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SOURCE TESTING ASSOCIATION | Annual Guide 2015 4 Changes to the Quality Assurance Standard EN14181 I t is just over 10 years since EN14181 was first published [1] and the power industry sub sequently highlighted areas in which the Standard would require further development [2] . A CEN Technical Report, EN/TR 15983 [3] , was issued in order to provide further guidance on implementation. A new version of EN14181 was published in November 2014 in order to consolidate and extend the additional interim guidance which is to be withdrawn. It should be noted that Continuous Emissions Monitor ing (CEM) systems are referred to as Auto mated Measuring Systems (AMS) within the Standard and throughout this article. Regulatory Framework for Combustion and Incineration Plant e regulatory framework for large combustion plant defines Emission Limit Values (ELV) which are of key importance when implement ing EN14181. e Industrial Emissions Directive (IED), published in December 2010 [4] , replaces numerous European directives that govern the environmental regulation of process plant and this requires the application of Best Available Techniques (BAT). e IED applies, in its entirety, to new large com bustion plant (>50 MW net thermal input) permitted from Jan 7 2013 and to existing plant from Jan 1 2016, subject to a number of temporary derogations not described here. In cineration and coincineration plant are fully regulated un der the IED from January 7 2014. All plant have to comply with the general permitting and BAT provisions in Chapter II of the IED. Large combus tion plant must comply with Chapter III and Annex V of the IED. e ELV are defined for SO 2 , NO x and dust for large combustion plant fired by solid and liquid fuels and also CO for gasfired plant (Table 1). ELV are also defined for gas turbines (Table 2). e ELV apply during normal operation only for all plant types (excluding startup and shutdown). e tabulated ELV apply as monthly averages and a daily ELV is also specified as 110% of these monthly ELV. Peripheral measurements, that are required to correct the emission concentration to reference conditions, must also be measured continuously where applicable: oxygen, water vapour (not required if the pollutant is measured on a dry basis), temperature and pressure. Continuous monitoring is required for large combustion plant with a rated thermal input higher than 100MW, although there are specific derogations for SO 2 and dust that instead require sixmonthly periodic monitoring, noting that mercury shall also be measured at least once per year for coal and lignite fired plant. However, alternative procedures can be proposed in place of periodic monitoring of the main pollutants, e.g., calculation of SO 2 from fuel sulphur content. e IED strengthens the importance of Best Available Techniques (BAT) and permit conditions must comply with BAT Conclusions, drawn from the BAT Reference note (BREF) for each industrial sector, with in four years of publication. Effectively, tight er ELV and a wider range of pollutants and additional monitoring requirements may be defined within the sectoral BREF. e large combustion BREF is under revision and is likely to introduce substantially lower ELV and a wider range of continuouslymonitored species than the IED. is has been widely commented on and the final version should be published in 2015 when the requirements will be clarified. Incineration plant must comply with Chapter IV and Annex VI of the IED. Addi tional species are regulated and monitored continuously for incineration plant: CO, Total Organic Carbon (TOC), HCl and HF, with various derogations from continuous moni toring for HCl and HF which must instead then be monitored periodically along with trace metals, dioxins and furans. e IED defines a confidence interval (CI) to account for measurement uncertainty. e confidence interval is subtracted from the re portable hourly average concentration for combustion plant and the halfhourly average for incineration plant. e CI is also used as the basis for many of the subsequent QA assess ments described below. e defined confidence intervals are given in Table 3. Both combustion plant and incineration plant will be Table 1: Large plant ELV Table 2: Gas Turbine 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 SO 2 200 200 35 150 150 35 NO x 200 150 100 150 100 100 Dust 20 20 5 10 10 5 CO – – 100 – – 100 Ref O 2 dry 6% 3% 3% 6% 3% 3% IED Limits Gas Turbines (>50 MW thermal input) Existing Plant (Part 1) New Plant (Part 2) Natural gas Liquid fuel Natural gas Liquid fuel NO x 50 90 50 50 CO 100 100 100 100 Ref O 2 dry 15% 15% 15% 15%

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