Continuous emissions monitoring systems (CEMS) consist of an automated measuring system (AMS) and an automated evaluation system (AES) to monitor pollutants like SO2, NOx, CO2, and other parameters required by regulations. Quality assurance for CEMS involves three levels (QAL1-3) to ensure suitability, proper installation, ongoing calibration and performance checks. Annual surveillance testing (AST) is also required to verify the uncertainty of measurements. Challenges include full uncertainty analyses, statistical approaches, and uncertainty due to location variations. Proper selection of in-situ vs. extractive systems also impacts the measurement uncertainty.

1. Quality assurance and Standards
in CEMS
niknam@Piramoonco.comPouriya Niknam

2. Table of Content
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3.  Continuous emissions monitoring equipment is installed for a
number of reasons.
Regulatory compliance
Monitoring of plant performance
Calculation of emissions
environmental impact assessments
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Reasons For Continuous Monitoring

4. Continuous Emission Monitoring System
consists of:
1. system for automatic measuring
systems for measuring and monitoring
 AMS – Automated Measuring System
2. system for automatic evaluation
systems for the calculation of emissions
 AES – Automated Evaluation System
AMS
AES
Data
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5. How Emissions are Monitored
• Identify which pollutants require monitoring
• Identify which other parameters may
require monitoring
Acid Rain
Program
 SO2 mass emissions
 NOX emission rate
 CO2 mass emissions
 Heat Input
NOx Budget Trading
Program (NBP)
 NOX mass emissions
 Heat Input
 Stack Flow Rate
 Stack Moisture
 Opacity
 Fuel Flow Rate

6. Standard reference methods have been developed by CEN and ISO.
• API 555 section 9
•EPA Part 75
• EPA 40 CFR part 60 for new sources
•EPA 40 CFR part 51 for existing sources
•EN 13284
•Particulates (Total dust)
• Low levels < 50 mg/m3 EN 13284-1
• High levels > 50 mg/m3 ISO 9096
•Nitrogen oxides EN 14792
•Carbon monoxide EN 15058
•Sulphur dioxide EN 14791
•Total organic carbon EN 12619
•Hydrogen chloride EN 1911
•Hydrogen fluoride ISO 15713
•Oxygen EN 14789
•Water vapour EN 14790
Standards for Emission Monitoring
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7. Recent Protocol Changes EPA Protocol Gases Fall 2012 Update
Mixture Old Range New Range Old
Period
New
Period
NH3/N2 2 years 1 year
CO2/Air 100 to 500 ppm 360 to 420 ppm
CO2/N2 10 ppm to 20 % 5 ppm to 20 %
CO/Air 1 ppm – 10 % 40 to 500 ppb 8 years TBD
500 ppb to 10 % 8 years
H2S/N2 5 to 1000 ppm 1 to 1000 ppm
CH4/N2 500 ppb to 10 % 8 years
NO/N2 0.5 to 20 ppm 0.5 to 50 ppm 3 years 3 years
20 ppm to 1 % 50 ppm to 1 % 8 years 8 years
N2O/Air TBD 300 ppb to 5 % 6 years 8 years
NOX/N2 10 ppm to 1 % 3 ppm to 1 % 6 years 3 years
C3H8/N2 100 ppm to 2 % 5 ppb to 2 %
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8. 6.5 mg/Nm3 Or 6.5 ± 0.3mg/Nm3
Which one is True?
The Second one clearly defines the range of possible concentrations.
The “true” concentration would be in the range 6.2 – 6.8 mg/Nm3 with a
defined degree of confidence 95%
( 95times out of 100 the result would be within those bounds )
A day with more than three hourly average invalid values
A year with more than ten days with invalid values
MEASUREMENT UNCERTAINTY
The results would not be reliable in
What is uncertainty?
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10. ID = 16,75 m
OD = 17,75 m
0,54 1,75 3,25 5,41 11,34 13,50 15,00 16,21
0,54
1,75
3,25
5,41
11,34
13,50
15,00
16,21
16,75 m
End user data
x
• Installation Location
• Temperature
• dust concentration /size
• Pressure and pressure drop
• flow rate
• Humidity
• …
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11. Measurement Dependency
1 2 3 4 5 6
Overall Uncertainty:
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12. Measurement Uncertainty
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13. 13/36
It defines
3 quality assurance levels (QAL)
and
an annual surveillance test (AST)
EN 14181(complies with ISO 14956)
Quality Assurance Levels (QAL)

14. quality assurance levels
QAL 1 A procedure to demonstrate that the CEM is suitable for the intended
purpose before installation, by meeting standards
QAL 2 Installation of automatic measuring device (AMS),
calibration of AMS using the standard reference measuring method (SRM),
determination of measuring uncertainty/variability of AMS and
check for observance of present measuring uncertainties
QAL 3 Continuous quality assurance by the operator
(drift and precision of the AMS, verification on control card)
AST Annual surveillance test including SRM measurement
to check the uncertainty of the AMS values.
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15. QAL 3
AST
Suitability
Test
Installation
Calibration
Continuous Testing
Producer Operator Operator
QAL 1 QAL 2 Annual Testing
Quality Assurance Diagram
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16. 1. Initial and periodic calibration of equipment (QAL2)
2. Annual verification of calibration (AST)
3. Ongoing zero and span checks (QAL3)
4. Retention of records on file
5. Checking measured values are within cal. range (weekly)
Operator’s Responsibilities
After Installation of compliant equipment (QAL1, EN14956) by producer,
The Operator’s Responsibilities are:
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17. QAL 3
Instrument
Certification
Calibration On-going QA
Zero and Span
Time
QAL 2QAL 1
Purchase
Installation
Linearity Check
Calibration Check
AST
1 Year
EN 14956
prEN 15267-3
Certification
of AMS
Quality Assurance Diagram
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18. • Once only; during selection of measurement system
• Identification of all uncertainty sources
• Quantification of each uncertainty source
– Specification of equipment
– Actual circumstances
• Calculation of the total uncertainty
• Compliance test for uncertainty and response time
Challenges of Quality Assurance
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19. Impractical to do a full uncertainty analysis for each analyser:
– Statistical approach too complicated
– Lack of available data for older sites
– Uncertainty analysis excludes measurement location
– Confusion regarding which performance parameters
should be included.
Areas of concern of Quality Assurance
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20. QAL1 example
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21. Areas of concern of Quality Assurance
Responsible For QAL1 is the Instrument device suppliers
QAL 1 approved according to EN 15267
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23. Based on Performance criteria and test procedures EN 15267-3
and EN 14181 AMS are certified by
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24. 24/36

25. • After installation and every 3…5 years
• Calibration
– Accredited laboratory
– Sampling system included
– Determination of the valid calibration range
• Test for variability
– compliance test for uncertainty
• Functionality tests
Challenges of Quality Assurance
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26. time
Equipment
installation at
client’s site
QAL2
QAL1
AST1
AST
1 year
EN 14181
Calibration using reference measurements (SRM3
)
Calculation of variability and comparison to required uncertainty
Performance test
ISO 14956
Assessment of overall uncertainty
QAL2
At least every 5 years
EN 14181
Uncertainty check
QAL 3
or in the event of changes to the plant operation or repair of the AMS2
or violation of the calibration range
1 year
~~
EN 14181
Drift and precision check using
control charts and standard deviation
Manufacturer
Testlabs
Testlabs
Testlabs
Testlabs
Operator
(1) Annual Surveillance Test
(2) Automated Measuring System
(3) Standard Reference Method
Emissions from stationary
sources – quality assurance
for automatic measuring
equipment
Surveillance intervals and responsibilities
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27. Calibration functions for CO (AMS1)
0
5
10
15
20
25
30
0 10 20 30AMS
SRM
Automated Measuring System
Standard
Reference
Method
QAL2 challenge: low measured concentrations
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28. Calibration functions: SO2
y = 0,75x + 89,10
y = 0,89x + 42,50
0
50
100
150
200
250
300
350
0 100 200 300AMS
SRM
QAL2 challenge: High measured concentrations
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29. 29/36
QAL2 example

30. •A procedure to maintain and demonstrate the required quality of the
CEM during its normal operation by checking the zero and span readings
•Drift and precision is required to be measured frequently and regularly
to check whether the instrument remains within the required
specification
•The data collected is plotted using control charts
•Charts used to determine whether the instruments require maintenance
Challenges of Quality Assurance
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31. • Yearly verification test
• Functionality test
– Inspection of sampling system for leakages and
contamination
– Inspection on alignment of in-situ measurements
– Check on response time and linearity
– Check on documentation (log books, maintenance an
functionality reports)
– Serviceability
• Verification measurements
– Check on validity of calibration line
Challenges of Quality Assurance
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32. Example of AST
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33. in-situ or extractive?
• Sample conditioning
• Maintenance
• Cost
• Moisture removal
• Measurement Uncertainty
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35. The Right Selection
Higher
Uncertainty
lower
Uncertainty
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36. Thank you for your attention
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