Design Of Control System And Research On Control Method For Three-phase Slag Melting Furnace

The slag melting furnace can be applied to not only the ingredients production for the premelting slag but also the auxiliary production in supply of the melting slag for Electroslag furnace. Under the limitation to the technical level, many of controlling systems of slag melting furnaces apply the jog control. And they are produced by the workers’experience, so the control precision is not high and the slag effect is not good. Because of strong coupling among three electrodes, three electrodes are very difficult to keep stable which Seriously affects the process of melting slag.In a word, to study and design high level controlling systems of the slag melting furnace is the best and important way to improve the effect of slag melting furnaces.In this dissertation, considering the quality demands of the melting slag and the technology renovation for the melting slag controlling, with the construction project of1.6tons three-phase slag melting furnace which is used to supply melting slag for two25tons electro slag furnaces in some steel mill, the computer controlling system is developed. This system is the changeable neural network with decoupling and control functions and the core of the PLC controller. The whole system adopts the structure of the superior computer and the inferior computer. The hardware of the superior computer is composed by two sets of industrial computers of Advantech, which has the ability of using and spare using. The software adopts the superior configuration software of Siemens Company, which can fulfill monitoring during the production process of the slag melting furnace. And it can monitor the relative dates during the whole process of melting slag and the alarm informatioa. The hardware.of the inferior computer is composed by S7-300PLC of Siemens Company and the software adopts STEP7programme, which can finish the whole process controlling during the process of slag production. The whole net structure of the controlling system adopts the Industrial Ethernet to connect the superior computer and the PLC program.This dissertation states the process of melting slag and the composition of the three-phase slag melting furnaces in order to solve the coupling among three-phase during the production process of the three-phase slag melting furnaces and to establish a coupling mathematical model among three-phase to explain the existence and extent of the coupling of three-phase slag melting furnace. After the analysis of several controlling strategies, the controlling strategy of invariable drag resistance is adopted. Since the three-phase slag melting furnaces is changeable, nonlinear and strong coupling, the MPIDNN control arithmetic is adopted in order to decoupling control among three-phase of main circuit during the production process of melting slag. This method is established in theory and gets the good effect of simulation, which make it have the practical application value.