Aiming at the problem of high dosage of reductant and high ammonia escape in denitrification system of W-type flame boiler

a control strategy combining SCR Control+ control technology with balanced control method is proposed based on the partitioned hybrid dynamic ammonia injection technology

combining with 485 bus communication mode of Modbus RTU and the external control system of Distributed Control System(DCS). The specific scheme is as follows: 1) SCR Control+ overall emission optimization control is adopted; 2) a system expert database is established to serve as the basis of the partition ammonia spray equilibrium control model

and the dynamic matrix control(DMC) optimization control algorithm is used to adjust the control law flexibly

so as to make the unit adapt to the change of the controlled object's characteristics and unit's operating conditions and calculate the output NOx of each partition. By using the deviation of feedback value and the variation rate of deviation between the partitions

the control set is set up and compared with the target

so as to correct the valve opening of each partition and achieve the goal of precise equalization control zoning. This system has been applied to a W-type flame boiler unit in a power plant in Hunan province

and the result shows that good effects have been achieved in reducing the amount of reducing agent and controlling ammonia escape.