SIST ISO 17179:2019
Stationary source emissions - Determination of the mass concentration of ammonia in flue gas - Performance characteristics of automated measuring systems
Stationary source emissions - Determination of the mass concentration of ammonia in flue gas - Performance characteristics of automated measuring systems
ISO 17179:2016 specifies the fundamental structure and the most important performance characteristics of automated measuring systems for ammonia (NH3) to be used on stationary source emissions, for example, combustion plants where SNCR/SCR NOx control systems (deNOx systems) are applied. The procedures to determine the performance characteristics are also specified. Furthermore, it describes methods and equipment to determine NH3 in flue gases including the sampling system and sample gas conditioning system.
It describes extractive systems, based on direct and indirect measurement methods, and in situ systems, based on direct measurement methods, in connection with a range of analysers that operate using, for example, the following principles:
- ammonia conversion to, or reaction with NO, followed by chemiluminescence (CL) NOx difference measurement for ammonia (differential NOx);
- ammonia conversion to, or reaction with NO, followed by non-dispersive ultraviolet (NDUV) spectroscopy NOx difference measurement for ammonia (differential NOx);
- Fourier transform infrared (FTIR) spectroscopy;
- non-dispersive infrared (NDIR) spectroscopy with gas filter correlation (GFC);
- tuneable laser spectroscopy (TLS).
The method allows continuous monitoring with permanently installed measuring systems of NH3 emissions, and is applicable to measurements of NH3 in dry or wet flue gases, for process monitoring, long term monitoring of the performance of deNOx systems and/or emission monitoring.
Other equivalent instrumental methods can be used, provided they meet the minimum requirements proposed in ISO 17179:2016. The measuring system can be calibrated with certified gases, in accordance with ISO 17179:2016, or comparable methods.
The differential NOx technique using CL has been successfully tested on some power plants where the NOx concentration and NH3 concentration in flue gas after deNOx systems are up to 50 mg (NO)/m3 and 10 mg (NH3)/m3, respectively. AMS based on FTIR, NDIR with GFC and TLS has been used successfully in this application for measuring ranges as low as 10 mg (NH3)/m3.
Émission des sources fixes - Détermination de la concentration massique de l'ammoniac dans les gaz de combustion - Caractéristiques de performance des systèmes de mesure automatisés
Emisije nepremičnih virov - Določevanje masne koncentracije amoniaka v odpadnih plinih - Delovne karakteristike avtomatskih merilnih sistemov
Ta mednarodni standard določa temeljno strukturo in najpomembnejše delovne karakteristike avtomatskih merilnih sistemov za amoniak (NH3), ki se uporabljajo na emisijah nepremičnih virov, na primer na kurilnih napravah, kjer se uporabljajo sistemi za nadzor NOx SNCR/SCR (sistemi deNOx). Opredeljeni so tudi postopki za določanje značilnosti delovanja. Poleg tega opisuje metode in opremo za določanje NH3 v odpadnih plinih, vključno s sistemom za vzorčenje in sistemom za pripravo vzorčnega plina.
Ta mednarodni standard opisuje ekstraktivne sisteme, ki temeljijo na neposrednih in posrednih merilnih metodah, ter sisteme in situ, ki temeljijo na neposrednih merilnih metodah, v povezavi z vrsto analizatorjev, ki delujejo na primer z naslednjimi načeli:
– pretvorba amoniaka v NO ali reakcija z NO, čemur sledi merjenje kemoluminiscence (CL) NOx za amoniak (diferencialni NOx);
– pretvorba amoniaka v NO ali reakcija z NO, čemur sledi merjenje nedisperzne ultraviolične (NDUV) spektroskopije NOx za amoniak (diferencialni NOx);
– infrardeča spektroskopija s Fourierjevo transformacijo (FTIR);
– nedisperzna infrardeča (NDIR) spektroskopija s korelacijo plinskega filtra (GFC);
– nastavljiva laserska spektroskopija (TLS).
Metoda omogoča neprekinjeno spremljanje s stalno nameščenimi merilnimi sistemi za emisije NH3 in se uporablja za meritve NH3 v suhih ali mokrih odpadnih plinih, za spremljanje procesa, dolgoročno spremljanje delovanja sistemov za deNOx in/ali spremljanje emisij.
Uporabiti je mogoče tudi druge enakovredne instrumentalne metode, če izpolnjujejo minimalne zahteve, predlagane v tem mednarodnem standardu. Merilni sistem je mogoče umeriti s certificiranimi plini v skladu s tem mednarodnim standardom ali s primerljivimi metodami.
Tehnika diferencialnega NOx z uporabo CL je bila uspešno preskušena v nekaterih obratih, v katerih je koncentracija NOx in NH3 v odpadnih plinih za sistemi deNOx do 50 mg (NO)/m3 in
10 mg (NH3)/m3. AMS na osnovi FTIR, NDIR z GFC in TLS se uspešno uporablja v tej aplikaciji za tako nizka meritvena območja, kot je 10 mg (NH3)/m3.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2019
Emisije nepremičnih virov - Določevanje masne koncentracije amoniaka v
odpadnih plinih - Delovne karakteristike avtomatskih merilnih sistemov
Stationary source emissions - Determination of the mass concentration of ammonia in
flue gas - Performance characteristics of automated measuring systems
Émission des sources fixes - Détermination de la concentration massique de l'ammoniac
dans les gaz de combustion - Caractéristiques de performance des systèmes de mesure
automatisés
Ta slovenski standard je istoveten z: ISO 17179:2016
ICS:
13.040.40 Emisije nepremičnih virov Stationary source emissions
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 17179
First edition
2016-07-01
Stationary source emissions —
Determination of the mass
concentration of ammonia in flue
gas — Performance characteristics of
automated measuring systems
Émission des sources fixes — Détermination de la concentration
massique de l’ammoniac dans les gaz de combustion —
Caractéristiques de performance des systèmes de mesure automatisés
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 5
5 Principle . 6
6 Description of the automated measuring systems . 6
6.1 Sampling and sample gas conditioning systems . 6
6.2 Analyser equipment . 6
7 Performance characteristics . 6
7.1 Performance criteria . 6
7.2 Determination of the performance characteristics . 7
7.2.1 Performance test . 7
7.2.2 Ongoing quality control . 8
8 Measurement procedure . 8
8.1 General . 8
8.2 Choice of the measuring system . 8
8.3 Sampling . 9
8.3.1 Sampling location . 9
8.3.2 Sampling point(s) . 9
8.4 Data collection . 9
8.5 Calculation . 9
9 Quality assurance and quality control procedures .10
9.1 General .10
9.2 Frequency of checks .10
9.3 Calibration, validation and measurement uncertainty .11
10 Test report .11
Annex A (informative) Extractive differential NO measurement technique .13
x
Annex B (informative) Extractive direct NH measurement technique .17
Annex C (informative) In situ and direct NH measurement with TLS analyser .20
Annex D (normative) Operational gases .24
Annex E (normative) Procedures for determination of the performance characteristics
during the general performance test .26
Annex F (informative) Examples of the results for the assessment of ammonia AMS .34
Annex G (informative) Calculation of uncertainty of measurement of NH .36
Bibliography .40
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
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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
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The committee responsible for this document is ISO/TC 146, Air quality, Subcommittee SC 1, Stationary
source emissions.
iv © ISO 2016 – All rights reserved
Introduction
Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) NO control systems
x
are used for emission control of NO in flue gas from power generation plants, waste incinerators and
x
others. The NO reduction technologies require the injection of ammonia (NH ) and/or urea into flue
x 3
gas. The SCR system is designed to be operated at unreacted NH in flue gas (or remained NH in flue
3 3
3 3
gas) as small as possible (typically below 2 mg/m to 4 mg/m NH concentration) with more than
90 % NO reduction efficiency. The standardization of a measurement method of NH is thus strongly
x 3
desired for efficient operation and maintenance of the NO control systems and for minimization of
x
environmental impacts due to ammonia and NO .
x
INTERNATIONAL STANDARD ISO 17179:2016(E)
Stationary source emissions — Determination of the mass
concentration of ammonia in flue gas — Performance
characteristics of automated measuring systems
1 Scope
This International Standard specifies the fundamental structure and the most important performance
characteristics of automated measuring systems for ammonia (NH ) to be used on stationary source
emissions, for example, combustion plants where SNCR/SCR NO control systems (deNO systems) are
x x
applied. The procedures to determine the performance characteristics are also specified. Furthermore,
it describes methods and equipment to determine NH in flue gases including the sampling system and
sample gas conditioning system.
This International Standard describes extractive systems, based on direct and indirect measurement
methods, and in situ systems, based on direct measurement methods, in connection with a range of
analysers that operate using, for example, the following principles:
— ammonia conversion to, or reaction with NO, followed by chemiluminescence (CL) NO difference
x
measurement for ammonia (differential NO );
x
— ammonia conversion to, or reaction with NO, followed by non-dispersive ultraviolet (NDUV)
spectroscopy NO difference measurement for ammonia (differential NO );
x x
— Fourier transform infrared (FTIR) spectroscopy;
— non-dispersive infrared (NDIR) spectroscopy with gas filter correlation (GFC);
— tuneable laser spectroscopy (TLS).
The method allows continuous monitoring with permanently installed measuring systems of NH
emissions, and is applicable to measurements of NH in dry or wet flue gases, for process monitoring,
long term monitoring of the performance of deNO systems and/or emission monitoring.
x
Other equivalent instrumental methods can be used, provided they meet the minimum requirements
proposed in this International Standard. The measuring system can be calibrated with certified gases,
in accordance with this International Standard, or comparable methods.
The differential NO technique using CL has been successfully tested on some power plants where the
x
NO concentration and NH concentration in flue gas after deNO systems are up to 50 mg (NO)/m and
x 3 x
10 mg (NH )/m , respectively. AMS based on FTIR, NDIR with GFC and TLS has been used successfully
in this application for measuring ranges as low as 10 mg (NH )/m .
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.
ISO 9169, Air quality — Definition and determination of performance characteristics of an automatic
measuring system
ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
ISO 20988, Air quality — Guidelines for estimating measurement uncertainty
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
analyser
analytical part in an extractive or in situ AMS (3.3)
[SOURCE: ISO 12039:2001, 3.3]
3.2
automated measuring system
AMS
measuring system interacting with the flue gas under investigation, returning an output signal
proportional to the physical unit of the measurand (3.11) in unattended operation
Note 1 to entry: In the sense of this International Standard, an AMS is a system that can be attached to a duct or
stack to continuously or intermittently measure the mass concentration of NH passing through the duct.
[SOURCE: ISO 9169:2006, 2.1.2, modified.]
3.3
in situ AMS
non-extractive systems that measure the concentration directly in the duct or stack
Note 1 to entry: In situ systems measure either across the stack or duct or at a point within the duct or stack.
3.4
calibration of an automated measuring system
procedure for establishing the statistical relationship between values of the measurand (3.11) indicated
by the automated measuring system (3.2) and the corresponding values given by an independent method
of measurement implemented simultaneously at the same measuring point
3.5
efficiency of NH /NO
efficiency of a converter which oxidizes NH to NO
3.6
efficiency of NH /N
3 2
efficiency of a converter which reduces NH to N
3 2
3.7
influence quantity
quantity that is not the measurand (3.11) but that affects the result of the measurement
[SOURCE: ISO/IEC Guide 98-3:2008, B.2.10]
3.8
interference
cross-sensitivity
negative or positive effect upon the response of the measuring system, due to a component of the
sample that is not the measurand (3.11)
3.9
interferent
interfering substance
substance present in the air mass under investigation, other than the measurand (3.11), that affects the
response
[SOURCE: ISO 9169:2006, 2.1.12]
2 © ISO 2016 – All rights reserved
3.10
lack-of-fit
systematic deviation within the range of application between the measurement results obtained
by applying the calibration function to the observed response of the measuring system, measuring
reference materials (3.16) and the corresponding accepted value of such reference materials
Note 1 to entry: Lack of-fit may be a function of the measurement result.
Note 2 to entry: The expression “lack-of-fit” is often replaced in everyday language for linear relations by
“linearity” or “deviation from linearity”.
[SOURCE: ISO 9169:2006, 2.2.9, modified.]
3.11
measurand
particular quantity subject to measurement
[SOURCE: ISO/IEC Guide 98-3:2008, B.2.9, modified.]
3.12
NO /NO converter efficiency
efficiency with which the converter unit of a NO analyser reduces NO to NO
x 2
3.13
performance characteristic
one of the quantities assigned to equipment in order to define its performance
Note 1 to entry: Performance characteristics can be described by values, tolerances, or ranges.
3.14
period of unattended operation
maximum interval of time for which the performance characteristics (3.13) remain within a predefined
range without external servicing, e.g. refill, adjustment
Note 1 to entry: The period of unattended operation is often called maintenance interval.
[SOURCE: ISO 9169:2006, 2.2.11]
3.15
reference gas
gaseous mixture of stable composition used to calibrate the measuring system and which is traceable
to national or international standards
3.16
reference material
RM
substance or mixture of substances with a known concentration within specified limits, or a device of
known characteristics
Note 1 to entry: Normally used are calibration gases, gas cells, gratings, or filters.
[SOURCE: ISO 14385-1:2014, 3.20]
3.17
reference method
measurement method taken as a reference by convention, which gives the accepted reference value of
the measurand (3.11)
3.18
transport time in the measuring system
time period for transportation of the sampled gas from the inlet of the probe to the inlet of the
measurement instrument
3.19
response time
time interval between the instant when a stimulus is subjected to a specified abrupt change and the
instant when the response reaches and remains within specified limits around its final stable value,
determined as the sum of the lag time and the rise time in the rising mode, and the sum of the lag time
and the fall time in the falling mode
Note 1 to entry: Lag time, rise time and fall time are defined in ISO 9169:2006.
[SOURCE: ISO 9169:2006, 2.2.4]
3.20
span gas
gas or gas mixture used to adjust and check the span point (3.21) on the response line of the
measuring system
Note 1 to entry: This concentration is often chosen around 70 % to 80 % of full scale.
3.21
span point
value of the output quantity (measured signal) of the automated measuring system (3.2) for the purpose
of calibration, adjustment, etc. that represents a correct measured value generated by reference
material (3.16)
3.22
standard uncertainty
uncertainty (3.23) of the result of a measurement expressed as a standard deviation
[SOURCE: ISO/IEC Guide 98-3:2008, 2.3.1]
3.23
uncertainty (of measurement)
parameter, associated with the result of a measurement, that characterizes the dispersion of the values
that could reasonably be attributed to the measurand (3.11)
[SOURCE: ISO/IEC Guide 98-3:2008, 2.2.3]
3.24
validation of an automated measuring system
procedure to check the statistical relationship between values of the measurand (3.11) indicated by the
automated measuring system (3.2) and the corresponding values given by an independent method of
measurement implemented simultaneously at the same measuring point
3.25
zero gas
gas or gas mixture used to establish the zero point (3.26) on a calibration curve within a given
concentration range
[SOURCE: ISO 12039:2001, 3.4.2]
3.26
zero point
specified value of the output quantity (measured signal) of the AMS (3.2) and which, in the absence of
the measured component, represents the zero crossing of the calibration line
4 © ISO 2016 – All rights reserved
4 Symbols and abbreviated terms
e Residual (lack-of-fit) at level i
i
k Coverage factor
n Number of measurements
s Standard deviation of repeatability
r
Combined uncertainty of NH mass concentration
u()γ
NH
Expanded uncertainty of NH mass concentration
U()γ
NH
M Molar mass of NH (=17,031 g/mol)
c 3
V Molar volume (22,4 l/mol)
M
Volume fraction of NH
φ
NH
NH mass concentration in mg/m
γ
NH
NH mass concentration at standard conditions in mg/m (273,15 K; 101,325 kPa)
γ
S
NH mass concentration at reference conditions in mg/m (273,15 K; 101,325 kPa; O and
3 2
γ
R
H O corrected)
Average of the measured values x
i
x
x ith measured value
i
Average of the measured value at level i
x
i
Value estimated by the regression line at level i
ˆ
x
i
AMS Automated measuring system
CL Chemiluminescence
FTIR Fourier transform infrared
GFC Gas filter correlation
NDIR Non-dispersive infrared
NDUV Non-dispersive ultraviolet
QA Quality assurance
QC Quality control
SCR Selective catalytic reduction
SNCR Selective non-catalytic reduction
TLS Tuneable laser spectroscopy
5 Principle
This International Standard describes automated measurement systems for sampling, sample
conditioning, and determining NH content in flue gas using instrumental methods (analysers).
There are two types of automated measuring systems:
— extractive systems;
— in situ systems.
With extractive systems, the representative gas sample is taken from the stack with a sampling probe
and conveyed to the analyser through the sampling line and sample gas conditioning system.
In situ systems do not require any sample processing. For the installation of these systems, a
representative place in the stack is to be chosen.
The systems described in this International Standard measure NH concentration using instrumental
methods that shall meet the minimum performance specifications given.
6 Description of the automated measuring systems
6.1 Sampling and sample gas conditioning systems
Since ammonia (NH ) is condensable and highly reactive component, there are many opportunities for
loss of sample integrity due to condensation, deposition or other loss of ammonium compounds in the
sample transport system.
The details of the sampling and sample gas conditioning systems for each of automated measuring
systems are described in Annex A, Annex B, and Annex C.
6.2 Analyser equipment
Examples of the typical analytical methods available are described in Annex A (NO/NO CL technique
x
and NDUV technique), Annex B (FTIR and NDIR with GFC technique) and Annex C (TLS technique).
Instruments that use these techniques shall meet the performance characteristics as described in
Clause 7.
7 Performance characteristics
7.1 Performance criteria
Table 1 gives the performance characteristics and performance criteria of the analyser and
measurement system to be evaluated during general performance test, by means of ongoing QA/QC
in the laboratory and during field operation. Test procedures for the performance test are specified in
Annex E.
6 © ISO 2016 – All rights reserved
Table 1 — Main performance characteristics and criteria of AMS for measurement of ammonia
Performance characteristic Performance criterion Test procedure
a
Response time ≤400 s E.2
b
≤900 s
Standard deviation of repeatability in ≤2 % of the upper limit of the lowest E.3.2
laboratory at zero point measuring range used
Standard deviation of repeatability (NH ) in ≤2 % of the upper limit of the lowest E.3.3
laboratory at span point measuring range used
Lack-of-fit ≤ ±2 % of the upper limit of the lowest E.4
measuring range used
Zero drift within 24 h ≤ ±2 % of the upper limit of the lowest E.10
measuring range used
Span drift within 24 h ≤ ±2 % of the upper limit of the lowest E.10
measuring range used
Sensitivity to sample gas pressure, for a ≤ ±3 % of the upper limit of the lowest E.13
pressure change of 2 kPa measuring range used
Zero drift within the period of unattended ≤ ±3 % of the upper limit of the lowest E.11
operation measuring range used
Span drift within the period of unattended ≤ ±3 % of the upper limit of the lowest E.11
operation measuring range used
Sensitivity to ambient temperature, for a ≤ ±3 % of the upper limit of the lowest E.14
change of 10 K in the temperature range measuring range used
specified by the manufacturer
Sensitivity to electric voltage in the voltage ≤ ±2 % of the upper limit of the lowest E.15
c
range specified by the manufacturer measuring range used per 10 V
Cross-sensitivity ≤4 % of the upper limit of the lowest E.5
measuring range used
NO /NO converter efficiency, if applicable ≥95 % E.6
NH /NO converter efficiency, if applicable ≥90 % E.7
NH /N converter efficiency, if applicable ≥95 % E.7
3 2
Losses and leakage in the sampling line and ≤2 % of the measured value E.8 for losses and
conditioning system E.9 for leakage
Excursion of the measurement beam of ≤2 % of the measured value of the lowest E.12
cross-stack in situ AMS measuring range used
a
For emission monitoring from deNO systems.
x
b
For long term monitoring of changes in the deNO systems, especially the reduction of catalyst activity.
x
c
In the case of a nominal supply voltage of 200 V.
The measuring range is defined by two values of the measurand, or quantity to be supplied, within
which the limits of uncertainty of the measuring instrument are specified. The upper limit of the lowest
measuring range used should be set suitable to the application, such that the measurement values lie
within 20 % to 80 % of the measuring range.
7.2 Determination of the performance characteristics
7.2.1 Performance test
The performance characteristics of the AMS shall be determined during the general performance test.
The values of the performance characteristics determined shall meet the performance criteria specified
in Table 1. The procedures for the determination of these performance characteristics are described in
Annex E.
The ambient conditions applied during the general performance test shall be documented.
The measurement uncertainty of the AMS measured values shall be calculated in accordance with
ISO 14956 on the basis of the performance characteristics determined during the general performance
test and shall meet the level of uncertainty appropriate for the intended use.
7.2.2 Ongoing quality control
The user shall check specific performance characteristics during ongoing operation of the measuring
system with a periodicity specified in Table 2.
The measurement uncertainty during field application shall be determined by the user of the measuring
system in accordance with applicable international or national standards. For process monitoring (non-
regulatory application), the level of uncertainty shall be appropriate for the intended use. It can be
determined by a direct or an indirect approach for uncertainty estimation as described in ISO 20988.
The uncertainty of the measured values under field operation is not only influenced by the performance
characteristics of the analyser itself but also by uncertainty contributions due to
— the sampling line and conditioning system,
— the site specific conditions, and
— the calibration gases used.
8 Measurement procedure
8.1 General
The AMS shall be operated according to the manufacturer’s instructions.
The QA/QC procedures specified in Clause 9 shall be strictly observed.
During the measurement, the ambient conditions should be in the ranges applied during the general
performance test.
8.2 Choice of the measuring system
To choose an appropriate analyser, sampling line and conditioning unit, the following characteristics of
flue gases should be known before the field operation:
— ambient temperature range;
— temperature of the flue gas;
— water vapour content of the flue gas;
— dust load of the flue gas;
— expected concentration range of NH ;
— expected concentration of potentially interfering substances.
To avoid long response times and memory effects, the sampling line should be as short as possible. If
necessary, a bypass pump should be used. If there is a high dust loading in the sample gas, an appropriate
heated filter shall be used.
Before monitoring emissions, the user shall verify that the necessary QA/QC procedures have been
performed.
[3] [4]
NOTE Information on QA/QC procedures is provided in ISO 14385-1 and ISO 14385-2.
8 © ISO 2016 – All rights reserved
8.3 Sampling
8.3.1 Sampling location
The sampling location shall be an available space for the sampling equipment, analyser and possible
sampling platform requirements and construction, making a representative emission measurement
possible and is suitable for the measurement task. In addition, the sampling location shall be chosen
with regard to safety of the personnel, accessibility and availability of electrical power.
8.3.2 Sampling point(s)
It is necessary to ensure that the gas concentrations measured are representative of the average
conditions inside the flue gas duct. Therefore, the sampling points shall be selected to allow for a
representative sampling.
NOTE The selection of sampling points for representative sampling is described, e.g. in ISO 10396, where gas
stratification, fluctuations in gas velocity, temperature and others are mentioned.
8.4 Data collection
The values measured with the calibrated AMS at operating conditions of the flue gas shall be recorded
by an internal or external data logging system and averaged in accordance with the measurement task.
The volume content of water vapour in the flue gas (if necessary) should also be measured in parallel
and averaged over the sampling period of the NH measurement to express the NH concentrations for
3 3
dry flue gas conditions.
8.5 Calculation
Results of the measurement shall be expressed as mass concentrations at reference conditions.
If the NH concentration is provided as a volume concentration, Formula (1) shall be used to convert
−6
volume fraction of NH (10 ), φ , to NH mass concentrations, γ :
3 3
NH
NH
M
c
γφ=⋅ (1)
NH NH
V
M
where
is the NH mass concentration in mg/m ;
γ
NH
−6
is the volume fraction of NH (by volume, 10 );
φ
NH
M is the molar mass of NH (=17,031 g/mol);
c 3
V is the molar volume (=22,4 l/mol).
M
The NH concentration measured in the wet gas shall be corrected to the NH concentration at standard
3 3
conditions, using Formula (2):
t 101,325
γγ=⋅ ⋅ (2)
S NH
273,15 101,325+ p
where
is the NH mass concentration measured in the wet gas (mg/m );
γ
NH
is the NH mass concentration at standard conditions in mg/m (273,15 K; 101,325 kPa);
γ
S
t is the temperature (K);
p is the difference between the static pressure of the sample gas and the standard pressure (kPa).
If necessary, the NH concentration measured in the wet gas should be corrected to the NH
3 3
concentration at reference conditions, using Formula (3):
t 101,325 100%
γγ=⋅ ⋅ ⋅ (3)
R NH
273,15 101,325+ ph100%−
where
is the NH mass concentration measured in the wet gas (mg/m );
γ
NH
is the NH mass concentration at reference conditions in mg/m (273,15 K; 101,325 kPa; O and
3 2
γ
R
H O corrected);
t is the temperature (K);
p is the difference between the static pressure of the sample gas and the standard pressure (kPa);
h is the absolute water vapour content (by volume) (%).
9 Quality assurance and quality control procedures
9.1 General
Quality assurance and quality control (QA/QC) are important in order to ensure that the uncertainty of
the measured values for NH is kept within the limits specified for the measurement task.
9.2 Frequency of checks
AMS shall be adjusted and checked after the installation and then during continuous operation. Table 2
shows the minimum required test procedures and frequency of checks. The user shall implement the
relevant procedures for determination of performance characteristics or procedures described in this
subclause and Annex E. The results of the QA/QC procedures shall be documented.
Table 2 — Minimum checks and minimum frequency of checks for QA/QC during the operation
Check Minimum frequency Test procedure
Response time Once a year E.2
Standard deviation of repeatability at zero Once a year E.3.2
point
Standard deviation of repeatability (NH ) at Once a year E.3.3
span point
Lack-of-fit Once a year E.4
Sampling system and leakage check Once a year E.8, E.9
Beam alignment (in situ AMS only) Once a year E.12
Light intensity attenuation through Continuous basically According to
cleanliness and dust load (in situ AMS only) manufacturer’s
requirements
10 © ISO 2016 – All rights reserved
Table 2 (continued)
Check Minimum frequency Test procedure
Cleaning or changing of particulate filters at The particulate filters shall be changed According to
the sampling inlet and at the monitor inlet periodically depending on the dust load at manufacturer’s
the sampling site. During this filter change, requirements
the filter housing shall be cleaned.
NO /NO converter efficiency (if applicable) According to manufacturer’s E.6
recommendations
NH /N converter efficiency (if applicable) According to manufacturer’s E.7
3 2
recommendations
NH /NO converter efficiency (if applicable) According to manufacturers’ E.7
recommendations
Zero drift Once in the period of unattended operation E.11
or period specified by national standard
Span drift Once in the period of unattended operation E.11
or period specified by national standard
Regular maintenance of the analyser According to manufacturer’s According to
recommendations manufacturer’s
requirements
Calibration and validation of the analyser According to national or international 9.3
standards
The user shall implement a procedure to guarantee that the reference materials used meet the
uncertainty requirement specified in Annex D, e.g. by comparison with a reference gas of higher quality.
9.3 Calibration, validation and measurement uncertainty
Permanently installed AMS for continuous monitoring shall be calibrated and validated by comparison
with an independent method of measurement. The validation shall include the determination of the
uncertainty of the measured values obtained by the calibrated AMS.
The AMS shall be subject to adjustments and functional tests according to 9.2 before each calibration
and validation.
The calibration and validation of the AMS shall be performed at regular intervals and after repair of the
analyser in accordance with applicable national or international standards.
The uncertainty of measured values obtained by permanently installed AMS for continuous monitoring
shall be determined by comparison measurements with an independent method of measurement as
part of the calibration and validation of the AMS. This ensures that the measurement uncertainty is
representative of the application at the specific plant.
NOTE The determination of the uncertainty of measured values obtained by permanently installed AMS for
continuous monitoring on the basis of a comparison with an independent method of measurement is described,
e.g. in ISO 20988.
The uncertainty of the measured values shall meet the uncertainty criterion specified for the
measurement objective.
10 Test report
The test report shall be in accordance with international or national regulations. If not specified
otherwise, it shall include at least the following information:
a) a reference to this International Standard, i.e. ISO 17179;
b) a description of the measurement objective;
c) the principle of gas sampling;
d) an information about the analyser and description of the sampling and conditioning line;
e) the identification of the analyser used, and the performance characteristics of the analyser, listed
in Table 1;
f) the operating range;
g) the sample gas temperature, sample gas pressure and optical path length through an optical cell (it
is needed for only in situ measurement);
h) the details of the quality and the concentration of the span gases used;
i) a description of plant and process;
j) the identification of the sampling plane;
k) the actions taken to achieve representative samples;
l) a description of the location of the sampling point(s) in the sampling plane;
m) a description of the operating conditions of the plant process;
n) the changes in the plant operations during sampling;
o) the sampling date, time and duration;
p) the time averaging on relevant periods;
q) the measured values;
r) the measurement uncertainty;
s) the results of any checks;
t) any deviations from this International Standard.
12 © ISO 2016 – All rights reserved
Annex A
(informative)
Extractive differential NO measurement technique
x
A.1 Measuring principle based on differential NO technique
x
The analysis principle is based upon a differential NO technique; whereby NH in flue gas is converted
x 3
to NO or N before the gas is entering an NO/NO analyser and the NH signal is obtained by difference
2 x 3
from a separate, total NO measurement.
x
The following conversions are possible:
a) conversion of NH to N : measurement of difference between NO and (NO – NH );
3 2 x x 3
b) conversion of NH to NO: measurement of difference between NO and (NO + NH ).
3 x x 3
As an analyser for NO, a chemiluminescence (CL) analyser, a non-dispersive ultraviolet (NDUV) analyser
or all other suitable NO analyser can be used.
Ammonia levels are determined by comparing the NH + NO measurement with a NO measurement
3 x x
without NH conversion conducted in parallel. Ammonia concentration is determined by the difference
between the measurement values.
A.2 Description of the automated measuring system
A.2.1 General
A representative volume of flue gas is extracted from the emission source for a fixed period of time at
a controlled flow rate. Dust present in the volume sampled is removed by filtration before the sample
gas is conditioned and passes to the analytical instrument. Figure A.1 shows a typical arrangement of a
complete measuring system for NH .
Key
1 sampling probe, heated (if necessary)
2 particle filter (in-stack or out-stack)
3, 3′ zero and span gas inlet
4 NH converter (NH /N converter or NH /NO converter; in-stack or out-stack)
3 3 2 3
5, 5′ NO /NO converter
6, 6′ moisture removal system
7, 7′ pump
8 NO/NO analyser (one analyser or two separate analysers)
x
Figure A.1 — Diagram of the measuring system (example)
A.2.2 Components of the sampling and the sample gas conditioning systems
A.2.2.1 Sampling probe
The sampling probe shall be made of suitable, corrosion-resistant material (e.g. stainless steel without
Mo, borosilicate glass, ceramic; PTFE is only suitable for flue gas temperature lower than 200 °C). At
temperatures greater than 250 °C, stainless steel containing Mo can convert NH to NO. Any materials
made from copper or copper-based alloys are not to be used.
A.2.2.2 Filter
The filter is needed to remove the particulate matter, in order to protect the sampling system and
the analyser. The filter shall be made of ceramic, PTFE, borosilicate glass or sintered metal. The filter
shall be heated above the water or acid dew-point. A filter that retains particles greater than 2 μm
is recommended. The size of the filter shall be determined from the sample flow required and the
manufacturer’s data on the flow rate per unit area.
The temperature of the sampling probe and the filter is considered higher than the water or acid dew-
point, since the sampling point is usually chosen after the outlet of deNO systems.
x
A.2.2.3 NH converter
Depending on the used process, there are two options for the conversion of NH .
A.2.2.3.1 Converter of NH to NO
The catalytic converter (e.g. consisting of precious metals, such as platinum) operates at about 700 °C
and converts NH to NO according to the following reaction:
4NH + 5O → 4NO + 6H O.
3 2 2
14 © ISO 2016 – All rights reserved
A.2.2.3.2 Converter of NH to N
3 2
The converter contains a catalyst similar to that for deNO processes. It works around 250 °C to 350 °C
x
and converts NH to N according to the following reaction:
3 2
4NO + 4NH + O → 4N + 6H O.
3 2 2 2
When the converter of NH to N is used, the concentration of NO in the flue gas shall be higher than
3 2
that of NH .
A.2.2.4 Sampling line
The sampling line shall be made of PTFE, PFA or stainless steel without Mo, e.g. 304 SS. The lines
shall be operated at 15 °C above the dew-point of condensable substances (generally the water or acid
dew-point). The tube diameter should be appropriately sized to provide a flow rate that meets the
requirements of the analysers, under selected line length and the degree of pressure drop in the line, as
well as the performance of the sampling pump used.
A.2.2.5 NO converter
x
NO /NO converter: The converter shall consist of a heated furnace maintained at a constant temperature
and is made of material such as stainless steel, tungsten, spectroscopically pure carbon or quartz. It
shall be capable of converting at least 95 % of NO to NO.
A.2.2.6 Moisture removal system
The moisture removal system shall be used to separate water vapour from the flue gas. The dew-
point shall be sufficiently below the ambient temperature. A relative humidity equivalent to a cooling
temperature of 2 °C to 5 °C is suggested. Sufficient cooling is required for the volume of gas being
sampled and the amount of water vapour that it contains.
A.2.2.7 Sampling pump
A sampling pump is used to withdraw a continuous sample from the duct through the sampling system.
This may be a diaphragm pump, a metal bellows pump, an ejector pump or other pumps. The pump shall
be constructed of corrosion-resistant material. The performance of the pump shall be such that it can
supply the analyser with the gas flow required. In order to reduce the transport time in the sampling
line and the risk of physicochemical transfor
...
INTERNATIONAL ISO
STANDARD 17179
First edition
2016-07-01
Stationary source emissions —
Determination of the mass
concentration of ammonia in flue
gas — Performance characteristics of
automated measuring systems
Émission des sources fixes — Détermination de la concentration
massique de l’ammoniac dans les gaz de combustion —
Caractéristiques de performance des systèmes de mesure automatisés
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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.
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ii © ISO 2016 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 5
5 Principle . 6
6 Description of the automated measuring systems . 6
6.1 Sampling and sample gas conditioning systems . 6
6.2 Analyser equipment . 6
7 Performance characteristics . 6
7.1 Performance criteria . 6
7.2 Determination of the performance characteristics . 7
7.2.1 Performance test . 7
7.2.2 Ongoing quality control . 8
8 Measurement procedure . 8
8.1 General . 8
8.2 Choice of the measuring system . 8
8.3 Sampling . 9
8.3.1 Sampling location . 9
8.3.2 Sampling point(s) . 9
8.4 Data collection . 9
8.5 Calculation . 9
9 Quality assurance and quality control procedures .10
9.1 General .10
9.2 Frequency of checks .10
9.3 Calibration, validation and measurement uncertainty .11
10 Test report .11
Annex A (informative) Extractive differential NO measurement technique .13
x
Annex B (informative) Extractive direct NH measurement technique .17
Annex C (informative) In situ and direct NH measurement with TLS analyser .20
Annex D (normative) Operational gases .24
Annex E (normative) Procedures for determination of the performance characteristics
during the general performance test .26
Annex F (informative) Examples of the results for the assessment of ammonia AMS .34
Annex G (informative) Calculation of uncertainty of measurement of NH .36
Bibliography .40
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 on 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 the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 146, Air quality, Subcommittee SC 1, Stationary
source emissions.
iv © ISO 2016 – All rights reserved
Introduction
Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) NO control systems
x
are used for emission control of NO in flue gas from power generation plants, waste incinerators and
x
others. The NO reduction technologies require the injection of ammonia (NH ) and/or urea into flue
x 3
gas. The SCR system is designed to be operated at unreacted NH in flue gas (or remained NH in flue
3 3
3 3
gas) as small as possible (typically below 2 mg/m to 4 mg/m NH concentration) with more than
90 % NO reduction efficiency. The standardization of a measurement method of NH is thus strongly
x 3
desired for efficient operation and maintenance of the NO control systems and for minimization of
x
environmental impacts due to ammonia and NO .
x
INTERNATIONAL STANDARD ISO 17179:2016(E)
Stationary source emissions — Determination of the mass
concentration of ammonia in flue gas — Performance
characteristics of automated measuring systems
1 Scope
This International Standard specifies the fundamental structure and the most important performance
characteristics of automated measuring systems for ammonia (NH ) to be used on stationary source
emissions, for example, combustion plants where SNCR/SCR NO control systems (deNO systems) are
x x
applied. The procedures to determine the performance characteristics are also specified. Furthermore,
it describes methods and equipment to determine NH in flue gases including the sampling system and
sample gas conditioning system.
This International Standard describes extractive systems, based on direct and indirect measurement
methods, and in situ systems, based on direct measurement methods, in connection with a range of
analysers that operate using, for example, the following principles:
— ammonia conversion to, or reaction with NO, followed by chemiluminescence (CL) NO difference
x
measurement for ammonia (differential NO );
x
— ammonia conversion to, or reaction with NO, followed by non-dispersive ultraviolet (NDUV)
spectroscopy NO difference measurement for ammonia (differential NO );
x x
— Fourier transform infrared (FTIR) spectroscopy;
— non-dispersive infrared (NDIR) spectroscopy with gas filter correlation (GFC);
— tuneable laser spectroscopy (TLS).
The method allows continuous monitoring with permanently installed measuring systems of NH
emissions, and is applicable to measurements of NH in dry or wet flue gases, for process monitoring,
long term monitoring of the performance of deNO systems and/or emission monitoring.
x
Other equivalent instrumental methods can be used, provided they meet the minimum requirements
proposed in this International Standard. The measuring system can be calibrated with certified gases,
in accordance with this International Standard, or comparable methods.
The differential NO technique using CL has been successfully tested on some power plants where the
x
NO concentration and NH concentration in flue gas after deNO systems are up to 50 mg (NO)/m and
x 3 x
10 mg (NH )/m , respectively. AMS based on FTIR, NDIR with GFC and TLS has been used successfully
in this application for measuring ranges as low as 10 mg (NH )/m .
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.
ISO 9169, Air quality — Definition and determination of performance characteristics of an automatic
measuring system
ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
ISO 20988, Air quality — Guidelines for estimating measurement uncertainty
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
analyser
analytical part in an extractive or in situ AMS (3.3)
[SOURCE: ISO 12039:2001, 3.3]
3.2
automated measuring system
AMS
measuring system interacting with the flue gas under investigation, returning an output signal
proportional to the physical unit of the measurand (3.11) in unattended operation
Note 1 to entry: In the sense of this International Standard, an AMS is a system that can be attached to a duct or
stack to continuously or intermittently measure the mass concentration of NH passing through the duct.
[SOURCE: ISO 9169:2006, 2.1.2, modified.]
3.3
in situ AMS
non-extractive systems that measure the concentration directly in the duct or stack
Note 1 to entry: In situ systems measure either across the stack or duct or at a point within the duct or stack.
3.4
calibration of an automated measuring system
procedure for establishing the statistical relationship between values of the measurand (3.11) indicated
by the automated measuring system (3.2) and the corresponding values given by an independent method
of measurement implemented simultaneously at the same measuring point
3.5
efficiency of NH /NO
efficiency of a converter which oxidizes NH to NO
3.6
efficiency of NH /N
3 2
efficiency of a converter which reduces NH to N
3 2
3.7
influence quantity
quantity that is not the measurand (3.11) but that affects the result of the measurement
[SOURCE: ISO/IEC Guide 98-3:2008, B.2.10]
3.8
interference
cross-sensitivity
negative or positive effect upon the response of the measuring system, due to a component of the
sample that is not the measurand (3.11)
3.9
interferent
interfering substance
substance present in the air mass under investigation, other than the measurand (3.11), that affects the
response
[SOURCE: ISO 9169:2006, 2.1.12]
2 © ISO 2016 – All rights reserved
3.10
lack-of-fit
systematic deviation within the range of application between the measurement results obtained
by applying the calibration function to the observed response of the measuring system, measuring
reference materials (3.16) and the corresponding accepted value of such reference materials
Note 1 to entry: Lack of-fit may be a function of the measurement result.
Note 2 to entry: The expression “lack-of-fit” is often replaced in everyday language for linear relations by
“linearity” or “deviation from linearity”.
[SOURCE: ISO 9169:2006, 2.2.9, modified.]
3.11
measurand
particular quantity subject to measurement
[SOURCE: ISO/IEC Guide 98-3:2008, B.2.9, modified.]
3.12
NO /NO converter efficiency
efficiency with which the converter unit of a NO analyser reduces NO to NO
x 2
3.13
performance characteristic
one of the quantities assigned to equipment in order to define its performance
Note 1 to entry: Performance characteristics can be described by values, tolerances, or ranges.
3.14
period of unattended operation
maximum interval of time for which the performance characteristics (3.13) remain within a predefined
range without external servicing, e.g. refill, adjustment
Note 1 to entry: The period of unattended operation is often called maintenance interval.
[SOURCE: ISO 9169:2006, 2.2.11]
3.15
reference gas
gaseous mixture of stable composition used to calibrate the measuring system and which is traceable
to national or international standards
3.16
reference material
RM
substance or mixture of substances with a known concentration within specified limits, or a device of
known characteristics
Note 1 to entry: Normally used are calibration gases, gas cells, gratings, or filters.
[SOURCE: ISO 14385-1:2014, 3.20]
3.17
reference method
measurement method taken as a reference by convention, which gives the accepted reference value of
the measurand (3.11)
3.18
transport time in the measuring system
time period for transportation of the sampled gas from the inlet of the probe to the inlet of the
measurement instrument
3.19
response time
time interval between the instant when a stimulus is subjected to a specified abrupt change and the
instant when the response reaches and remains within specified limits around its final stable value,
determined as the sum of the lag time and the rise time in the rising mode, and the sum of the lag time
and the fall time in the falling mode
Note 1 to entry: Lag time, rise time and fall time are defined in ISO 9169:2006.
[SOURCE: ISO 9169:2006, 2.2.4]
3.20
span gas
gas or gas mixture used to adjust and check the span point (3.21) on the response line of the
measuring system
Note 1 to entry: This concentration is often chosen around 70 % to 80 % of full scale.
3.21
span point
value of the output quantity (measured signal) of the automated measuring system (3.2) for the purpose
of calibration, adjustment, etc. that represents a correct measured value generated by reference
material (3.16)
3.22
standard uncertainty
uncertainty (3.23) of the result of a measurement expressed as a standard deviation
[SOURCE: ISO/IEC Guide 98-3:2008, 2.3.1]
3.23
uncertainty (of measurement)
parameter, associated with the result of a measurement, that characterizes the dispersion of the values
that could reasonably be attributed to the measurand (3.11)
[SOURCE: ISO/IEC Guide 98-3:2008, 2.2.3]
3.24
validation of an automated measuring system
procedure to check the statistical relationship between values of the measurand (3.11) indicated by the
automated measuring system (3.2) and the corresponding values given by an independent method of
measurement implemented simultaneously at the same measuring point
3.25
zero gas
gas or gas mixture used to establish the zero point (3.26) on a calibration curve within a given
concentration range
[SOURCE: ISO 12039:2001, 3.4.2]
3.26
zero point
specified value of the output quantity (measured signal) of the AMS (3.2) and which, in the absence of
the measured component, represents the zero crossing of the calibration line
4 © ISO 2016 – All rights reserved
4 Symbols and abbreviated terms
e Residual (lack-of-fit) at level i
i
k Coverage factor
n Number of measurements
s Standard deviation of repeatability
r
Combined uncertainty of NH mass concentration
u()γ
NH
Expanded uncertainty of NH mass concentration
U()γ
NH
M Molar mass of NH (=17,031 g/mol)
c 3
V Molar volume (22,4 l/mol)
M
Volume fraction of NH
φ
NH
NH mass concentration in mg/m
γ
NH
NH mass concentration at standard conditions in mg/m (273,15 K; 101,325 kPa)
γ
S
NH mass concentration at reference conditions in mg/m (273,15 K; 101,325 kPa; O and
3 2
γ
R
H O corrected)
Average of the measured values x
i
x
x ith measured value
i
Average of the measured value at level i
x
i
Value estimated by the regression line at level i
ˆ
x
i
AMS Automated measuring system
CL Chemiluminescence
FTIR Fourier transform infrared
GFC Gas filter correlation
NDIR Non-dispersive infrared
NDUV Non-dispersive ultraviolet
QA Quality assurance
QC Quality control
SCR Selective catalytic reduction
SNCR Selective non-catalytic reduction
TLS Tuneable laser spectroscopy
5 Principle
This International Standard describes automated measurement systems for sampling, sample
conditioning, and determining NH content in flue gas using instrumental methods (analysers).
There are two types of automated measuring systems:
— extractive systems;
— in situ systems.
With extractive systems, the representative gas sample is taken from the stack with a sampling probe
and conveyed to the analyser through the sampling line and sample gas conditioning system.
In situ systems do not require any sample processing. For the installation of these systems, a
representative place in the stack is to be chosen.
The systems described in this International Standard measure NH concentration using instrumental
methods that shall meet the minimum performance specifications given.
6 Description of the automated measuring systems
6.1 Sampling and sample gas conditioning systems
Since ammonia (NH ) is condensable and highly reactive component, there are many opportunities for
loss of sample integrity due to condensation, deposition or other loss of ammonium compounds in the
sample transport system.
The details of the sampling and sample gas conditioning systems for each of automated measuring
systems are described in Annex A, Annex B, and Annex C.
6.2 Analyser equipment
Examples of the typical analytical methods available are described in Annex A (NO/NO CL technique
x
and NDUV technique), Annex B (FTIR and NDIR with GFC technique) and Annex C (TLS technique).
Instruments that use these techniques shall meet the performance characteristics as described in
Clause 7.
7 Performance characteristics
7.1 Performance criteria
Table 1 gives the performance characteristics and performance criteria of the analyser and
measurement system to be evaluated during general performance test, by means of ongoing QA/QC
in the laboratory and during field operation. Test procedures for the performance test are specified in
Annex E.
6 © ISO 2016 – All rights reserved
Table 1 — Main performance characteristics and criteria of AMS for measurement of ammonia
Performance characteristic Performance criterion Test procedure
a
Response time ≤400 s E.2
b
≤900 s
Standard deviation of repeatability in ≤2 % of the upper limit of the lowest E.3.2
laboratory at zero point measuring range used
Standard deviation of repeatability (NH ) in ≤2 % of the upper limit of the lowest E.3.3
laboratory at span point measuring range used
Lack-of-fit ≤ ±2 % of the upper limit of the lowest E.4
measuring range used
Zero drift within 24 h ≤ ±2 % of the upper limit of the lowest E.10
measuring range used
Span drift within 24 h ≤ ±2 % of the upper limit of the lowest E.10
measuring range used
Sensitivity to sample gas pressure, for a ≤ ±3 % of the upper limit of the lowest E.13
pressure change of 2 kPa measuring range used
Zero drift within the period of unattended ≤ ±3 % of the upper limit of the lowest E.11
operation measuring range used
Span drift within the period of unattended ≤ ±3 % of the upper limit of the lowest E.11
operation measuring range used
Sensitivity to ambient temperature, for a ≤ ±3 % of the upper limit of the lowest E.14
change of 10 K in the temperature range measuring range used
specified by the manufacturer
Sensitivity to electric voltage in the voltage ≤ ±2 % of the upper limit of the lowest E.15
c
range specified by the manufacturer measuring range used per 10 V
Cross-sensitivity ≤4 % of the upper limit of the lowest E.5
measuring range used
NO /NO converter efficiency, if applicable ≥95 % E.6
NH /NO converter efficiency, if applicable ≥90 % E.7
NH /N converter efficiency, if applicable ≥95 % E.7
3 2
Losses and leakage in the sampling line and ≤2 % of the measured value E.8 for losses and
conditioning system E.9 for leakage
Excursion of the measurement beam of ≤2 % of the measured value of the lowest E.12
cross-stack in situ AMS measuring range used
a
For emission monitoring from deNO systems.
x
b
For long term monitoring of changes in the deNO systems, especially the reduction of catalyst activity.
x
c
In the case of a nominal supply voltage of 200 V.
The measuring range is defined by two values of the measurand, or quantity to be supplied, within
which the limits of uncertainty of the measuring instrument are specified. The upper limit of the lowest
measuring range used should be set suitable to the application, such that the measurement values lie
within 20 % to 80 % of the measuring range.
7.2 Determination of the performance characteristics
7.2.1 Performance test
The performance characteristics of the AMS shall be determined during the general performance test.
The values of the performance characteristics determined shall meet the performance criteria specified
in Table 1. The procedures for the determination of these performance characteristics are described in
Annex E.
The ambient conditions applied during the general performance test shall be documented.
The measurement uncertainty of the AMS measured values shall be calculated in accordance with
ISO 14956 on the basis of the performance characteristics determined during the general performance
test and shall meet the level of uncertainty appropriate for the intended use.
7.2.2 Ongoing quality control
The user shall check specific performance characteristics during ongoing operation of the measuring
system with a periodicity specified in Table 2.
The measurement uncertainty during field application shall be determined by the user of the measuring
system in accordance with applicable international or national standards. For process monitoring (non-
regulatory application), the level of uncertainty shall be appropriate for the intended use. It can be
determined by a direct or an indirect approach for uncertainty estimation as described in ISO 20988.
The uncertainty of the measured values under field operation is not only influenced by the performance
characteristics of the analyser itself but also by uncertainty contributions due to
— the sampling line and conditioning system,
— the site specific conditions, and
— the calibration gases used.
8 Measurement procedure
8.1 General
The AMS shall be operated according to the manufacturer’s instructions.
The QA/QC procedures specified in Clause 9 shall be strictly observed.
During the measurement, the ambient conditions should be in the ranges applied during the general
performance test.
8.2 Choice of the measuring system
To choose an appropriate analyser, sampling line and conditioning unit, the following characteristics of
flue gases should be known before the field operation:
— ambient temperature range;
— temperature of the flue gas;
— water vapour content of the flue gas;
— dust load of the flue gas;
— expected concentration range of NH ;
— expected concentration of potentially interfering substances.
To avoid long response times and memory effects, the sampling line should be as short as possible. If
necessary, a bypass pump should be used. If there is a high dust loading in the sample gas, an appropriate
heated filter shall be used.
Before monitoring emissions, the user shall verify that the necessary QA/QC procedures have been
performed.
[3] [4]
NOTE Information on QA/QC procedures is provided in ISO 14385-1 and ISO 14385-2.
8 © ISO 2016 – All rights reserved
8.3 Sampling
8.3.1 Sampling location
The sampling location shall be an available space for the sampling equipment, analyser and possible
sampling platform requirements and construction, making a representative emission measurement
possible and is suitable for the measurement task. In addition, the sampling location shall be chosen
with regard to safety of the personnel, accessibility and availability of electrical power.
8.3.2 Sampling point(s)
It is necessary to ensure that the gas concentrations measured are representative of the average
conditions inside the flue gas duct. Therefore, the sampling points shall be selected to allow for a
representative sampling.
NOTE The selection of sampling points for representative sampling is described, e.g. in ISO 10396, where gas
stratification, fluctuations in gas velocity, temperature and others are mentioned.
8.4 Data collection
The values measured with the calibrated AMS at operating conditions of the flue gas shall be recorded
by an internal or external data logging system and averaged in accordance with the measurement task.
The volume content of water vapour in the flue gas (if necessary) should also be measured in parallel
and averaged over the sampling period of the NH measurement to express the NH concentrations for
3 3
dry flue gas conditions.
8.5 Calculation
Results of the measurement shall be expressed as mass concentrations at reference conditions.
If the NH concentration is provided as a volume concentration, Formula (1) shall be used to convert
−6
volume fraction of NH (10 ), φ , to NH mass concentrations, γ :
3 3
NH
NH
M
c
γφ=⋅ (1)
NH NH
V
M
where
is the NH mass concentration in mg/m ;
γ
NH
−6
is the volume fraction of NH (by volume, 10 );
φ
NH
M is the molar mass of NH (=17,031 g/mol);
c 3
V is the molar volume (=22,4 l/mol).
M
The NH concentration measured in the wet gas shall be corrected to the NH concentration at standard
3 3
conditions, using Formula (2):
t 101,325
γγ=⋅ ⋅ (2)
S NH
273,15 101,325+ p
where
is the NH mass concentration measured in the wet gas (mg/m );
γ
NH
is the NH mass concentration at standard conditions in mg/m (273,15 K; 101,325 kPa);
γ
S
t is the temperature (K);
p is the difference between the static pressure of the sample gas and the standard pressure (kPa).
If necessary, the NH concentration measured in the wet gas should be corrected to the NH
3 3
concentration at reference conditions, using Formula (3):
t 101,325 100%
γγ=⋅ ⋅ ⋅ (3)
R NH
273,15 101,325+ ph100%−
where
is the NH mass concentration measured in the wet gas (mg/m );
γ
NH
is the NH mass concentration at reference conditions in mg/m (273,15 K; 101,325 kPa; O and
3 2
γ
R
H O corrected);
t is the temperature (K);
p is the difference between the static pressure of the sample gas and the standard pressure (kPa);
h is the absolute water vapour content (by volume) (%).
9 Quality assurance and quality control procedures
9.1 General
Quality assurance and quality control (QA/QC) are important in order to ensure that the uncertainty of
the measured values for NH is kept within the limits specified for the measurement task.
9.2 Frequency of checks
AMS shall be adjusted and checked after the installation and then during continuous operation. Table 2
shows the minimum required test procedures and frequency of checks. The user shall implement the
relevant procedures for determination of performance characteristics or procedures described in this
subclause and Annex E. The results of the QA/QC procedures shall be documented.
Table 2 — Minimum checks and minimum frequency of checks for QA/QC during the operation
Check Minimum frequency Test procedure
Response time Once a year E.2
Standard deviation of repeatability at zero Once a year E.3.2
point
Standard deviation of repeatability (NH ) at Once a year E.3.3
span point
Lack-of-fit Once a year E.4
Sampling system and leakage check Once a year E.8, E.9
Beam alignment (in situ AMS only) Once a year E.12
Light intensity attenuation through Continuous basically According to
cleanliness and dust load (in situ AMS only) manufacturer’s
requirements
10 © ISO 2016 – All rights reserved
Table 2 (continued)
Check Minimum frequency Test procedure
Cleaning or changing of particulate filters at The particulate filters shall be changed According to
the sampling inlet and at the monitor inlet periodically depending on the dust load at manufacturer’s
the sampling site. During this filter change, requirements
the filter housing shall be cleaned.
NO /NO converter efficiency (if applicable) According to manufacturer’s E.6
recommendations
NH /N converter efficiency (if applicable) According to manufacturer’s E.7
3 2
recommendations
NH /NO converter efficiency (if applicable) According to manufacturers’ E.7
recommendations
Zero drift Once in the period of unattended operation E.11
or period specified by national standard
Span drift Once in the period of unattended operation E.11
or period specified by national standard
Regular maintenance of the analyser According to manufacturer’s According to
recommendations manufacturer’s
requirements
Calibration and validation of the analyser According to national or international 9.3
standards
The user shall implement a procedure to guarantee that the reference materials used meet the
uncertainty requirement specified in Annex D, e.g. by comparison with a reference gas of higher quality.
9.3 Calibration, validation and measurement uncertainty
Permanently installed AMS for continuous monitoring shall be calibrated and validated by comparison
with an independent method of measurement. The validation shall include the determination of the
uncertainty of the measured values obtained by the calibrated AMS.
The AMS shall be subject to adjustments and functional tests according to 9.2 before each calibration
and validation.
The calibration and validation of the AMS shall be performed at regular intervals and after repair of the
analyser in accordance with applicable national or international standards.
The uncertainty of measured values obtained by permanently installed AMS for continuous monitoring
shall be determined by comparison measurements with an independent method of measurement as
part of the calibration and validation of the AMS. This ensures that the measurement uncertainty is
representative of the application at the specific plant.
NOTE The determination of the uncertainty of measured values obtained by permanently installed AMS for
continuous monitoring on the basis of a comparison with an independent method of measurement is described,
e.g. in ISO 20988.
The uncertainty of the measured values shall meet the uncertainty criterion specified for the
measurement objective.
10 Test report
The test report shall be in accordance with international or national regulations. If not specified
otherwise, it shall include at least the following information:
a) a reference to this International Standard, i.e. ISO 17179;
b) a description of the measurement objective;
c) the principle of gas sampling;
d) an information about the analyser and description of the sampling and conditioning line;
e) the identification of the analyser used, and the performance characteristics of the analyser, listed
in Table 1;
f) the operating range;
g) the sample gas temperature, sample gas pressure and optical path length through an optical cell (it
is needed for only in situ measurement);
h) the details of the quality and the concentration of the span gases used;
i) a description of plant and process;
j) the identification of the sampling plane;
k) the actions taken to achieve representative samples;
l) a description of the location of the sampling point(s) in the sampling plane;
m) a description of the operating conditions of the plant process;
n) the changes in the plant operations during sampling;
o) the sampling date, time and duration;
p) the time averaging on relevant periods;
q) the measured values;
r) the measurement uncertainty;
s) the results of any checks;
t) any deviations from this International Standard.
12 © ISO 2016 – All rights reserved
Annex A
(informative)
Extractive differential NO measurement technique
x
A.1 Measuring principle based on differential NO technique
x
The analysis principle is based upon a differential NO technique; whereby NH in flue gas is converted
x 3
to NO or N before the gas is entering an NO/NO analyser and the NH signal is obtained by difference
2 x 3
from a separate, total NO measurement.
x
The following conversions are possible:
a) conversion of NH to N : measurement of difference between NO and (NO – NH );
3 2 x x 3
b) conversion of NH to NO: measurement of difference between NO and (NO + NH ).
3 x x 3
As an analyser for NO, a chemiluminescence (CL) analyser, a non-dispersive ultraviolet (NDUV) analyser
or all other suitable NO analyser can be used.
Ammonia levels are determined by comparing the NH + NO measurement with a NO measurement
3 x x
without NH conversion conducted in parallel. Ammonia concentration is determined by the difference
between the measurement values.
A.2 Description of the automated measuring system
A.2.1 General
A representative volume of flue gas is extracted from the emission source for a fixed period of time at
a controlled flow rate. Dust present in the volume sampled is removed by filtration before the sample
gas is conditioned and passes to the analytical instrument. Figure A.1 shows a typical arrangement of a
complete measuring system for NH .
Key
1 sampling probe, heated (if necessary)
2 particle filter (in-stack or out-stack)
3, 3′ zero and span gas inlet
4 NH converter (NH /N converter or NH /NO converter; in-stack or out-stack)
3 3 2 3
5, 5′ NO /NO converter
6, 6′ moisture removal system
7, 7′ pump
8 NO/NO analyser (one analyser or two separate analysers)
x
Figure A.1 — Diagram of the measuring system (example)
A.2.2 Components of the sampling and the sample gas conditioning systems
A.2.2.1 Sampling probe
The sampling probe shall be made of suitable, corrosion-resistant material (e.g. stainless steel without
Mo, borosilicate glass, ceramic; PTFE is only suitable for flue gas temperature lower than 200 °C). At
temperatures greater than 250 °C, stainless steel containing Mo can convert NH to NO. Any materials
made from copper or copper-based alloys are not to be used.
A.2.2.2 Filter
The filter is needed to remove the particulate matter, in order to protect the sampling system and
the analyser. The filter shall be made of ceramic, PTFE, borosilicate glass or sintered metal. The filter
shall be heated above the water or acid dew-point. A filter that retains particles greater than 2 μm
is recommended. The size of the filter shall be determined from the sample flow required and the
manufacturer’s data on the flow rate per unit area.
The temperature of the sampling probe and the filter is considered higher than the water or acid dew-
point, since the sampling point is usually chosen after the outlet of deNO systems.
x
A.2.2.3 NH converter
Depending on the used process, there are two options for the conversion of NH .
A.2.2.3.1 Converter of NH to NO
The catalytic converter (e.g. consisting of precious metals, such as platinum) operates at about 700 °C
and converts NH to NO according to the following reaction:
4NH + 5O → 4NO + 6H O.
3 2 2
14 © ISO 2016 – All rights reserved
A.2.2.3.2 Converter of NH to N
3 2
The converter contains a catalyst similar to that for deNO processes. It works around 250 °C to 350 °C
x
and converts NH to N according to the following reaction:
3 2
4NO + 4NH + O → 4N + 6H O.
3 2 2 2
When the converter of NH to N is used, the concentration of NO in the flue gas shall be higher than
3 2
that of NH .
A.2.2.4 Sampling line
The sampling line shall be made of PTFE, PFA or stainless steel without Mo, e.g. 304 SS. The lines
shall be operated at 15 °C above the dew-point of condensable substances (generally the water or acid
dew-point). The tube diameter should be appropriately sized to provide a flow rate that meets the
requirements of the analysers, under selected line length and the degree of pressure drop in the line, as
well as the performance of the sampling pump used.
A.2.2.5 NO converter
x
NO /NO converter: The converter shall consist of a heated furnace maintained at a constant temperature
and is made of material such as stainless steel, tungsten, spectroscopically pure carbon or quartz. It
shall be capable of converting at least 95 % of NO to NO.
A.2.2.6 Moisture removal system
The moisture removal system shall be used to separate water vapour from the flue gas. The dew-
point shall be sufficiently below the ambient temperature. A relative humidity equivalent to a cooling
temperature of 2 °C to 5 °C is suggested. Sufficient cooling is required for the volume of gas being
sampled and the amount of water vapour that it contains.
A.2.2.7 Sampling pump
A sampling pump is used to withdraw a continuous sample from the duct through the sampling system.
This may be a diaphragm pump, a metal bellows pump, an ejector pump or other pumps. The pump shall
be constructed of corrosion-resistant material. The performance of the pump shall be such that it can
supply the analyser with the gas flow required. In order to reduce the transport time in the sampling
line and the risk of physicochemical transformation of the sample, the gas flow can be greater than that
required for the analytical units.
A.2.2.8 Flow controller and flow meter
The flow controller and flow meter are used to set the required flow. They shall be constructed of
corrosion-resistant material. As an alternative, a negative pressure flow control without contact to
measuring gas shall be used.
A.2.3 NO analyser
x
A.2.3.1 General
One analyser or two different analysers may be used for the measurement of NO, CL, NDUV or any other
suitable NO analyser may be used.
NOTE The measurement uncertainty using two different analysers is likely to be larger than that using one
analyser.
A.2.3.2 Chemiluminescent analyser
The CL analyser typically consists of the following principal components:
— ozone generator;
— reaction chamber;
— optical filter;
— photodetector or photodiode detector;
— ozone removal device.
A.2.3.3 NDUV analyser
The NDUV analyser typically consists of the following principal components:
— light source;
— optical and/or gas filters;
— measurement cell;
— photodetector;
— calibration cell to be used for QC drift check.
16 © ISO 2016 – All rights reserved
Annex B
(informative)
Extractive direct NH measurement technique
B.1 Measuring principle based on
...
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