Numerical Simulation Research On The Flow Field Of The Entrance Flue Of SCR DeNOx Reactor

With nitrogen oxides(NOx) emission standards to be more stringent, it attracts more and more attention to reduce nitrogen oxides from coal-fired power plants. The selective catalytic reduction(SCR) technology for flue gas has been used widely in power plants all over the world, which has the advantage of the high denitration efficiency, reliability service, no by-products, simple device, and so on. In recent years, the research on SCR DeNOx technology mainly focuses on the optimization of flow field of SCR and the preparation of catalyst. Research focus is how to improve denitration efficiency, extend the life of the catalyst, and so on. With the development of computational fluid dynamics and computer technology, we can simulate SCR DeNOx system using of efficient, convenient computational fluid dynamics software. The results can provide important parameters for the design and improvement of flue, guide vanes and the injection system.Using computational fluid dynamics software FLUENT, the flow field of the entrance flue of SCR in a 600MW power plant unit is simulated in this paper. The main research contents and results are as follows. The flow field of the entrance flue of SCR is simulated when the number of guide vanes is different. The results show that with the increase of the number of guide vanes, the flow field of flue becomes more uniform and the pressure drop is greater. Meantime, the effect of guide vanes becomes weak when the distribution of guide vanes gets to a certain extent. The role of injection grid to the flow field of flue is analyzed, the results show that injection grid pipings can improve the flow field of flue and the role of double-pipe arrangement is better than single pipeline. The mixing of flue gas and reducing agent in entrance flue of SCR is numerical simulated. The results show that it can improve the mixing and the concentration distribution of flue gas and reducing agent in the flue by dividing the nozzles as different areas and setting different injection speeds. Moreover, single-pipeline in the injection grid is more beneficial to the distribution of flue gas and reducing agent than double-pipelines.