ABSTRACT
Oxides of nitrogen are produced primarily as nitric oxide (NO) in the hotter regions of the combustion reaction zone of the combustor. Nitrogen oxides (NOx) found in the exhaust are the products of the combustion of hydrocarbon fuels in air. In addition to low NOx combustor designs, the methods currently in use to reduce emissions are water injection and steam injection into the combustor, and a selective catalytic reactor (SCR) in the turbine exhaust. Both water and steam injection increase the power output of the gas turbine by adding to the mass flow through the turbine. During the early development of gas turbines, water was injected into the compressor, diffuser, or combustor to increase power output. The steam injection rate for a typical aeroderivative gas turbine operating at 25 megawatts is 3.3% of the compressor inlet air flow. NOx removal efficiency peaks at a different temperature for different catalysts.
