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Comments on the Quality Assurance Standard EN14181. VGB Working Group Emissions Monitoring. VGB Working Group Emissions Monitoring. The following organisations are represented on the working group: VGB PowerTech (DE) - Chair KEMA (NL) EDF (FR) ESB (IRL) Laborelec (BE) E.ON (UK)

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Comments on the Quality Assurance Standard EN14181

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Comments on the quality assurance standard en14181 l.jpg

Comments on the Quality Assurance Standard EN14181

VGB Working Group

Emissions Monitoring


Vgb working group emissions monitoring l.jpg

VGB Working GroupEmissions Monitoring

  • The following organisations are represented on the working group:

    • VGB PowerTech (DE) - Chair

    • KEMA (NL)

    • EDF (FR)

    • ESB (IRL)

    • Laborelec (BE)

    • E.ON (UK)

    • Helsingin Energia (FI)

    • E.ON (DE)


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AMS Quality Assurance – the EN14181 model

Source: Gould, R., QA of AMS, MCERTS Conference, Bretby, 2003


En14181 operator s responsibilities l.jpg

EN14181 – Operator’s Responsibilities

  • Installation of compliant equipment (QAL1, EN14956)

  • Initial and periodic calibration of equipment (QAL2)

  • Annual verification of calibration (AST)

  • Ongoing zero and span checks (QAL3)

  • Retention of records on file

  • Checking measured values are within cal. range (weekly)


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EN14181 – Industry Response

  • Welcome structure, clarity and consistency provided by new standard.

  • Significant extra costs to industry

  • Concerns relate to certain aspects considered to be

    • inappropriate or impractical to implement, or

    • impose excessive cost or burden on operator

  • Request early revision to standard to address these areas of concern


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Areas of Concern (Summary)

6. Determining control limits

7. Easy to trigger QAL2 (expensive!)

2. Low load factor plant

3. Cert range

4. Cal function

5. Peripherals

  • Requirement for complex uncertainty analysis


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Areas of concern (1) – QAL1

  • 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.


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VGB Proposal (1)

  • VGB supports a simplified approach whereby instrument certified range must be <2.5 x ELV, per type certification in field trials

  • This substitutes performance testing, under the recognised certification schemes, for uncertainty analysis

  • Outcome similar to existing requirement

  • Already applies in some member states


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Areas of Concern (2) – QAL2

  • Low load factor plant should not be required to operate to prove the AMS

  • Similarly for a second fuel or configuration used for a small proportion of the time

  • Where emissions concentrations are very low, QAL2 using SRM yields “random” cal functions (but may pass variability test!)


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Example: low measured concentrations

Source: N Faniel, Laborelec


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VGB Proposal (2)

  • VGB supports a flexible interpretation for cases of low load factor plant or very low emissions levels, including:

    • Exemption of plant operating <1250 hours per annum

    • Exclusion of calibration time from reported unavailability

    • Calibration using reference materials where SRM not appropriate


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Areas of Concern (3) – Calibration Range

  • Valid calibration range limited to 10% above max measured concentration (ŷs,max + 10%)

  • Limit is too narrow; creates perverse incentive to maximise emissions during test (e.g., deliberate burning of highest sulphur fuel)

  • Inappropriate to apply this limit to hourly average measurements, will repeatedly trigger costly QAL2


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VGB Proposal (3)

  • VGB supports the extension of the valid calibrated range to 2.5 x ELV in accordance with the linearity test

    • This is consistent with the instrument range advised in the standard

    • Would allow plant to be operated normally during the tests

    • Calibration of plant with low emissions (<30% ELV) should be based on reference materials


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Areas of Concern (4) – Calibration Function

  • Where measured data is clustered at high levels, poor quality calibration function may result. Inclusion of zero values would add information

  • High measured values lead to difficulties in passing the variability criterion, even where R2 correlation is close to 1.

  • Conversely, with low measured values, variability test may validate poor cal function


Example high measured concentrations l.jpg

Calibration functions: SO2

350

300

250

200

SRM

y = 0,89x + 42,50

150

y = 0,75x + 89,10

100

50

0

0

100

200

300

AMS

Example: High measured concentrations

Source: N Faniel, Laborelec


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VGB Proposals (4)

  • VGB supports a clarification of the standard to allow inclusion of measured zero values in the calculation of the cal. function

  • VGB supports a flexible interpretation of the standard for plant with very low emissions, or dust monitors close to the ELV


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Areas of Concern (5) - Peripherals

  • Variations between AMS and SRM peripheral readings may be due to actual differences between locations

  • It is unjustified to force the AMS and SRM to read the same by applying a QAL2-style calibration

  • Functional check is more appropriate

  • Calculated H2O may be more accurate than measured


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VGB Proposals (5)

  • VGB supports the view that functional checks, rather than QAL2 calibrations, are appropriate for peripheral measurements

  • VGB recommends that where fuel composition is well known,calculated values of H2O may be used


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Areas of Concern (6) – QAL3

  • Control limits of analyser based on SAMS – difficult to determine

  • Complex uncertainty analysis required. Not clear what parameters to include; data may be unavailable

  • Unfair to penalise analysers with better performance

  • Control limit should be fixed percentage of ELV


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VGB Proposal (6)

  • VGB supports a simplified approach that eliminates the need for uncertainty analysis by the operator, and specifies control limits as a fixed percentage of the ELV.

  • Auto-calibration, with recording of cumulative drift, should be allowed as QAL3


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Areas of Concern (7) - AST

  • Many situations trigger a QAL2 (e.g. a change in fuel), in some of which an AST may be sufficient to verify the cal function


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QAL2 “triggers”

  • On installation and every 5 (3) years

  • Change of fuel, process or abatement system

  • Modification or repair to AMS

  • AST: cal function fails on validity or variability criteria

  • 40% of measured values outside calibration range over a week (or 5% over 5 weeks)


Qal2 triggers23 l.jpg

QAL2 “triggers”

  • On installation and every 5 (3) years

  • Change of fuel, process or abatement system

  • Modification or repair to AMS

  • AST: cal function fails on validity or variability criteria

  • 40% of measured values outside calibration range over a week (or 5% over 5 weeks)


Areas of concern 7 ast24 l.jpg

Areas of Concern (7) - AST

  • Many situations trigger a QAL2 (e.g. a change in fuel), in some of which an AST may be sufficient to verify the cal function

  • On failure of AST, temporary adjustment of cal function should be allowed, pending QAL2

  • On-site Cross-interference testing is onerous and should not be necessary where equipment is certified


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Areas of Concern (7) – AST

  • Functional tests could reasonably be carried out by operator and audited by accredited lab

  • The available 10% extension of the calibrated range is too limited

  • No acknowledgement of the uncertainty of the SRM, which may be similar to that of the AMS


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VGB Proposal (7)

  • VGB supports:

  • Use of an AST in some circumstances where a QAL2 is currently specified;

  • Flexibility in allowing operators to carry out functional checks;

  • Explicit treatment of uncertainty of test methods


Conclusions l.jpg

Conclusions

  • The standard brings welcome benefits

  • We have identified certain aspects that we consider impractical in implementation or inappropriate, or to impose unnecessary costs or burdens on the operator

  • We respectfully propose modification of these aspects and request early revision of the standard incorporating these proposals


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