The connotation of the furnace automatic steelmaking can be divided into two levels: first level, instead of into the (hand) for oxygen, power supply and charging operation, smelting end automatically determine at the same time, will this level is still called automatic steelmaking; The second level, instead of into the optimization (brain) smelting process, such as power curve optimization, power optimization, oxygen blowing optimization, calls this level intelligent steelmaking. As a result, some intelligent electrical parameter adjustment and the control system, such as NAC IAF, AMIGE company SmartARC. SimeltNEC of the SIEMENS company, is by no means all of intelligent steelmaking. At present, the automatic electric arc furnace (smart) steelmaking technology also greatly lagged behind the converter steelmaking, the raw material with the former system more open and more diverse, the energy input is more complex, and process characteristics of cycle longer.
Electric furnace steelmaking control model is divided into static model and dynamic model.
Static model is based on the theoretical calculation of heat balance and material balance, or before the furnace data statistical analysis results to some model is established, and through the model to obtain a set of static smelting process curve. In the smelting process is always in constant change, especially the contemporary advanced electric arc furnace in such aspects as energy input, the structure of the main raw materials are more complicated, but for saving energy and reducing consumption, accurate judgement of smelting end put forward higher requirements, such as static model is obviously difficult to do. Dynamic model was built based on simple feedback control model. Dynamic control system including metallurgy process database, expert system and intelligent control model, the whole process of smelting, prediction and optimization.
In the electric arc furnace production, have a lot in common with the converter steelmaking process, the main difference between electrode control. Numerical and arc length to the power of electric arc furnace; When the electric furnace transformer secondary voltage must be related to arc equivalent resistance.
When electric furnace in the process of work, especially in the furnace charge culture period, arc discharge gap change, often leave the normal working state of all kinds of poor prone (from electrode with metallic short circuit break the arc until deviation) takes place continuously. The change of the length of the arc discharge inevitably leads to the change of the input power, which destroys the process specification. Therefore, the basic requirement for the work of electric arc furnace is the best power maintain norms of arc length. To keep constant arc length, but by means of continuous adjustment under each electrode arc gap length method to achieve. That is, adjusting the electric arc furnace power one of the most common method is taken by moving electrode position to change the arc length method.
The uneven due to melt in the furnace charge, electrical system, often have impact current and short circuit phenomenon. In this case, if you take a manual adjustment, the operator is difficult to do, In addition, if the number of electrode consideration together (three phase furnace with three electrodes) and large stove electrode weight problems, more difficult is manual adjustment. Therefore, must be equipped with electric arc furnace electrode lift automatic regulator. Arc furnace regulator regulate conditions and tasks is complex. When melting slag, arc length of a millimeter in not a very big range produces several megawatts of power. Many thousands of degrees, at this point, the arc temperature by molten metal under the electrode rapidly and melting, evaporation, splash violently, and arc moved to the nearby metal block. Therefore, arc length and arc current, and power changes constantly. When the current is less than the rating, less electricity into furnace, melting time long, power and electrode consumption are increased; And when the current is very large, even several seconds can make the line loss increases greatly, decrease input in furnace electricity and equipment of the indicators reduced. At this point, the arc length is
Short, especially when the electrodes in contact with the red heat or liquid metal can actually produce the metal suffer the risk of carburization, this kind of phenomenon in the smelting of various alloy are not allowed to occur. Visible, in the power of the electric arc furnace to maintain the best specification is a particularly difficult task, melting the steel quality and the utilization ratio of equipment are related to this.
Each phase electrode is equipped with a separate automatic regulator. The main part of the regulator including prime mover control electrode lifting and regulator ontology. Regulator is a kind of system is very sensitive to changes of the electrical equipment within the furnace, it according to the electric signal control electrode lifting the stove.