THE SOURCE TESTING ASSOCIATION ANNUAL GUIDE 2012
allowance for the thermal efficiency of the plant, as shown in Figure 1. Again, this is a simplification since there are additional provisions for certain fuel types and reduced annual operating hours. For gas turbines, ELVs apply only above 70% load and limit values do not apply to gas turbines for emergency use that operate for less than 500 operating hours per year. For new gas turbines, the efficiency allowance applies to open cycle gas turbines only. These levels of NOx are low, and challenging from a monitoring point of view, but they can generally be achieved using lean premix combustion systems, for natural gas firing. In general terms, for a given calendar year, the validated monthly average must not exceed the ELV and the validated daily average must not exceed 110% of the ELV. In addition, 95% of all validated hourly averages must not exceed 200% of the ELV. The validated hourly aver- age is obtained by subtracting a defined confidence interval (CI) from the CEM reading having already corrected to reporting conditions. Combustion plant permitted before 27 Nov 2002, may be exempted from ELV compliance in the period 1 Jan 2016 to 30 Jun 2020, subject to at least meeting their existing ELVs, provided that the total tonnage of each pollutant is controlled at the Member State level. This can apply to one or more of the individual pollutants (excluding CO). Essentially, ELV compliance is deferred by operating for less time when compared with a baseline period of 2001 to 2010. Member States must submit their Transitional National Plans to the Commission by 1 Jan 2013.
Monitoring requirements
Emissions monitoring underpins all of the compliance and reporting requirements of the IED and is to be considered within BAT Conclusions. Monitoring provisions must be included in the permit conditions. Compliance is determined on the basis of monitoring results which must be assessed at least annually and which must be publicly available. For large combustion plant, detailed monitoring provisions for emission to air are specified in Annex V and the competent authority is required to determine the location of the sampling or measurement points to be used for emissions monitoring. Practically, this is likely to be satisfied by the competent authority approving monitoring points that are proposed and justified by the Operator.
Monitoring and compliance requirements are included within the three year IED review process and the detailed provisions may be amended from time to time to take account of scientific and technical progress.
Monitoring Provisions for Large Combustion Plant When and what to monitor
Continuous monitoring is formally required by the IED, for plant with a rated thermal input higher than 100 MW, for SO2
, NOx and Dust. CO
is also required for gas fired plant. Oxygen, temperature, pressure and water vapour must also be measured in order to correct the emissions to the required reporting conditions, although water is not required if the pollutant is measured on a dry basis.
Continuous monitoring may not be required, by agreement with the competent authority, for SO2
and Dust when firing natural gas, for SO2
from fuel sulphur content. However, mercury shall be measured at least once per year for coal and lignite fired plant (a new requirement).
8 Source Testing Association Annual Guide 2012
when firing oil with a known sulphur content on unabated plant, for SO2 when firing biomass with a demonstrably low sulphur content and for low load factor plant (with a remaining life span of less than 10 000 operating hours). In these situations, six monthly periodic monitoring is required or an acceptable alternative procedure, e.g., calculation of SO2
Figure 1 NOx limits for existing gas turbines
IED Limits Gas Turbines ( >50 MW thermal input ) Existing Plant (part 1) Natural gas 50
NOx CO
Ref O2 dry 100 15%
Species NOx
CO O2
H20 100 15% Table 2 Mandatory emission limit values for gas turbines
ELV24h (mg/m3 55
110
10% 6%
Table 3 Required certification ranges for existing and new gas turbine plant )
Required certification range (mg/m3 < 137.5 < 275
< 25% < 15%
)
Liquid fuel 90
New Plant (part 2) Natural gas 50
100 15%
Liquid fuel 50
100 15%
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