Ammonia injection grid (AIG) is used to introduce vaporized ammonia (NH3) into an exhaust gas stream for nitrous oxide (NOx) reduction in selective catalytic reduction (SCR) systems. Computational and experimental studies on the AIG resulted in significant improvements in the turbulence mixing between the injected ammonia and the exhaust gas. Improved mixing is instrumental to maximize catalyst performance, extend catalyst life time, minimize catalyst volume, decrease system pressure drop, minimize reagent use and ammonia slip, minimize the overall size of the SCR system, and minimize risks associated with designing the SCR system. It is found that an AIG with a turbulence-generating edge dramatically increases the mixing efficiency and, therefore, reduces the mixing distance required to obtain acceptable distributions of the NH3 to NOx ratio. Results indicate over 50% reduction of the required mixing distance due to the turbulence generating edge. This work summarizes the obtained results from computational CFD simulations for two-dimensional and three-dimensional models, however the proposed arrangement of the injection grid has been successfully tested in laboratory experiments and applied to several commercial power generating systems. The commercial performance results will be reported in the subsequent publications.

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