comments on the quality assurance standard en14181

Comments on the Comments on the Quality Assurance Quality Assurance Standard EN14181Standard EN14181

VGB Working Group VGB Working Group

Emissions MonitoringEmissions Monitoring

VGB Working GroupVGB Working GroupEmissions MonitoringEmissions Monitoring

The following organisations The following organisations are represented on the are represented on the working group:working group:– VGB PowerTech (DE) - ChairVGB PowerTech (DE) - Chair– KEMA (NL)KEMA (NL)– EDF (FR)EDF (FR)– ESB (IRL)ESB (IRL)– Laborelec (BE)Laborelec (BE)– E.ON (UK)E.ON (UK)– Helsingin Energia (FI)Helsingin Energia (FI)– E.ON (DE)E.ON (DE)

AMS Quality Assurance – the AMS Quality Assurance – the EN14181 modelEN14181 model

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

EN14181 – Operator’s EN14181 – Operator’s ResponsibilitiesResponsibilities

Installation of compliant equipment (QAL1, Installation of compliant equipment (QAL1, EN14956)EN14956)

Initial and periodic calibration of Initial and periodic calibration of equipment (QAL2)equipment (QAL2)

Annual verification of calibration (AST)Annual verification of calibration (AST) Ongoing zero and span checks (QAL3)Ongoing zero and span checks (QAL3) Retention of records on fileRetention of records on file Checking measured values are within cal. Checking measured values are within cal.

range (weekly)range (weekly)

EN14181 – Industry ResponseEN14181 – Industry Response

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

Significant extra costs to industrySignificant extra costs to industry Concerns relate to certain aspects Concerns relate to certain aspects

considered to beconsidered to be– inappropriate or impractical to implement, orinappropriate or impractical to implement, or– impose excessive cost or burden on operatorimpose excessive cost or burden on operator

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

Areas of Concern (Summary)Areas of Concern (Summary)

1.Requirement for complex uncertainty analysis

2. Low load factor plant3. Cert range4. Cal function5. Peripherals

6. Determining control limits7. Easy to trigger QAL2 (expensive!)

Areas of concern (1) – QAL1Areas of concern (1) – QAL1

Impractical to do a full uncertainty Impractical to do a full uncertainty analysis for each analyser:analysis for each analyser:

– Statistical approach too complicatedStatistical approach too complicated

– Lack of available data for older sitesLack of available data for older sites

– Uncertainty analysis excludes Uncertainty analysis excludes measurement locationmeasurement location

– Confusion regarding which performance Confusion regarding which performance parameters should be included.parameters should be included.

VGB Proposal (1)VGB Proposal (1)

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

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

Outcome similar to existing requirementOutcome similar to existing requirement Already applies in some member statesAlready applies in some member states

Areas of Concern (2) – QAL2Areas of Concern (2) – QAL2

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

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

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

Example: low measured concentrationsExample: low measured concentrationsCalibration functions for CO (AMS1)

0

5

10

15

20

25

30

0 10 20 30AMS

SR

M

Source: N Faniel, Laborelec


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

– Exemption of plant operating <1250 hours per Exemption of plant operating <1250 hours per annumannum

– Exclusion of calibration time from reported Exclusion of calibration time from reported unavailability unavailability

– Calibration using reference materials where Calibration using reference materials where SRM not appropriateSRM not appropriate

Areas of Concern (3) – Calibration Areas of Concern (3) – Calibration RangeRange

Valid calibration range limited to 10% Valid calibration range limited to 10% above max measured concentration (above max measured concentration (ŷŷs,s,maxmax + 10%)+ 10%)

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

Inappropriate to apply this limit to hourly Inappropriate to apply this limit to hourly average measurements, will repeatedly average measurements, will repeatedly trigger costly QAL2trigger costly QAL2


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

– This is consistent with the instrument range This is consistent with the instrument range advised in the standardadvised in the standard

– Would allow plant to be operated normally Would allow plant to be operated normally during the testsduring the tests

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

Areas of Concern (4) – Calibration Areas of Concern (4) – Calibration FunctionFunction

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

High measured values lead to difficulties in High measured values lead to difficulties in passing the variability criterion, even passing the variability criterion, even where Rwhere R22 correlation is close to 1. correlation is close to 1.

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

Example: High measured concentrationsExample: High measured concentrations

Source: N Faniel, Laborelec

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

SR

M

VGB Proposals (4)VGB Proposals (4)

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

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

Areas of Concern (5) - PeripheralsAreas of Concern (5) - Peripherals

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

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

Functional check is more appropriateFunctional check is more appropriate Calculated HCalculated H22O may be more accurate O may be more accurate

than measuredthan measured

VGB Proposals (5)VGB Proposals (5)

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

VGB recommends that VGB recommends that where fuel where fuel composition is well known,composition is well known, calculated calculated values of Hvalues of H22O may be usedO may be used

Areas of Concern (6) – QAL3Areas of Concern (6) – QAL3

Control limits of analyser based on SControl limits of analyser based on SAMSAMS – – difficult to determinedifficult to determine

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

Unfair to penalise analysers with better Unfair to penalise analysers with better performanceperformance

Control limit should be fixed percentage of Control limit should be fixed percentage of ELVELV


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

Auto-calibration, with recording of Auto-calibration, with recording of cumulative drift, should be allowed as cumulative drift, should be allowed as QAL3QAL3

Areas of Concern (7) - ASTAreas of Concern (7) - AST

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

QAL2 “triggers”QAL2 “triggers”

On installation and every 5 (3) yearsOn installation and every 5 (3) years Change of fuel, process or abatement Change of fuel, process or abatement

systemsystem Modification or repair to AMSModification or repair to AMS AST: cal function fails on validity or AST: cal function fails on validity or

variability criteriavariability criteria

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

QAL2 “triggers”QAL2 “triggers”

On installation and every 5 (3) yearsOn installation and every 5 (3) years Change of fuel, process or abatement Change of fuel, process or abatement

systemsystem Modification or repair to AMSModification or repair to AMS AST: cal function fails on validity or AST: cal function fails on validity or

variability criteriavariability criteria

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

Areas of Concern (7) - ASTAreas of Concern (7) - AST

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

On failure of AST, temporary adjustment of On failure of AST, temporary adjustment of cal function should be allowed, pending cal function should be allowed, pending QAL2QAL2

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

Areas of Concern (7) – ASTAreas of Concern (7) – AST

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

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

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


VGB supports:VGB supports:

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

Flexibility in Flexibility in allowing operators to carry allowing operators to carry out functional checksout functional checks;;

Explicit treatment of uncertainty of Explicit treatment of uncertainty of test methodstest methods

ConclusionsConclusions

The standard brings welcome benefitsThe standard brings welcome benefits

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

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

comments on the quality assurance standard en14181

Documents