Nitrogen oxides (NO x) are the main emissions of concern from gas turbines. Section 60.332 contains a limitation of NO x emissions from gas turbines. The limit of NO x emissions from stationary gas turbines is determined by one of the following equations:
A.If an electric utility stationary gas turbine has a heat input at peak load that is greater than 100 million Btu/hr (107.2 gigajoules/hr) based on the lower heating value of the fuel, the allowable NOx emissions are computed with equation #1. (Section 60.332(b) of the rule). STD = 0.0075 (14.4/Y) + F
B.If the stationary gas turbine has a heat input at peak load equal to or greater than 10 million Btu/hr (10.7 gigajoules/hr) but less than or equal to 100 million But/hr (107.2 gigajoules/hr) based on the lower heating value of the fuel, the allowable NO x emissions are computed with equation #2. (Section 60.332(c) of the rule). STD = 0.015 (14.4/Y) + F
Where:
STD = the allowable NO x emission (percent by volume at 15% oxygen on a dry basis)
Y = manufacturer’s rated heat rate at the manufacturer’s rated load, or the actual measured heat rate based on the lower heating value of the fuel as measured at actual peak load for the facility. “Y” cannot exceed 14.4 kilojoules/watt hour.
F = the percent NO x by volume from fuel bound nitrogen. Nitrogen is found in fossil fuels and when the fuel is burned, nitrogen oxides can form. Table 1 illustrates how to determine “F.”
Table 1. Determining F from Nitrogen Content Fuel
Fuel-bound nitrogen (% by weight) | F (NO x % by volume) |
N~0.015 | 0 |
0.015<N~0.1 | 0.04(N) |
0.1<N~0.25 | 0.004+0.0067(N-0.1) |
N>0.25 | 0.005 |
Note: N = the nitrogen content of the fuel (% by weight) | |
C. Stationary gas turbines with a manufacturer’s rated base load at ISO conditions of 30 megawatts (30 million watts, which is equivalent to 107.2 gigajoules/hr) or less must meet the NO x limits calculated from equation B except as provided in Section 60.332(b) of the rule (this is summarized above in “A”). (Section 60.332(d) of the rule).
Note: the first condition above is for “electric utility stationary gas turbines”, but the other two conditions are for “stationary gas turbines.”
