Abstract
As intermittent renewable energies are introduced into the power grid, Natural Gas-fired Gas Turbine Combined Cycle (NGCC) is expected to increase frequent start-up, frequent shut-down, and partial-load operation time to stabilize the frequency of the power grid. These transient operations of the NGCC significantly change the ratio of NO2/NOx in the exhaust gas. Therefore, it is necessary to develop an efficient de-NOx system applicable across the range of potential NO2/NOx ratios. In this study, a modification of the de-NOx reaction scheme of Nova et al. (2011) was established, eventually consisting of 8 elementary reactions including 7 chemical species, with the activation energies and the preexponential factors of the reaction rate equations. The two-dimensional unsteady state numerical simulation code was developed and fitted using experimental results obtained under elementary conditions with a honeycomb-shaped SCR catalyst commonly employed at actual NGCC power plants. The numerical simulation utilizing the modified scheme accurately predicted transient changes and equilibrium concentrations of NOx and NH3 in the NGCC exhaust under transient operations with a wide range of NO2/NOx ratios.
