SIST-TS CEN/TS 15747:2009
(Main)Solid recovered fuels - 14C-based methods for the determination of the biomass content
Solid recovered fuels - 14C-based methods for the determination of the biomass content
This Technical Specification specifies the test methods for the determination of the biomass carbon content in solid recovered fuels based on the 14C content. The biomass fraction by weight and by energy are calculated from the biomass carbon content.
Feste Sekundärbrennstoffe - 14C-Verfahren zur Bestimmung des Gehaltes an Biomasse
Diese Technische Spezifikation legt die Prüfverfahren zur Bestimmung des Kohlenstoffgehaltes von Biomasse
in festen Sekundärbrennstoffen auf der Grundlage des 14C-Gehaltes fest. Der Massenanteil an Biomasse und
der Biomasse-Energieanteil werden aus dem Massenanteil an Kohlenstoff der Biomasse berechnet.
Combustibles solides de récupération - Méthodes basées sur le 14C pour la détermination de la teneur en biomasse
Trdno alternativno gorivo - Metode za določevanje vsebnosti biomase na osnovi izotopa ogljika 14C
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 15747:2009
01-januar-2009
7UGQRDOWHUQDWLYQRJRULYR0HWRGH]DGRORþHYDQMHYVHEQRVWLELRPDVHQDRVQRYL
L]RWRSDRJOMLND&
Solid recovered fuels - 14C-based methods for the determination of the biomass content
Feste Sekundärbrennstoffe - 14C-Verfahren zur Bestimmung des Gehaltes an Biomasse
Combustibles solides de récupération - Méthodes basées sur le 14C pour la
détermination de la teneur en biomasse
Ta slovenski standard je istoveten z: CEN/TS 15747:2008
ICS:
75.160.10 Trda goriva Solid fuels
SIST-TS CEN/TS 15747:2009 en,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TS CEN/TS 15747:2009
TECHNICAL SPECIFICATION
CEN/TS 15747
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
October 2008
ICS 75.160.10
English Version
14
Solid recovered fuels - C-based methods for the determination
of the biomass content
14
Combustibles solides de récupération - Méthodes basées Feste Sekundärbrennstoffe - C-Verfahren zur
14
sur le C pour la détermination de la teneur en biomasse Bestimmung des Gehaltes an Biomasse
This Technical Specification (CEN/TS) was approved by CEN on 11 May 2008 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 15747:2008: E
worldwide for CEN national Members.
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Contents Page
Foreword.3
Introduction .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .5
4 Symbols and abbreviations .5
5 Equipment and reagents.6
6 Principle.7
7 Procedure .7
8 Measurements.8
9 Calculation.9
10 Test report .11
14
Annex A (normative) C Determination by Proportional Scintillation-counter Method (PSM).12
14
Annex B (normative) C Determination by Beta-ionisation (BI) .16
14
Annex C (normative) C Determination by Accelerator Mass Spectrometry (AMS) .20
Annex D (informative) Exclusions, mentioned in CEN/TS 15440, which can be resolved using the
14
C method.25
Bibliography .26
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Foreword
This document (CEN/TS 15747:2008) has been prepared by Technical Committee CEN/TC 343 “Solid
Recovered Fuels”, the secretariat of which is held by SFS.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Specification: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and the United Kingdom.
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Introduction
14
The determination of the biomass carbon content using the C method is based on the well established
analytical procedures that are used for the determination of the age of carbon containing objects. It can be
used for normal sample types, sample types that cannot be analysed accurately with the methods described
in CEN/TS 15440 (1) (see Annex D), samples with a biomass carbon content below 5%, and for reference
measurements.
14
For the determination of the biomass carbon content based on the C method a general sample preparation
14
and the three common used methods for the determination of the C content are described. With this modular
14
approach it will be possible for normally equipped laboratories to prepare samples for the C content, and to
14 14
determine the C content with their own equipment or to outsource the determination of the C content to
laboratories that specialize in this matter.
14
For the collection from the sample of the C content, generally accepted methods for the conversion of the
14
carbon present in the sample to CO are described. For the measurement of the C content, methods are
2
selected that are already generally accepted as methods for the determination of the age of objects.
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1 Scope
This Technical Specification specifies the test methods for the determination of the biomass carbon content in
14
solid recovered fuels based on the C content. The biomass fraction by weight and by energy are calculated
from the biomass carbon content.
2 Normative references
The following referenced documents are indispensable for the application 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.
CEN/TS 15400, Solid recovered fuels — Methods for the determination of calorific value
CEN/TS 15413, Solid recovered fuels — Methods for the preparation of the test sample from the laboratory
sample
CEN/TS 15442, Solid recovered fuels — Methods for sampling
CEN/TS 15443, Solid recovered fuels — Methods for laboratory sample preparation
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
biogenic carbon
mass fraction of total carbon that was produced in natural processes by living organisms but not fossilized or
derived from fossil resources
3.2
biomass carbon
equivalent to biogenic carbon
3.3
biomass content
mass fraction of biomass material present in the sample
3.4
isotope abundance
fraction of atoms of a particular isotope of an element
3.5
percentage modern Carbon (pmC)
percent modern carbon relative to the NIST Oxalic acid standard reference material SRM4990B. The
internationally accepted radiocarbon dating reference value is 95 percent of the activity, in AD 1950, of this
NBS oxalic acid SRM4990B. In 2006 the value of 100% biogenic carbon was set at 107 pmC.
4 Symbols and abbreviations
14
C Carbon isotope with an atomic mass of 14
AMS Accelerator Mass Spectrometry
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β Beta particle, electron emitted during radioactive decay
BI Βeta Ionisation
Bq Bequerel, desintegrations per second
daf dry ash free
DPM Disintegrations per minute
CPM Counts per minute
GM Geiger Müller
LLD Lower Limit of Detection
MOP 3-Methoxy 1-propyl amine
LSC Liquid Scintillation Counter or Liquid Scintillation Counting
REF Reference value of 100% biogenic carbon
PSM Proportional Scintillation-counter Method
pmC percentage modern Carbon, carbon mass fraction from biogenic origin
RSD Relative Standard Deviation
SRF Solid Recovered Fuel
UHV Upper Heating Value
5 Equipment and reagents
Carbamate solution (e.g. Carbasorb® E)
Scintillation cocktail (e.g. Permafluor® E+)
Glass bottle (standard glass sample bottles with plastic screw caps that are resistant to 4M NaOH)
4 M NaOH absorption liquid
For the preparation of a carbonate free absorption liquid, preparation using freshly opened NaOH pellet
containers is sufficient. Dissolve the NaOH pellets in a small amount of water (the heat produced during the
dissolution process will enhance the dissolution process. Small amounts of precipitation are an indication of
the presence of Na CO . By decanting the clear phase the almost carbonate free solution can be diluted to the
2 3
desired volume. As the dissolution of NaOH is an exothermic process extra care should be taken as boiling of
the concentrated solution during dilution can occur.
For high precision measurements the following procedure can be used to produce a carbonate free NaOH
solution.
6700 ml demineralised water
1120 g NaOH pellets
300 ml saturated Ba(OH) solution. (± 25 g Ba(OH) in 300 ml demineralised water)
2 2
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Dissolve the NaOH pellets in the demineralised water (use magnetic stirrer)
Heat the solution and the saturated Ba(OH) solution to 80 °C, and mix the two solutions. Cool down
2
the solution to -8 °C, stop the stirring and leave the solution overnight at -8 °C. After filtration the
solution is ready for use. Keep stored in a well-sealed container.
A list of equipment and reagents necessary for conversion and for the different measurements is presented in
the Annexes.
6 Principle
The methods for the determination of the biomass carbon content specified in this Technical Specification are
14
based on the determination of the C content. The amount of biomass carbon in solid recovered fuel is
14
proportional to this C content.
Complete combustion is carried out in a way to comply with the requirements of the subsequent measurement
14
of the C content. This measurement is carried out according to one of the three methods, Proportional
Scintillation Method (PSM), Beta Ionisation (BI) or Accelerated Mass Spectrometry (AMS). These methods are
considered equivalent, giving the same results within the scope of this Technical Specification. The results are
expressed as the percentage biomass carbon in the total carbon content. The fraction of biomass content by
weight and the fraction of biomass by energy content are calculated from the biomass carbon content, using
the biomass carbon content and the energy content of the biomass fraction that is present in the sample.
7 Procedure
7.1 Sampling
Sampling, transport, storage of the solid recovered fuel shall be conducted according CEN/TS 15442 and
CEN/TS 15443. Preparation of the test sample shall be conducted according to CEN/TS 15413.
14
7.2 Conversion of the carbon present in the sample to a suitable sample for C
determination
14
For the conversion of the sample to a form that can be used for the determination of the C content, three
methods are allowed: combustion in a calorimetric bomb (see 7.3), combustion in a tube furnace (see 7.5) and
combustion in a laboratory scale combustion apparatus (see 7.6). The carbon dioxide formed is then
absorbed in a suitable solution, which depends on the combustion method and the selected method for the
14
subsequent C measurement. For the PSM detection method two absorption solutions are possible. However
when substantial chemical or optical quenching is foreseen (high NO values, formation of coloured
x
substances) collection of the CO shall be done in the NaOH solution. The use of pure oxygen or a mix of
2
oxygen and argon during combustion will reduce the formation of nitrous oxides to an acceptable level.
7.3 Combustion of the sample in a calorimetric bomb
For the determination of the calorific value of the sample, CEN/TS 15400 shall be used. After the complete
combustion in the oxygen bomb the combustion gases are collected in a gas bag as described in 7.4. For the
14
determination of the C content by PSM the carbon dioxide shall be collected in a cooled mixture of
14
carbamate solution and a suitable scintillation liquid. For the determination of the C content by AMS or BI the
carbon dioxide shall be collected in a 4 M NaOH solution. For AMS, alternatively ca. 2 ml of the CO gas can
2
be taken from the bag using a glass syringe and the gas can be transferred to the AMS target preparations
system. As the bomb volume is released to atmospheric pressure, there will be a residual amount leftover in
the bomb that is directly related to the pressure in the bomb after the combustion (with a residual pressure of
25 bar 4% of the combustion gas will be left after release to atmospheric pressure).
To overcome this artefact:
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a) Perform the calibration and the analysis taking account of this residual amount by using the pressure
correction factor.
b) Use the vacuum pump to remove the residue.
c) Flush the bomb with Argon and collect the CO in the rinsing gases as well.
2
7.4 Adsorption of the gas sample
The gas sample bag is connected to a small pump with a connection line into a 20 ml “Packard” Scintillation
vial, filled with a mixture of 10 ml of Carbosorb E sorption liquid and 10 ml of Permafluor E+ Scintillation
cocktail, placed in an ice bath, to remove the heat of the exothermic carbamate formation reaction. The
-1 -1
pumping speed is low, typical 50 ml.min to 60 ml.min .The transfer of the gas from the bag takes about 2 h
to 3 h. After the sample is collected it can be counted on a Liquid Scintillation Counter. Blank samples should
also be counted at the same time to allow that small day-to-day variations in the background can be
accounted for.
7.5 Combustion of the sample in a tube furnace
Using a tube furnace only a complete combustion of the sample is acceptable. For the determination of the
14
C content by PSM the carbon dioxide shall be done using a suitable impinger filled with a cooled mixture of
14
Carbosorb and a suitable scintillation liquid or a 4 M NaOH solution. For the determination of the C content
by AMS or BI the carbon dioxide shall be collected using a suitable impinger filled with a 4 M NaOH solution.
As an alternative the CO can be trapped by means of a cryogenic trap. In that case the cryogenic trap shall
2
consist of a water trap (dry ice in ethanol or acetone) followed by a cryogenic trap. Care shall be taken to
avoid formation of liquid oxygen, which can be achieved by heating the trap slightly above the boiling point of
oxygen, using liquid argon or by performing the separation at diminished pressure.
7.6 Combustion of the sample in a laboratory scale combustion apparatus
The lab-scale combustion apparatus shall be able to combust the SRF at a constant rate, with a complete
14
conversion of the carbon present to CO . For the determination of the C content by PSM the carbon dioxide
2
shall be collected using a suitable impinger filled with a cooled mixture of Carbosorb and a suitable scintillation
14
liquid or a 4 M NaOH solution. For the determination of the C content by AMS or BI the CO shall be
2
collected using a suitable impinger filled with a 4 M NaOH solution. As a result of the absorption of the CO a
2
large volume reduction of the gas volume will be observed after trapping. Therefore the gas pump is to be
positioned in front of the impinger, and the gas pump used shall be gas tight.
As an alternative the CO can be trapped by means of a cryogenic trap. In that case the cryogenic trap shall
2
consist of a water trap (dry ice in ethanol or acetone) followed by a cryogenic trap. Care shall be taken to
avoid formation of liquid oxygen, which can be achieved by heating the trap slightly above the boiling point of
oxygen, using liquid argon or performing the separation at diminished pressure. As an alternative, when AMS
is being used, CO may be collected by mixing homogenized SRF with cupric oxide (CuO) in a sealed,
2
evacuated quartz or Vycor glass tube. 20 mTorr water can be added to the tube prior to introduction of the
CO to help remove sulfur compounds. The tube is heated to 900 °C for 3 h to 5 h. The CO is collected by
2 2
breaking the tube using a tube-cracker connected to an evacuated glass collection line.
8 Measurements
14
The measurement of the C content of the sample shall be done according to one of the methods as
described in the Annexes of this TS. When collected samples are sent to specialized labs, the samples should
be stored in a way that no CO from air can enter the absorption solution. A check on the in leak of CO from
2 2
air shall be performed by preparing laboratory blank’s during the sampling stage.
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For the determination of the 0% biomass content the combustion of a coal standard (e.g. BCR 181) can be
used.
For the 100% Biomass content the NIST Oxalic acid primary standard (SRM 4990b) can be used. For routine
checks a wood standard calibrated against the oxalic acid will be sufficient.
For the determination of the radiocarbon content in SRF material the following performance characteristics
shall be met.
Range 5 pmC to 120 pmC corresponding to 5% to 100% Biogenic Carbon content
RSD 5% in the range 5 pmC to 10 pmC
corresponding to 0% to 10% Biogenic Carbon (e.g. 7,0% +/- =<0,35%)
RSD 2% in the range 10pmC to 120 pmC
corresponding to 10% to 100% Biogenic Carbon.
NOTE 1 The BI and AMS techniques can be used in the lower range (0% – 5 % Biogenic carbon) or if higher precision
is demanded.
NOTE 2 The upper limit of 120 pmC is the working range of common biomass components, with optional extension to
higher levels (e.g. for the measurement of bomb activity levels)
9 Calculation
Before the above-ground hydrogen bomb testing (started around 1955 and terminated in 1962) the
14
atmospheric C level had been constant to within a few percent, for the past millennium. Hence a sample
grown during this time has a well defined 'modern' activity, and the fossil contribution could be determined in a
14 14
straightforward way. However, C created during the weapons testing increased the atmospheric C level to
14
up to 200 pmC in 1962, with a decline to 107 pmC in 2006. The C activity of a sample grown since 1962 will
14
be elevated according to the average C level over the growing interval. However in the already existing
ASTM standard ASTM D-6866-5 (2) the 100% biogenic C value of 107 pmC is used. This value shall be the
base of calculations; other values are only acceptable if they are based on experimental evidence. From the
107 pmC value the correction factor of 0,93 is derived.
14
For the calculation of the biomass carbon content a C content of 100/0,93 pmC or 13,56/0,93 DPM per gram
C will be regarded as a 100% biomass carbon content. (as of the writing of this Technical Specification,
November 2006)
This correction value of 0,93 is in accordance with the value that is given in ASTM D 6866-05.
14 12 13 12
For high precision pmC measurements the C/ C and C/ C isotopic ratios must be determined as
correction for isotopic fractionation should be done. During working up of the sample this fractionation can
occur if only a part of the combusted sample is analysed. In biomass small variations in carbon isotope ratio's
occur as well, it depends on the type of photosynthesis that formed the biomass. Most biomass (e.g. wood) is
of the so-called C3 type photosynthesis, some tropical plants (corn, tropical grasses) are of the C4 type
photosynthesis. For SRF applications the maximum error is estimated to be well below 1% as for 100% C4
biomass a value of 99% biomass will be measured if no isotope correction is done.
The fraction of biomass content by weight and the fraction of biomass by energy content shall be calculated
using the biomass carbon in the solid recovered fuel and the carbon and energy content of the biomass
fraction. The default mean values for SRF, as calculated in Table 1, shall be used. The table is composed of
materials that are expected to be present in the commonly used SRF materials, where the bark values in the
table also represent mixed wood materials like wood cuttings and the hard wood values represent the wood
fraction in general. The averages calculated assume equal fractions of all categories. With a total biomass
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content in SRF of around 50%, variations in the different fractions of the biomass SRF material are
insignificant. If the origin of the biomass is known, then more exact values may be used.
Table 1 — Typical values for biomass fractions
Material Carbon pmC UHV
% (daf) % (daf) MJ/kg (daf)
Wood (coniferous and 50 114 19
deciduous)
Bark 52 111 18
Paper 47 114 17
Fresh biomass (2006) 48 107 18
Mean SRF value 49 112 18
9.1 Example for PSM measurements
14
In a carbamate solution obtained from a calorific bomb combustion of pure wood (REF = 114 pmC) a C
activity of 6,12 DPM is measured.
In the bomb an amount of 1,050 gram of sample was combusted (air dry).
Then the biomass carbon content (on air dry base) will be:
6,12 / (13,56× 114/100)/ 1,050 × 100 = 37,7 % Biogenic Carbon
9.2 Example for BI or AMS measurements
In a 1 M NaOH solution the combustion gases produced by the laboratory scale combustion of a SRF sample
(REF = 112 pmC) are trapped.
In the CO that was collected from this solution a modern carbon fraction of 61,7 pmC was measured.
2
The total carbon content in the sample was 52,0%.
Then the biomass content will be 52,0 x 61,7/100 / (112/100) = 28,6% Biogenic Carbon.
9.3 Example of conversion from biogenic carbon content to biomass content
In a SRF sample an amount of 20,0 % of Biogenic carbon was measured.
The biomass fraction of the SRF sample was estimated to be a paper fraction containing 46,6 % of carbon.
The biomass content then will be 20,0 x 100/46,6 = 42,9 % biomass content (on weight base).
The biomass energy content will be 20,0 x 17,2/46,6 = 7,38 MJ/kg.
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9.4 Example of conversion from biogenic carbon content to biomass energy content with a mixed
biomass fraction
In a SRF sample an amount of 20 % of Biogenic carbon was measured.
The biomass fraction of the SRF sample was estimated to consist of 30 % of bark and 70% of paper.
The biomass content will be 30/100 x 20 x 100/52 + 70/100 x 20 x 100/47 = 41,3 % (on weight base)
The biomass content will be 30/100 x 20 x 18/52 + 70/100 x 20 x 17/47 = 7,10 MJ/kg (on energy base).
10 Test report
The test report shall contain at least the following information:
a) A reference to this European Technical Specification (CEN/TS 15747).
b) The results of the test including the basis on which they are expressed and application of the isotope
correction.
c) Biomass content by weight, carbon, calorific value total carbon.
d) Identification of the laboratory performing the test and the date of the test.
e) Identification of product (sample) tested.
f) Any operation not included in this European Technical Specification, or regarded as optional.
g) Any unusual features noted during the test procedure.
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Annex A
(normative)
14
C Determination by Proportional Scintillation-counter Method (PSM)
A.1 Introduction
14
This normative Annex describes the procedure for the determination of the C determination by Proportional
Scintillation-counter Method (PSM) in carbonate solutions or carbamate solutions obtained from the
combustion of SRF samples in a calorimetric bomb, a tube furnace or a laboratory scale combustion device as
described in this TS.
A.2 Principle
14
PSM (also called Liquid Scintillation Counter method, LSC) determines the isotope abundance of C indirectly,
14
through its emission of β particles due to the radioactive decay of the C isotope. The β particles are
observed through their interaction with scintillation molecules. The CO formed by the combustion of SRF is
2
trapped in a carbamate solution. This solution is mixed with the organic solution containing the scintillation
14
molecules and the C activity of this mixture is measured in a Proportional (Liquid) Scintillation Counter.
A.3 Reagents and materials
Oxalic acid primary standard (SRM 4990b)
HCl solution (5 M)
Scintillation liquid
Carbamate solution
14
C substance for standard addition purposes
A.4 Apparatus
-12
The extremely low natural levels of radiocarbon in the earth's atmosphere (about 1 × 10 %) requires extra
14
precautions for accurate measurement of C. Care should be taken to eliminate the influence of cosmic and
environmental background radiation, other radioisotopes being present, electronic noise and instability, and
other factors. These background factors limit the accuracy, precision, and range of the radiocarbon dating
method as finite ages can only be calculated where sample activity is at least 3 standard deviations above
background activity (Gupta and Polach, 1985 (3)). Any Liquid Scintillation Counter used should meet these
specifications.
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Figure A.1 — Liquid Scintillation Counter
A.5 Procedure
An absorption flask is loaded with a known volume of CO absorbent, e.g. with Carbosorb. The absorbing
2
-3
capacity of Carbosorb of about 4,8× 10 M/ml must be taken into account; no more than 80% of this capacity
should be used. The flask must be cooled in ice during the absorption process. The sample gas is acquired
from a flue gas duct or from a gas bag. In either case, the sample has to be dried and the CO concentration
2
of the dried sample has to be known (either by a flue gas monitor or by ultimate analysis of the solid sample
that was used to generate the CO ). If acquired directly from a flue gas duct, the sample volume has to be
2
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measured with a gas meter and corrected for the volume of CO absorbed by the MOP (3-methoxy 1-propyl
2
amine, the active component in Carbosorb). After absorption of the CO , the absorbent is transferred to the
2
measuring vial. An equal volume of the scintillation cocktail is added and the mixture is homogenized.
Then the vial containing the mixture is placed in the LSC and measured. Typical counting times are 6 h to
24 h.
14
The activity of a sample is compared with the activity of a reference material. The number of C registrations
14
(=β counts of C decay in radiometric detectors (LSC) is related to the number of registrations of the
reference sample under the same conditions.
Standard addition techniques shall be used to check for the occurrence of chemical or optical quenching for
14
each sampling or sample type. For that purpose C labelled components shall be used.
Measurement shall be performed together with
...
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