To solve the problems of uneven distribution of NO_x concentration at the outlet and excessive ammonia escape in the actual SCR operation of power plants

the SCR DeNO_x reactor was simulated numerically and a new ammonia injection optimization method for dual control of ammonia slip and nitrogen oxides emission was proposed. Taking the SCR DeNO_x system of a 660 MW unit as an example

a numerical model of visual flow field and DeNO_x reaction was established

and the change of the partitioned outlet NO_x concentration

ammonia slip and partitioned DeNO_x efficiency under different total ammonia nitrogen ratios were analyzed and compared. The results show that the relationship between partitioned DeNO_x efficiency

outlet NO_x and ammonia concentration

with the partitioned ammonia-nitrogen ratio is a two-parts linear relation separated by an inflection point

and the inflection point occurs when partitioned ammonia-nitrogen ratio is about 1.15. On this basis

the present study proposes a new optimization method for ammonia/nitrogen dual control optimization based on the combination of piecewise fitting function and optimization matrix equation. It is predicted that the 660 MW unit by using 5 zones and 42 nozzles for ammonia injection regulation

and the optimized total ammonia injection volume will decrease by 7.2% at the best compared with the uniform ammonia injection working condition. Relative standard deviation of outlet NO_x concentration and ammonia slip volume will decrease to 9.4% and 4.2% respectively

and the outlet uniformity will be significantly improved

and there is no locally over DeNO_x phenomenon.