The Design Of Dense Phase Pulverized Coal Injection Automatic Control System For Shougang Jingtang

Pulverized coal injection (PCI) in blast furnace is an important link in the ironmaking production process. The application of PCI not only reduces the coke ratio, decline the pig iron cost, but also provides a means for the blast furnace smelting furnace temperature adjustment. Therefore stable and reliable PCI control system is a means to achieve the efficiency of iron and steel enterprises, ensure blast furnace condition along the lines.The research object of this dissertation is dense phase PCI control system of 5500m3 blast furnace with tanks in parallel and dual series in Shougang Jingtang. The design and optimization of PCI control system for large blast furnace is studied to achieve automatic control and pulverized coal injection coal rate stability regulation based on the production process requirements, system configuration and equipment level. The main contents of this dissertation are as follows:(1) Analyzed the dense phase PCI process and the characteristics of the system configuration, and established the flow chart of control function according to the control functional requirements.(2) Proposed a compound control strategy including pulverized coal, the main air compensating tank pressure, and flow control in order to solve low control precision, lag adjustment of the traditional control strategy.(3) Proposed a coal injection rate control method for dual series PCI system based on tank weight change in order to solve the coal rate fluctuation problem caused by the inaccurate detecting value from the pulverized coal mass flow meter.(4) Designed hardware architecture and software program of the automatic control system of coal injection, developed the man-machine monitoring interface on the platform of rockwell automation PLC control system according to the control strategy and control function demand, and realized the pulverized coal injection automatic control and coal injection rate automatic adjustment.(5) Optimized coal injection rate selection, tank pressure stability and limit interlock program in order to solve problems of the detected coal rate fluctuation, coal pipe blocking and outage high after the operation of the system, and to achieve the accurate detection of the pulverized coal rate and coal injection system stable operation.The design and optimization of the control system in this dissertation solved the difficult problem of coal injection rate automatic adjustment for dual series PCI system caused by the detected values fluctuation of mass flow meter when the coal rate is high, and realized PCI system automatic control and the stabilize coal injection rate adjustment.Since put into operation, the control system is stable operation, quick response and high control precision. The PCI control system is stable and meets the control requirements when the maximum blast furnace coal injection capacity daily and the maximum blast furnace coal ratio achieves 113 t/h and 222.7 kg/t.Fe respective to guarantee daily output 13000 tons. The PCI control system has provided the safeguard for large blowing smelting blast furnace and has strong practicability.