B. Determination of N2O emissions U.K.
B.1.Annual N2O emissionsU.K.
The operator shall monitor emissions of N2O from nitric acid production using continuous emissions measurement. The operator shall monitor emissions of N2O from adipic acid, caprolactam, glyoxal and glyoxylic acid production using a measurement-based methodology for abated emissions and a calculation-based method (based on a mass balance methodology) for temporary occurrences of unabated emissions.
For each emission source where continuous emissions measurement is applied, the operator shall consider the total annual emissions to be the sum of all hourly emissions using the following formula:
N2O emissionsannual [t] = Σ [N2O conchourly [mg/Nm3] * flue gas flowhourly [Nm3/h]] * 10–9
Where:
=
total annual emissions of N2O from the emission source in tonnes N2O
=
hourly concentrations of N2O in mg/Nm3 in the flue gas flow measured during operation
=
flue gas flow determined in Nm3/h for each hourly concentration
B.2.Hourly N2O emissionsU.K.
The operator shall calculate annual average hourly N2O emissions for each source where continuous emission measurement is applied using the following equation:
Where:
=
annual average hourly N2O emissions in kg/h from the source;
=
hourly concentrations of N2O in mg/Nm3 in the flue gas flow measured during operation;
=
flue gas flow determined in Nm3/h for each hourly concentration.
The operator shall determine hourly N2O concentrations [mg/Nm3] in the flue gas from each emission source using a measurement-based methodology at a representative point, after the NOx/N2O abatement equipment, where abatement is used. The operator shall apply techniques capable of measuring N2O concentrations of all emission sources during both abated and unabated conditions. Where uncertainties increase during such periods, the operator shall take them into account in the uncertainty assessment.
The operator shall adjust all measurements to a dry gas basis where required and report them consistently.
B.3.Determination of flue gas flowU.K.
The operator shall use the methods for monitoring flue gas flow set out in Article 43(5) of this Regulation for measuring the flue gas flow for N2O emissions monitoring. For nitric acid production, the operator shall apply the method in accordance with point (a) of Article 43(5) unless it is technically not feasible. In that case and upon approval by the competent authority, the operator shall apply an alternative method, including by a mass balance methodology based on significant parameters such as ammonia input load, or determination of flow by continuous emissions flow measurement.
The flue gas flow shall be calculated in accordance with the following formula:
Vflue gas flow [Nm3/h] = Vair * (1 – O2,air)/(1 – O2,flue gas)
Where:
=
Total input air flow in Nm3/h at standard conditions;
=
Volume fraction of O2 in dry air [= 0,2095];
=
Volume fraction of O2 in the flue gas.
The Vair shall be calculated as the sum of all air flows entering the nitric acid production unit.
The operator shall apply the following formula, unless stated otherwise in its monitoring plan:
Vair = Vprim + Vsec + Vseal
Where:
=
Primary input air flow in Nm3/h at standard conditions;
=
Secondary input air flow in Nm3/h at standard conditions;
=
Seal input air flow in Nm3/h at standard conditions.
The operator shall determine Vprim by continuous flow measurement before the mixing with ammonia takes place. The operator shall determine Vsec by continuous flow measurement, including where the measurement is before the heat recovery unit. For Vseal the operator shall consider the purged airflow within the nitric acid production process.
For input air streams accounting for cumulatively less than 2,5 % of the total air flow, the competent authority may accept estimation methods for the determination of that air flow rate proposed by the operator based on industry best practices.
The operator shall provide evidence through measurements under normal operating conditions that the flue gas flow measured is sufficiently homogeneous to allow for the proposed measurement method. Where non-homogeneous flow is confirmed through these measurements, the operator shall take that into account when determining appropriate monitoring methods and when calculating the uncertainty in the N2O emissions.
The operator shall adjust all measurements to a dry gas basis and report them consistently.
B.4.Oxygen (O2) concentrationsU.K.
The operator shall measure the oxygen concentrations in the flue gas where necessary for calculating the flue gas flow in accordance with subsection B.3 of this section of Annex IV. In doing so, the operator shall comply with the requirements for concentration measurements within Article 41(1) and (2). In determining the uncertainty of N2O emissions, the operator shall take the uncertainty of O2 concentration measurements into account.
The operator shall adjust all measurements to a dry gas basis where required and report them consistently.
B.5.Calculation of N2O emissionsU.K.
For specific periods of unabated emissions of N2O from adipic acid, caprolactam, glyoxal and glyoxylic acid production, including unabated emissions from venting for safety reasons and when abatement plant fails, and where continuous emissions monitoring of N2O is technically not feasible, the operator shall subject to the approval of the specific methodology by the competent authority calculate N2O emissions using a mass balance methodology. For this purpose the overall uncertainty shall be similar to the result of applying the tier requirements of Article 41(1) and (2). The operator shall base the calculation method on the maximum potential emission rate of N2O from the chemical reaction taking place at the time and the period of the emission.
The operator shall take the uncertainty in any calculated emissions for a specific emission source into account in determining the annual average hourly uncertainty for the emission source.
B.6.Determination of activity production ratesU.K.
Production rates shall be calculated using daily production reports and hours of operation.
B.7.Sampling ratesU.K.
Valid hourly averages or averages for shorter reference periods shall be calculated in accordance with Article 44 for:
concentration of N2O in the flue gas;
total flue gas flow where this is measured directly and where required;
all gas flows and oxygen concentrations necessary to determine the total flue gas flow indirectly.