SIST-TS CEN/TS 17021:2017
(Main)Stationary source emissions - Determination of the mass concentration of sulphur dioxide by instrumental techniques
Stationary source emissions - Determination of the mass concentration of sulphur dioxide by instrumental techniques
This Technical Specification describes a method for sampling and determining the concentration of gaseous sulphur dioxide (SO2) emissions from stacks. This method is based on instrumental techniques. It is applicable to both periodic measurements and the calibration of automated measuring systems permanently installed on stacks, for regulatory or other purposes.
Emissionen aus stationären Quellen - Ermittlung der Massenkonzentration von Schwefeldioxid mit instrumentellen Verfahren
Diese Technische Spezifikation beschreibt ein Verfahren zur Probenahme und Bestimmung der Konzentration von gasförmigem Schwefeldioxid (SO2) in Emissionen aus Abgaskanälen. Dieses Verfahren liegt den Techniken instrumenteller Analytik zugrunde. Es ist anwendbar bei wiederkehrenden Messungen und bei der Kalibrierung von automatischen Messeinrichtungen (AMS), die aus gesetzgeberischen oder anderen Gründen stationär an einem Abgaskanal installiert sind.
Émissions de sources fixes - Mesurage des émissions de dioxyde de soufre par des techniques instrumentales
La présente Spécification technique décrit une méthode de prélèvement et de détermination de la concentration des émissions de dioxyde de soufre gazeux (SO2) des cheminées. Cette méthode s’appuie sur des techniques instrumentales. Elle est applicable tant aux mesurages périodiques qu’à l’étalonnage des systèmes de mesurage automatisés installés à demeure sur des cheminées, à des fins réglementaires ou autres.
Emisije nepremičnih virov - Določevanje masne koncentracije žveplovega dioksida z instrumentalnimi tehnikami
Ta tehnična specifikacija opisuje metodo vzorčenja in določevanja koncentracije emisij plinastega žveplovega dioksida (SO2) iz odvodnikov. Ta metoda temelji na instrumentalnih tehnikah. Uporablja se za redno spremljanje in kalibracijo avtomatskih merilnih sistemov, ki so trajno nameščeni na odvodnike, in sicer za regulativne ter druge namene.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2017
(PLVLMHQHSUHPLþQLKYLURY'RORþHYDQMHPDVQHNRQFHQWUDFLMHåYHSORYHJDGLRNVLGD
]LQVWUXPHQWDOQLPLWHKQLNDPL
Stationary source emissions - Determination of the mass concentration of sulphur
dioxide by instrumental techniques
Emissionen aus stationären Quellen - Ermittlung der Massenkonzentration von
Schwefeldioxid mit instrumentellen Verfahren
Émissions de sources fixes - Mesurage des émissions de dioxyde de soufre par des
techniques instrumentales
Ta slovenski standard je istoveten z: CEN/TS 17021:2017
ICS:
13.040.40 (PLVLMHQHSUHPLþQLKYLURY Stationary source emissions
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN/TS 17021
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
January 2017
TECHNISCHE SPEZIFIKATION
ICS 13.040.40
English Version
Stationary source emissions - Determination of the mass
concentration of sulphur dioxide by instrumental
techniques
Émissions de sources fixes - Détermination de la Emissionen aus stationären Quellen - Ermittlung der
concentration massique en dioxyde de soufre par des Massenkonzentration von Schwefeldioxid mit
techniques instrumentales instrumentellen Verfahren
This Technical Specification (CEN/TS) was approved by CEN on 23 October 2016 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, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, 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: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17021:2017 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Symbols and abbreviations . 11
4.1 Symbols . 11
4.2 Abbreviated terms . 12
5 Principle . 12
5.1 General . 12
5.2 Measuring principle . 12
6 Description of the measuring system . 13
6.1 General . 13
6.2 Sampling and sample gas conditioning system . 14
6.3 Analyser equipment . 16
7 Performance characteristics of the method . 16
8 Suitability of the measuring system for the measurement task . 18
9 Field operation . 18
9.1 Measurement section and measurement plane . 18
9.2 Sampling strategy. 19
9.3 Choice of the measuring system . 19
9.4 Setting of the measuring system on site . 20
10 Ongoing quality control . 22
10.1 Introduction . 22
10.2 Frequency of checks . 22
11 Expression of results . 23
12 Measurement report . 23
Annex A (informative) Example of uncertainty estimation for the method and compliance
with required emissions measurement uncertainty . 24
A.1 General . 24
A.2 Elements required for the uncertainty determinations . 24
A.3 Example uncertainty budget . 27
A.4 Evaluation of compliance with a required measurement uncertainty . 32
Annex B (informative) Calculation of the uncertainty associated with a concentration
expressed under dry conditions and at an oxygen reference concentration . 34
B.1 Uncertainty associated with a concentration expressed under dry conditions. 34
B.2 Uncertainty associated with a concentration expressed at a O reference
concentration . 36
Annex C (normative) Annual lack of fit test . 38
C.1 Description of test procedure . 38
C.2 Establishment of the regression line . 38
C.3 Calculation of the residuals . 39
C.4 Test requirements . 39
Annex D (informative) Annual check of conditioning system . 40
D.1 General . 40
D.2 Demonstration via proficiency testing scheme participation . 40
D.3 Demonstration via direct user testing of conditioning system . 40
Annex E (informative) Procedure for correction of data from drift effect. 42
Annex F (informative) Chemistry of SO aqueous solubility . 44
Bibliography . 45
European foreword
This document (CEN/TS 17021:2017) has been prepared by Technical Committee CEN/TC 264 “Air
quality”, the secretariat of which is held by DIN.
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.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
1 Scope
This Technical Specification describes a method for sampling and determining the concentration of
gaseous sulphur dioxide (SO ) emissions from stacks. This method is based on instrumental techniques.
It is applicable to both periodic measurements and the calibration of automated measuring systems
permanently installed on stacks, for regulatory or other purposes.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 15259:2007, Air quality - Measurement of stationary source emissions - Requirements for
measurement sections and sites and for the measurement objective, plan and report
EN 14793:2016, Stationary source emission - Demonstration of equivalence of an alternative method with
a reference method
EN 15267-4, Air quality - Certification of automated measuring systems - Part 4: Performance criteria and
test procedures for automated measuring systems for periodic measurements of emissions from stationary
sources
EN ISO 14956:2002, Air quality - Evaluation of the suitability of a measurement procedure by comparison
with a required measurement uncertainty (ISO 14956:2002)
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard reference method
SRM
reference method prescribed by European or national legislation
[SOURCE: EN 15259:2007]
3.2
reference method
RM
measurement method taken as a reference by convention, which gives the accepted reference value of
the measurand
NOTE 1 A reference method is fully described.
NOTE 2 A reference method can be a manual or an automated method.
NOTE 3 Alternative methods can be used if equivalence to the reference method has been demonstrated.
[SOURCE: EN 15259:2007]
3.3
alternative method
AM
measurement method which complies with the criteria given by this Technical Specification with
respect to the reference method
Note 1 to entry: An alternative method can consist of a simplification of the reference method.
[SOURCE: EN 14793:2017]
3.4
measuring system
set of one or more measuring instruments and often other devices, including any reagent and supply,
assembled and adapted to give information used to generate measured quantity values within specified
intervals for quantities of specified kinds
[SOURCE: JCGM 200:2012]
3.5
automated measuring system
AMS
entirety of all measuring instruments and additional devices for obtaining a result of measurement
Note 1 to entry: Apart from the actual measuring device (the analyser), an AMS includes facilities for taking
samples (e.g. probe, sample gas lines, flow meters and regulator, delivery pump) and for sample conditioning (e.g.
dust filter, pre-separator for interferents, cooler, converter). This definition also includes testing and adjusting
devices that are required for functional checks and, if applicable, for commissioning.
Note 2 to entry: The term “automated measuring system” (AMS) is typically used in Europe. The term
“continuous emission monitoring system” (CEMS) is also typically used in the UK and USA.
[SOURCE: EN 15267-4:2017]
3.6
portable automated measuring system
P-AMS
automated measuring system which is in a condition or application to be moved from one to another
measurement site to obtain measurement results for a short measurement period
Note 1 to entry: The measurement period is typically 8 h for a day.
Note 2 to entry: The P-AMS can be configured at the measurement site for the special application but can be
also set-up in a van or mobile container. The probe and the sample gas lines are installed often just before the
measurement task is started.
[SOURCE: EN 15267-4:2017]
3.7
calibration
set of operations that establish, under specified conditions, the relationship between values of
quantities indicated by a measuring method or measuring system, and the corresponding values given
by the applicable reference
Note 1 to entry: In case of automated measuring system (AMS) permanently installed on a stack the applicable
reference is the standard reference method (SRM) used to establish the calibration function of the AMS.
Note 2 to entry: Calibration should not be confused with adjustment of a measuring system.
[SOURCE: EN 15058:2017]
3.8
adjustment
set of operations carried out on a measuring system so that it provides prescribed indications
corresponding to given values of a quantity to be measured
Note 1 to entry: The adjustment can be made directly on the instrument or using a suitable calculation
procedure.
[SOURCE: EN 15058:2017]
3.9
span gas
test gas used to adjust and check a specific point on the response line of the measuring system
Note 1 to entry: This concentration is often chosen around 80 % of the upper limit of the range
3.10
measurand
particular quantity subject to measurement
[SOURCE: EN 15259:2007]
Note 1 to entry: The measurand is a quantifiable property of the stack gas under test, for example mass
concentration of a measured component, temperature, velocity, mass flow, oxygen content and water vapour
content.
3.11
interference
negative or positive effect upon the response of the measuring system, due to a component of the
sample that is not the measurand
3.12
influence quantity
quantity that is not the measurand but that affects the result of the measurement
Note 1 to entry: Influence quantities are e.g. presence of interfering gases, ambient temperature, pressure of the
gas sample.
3.13
ambient temperature
temperature of the air around the measuring system
3.14
emission limit value
ELV
limit value given in regulations such as EU Directives, ordinances, administrative regulations, permits,
licences, authorizations or consents
Note 1 to entry: ELV can be stated as concentration limits expressed as half-hourly, hourly and daily averaged
values, or mass flow limits expressed as hourly, daily, weekly, monthly or annually aggregated values.
3.15
measurement site
place on the waste gas duct in the area of the measurement plane(s) consisting of structures and
technical equipment, for example working platforms, measurement ports, energy supply
Note 1 to entry: Measurement site is also known as sampling site.
[SOURCE: EN 15259:2007]
3.16
measurement plane
plane normal to the centreline of the duct at the sampling position
Note 1 to entry: Measurement plane is also known as sampling plane.
[SOURCE: EN 15259:2007]
3.17
measurement port
opening in the waste gas duct along the measurement line, through which access to the waste gas is
gained
Note 1 to entry: Measurement port is also known as sampling port or access port.
[SOURCE: EN 15259:2007]
3.18
measurement line
line in the measurement plane along which the measurement points are located, bounded by the inner
duct wall
Note 1 to entry: Measurement line is also known as sampling line.
[SOURCE: EN 15259:2007]
3.19
measurement point
position in the measurement plane at which the sample stream is extracted or the measurement data
are obtained directly
Note 1 to entry: Measurement point is also known as sampling point.
[SOURCE: EN 15259:2007]
3.20
performance characteristic
one of the quantities (described by values, tolerances, range) assigned to equipment in order to define
its performance
3.21
response time
duration between the instant when an input quantity value of a measuring instrument or measuring
system is subjected to an abrupt change between two specified constant quantity values and the instant
when a corresponding indication settles within specified limits around its final steady value
Note 1 to entry: By convention time taken for the output signal to pass from 0 % to 90 % of the final variation of
indication.
3.22
short-term zero drift
difference between two zero readings at the beginning and at the end of the measurement period
3.23
short-term span drift
difference between two span readings at the beginning and at the end of the measurement period
3.24
lack of fit
systematic deviation within the range of application between the measurement result obtained by
applying the calibration function to the observed response of the measuring system measuring test
gases and the corresponding accepted value of such test gases
Note 1 to entry: Lack of fit can be a function of the measurement result.
Note 2 to entry: The expression “lack of fit” is often replaced in everyday language by “linearity” or “deviation
from linearity”.
3.25
repeatability in the laboratory
closeness of the agreement between the results of successive measurements of the same measurand
carried out under the same conditions of measurement
Note 1 to entry: Repeatability conditions include:
— same measurement method;
— same laboratory;
— same measuring system, used under the same conditions;
— same location;
— repetition over a short period of time.
Note 2 to entry: Repeatability can be expressed quantitatively in terms of the dispersion characteristics of the
results.
Note 3 to entry: In this Technical Specification the repeatability is expressed as a value with a level of
confidence of 95 %.
3.26
repeatability in the field
closeness of the agreement between the results of simultaneous measurements of the same measurand
carried out with two sets of equipment under the same conditions of measurement
Note 1 to entry: These conditions include:
— same measurement method;
— two sets of equipment, the performances of which are fulfilling the requirements of the measurement
method, used under the same conditions;
— same location;
— implemented by the same laboratory;
— typically calculated on short periods of time in order to avoid the effect of changes of influence parameters
(e.g. 30 min).
Note 2 to entry: Repeatability can be expressed quantitatively in terms of the dispersion characteristics of the
results.
Note 3 to entry: In this Technical Specification, the repeatability under field conditions is expressed as a value
with a level of confidence of 95 %.
3.27
reproducibility in the field
closeness of the agreement between the results of simultaneous measurements of the same measurand
carried out with several sets of equipment under the same conditions of measurement
Note 1 to entry: These conditions are called field reproducibility conditions and include:
— same measurement method;
— several sets of equipment, the performances of which are fulfilling the requirements of the measurement
method, used under the same conditions;
— same location;
— implemented by several laboratories.
Note 2 to entry: Reproducibility can be expressed quantitatively in terms of the dispersion characteristics of the
results.
Note 3 to entry: In this Technical Specification, the reproducibility under field conditions is expressed as a value
with a level of confidence of 95 %.
3.28
residence time in the measuring system
time period for the sampled gas to be transported from the inlet of the probe to the inlet of the
measurement cell
3.29
uncertainty
parameter associated with the result of a measurement that characterizes the dispersion of the values
that could reasonably be attributed to the measurand
3.30
standard uncertainty
u
uncertainty of the result of a measurement expressed as a standard deviation
3.31
combined uncertainty
u
c
standard uncertainty attached to the measurement result calculated by combination of several standard
uncertainties according to the principles laid down in ISO/IEC Guide 98-3 (GUM)
3.32
expanded uncertainty
U
quantity defining an interval about the result of a measurement that may be expected to encompass a
large fraction of the distribution of values that could reasonably be attributed to the measurand
U ku× c
Note 1 to entry: In this European Technical Specification, the expanded uncertainty is calculated with a level of
confidence of 95 %.
Note 2 to entry: The expression overall uncertainty is sometimes used to express the expanded uncertainty.
3.33
uncertainty budget
calculation table combining all the sources of uncertainty according to EN ISO 14956 or
ISO/IEC Guide 98-3 in order to calculate the combined uncertainty of the method at a specified value
4 Symbols and abbreviations
4.1 Symbols
For the purposes of this document, the following symbols apply.
A(t ) (result given by the analyser after adjustment at t at span point – result given by the
0 0
analyser after adjustment at t at zero point) / (calibration gas concentration at span point
– calibration gas concentration at zero point)
B(t ) result given by the analyser after adjustment at t at zero point
0 0
C measured concentration
C measured concentration corrected for drift
corr
Drift(A) {[(result given by the analyser during the drift check at t at span point – result given by
end
the analyser during the drift check at t at zero point) / (calibration gas concentration at
end
span point – calibration gas concentration at zero point)] – A(t )} / (t – t )
0 end 0
Drift(B) (result given by the analyser during the drift check at t at zero point – result given by the
end
analyser after adjustment at t at zero point) / (t – t )
0 end 0
f volume fraction
=
k coverage factor
M molar mass
mol
t time
t time of adjustment
t time of check for drift at the end of the measurement period
end
u standard uncertainty
u combined uncertainty
c
U expanded uncertainty
V molar volume
mol
4.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
AM alternative method
AMS automated measuring system
P-AMS portable automated measuring system
PTFE polytetrafluoroethene
SRM standard reference method
5 Principle
5.1 General
This Technical Specification describes a method for sampling and determining SO emissions using an
instrumental technique. This Technical Specification does not prescribe a specific technique; however,
it does prescribe performance criteria in Clause 7 for the analyser and the associated sampling system
(the complete measuring system). The performance characteristics of the method shall meet these
performance criteria. This Technical Specification also specifies requirements and recommendations
for ongoing quality assurance and quality control in Clause 10.
5.2 Measuring principle
The measuring systems used for SO measurements shall be extractive and typically comprise of the
following parts:
— a sampling probe;
— a filter;
— a sample gas line;
— a conditioning system;
— an analytical instrument.
There are a number of instrumental techniques available for the analyser, which can measure SO in
emissions. Examples include infrared (IR) absorption, ultraviolet (UV) absorption, UV fluorescence and
electrochemical cells. The complete sampling system and analytical system is known as a portable
automated measuring system (P-AMS).
The concentration of SO is measured as a volume concentration if the analyser is calibrated using a
volume concentration standard. The final results for reporting are expressed in milligrams per cubic
metre (mg/m ) and reported at standard conditions (see Clause 11).
6 Description of the measuring system
6.1 General
A sample is extracted from the emission source for the required period of time at a controlled flow rate.
A filter removes the dust in the sampled volume before the sample is conditioned (unless
configuration 4 is being used) and passed to the analyser.
Different sampling and conditioning configurations are available in order to avoid the water vapour
condensation in the measuring system.
Possible configurations are:
— Configuration 1: removal of water vapour by condensation using a cooling system;
— Configuration 2: removal of water vapour through elimination using a permeation drier;
— Configuration 3: dilution with dry, clean ambient air or nitrogen of the gas to be characterized;
— Configuration 4: maintaining a temperature of all parts of the sampling system up to the analyser.
It is important that all parts of the sampling equipment upstream of the analyser are made of materials
that do not react with or absorb SO .
All components coming into contact with the gas shall be maintained at a temperature of at least 160 °C.
For configuration 1 this only applies to components upstream of the conditioning unit. For
configuration 3 this only applies to components upstream of the point of dilution. Heating is not
required post the dilution point as it is a requirement to decrease the sample acid dew point to below
ambient temperature (see 6.2.4.2).
NOTE For configuration 2 it can be necessary to introduce pre-cooling apparatus before the permeation drier
to avoid temperatures of over 120 °C at the permeation tubes as this is likely to cause damage.
If there are droplets present in the stack gas it should be discussed with the local competent authority if
this method is appropriate.
The conditions and layout of the sampling equipment contribute to the combined uncertainty of the
measurement. In order to minimize this contribution this Technical Specification specifies performance
criteria for the sampling system given in Table 1.
Alternative conditioning systems exist and may be acceptable, provided they fulfil the requirements of
this Technical Specification. For example, some systems put gas in depression using a simple Sonic
nozzle in the collection probe in order to create a partial vacuum (between 50 hPa and
100 hPa absolute) so that the head of collection and the sample gas line does not need to be heated and
water vapour condensation is avoided.
Additional analysers for other species shall not be used in series with the described measuring system
unless it is known that there are no compatibility issues. For example, chemiluminescence analysers
under certain conditions can convert H S to SO , hence the SO analyser shall not be used downstream
2 2 2
of a chemiluminescence analyser.
6.2 Sampling and sample gas conditioning system
6.2.1 Sampling probe
In order to reach the measurement points in the measurement plane, probes of different lengths and
inner diameters may be used. The design and configuration of the probe used shall ensure the residence
time of the sample gas within the probe is minimized in order to reduce the response time of the
measuring system.
NOTE 1 The probe can be marked before sampling in order to demonstrate that the measurement points in the
measurement plane have been reached.
NOTE 2 A sealable connection can be installed on the probe in order to introduce test gases for adjustment.
6.2.2 Filter
The filter and filter holder shall be made of inert material (e.g. ceramic or sinter metal with an
appropriate pore size) and be maintained at a temperature of at least 160 °C. The particle filter shall be
changed or cleaned periodically depending on the dust loading at the measurement site.
NOTE Overloading of the particle filter can increase the pressure drop in the sample gas line.
6.2.3 Sample gas line
The sample gas line shall be heated to a temperature of at least 160 °C between the probe and the
conditioning system. It shall be made of a suitable corrosion resistant material (e.g. stainless steel,
borosilicate glass, ceramic or titanium; PTFE is only suitable for flue gas temperatures lower
than 200 °C).
NOTE 1 The sample gas line does not require heating if a dilution system is used (configuration 3).
NOTE 2 The dew point of sulphuric acid is 120 °C to 150 °C. Some studies have shown that the dew points for
some sulphate salts are typically 50 °C to 60 °C.
6.2.4 Sample gas conditioning system
6.2.4.1 Sample cooler (configuration 1) and permeation drier (configuration 2)
The sample gas cooler or the permeation drier are used before the gas enters the analyser in order to
separate water vapour from the flue gas. A dew point temperature of 4 °C shall not be exceeded at the
outlet of the conditioning system.
Due to ammonium-salt deposition on the tubes, permeation systems cannot be used when NH is
present. Annex F provides some information on the chemistry of SO in the presence of NH .
2 3
Bacterial growth can take place under the moist conditions that occur within sample driers. An
appropriate procedure for the inspection and routine cleaning, if required, of the drier shall be in place
in order to prevent bacterial growth. Any manufacturer recommendations in this regard shall be
followed.
NOTE The concentrations provided by this sampling configuration are considered to be given on dry basis.
However, the results can be corrected for the remaining water vapour (see EN 14790:2017, Annex B).
6.2.4.2 Dilution system (configuration 3)
The dilution technique is an alternative to hot-gas monitoring or sample gas drying. The flue gas is
diluted with dry, clean, ambient air or nitrogen free from SO . Dilution shall be either in-stack or out-
stack. The dilution ratio shall be chosen according to the objectives of the measurement and shall be
compatible with the range of the analyser. It shall remain constant throughout the period of the test.
Dilution ratios are dependent upon changes in the flue gas density. Changes in the flue gas temperature,
molecular weight and total stack pressure can affect the ratio and resultant concentration
measurements.
NOTE 1 If significant changes in the stack temperature are expected an out-stack dilution system or a heated
in-stack dilution probe can be used to control the effects of the variation in temperature.
NOTE 2 The pressure effect has been found to be linear, corresponding to approximately a 1 % increase in
reading for a 3,5” H O increase in absolute pressure [EPA, 1994], so a correction can be applied to control the
effects of the variation in pressure.
The dilution shall reduce the dew point temperature to below the ambient level. The dew point
temperature at the outlet of the analyser shall be determined in order to correct the results and give
them on a dry basis (see Annex B in EN 14790:2017) if the dew-point temperature is greater than 4 °C.
The uncertainty associated with this correction shall be included in the uncertainty budget (see
Annex B).
6.2.4.3 Heated sample gas line and heated analyser (configuration 4)
The temperature of the components coming into contact with the gas upstream of the heated analyser
shall be maintained at a temperature of at least 160 °C.
The concentrations are given on wet basis and shall be corrected so that they are expressed on dry
basis. The correction shall be made from the water vapour concentration in the flue gas and the
uncertainty associated with this correction shall be included in the uncertainty budget (see Annex B).
6.2.5 Sample gas pump
When a pump is not an integral part of the analyser, an external pump is necessary to draw the flue gas
through the apparatus. It shall be capable of operating to the flow and pressure requirements specified
by the analyser manufacturer. The pump shall be resistant to corrosion, and compatible with the
requirements of the analyser to which it is connected. The whole sampling system associated with the
analyser, including the pump, shall meet the criterion in Table 1 related to the influence of gas pressure.
NOTE 1 The quantity of sample gas required can vary between 15 l/h and 500 I/h, depending upon the
analyser and the expected response time.
NOTE 2 A sample pump is not be required if a dilution system is used.
6.2.6 Secondary filter
The secondary filter is used to separate fine dust, with a pore size of 1 µm to 2 μm. For example it can be
made of glass-fibre, sintered ceramic, stainless steel or PTFE-fibre.
6.2.7 Flow controller and flow meter
This apparatus sets the required flow. A corrosion resistant material shall be used. The sample flow rate
into the analyser shall be maintained within the analyser manufacturer’s requirements.
NOTE No additional flow controller or flow meter is necessary when they are part of the analyser itself.
6.3 Analyser equipment
6.3.1 General
The analytical techniques used to measure SO can include, but are not restricted to, the following:
— electrochemical cells;
— non-dispersive infrared (NDIR);
— Fourier transform infrared (FTIR) spectroscopy;
— ultraviolet absorption (UVA);
— ultraviolet fluorescence (UF).
This Technical Specification does not prescribe the technique. Instead, this Technical Specification
specifies performance criteria (see Table 1), regardless of the technique used to measure SO .
Additional requirements described in method specific standards shall be observed.
6.3.2 Pressure and temperature effects
The output signal of the analyser is proportional to the density of SO (number of SO molecules)
2 2
present in the measurement cell and depends on the absolute pressure and temperature in the
measurement cell.
NOTE The effects of variations of pressure and temperature in the measurement cell can have been taken
into account by the manufacturer.
6.3.3 Sampling pump for the analyser
The sampling pump can be separate or part of the analyser. In any case, it shall be capable of operating
within the specified flow requirements of the manufacturer of the analyser and pressure conditions
required for the measurement cell.
NOTE A sampling pump is not be required if a dilution system is used.
7 Performance characteristics of the method
Table 1 gives an overview of the performance characteristics of the whole measurement method
including the analyser and the sampling and sample gas conditioning system. When this Technical
Specification is used as an alternative method (AM) to a standard reference method (SRM), these
performance characteristics shall be determined in a general performance test according to the test
procedures described in EN 15267-4:2016 (that includes demonstration of equivalence to the SRM in
accordance with EN 14793:2016), by an independent test laboratory accredited or recognized by the
competent authorities for the implementation of tests procedures of EN 15267-4:2016.
The independent test laboratory shall check the conformity of the P-AMS with the performance
criterion attached to each performance characteristics. The maximum allowable deviations as absolute
values of the measured values are given as mass concentrations or as percentages of the upper limit of
the range.
The applicable range is defined as 1,5 times the ELV for waste incineration processes and 2,5 times the
ELV for all other processes.
NOTE At the time of publication the Industrial Emissions Directives defines the applicable range of 1,5 times
the ELV for waste incineration processes and 2,5 times the ELV for all other processes.
Table 1 — Performance characteristics of the method and associated performance criteria for
the laboratory test (L) and the field test (F)
Performance characteristic L F Performance Performance
criterion characteristic to
be included in the
uncertainty
budget
Response time X X ≤ 200 s
a
Detection limit X ≤ 2,0 %
a b
Repeatability standard deviation at zero point X ≤ 2,0 % X
a b
Repeatability standard deviation at span point X ≤ 2,0 % X
a b
Reproducibility standard deviation X ≤ 3,3 % X
a
Lack of fit X ≤ 2,0 % X
a
Short-term zero drift X ≤ 2,0 % X
a
Short-term span drift X ≤ 2,0 % X
a
Influence of ambient temperature change X ≤ 5,0 % X
from 5 °C to 25 °C and from 40 °C to 20 °C at zero
point
a
Influence of ambient temperature change X ≤ 5,0 % X
from 5 °C to 25 °C and from 40 °C to 20 °C at
span point
a
Influence of sample gas pressure at span point, X ≤ 2,0 % X
for a change Δp of 3 kPa
a
Influence of sample gas flow on extractive P-AMS X ≤ 2,0 % X
for a given specification by the manufacturer
a
Influence of voltage, at –15 % below and at X ≤ 2,0 % X
+10 % above nominal supply voltage
a
Influence of vibration X ≤ 2,0 % X
c
Cross-sensitivity X Total ≤ 4,0 % X
d
Losses and leakage in the sample gas line and X ≤ 2,0 % of the X
sample gas conditioning system measured value
a
Percentage value of upper limit of certification range unless specified otherwise.
b
The repeatability in the laboratory or the reproducibility in the field shall be used, whichever is greater. If
the repeatability in the laboratory is used, only one of both values shall be included in the calculation: the first
possibility is to choose the repeatability standard deviation got from laboratory tests corresponding to the
closest concentration to the actual concentration in stack, or the higher (relative) standard deviation of
repeatability independently of the concentration measured in stack.
c
Interferents that shall be tested are at least those given in EN 15267–4:2016, Annex B. The sums of
contributions to uncertainty producing positive and negative effects are calculated separately. The maximum
of their absolute value shall be compared with the performance criterion.
d
If the leak test is performed under severe conditions of depression, then the leak can be considered as
negligible in normal conditions.
8 Suitability of the measuring system for the measurement task
An uncertainty budget shall be established by the user to determine for which measurement range the
measuring system fulfils the uncertainty requirement.
If this method is used as an alternative to a standard reference method, the relative expanded
uncertainty, calculated on a dry basis and before correction to oxygen reference concentration, shall not
exceed 15 % of the daily emission limit value (ELV) or at the lowest limit value fixed to the plant by the
local authority.
The measurement range that could be covered by the measuring system can be extended if the user
demonstrates that the uncertainty with the actual variation range of influence quantities and values of
interferents at a particular plant is lower than the maximum allowable expanded uncertainty.
Table 1 indicates which performance characteristics shall be included in the uncertainty budget.
The principle of calculation of the combined standard uncertainty is based on the law of propagation of
uncertainty laid down in ISO/IEC Guide 98-3 (GUM):
— determine the standard uncertainties attached to the performance characteristics to be included in
the calculation of the uncertainty budget according to ISO/IEC Guide 98-3;
— calculate the uncertainty budget by combining all the standard uncertainties according to
ISO/IEC Guide 98-3, including the uncertainty of the calibration gas;
— values of standard uncertainty that are less than 5 % of the maximum standard uncertainty may be
neglected;
— calculate the combined standard uncertainty of the measured value, reported as a dry gas value at
actual concentration of oxygen.
NOTE When the concentration of a measured component is expressed at an O2 reference concentration (e.g.
3 % or 11 %), the correction affects the uncertainty and can be significant, particularly if there is a significant
difference between the actual and reference O concentrations. Annex B provides guidance on how to account for
this additional uncertainty.
Table 2 — Default influence quantities to be applied for the determination of the uncertainty
budget
Influence quantity Default variations range on site
Ambient temperature ±15 °C
Electric voltage at span level 230 V ± 20 V
Table 2 provides default values that can be used in the absence of on-site information. An example of
the evaluation of an uncertainty budget is given in Annex A.
9 Field operation
9.1 Measurement section and measurement plane
Emission me
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