Standard Operating Procedure (SOP) for Compliance Monitoring ...

Correcting CEM readings to Oxygen Contents Specified by Emission Standards
1. Background
It is common for concentration emissions standards to be corrected to a specific oxygen (O 2 )
concentration. When concentration emissions standards are corrected to a specified O 2 concentration,
sources that otherwise would not meet the standard cannot simply comply by allowing more ambient
air into the turbine exhaust stack. Instead, concentration readings must be adjusted to whatever
specific O 2 level is specified in the standard.
1.1 Calculation Procedure
Pollution concentrations are adjusted to the O 2 concentration specified in a standard according to
Equation 1:
(Eq. 1)
Where
Conc. i (Std. O 2 ) = the pollutant concentration at the O 2 level specified in the standard
Conc. i (Measured O 2 ) = the pollutant concentration measured in the exhaust stack
20.9% = O 2 concentration in the atmosphere
Std. O 2 % = O 2 concentration specified in the standard
1.2 Example Calculation
Suppose the NO x standard for a gas-fired turbine is 70 mg/Nm 3 at 15% O 2 , and the measured value is
68 ppm at 17% O 2 . Does the turbine meet the emissions standard
Where
Conc. i (Std. O 2 ) = 68 ppm (20.9−15) ÷ (20.9−17)
Conc. i (Std. O 2 ) = 68 ppm (1.51)
Conc. i (Std. O 2 ) = 103 ppm at 15% O 2 .
Therefore, the measured value does not meet the emissions standard.
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