NUMERICAL SIMULATION OF FLOW AND NOx REDUCTION IN A DE-NOx CATALYST HONEYCOMB

A selective catalytic de-NOx system, operated around 350 degrees C, offers a very efficient method to reduce the NOx concentration in flue gas, and is therefore widely used in thermal power plants. In order to precisely predict the lifetime and efficiency of the system, it is of great importance to understand the NOx reduction mechanism in a honeycomb rectangular channel of a de-NOx catalyst. In this study, the effects of turbulent and laminar flow behavior in a honeycomb rectangular channel on the NOx reduction reaction is investigated using large-eddy simulations (LES). The results show that the NOx reduction reaction is strongly affected by inner flow behavior. The NOx reduction rate on the catalyst surface for the turbulent flow is higher than that for laminar flow. This is due to the fact that the diffusion of NOx in the vicinity of the wall is dominated only by molecular diffusion during laminar flow, whereas it is enhanced by turbulent motion during turbulent flow.