Changes to the CEM Quality Assurance Standard EN14181 David Graham.pdf · Changes to the CEM...
Transcript of Changes to the CEM Quality Assurance Standard EN14181 David Graham.pdf · Changes to the CEM...
Changes to the CEM Quality Assurance Standard EN14181
VGB European Working Group - Emissions Monitoring
Frans Blank, DNV-GL, The Netherlands (Chair)
Celia Juilleron, EDF, France
Simon Barry, ESB, Ireland
Alessio Baldini, ENEL, Italy
Nathalie Faniel, Laborelec, Belgium (Co-author)
David Graham, E.ON Technologies, UK (Lead author)
Volker Hamacher, VGB Secretariat
Anna Häyrinen, Helsinki Energy, Finland
Henril Harnevie, Vattenfall, Sweden
Johannes Mayer, E.ON Engineering, Germany
Andrea Krizova, CEZ, Czech Republic
CEM 2014, Istanbul, May 2014
Regulatory framework for power plant
Industrial Emissions Directive (IED): Emission Limit Values (ELV)
Compliance:
Monthly ELV
Daily (110% ELV)
Hourly annual 95
percentile (200% ELV)
IED Annex V ( > 300 MW thermal input)
Existing Plant (Part 1) New Plant (Part 2)
Solid fuel Liquid fuel Natural gas Solid fuel Liquid fuel Natural gas
SO2 200 200 35 150 150 35
NOx 200 150 100 150 100 100
Dust 20 20 5 10 10 5
CO - - 100 - - 100
Ref. O2 dry 6% 3% 3% 6% 3% 3%
IED Limits Gas Turbines ( > 50 MW thermal input)
Natural gas Liquid fuel Natural gas Liquid fuel
NOx 50 90 50 50
CO 100 100 100 100
Ref. O2 dry 15% 15% 15% 15%
Existing Plant (Part 1) New Plant (Part 2)
Regulatory framework for (co-)incinerators: IED ELV
Cwaste Incineration Annually Cproc Co-incineration Biomass
Daily average Half-hourly OR Daily average
11% O2 dry A (100%) B (97%) mg/m3 6% O2 dry
Species Continuous mg/m3
mg/m3
50 - 100 MW 100 - 300 MW > 300 MW
SO2 50 200 50 200 200 200
NOx 200 400 200 350 300 300
Dust 10 30 10 50 30 30
CO 50 100 150
TOC 10 20 10
HCl 10 60 10
HF 1 4 2
Trace species Periodic mg/m3
30m - 8h All plant
Cd+Th 0.05 0.05
Hg 0.05 0.05
Sb+As+Pb+Cr+Co+ 0.50 0.50
Cu+Mn+Ni+V
Periodic ng/m3
6h - 8h ng/m3
Dioxins and furans 0.10 0.10
Notes: Notes:
1. CO daily limit is applied as annual percentile (97%). 1. Dust limit also applies to < 50MW as 50 mg/m3
2. CO percentile B is defined as 95% of 10 min averages (daily basis). 2. Half-hourly limits may not apply
3. CO limits may be relaxed to 100 mg/m3 hourly average for FBC. 3. Convert to common O2 reference
4. NOx daily limit 400 mg/m3 existing plant < 6 t/h (permit by 28/12/02)
5. NOx percentiles apply only to plant above 6 t/h.
6. Incinerator ELVs apply if >40% by heat is from hazardous waste.
Permit or actual levels if ELV not defined
Implications for Quality Assurance of AMS
Daily ELV is now defined for all plant types (existing and new)
Daily ELV is used for defining QA requirements
Daily ELV is lower than before - even lower when the Best
Available Techniques (BAT) Conclusions are published
(2015?) AMS remains fit for purpose?
BAT Conclusions may require additional continuous
monitoring for large coal combustion plant, e.g., Hg
EC (2003), Integrated Pollution Prevention and Control (IPPC)
Reference Document on the General Principles of Monitoring
Technical Report with non-mandatory guidance on
monitoring (2014?)
Background to EN14181
EN 14181: 2004 ‘Stationary Source Emissions - Quality
Assurance of Automated Measuring Systems’ (AMS = CEM)
Operator’s responsibilities:
Installation of compliant
equipment (QAL1)
In-situ calibration of CEMs
using an accredited test
laboratory (QAL2)
Annual check of the calibration
(AST)
Ongoing QA based on regular
zero and span checks (QAL3)
Submission of QAL2, QAL3
and AST reports and ongoing
maintenance of records
Checking of hourly averages
against the Valid Calibration
Range (weekly)
Changes to EN 14181:2004
Early experience indicated various issues (e.g., VGB in 2009)
Technical Report provided clarifications (TR 15983:2010)
Consolidation of guidance with standard prEN 14181 (2014)
Uncertainty requirements are replaced throughout by the
Maximum Permissible Uncertainty (MPU)
For plant under the IED, MPU = the specified Confidence
Interval (at 95%) at the Daily ELV
Example: 20% of 55 mg/m3 MPU = 11 mg/m3
Measuring Range of AMS can be selected to match the
anticipated maximum short term (hourly or half-hourly) ELV
Significant changes summarised in Annex K of prEN 14181
Confidence Interval requirements (MPU)
Species Confidence interval (95%)
SO2 20%
NOx 20%
Dust 30%
CO 10%
TOC 30%
HCl 40%
HF 40%
Notes:
TOC = Total Organic
Carbon
Ammonia generally
assumed to be 40%
MPU defined at the Daily
ELV concentration
As the Daily ELV reduces – the required Certification
Range reduces – AMS may no longer comply
Background to EN14181
EN 14181: 2004 ‘Stationary Source Emissions - Quality
Assurance of Automated Measuring Systems’ (AMS = CEM)
EN15267-3 AMS Certification (QAL1)
EN 15267-3 is now a normative reference within prEN 14181
For large combustion plant: certification range < 2.5*Daily ELV
For (co-)incinerators: certification range < 1.5*Daily ELV
Total uncertainty at certification < 75% of the IED requirement
Example: Daily ELV for NOx on a gas turbine: 55 mg/m3
IED Confidence Interval: 20%
Certification range:< 2.5*ELV ;< 137.5 mg/m3 NO2 (< 67 ppm)
Certification uncertainty: < 75% of 20% of Daily ELV
: < 8.25 mg/m3 NO2 (< 4 ppm)
Quality Assurance Level 1 (QAL1) (Annex I)
Existing certified instruments that can no longer meet the
uncertainty requirements, due to lower ELV, may be approved
by the Competent Authority, e.g., on the basis that the
remaining QA requirements are satisfied (QAL2, QAL3, AST)
Existing uncertified AMS installations may be approved by the
Competent Authority
Existing instruments that do not formally meet the certification
requirements, the Operator should consider measures to
reduce the measurement uncertainty, e.g., air conditioning the
AMS shelter
Normative reference to EN 15259 has been added.
Representative sampling points must be defined with no
interference or disturbance between AMS & SRM
Functional testing
Quality Assurance Level 2 (QAL2): Background
QAL2 & AST
Activity
Extractive
AMS
In-situ
AMS
Alignment & cleanliness x
Sampling system x
Documentation and records x x
Serviceability x x
Leak test x
Zero & span check x x
Linearity x x
Interferences x x
Zero & span drift (QAL3 audit) x x
Response time x x
Report x x
Quality Assurance Level 2 (QAL2)
Functional tests (performed before stack testing)
• Identical now for both QAL2 & AST and recommended for
peripherals (O2, H2O)
• Recommendation that they are performed not more than one
month prior to the QAL2 or AST
• Requirement for functional testing to be conducted by an
experienced test lab recognised by the Competent Authority
• Linearity test range is at ‘least the short term ELV’ rather than
being ‘two times the emission limit’
• Response time must meet the EN 15267-3 performance
criterion, rather than the original certification result
Quality Assurance Level 2 (QAL2)
Functional tests (performed before stack testing)
• In-situ analysers may need to be removed from the stack to
conduct a zero and span check
• Documentation must now include details of the AMS
certification
Quality Assurance Level 2 (QAL2): Background
AMS
Valid
Calibration
Range 10%
Data
Range
Analysis
method
depends
on Data
Range
Weekly reportable data check by Operator: Background
The Valid Calibration Range (VCR) is defined as a 10%
extension of the QAL2 concentration data.
If the following criteria are exceeded, then a new QAL2 must
be performed within 6 months:
○ More than 5% of the reportable hourly averages, calculated
weekly, are outside of the valid calibration range for more
than 5 weeks in a year
○ More than 40% of the measured values from the CEM,
calculated weekly, are outside of the valid calibration range
for one or more weeks
Quality Assurance Level 2 (QAL2)
QAL2/AST testing
• Clarification that all QAL2/AST testing shall be conducted by
an ISO 17025 accredited test laboratory or one that is
approved directly by the Competent Authority
• An AST may replace a repeat QAL2 provided that the AST
measured values and at least 95% of the AMS short term
averages, reported since the previous AST, are < MPU
• Recommendation that QAL2 can be applied to peripherals
(O2, H2O)
• Water vapour values from a calibrated AMS or calculated
water vapour values (for wet abatement systems) can be
used to correct SRM measurements to a wet or dry basis
Quality Assurance Level 2 (QAL2)
QAL2/AST testing
• Outliers must be identified, reported and retained in data
tables and calibration graphs
• Outlier assessment method and justification for excluding
outliers must be documented in the QAL2/AST report
• Recommendation that additional test points are obtained to
allow for outliers
• Exclusion of invalid data from the initial data set must also be
justified in the QAL2/AST report, e.g., start-up or shut-down
events
Quality Assurance Level 2 (QAL2): Method C
Valid
Calibration
Range
Data
Range
Annex E
Carbon monoxide
Daily ELV = 100 mg/m3
Low level data cluster
High level
test point
Low level
test point
Quality Assurance Level 2 (QAL2)
• New procedure for low level data clusters (Method C)
• Criteria for selection of calibration approach and cluster
identification changed from 15% of ELV to MPU, e.g., data
range < 20% of ELV for NOx
• Valid Calibration Range (VCR) – extension beyond highest
data point by 10% - or at least extend up to 20% of ELV
• VCR exceedances (weekly data check) for plant failures
and discontinuous plant operation now considered
• Variability (scatter) test - procedure has been adapted for
treatment of low level clusters (reference points excluded)
• VCR can be extended using AST data, with permission of
the competent authority (up to 50% ELV)
Quality Assurance Level 3 (QAL3)
• Any type of manual or automated control chart can be used
• Enhanced description of QAL3 requirements including the
selection and use of control charts and the execution of zero
and span measurements
• Control charts - Exponentially Weighted Moving Average and
Shewhart control chart examples added (CUSUM retained)
• General requirement on the Operator to ensure that AMS
internal checks or compensation systems are active and
operational and that AMS alarms are received by plant
personnel so that corrective action can be taken at all times
• Built-in procedures are allowed as an alternative to an
external QAL3 (data available to the Operator / auditing)
Quality Assurance Level 3 (QAL3)
• Frequency - at least once per maintenance interval and at
least once per month for uncertified AMS
• For maintenance intervals > 1/month, justify with internal
checks and, for multi-component analysers, a monthly span
check of one gas component
• Hot spares (fully independent back-up AMS) can extend
QAL3 to an annual check provided that an alarm is raised
when the difference between the two AMS is > 5% of the
short-term ELV for more than 5 consecutive measurements
• Control chart limits can be based on the MPU rather than a
detailed uncertainty assessment. Alarm limit cannot be >50%
MPU; Warning limit may be set at 25% MPU
Quality Assurance Level 3 (QAL3)
• For audit purposes, QAL3 documentation must include a
history of the checks and the actions taken when exceeding
control chart limits and charts should be stored for five years
• Alternative reference materials can be used, such as optical
filters, provided that these are certified as being QAL3
compliant under EN 15267-3
Concluding remarks
EN14181 has improved the QA of AMS and has provided a
good framework for Operators to improve monitoring
Pr EN14181:2014 improves and clarifies the standard and
addresses common difficulties, e.g., low level data clusters
Remaining points that will require approval by the Competent
Authority:
i) not applying QAL2 calibration factors if the agreement
between AMS and SRM is less than half of MPU
ii) extending the Valid Calibration Range beyond the daily ELV
using reference materials
iii) simplification of functional test requirements for multi-
component analysers