference in normalized total heat
production between the two sample weights (4 g and 2 g) is non-significant (less than 10 relative-%
difference) no more tests are required; 4 g sample mass is proper to use. If, however, the difference is
significant additional tests with 1 g and 3 g sample weight shall be made to fin
...