Evaluation of the nitrogen oxide emission level for a steam supply with natural gas into the combustion chamber of a gas turbine unit

Numerical simulation results on the effect of the operation parameters for a combustion chamber of a combined-cycle plant (CCP) with steam injection [1] for the combined production of heat and electric energy upon a reduction in nitrogen oxide emission are represented. Calculations are carried out for lean mixtures with $\alpha = 1.2$–$1.4$ and great steam consumptions of $30$–$42$%. The reaction analysis has shown that the main contribution in $\mathrm{NO}_x$ formation was given by reactions with the advanced Zel'dovich thermal mechanism, and the reaction contribution with the participation of $\mathrm{N_2O}$ into the $\mathrm{NO}$ formation was an order of magnitude higher than that by the mechanism of the prompt $\mathrm{NO}$ formation. $\mathrm{NO}_2$ does not form at high temperatures and only takes part in the conversion into $\mathrm{NO}$ in reactions with the participation of nitric acid. It is shown that the optimum choice of operation conditions for the combustion chamber of the CCP makes it possible to obtain the $\mathrm{NO}_x$ content in the combustion products in some $\mathrm{mill}^{-1}$(ppm). According to calculations, steam injection does not increase $\mathrm{CO}$ emission. A comparison with the experiment is given.