Numerical Study On Aerodynamic Field Flow Of SCR Denitration System Flue

In recent years, as the discussion of "ultra-low" emission in thermal power industry is raised again, emission requirements of nitrogen oxide become more and more strict. Because of high denitration efficiency and mature technology, the selective catalytic reduction (SCR) technique has always been a priority in NOX emission control.By using Fluent, the aerodynamic flow field of the original SCR model in a 300MW power plant was simulated in this paper. The distribution of velocity, flow characteristics and total pressure loss were analyzed. After that, the effects of deflectors and vortex tubes on the velocity field in ammonia injection system and reactor were researched combination of the above analysis. Then according to the defects of ammonia injection system, original design model was improved through increasing diameter, tilt angle and changing nozzle position. Finally, optimal scheme whose velocity and concentration coefficients of deviation meet engineering requirements is obtained.The results show that the uniformities of original velocity and concentration are poor. Deflectors can conspicuously improve flue gas flow in outstretched passage as well as velocity and NH3/NO distribution in reactor. When vortex tubes are installed, the characteristic of flue gas near the wall is changed and the inequality of velocity distribution at catalyst inlet is eliminated effectively. Meanwhile total pressure loss and concentration uniformity have little change. The increase of diameter and angle of vortex mixers can enhance turbulent mixing of ammonia-nitrogen in ammonia injection system. Concentration uniformity in reactor is optimized combining with the matching nozzle position.