Changes to the CEM Quality Assurance Standard EN14181 David Graham.pdf · Changes to the CEM Quality Assurance Standard EN14181 VGB European Working Group - Emissions Monitoring

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


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


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


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


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


• 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)


Zero and span drift checks at regular intervals


• 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)


• 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


• 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

Documents

Changes to the CEM Quality Assurance Standard EN14181 David Graham.pdf · Changes to the CEM Quality Assurance Standard EN14181 VGB European Working Group - Emissions Monitoring