Archived: Proposed guidelines: reducing nitrogen oxide emissions from stationary combustion turbines: chapter 4


4. NOx Emission Limits

4.1. These Guidelines recommend NOx emission limits for combustion turbines. These limits can be met using one of the following methods:

  1. the output-based method; or
  2. the concentration-based method.

4.2. The NOx emission limits in tables 1 and table2 are a function of turbine application and power rating (expressed in MW). These limits do not apply during start-up periods and shut-down periods, during periods of part-load operation or when the ambient temperature at the point of air intake is less than -18°C.

4.3. Output-based method

Under the output-based method, limits are expressed as emission intensity (mass of NOx per unit output of shaft or electrical energy). To conform with these Guidelines, an operator should meet the applicable emission limit mentioned in Table 1. The NOx emission limits take into consideration the quantity of energy produced by the combustion turbine, calculated in gigajoules (GJ), as well as the emissions, calculated in grams (g) of NOx.

Table 1: Natural gas combustion turbines NO x emission limits - output-based method
Application Turbine power rating (MW) NOx emission limits
(g/GJ(power energy output))
Non-peaking combustion turbines - mechanical drive
≥1 and < 4
500
Non-peaking combustion turbines - electricity generation
≥1 and < 4
290
Peaking combustion turbines - alltable notea
≥1 and < 4
exempt
Non-peaking combustion turbines and peaking combustion turbines - all*
≥4 and ≤ 70
140
Non-peaking combustion turbines - alltable notea
> 70
85
Peaking combustion turbines - alltable notea
> 70
140

4.4. Concentration-based method

Under the concentration-based method, emission limits are expressed as concentration of NOx. If this method is chosen, the concentration of NOx at the combustion turbine exhaust should not exceed the limit set out in Table 2.

Table 2: Natural gas combustion turbines NOx emission limits - concentration-based method
Application Turbine power rating (MW) NOx emission limits (ppmvTable noteb) @ 15% O2
Non-peaking combustion turbines - mechanical drive
≥1 and < 4
75
Non-peaking combustion turbines - electricity generation
≥1 and < 4
42
Peaking combustion turbines - allTable notec
≥1 and < 4
exempt
Non-peaking combustion turbines and peaking combustion turbines - allTable notec
≥ 4 and ≤ 70
25
Non-peaking combustion turbines - allTable notec
> 70
15
Peaking combustion turbines - allTable notec
> 70
25
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