NOx Reduction by Means of the Inlet Fogging Approach

The issue of reconciling the growing demand for electricity with the need to preserve the integrity of the biosphere calls for greater attention to pollutant emissions and for stricter control of their release in the atmosphere. Moreover, the decrease in performance of gas turbines both in simple and in combined cycle applications, which is due to the high air temperatures, often requires the adoption of “compressor inlet air cooling systems” to recover these losses in power and efficiency. In recent years, of all the inlet air cooling systems, the fogging approach has had the most promising results in recovering the lost power output among all the available power enhancement techniques. Moreover, the fogging approach can be useful also to reduce the NOX emissions of gas turbines. This paper investigates the implementation of inlet fogging on a large series of commercial gas turbines. In particular, its effects on the recovery of lost power and on the reduction of NOX emissions are presented and discussed with reference to different climatic scenarios. The study also analyzes if fogging could be considered as one of the “Best Available Technologies” (BAT) in order to reduce NOX emissions in existing gas turbines power plants.