Design Of Process Control System Of A Rotary Klin Process For Nickel Iron Production

Rotary kiln process is an important part of nickel-iron production, whose operationefficiency and burning quality directly affects the cost and quality of the production ofnickel-iron. Material goes through the drying, heating and roasting process in the rotary kiln toproduce crude nickel-iron, which is a multivariable, strong coupling, large time delay andtime-varying nonlinear system. The control of most rotary kiln is traditional manual, limited tothe different operation level, the rotary kiln is difficult to achieve a stable and good control. Inorder to ensure continuous and stable operation of the rotary kiln, improve the rotary kilnburning quality, reduce the cost of the rotary kiln roasting, the study of automatic control hasbecome an important research topic.We have studied the production of nickel-iron rotary kiln process, the movement ofmaterial in the rotary kiln and the retention time and chemical reaction mechanism. Then thenickel-iron rotary kiln control requirements are put forward. Last, the control variable andcontrolled variable and disturbance variable are determined. We studied the nickel-iron rotarykiln control difficulties and designed a control program. The program puts forward the roastingmaterials temperature, oxygen content and kiln tail temperature as control objectives of therotary kiln. Based on the operating conditions identification, the intelligent sampling and PIDcontrol system are designed. At the same time, we design a ratio controller for the difficulty ofcoupling.The input variables of the nickel-iron rotary kiln include roasting materials temperature,kiln inlet temperature and pressure, oxygen content, kiln head temperature and pressure, theoutput variables include coal flow, natural gas valve opening and secondary valve opening. Thecontrol procedures include data processing module, the conditions recognition module,incremental PID module, intelligent sampling control module and ratio module etc. Thereal-time value of the rotary kiln system parameters and trend are analyzed to give the finalcontrol output.The composite control of the nickel-iron rotary kiln includes intelligent sampling controland incremental PID control. Combined with the rotary kiln relevant parameters trends andreal-time values, intelligent sampling control called "wait-watch-adjust” can adjust the output change for the strong disturbance, large time delay rotary kiln process. Incremental PIDeliminates the steady state error in the small bias, which adopts integral separation PID controlto avoid a large overshoot and ensure the control precision.When the rotary kiln is in stable conditions, in the case of other conditions remainunchanged, we collect a nickel-iron rotary kiln data. Then the mathematical model of kiln tailtemperature, oxygen content and burning zone temperature can be obtained through the MatlabSystem Identification Toolbox. The dynamic model of the rotary kiln process is compiled byCBF configuration software of ABB, the control program is established by SCL language ofSiemens software. At last, we use OPC communication to build the connection.The basic automation part of the control system includes network architecture andhardware configuration, the design of WINCC and STEP7program, Siemens profibuscommunication, industrial Ethernet communication and OPC communication. The controlalgorithm is programmed by siemens SCL language. The rationality and practicability of theautomatic control program is verified by dynamic simulation.