Taking the SCR de-NOxsystem in a 660 MW coal-fired unit as the research object

a three-dimensional numerical model was established by using the Gambit software.The characteristics of flow field distribution in the reactor were simulated.Moreover

the effects of ammonia injection strategies on uniformity of the NH3 distribution at entrance of the first catalyst layer were investigated.The results show that

due to the existence of two flue ducts with variable cross sections in the reactor

the flow field distribution at the ammonia injection grid(AGI)is extremely uneven

the relative deviation coefficient of flue gas velocity is 27.5%.When the linear ammonia injection strategy is adopted

the relative deviation coefficient of NH3 at entrance of the first catalyst layer is 25.3%.The relative deviation coefficient of NH3 at entrance of the first catalyst layer is 8.9% when the 10-area ammonia injection strategy is employed and that becomes5.6% when the 30-area ammonia injection strategy is adopted.The ammonia injection effect of partition ammonia injection strategy is obviously better than that of the linear ammonia injection strategy.