40 Air Monitoring


associated with plant operation and the correct interpretation of the plant status when reporting emissions (Part 4 Annex B);


- changes in the DAHS confi guration (with commentary); - reporting against the plant permit requirements (Figure 6);


- any additional functionality associated with remote emission control modules and associated data transmission; - the system time and the data back-up;


- the installation site for conformity with the manufacturer’s specifi cations and safe working;


- data transmission using, for example, injected signals and fault simulations;


- protection against unauthorised parameter changes, e.g., restricted user access;


- any special features, e.g., calculation of energy weighted ELVs or restrictions on the fuel feed;


- fl agging and evaluation of plant operating modes, e.g., start-up and shut-down or abatement malfunction;


- emissions report generation. Figure 6: DAHS reporting the data export capability and check the test mode of the DAHS.


• Data integrity: DAHS availability; tamper-proof; prevention of data loss; data back-up; DAHS identifi cation and time management.


• Documentation: check the completeness and accuracy of the DAHS documentation.


Table 1, in Part 3 of the standard, lists the characteristics that need to be tested, the type of test applicable (generic, specifi c or documentation) and the cross-references to the performance criteria in Parts 1 and 2 of the standard.


EN 17255 Part 4 – DAHS Installation and on-going QA/QC


Part 4 of the standard concerns the ongoing QA of the DAHS which is the responsibility of the plant operator and an independent test laboratory that is employed to verify the initial DAHS installation and then perform an annual functional test of the system.


The responsibilities of the plant operator and the test laboratory are listed below:


• Installation (operator/test laboratory) • QAL2 aspects (test laboratory) • Ongoing operation (operator) • Annual functional test (test laboratory) • Documentation (operator)


Installation The DAHS software installed by the operator must be certifi ed according to Part 3 of the standard and installed according to the manufacturer’s requirements, taking into account the conditions of the environmental permit. The DAHS location must be suffi ciently stable and vibration free with appropriate weather protection and temperature control. Signal interface components not tested under Part 3 must meet the requirements of Part 2 of the standard. The installation documentation requirements are extensive and are detailed in Annex A of Part 4.


QAL2 factors must be applied in the DAHS, consistent with the raw data inputs and taking any applied scaling factors into account. The Valid Calibration Range is also entered along with the QAL2 variability if this is used for data validation.


The test laboratory is required to check that the above requirements are fulfi lled and to record the baseline DAHS confi guration and software version(s). The test laboratory also checks the assignments of Input/Output (I/O) signals in the tabulated installation record and the status of all I/O analogue & digital signals, i.e., that the signals are live and functioning properly.


The operator is recommended to establish a test plan for the annual function test of the plant specifi c installation and confi guration of the DAHS and this plan is then updated following any system changes. The test laboratory then


performs the annual functional test (see below) and produces a comprehensive installation report that describes the: plant; DAHS (including certifi cation status); baseline confi guration/ parameter setting and results of the system and functional tests. Any observations or fi ndings relating to the implementation of the QAL2/AST are also reported. The installation report also contains a summary of results.


QAL2 aspects The test laboratory is required to perform an annual function test of the DAHS in co-ordination with the QAL2/ AST testing. This may be performed in parallel with either the AMS functional test or the QAL2/AST testing.


Ongoing operation The operator needs to implement QAL2 calibration functions and related parameters, including any Valid Calibration Range extensions from the AST, when these become available. Allowed numbers of exceedances of the Valid Calibration Range are based on an annual period so the time counter for monitoring exceedances needs to be reset by the operator in the DAHS. Prompt action is required in response to warnings, alarms and violations. There is also a requirement to perform a daily check of the completeness of reports and system messages. The operator needs to take corrective action as required, e.g., system repairs, and to document any interventions in the DAHS log book.


Annual Functional Test The test laboratory follows the test plan established during DAHS installation and checks the correct transmission of the: AMS measured signals, e.g., NOx; the AMS status signals, e.g., instrument malfunction, and the plant status signals, e.g., plant load and furnace temperature. The correct functioning of the redundant data recording system is also checked and, as above, the operator arranges correction of failures and errors and records interventions in the DAHS log book.


The annual functional test is very detailed and requires the checking of:


- parameter settings for each measurement channel including signal ranges, QAL2 parameters, reference values used for standardisation, averaging period, ELVs and data validation parameters, e.g., the Confi dence Interval;


- plant status signals, plant operating states, counter resets


The functional test report must contain at least a statement of objectives, a description of plant and materials handled, a description of the DAHS, results of the functional tests and a summary of results. Any deviations and potential impacts must be documented and justifi ed.


The functional test requires a combination of physical checks, e.g., signal injection, confi guration checks and data/reporting checks. The Competent Authority in each Member State will need to approve the independent and competent test laboratories that are allowed to perform this test.


Part 4 of the standard addresses the regulatory gap between the output terminals of the AMS (covered by EN 14181) and the emissions compliance reporting. However, the DAHS documentation that must be maintained by the plant operator is extensive and includes: an installation report; a functional test plan and annual test reports; maintenance records and training records. Close cooperation between the Plant Operator and the test laboratory is required. However, it should be noted that Part 4 of the standard is in fi nal draft and may be subject to change.


Summary


The EN 17255 standard, issued in four parts, addresses the QA/ QC of data received by a Data Acquisition and Handling System (DAHS) from Automated Measuring Systems (AMS) or CEMS that are subject to EN 14181. The DAHS may receive analogue or digital inputs from both the AMS and the operational plant.


The DAHS receives ‘raw’ data from the emissions, peripherals and stack fl ow AMS, and then averages, calibrates, standardises and validates the data for regulatory compliance reporting. Part 1 of the standard specifi es the rules for data handling and reporting. Part 2 specifi es the basic system requirements for data acquisition, data processing, data storage, data output, the generation of reports, system functions and data integrity. Part 3 defi nes the DAHS certifi cation or type approval process which requires testing of a single DAHS by an independent test laboratory followed by type approval by an independent certifi cation body. Part 4 defi nes the ongoing QA/QC performed by the operator and an independent test laboratory that performs an annual functional test of the DAHS. The operator is required to keep detailed records and to fully document the DAHS performance.


This standard applies to DAHS installed after the date of implementation of the standard but this depends on regulatory interpretation and best practice.


Author Contact Details David Graham, Uniper


Technology Centre, Ratcliffe-on-Soar, Nottingham NG11 0EE • +44(0)792 149 1164 • David.Graham@uniper.energy • https://www.uniper.energy/


Co-authors:


James Eldridge, Element James.Eldridge@element.com George Forster, a1-cbiss George.Forster@a1-cbiss.com Florian Schunke, Durag Gary Egerton, ABB


Florian.Schunke@durag.com Gary.Egerton@gb.abb.com


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IET MARCH / APRIL 2023


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