Continuous charging control technology of electric arc furnace

The continuous charging experience of DRI and HBI proves that the new concept of electric arc furnace process control system proposed by Danieli Automation has achieved good results.

Since the entire smelting process can be monitored continuously from the preparation of the electric arc furnace to tapping, the control system can realize continuous charging management for different charge materials, including: DRI direct reduced iron hot and cold materials, HBI charge, even two kinds of charge can be loaded at the same time. The control system can divide the charging process into several steps so that it can gradually achieve the intermediate process goals.

In the charging step of the electric arc furnace, it can be further subdivided into different stages. Each stage represents a basic unit of the process. The entire smelting process can be divided into the following stages: electric arc furnace preparation, batch melting, DRI direct reduced iron continuous charging, refining, and tapping.

The process control system and the basic automation system continuously cooperate with each other to obtain real-time process data, and report parameter setting values (fixed values and calculated values), which includes power input, continuous charging and all other equipment conditions (modules, burning Mouth, oxygen lance, etc).

The end point control of each stage is realized by the relevant rules established according to the following process parameters: energy (electric energy, molten pool enthalpy), time (power supply time), electrode position (relative to the arc point).

DRI direct reduced iron charge is changing to keep the molten pool within a predetermined temperature range. Then gradually increase the temperature of the molten pool to reach the required tapping superheat.

At the end of the continuous charging, the refining phase begins. During the refining process, the key parameter of the molten pool temperature will be continuously monitored until the tapping.

The target molten pool enthalpy is determined according to the weight and type of charge. The current enthalpy estimate is based on the energy balance model. The model can calculate the difference between the input energy (electrical energy and/or chemical energy) and various energy losses (heat radiation, heat taken by the flue gas, and electrical energy loss) at intervals. According to the current thermal state of the molten pool, the process control system can predict its theoretical average temperature. In particular, the continuous repeated calculation of the continuous charging amount is based on the extrapolation of these calculation results as a basis for repeated iterative predictions of molten steel in the next few minutes.

This new electric arc furnace process control method has the following remarkable features and advantages: It can improve the accuracy of process control, and by linking the energy input with the charged charge, it can reduce the energy consumption per ton of steel without affecting the quality of molten steel; The balance model can automatically optimize the recovery of various power failure delays; it can predict the future thermal state of the molten pool, thereby optimizing the control of continuous charging; it can predict the tapping time, thereby optimizing the management of the tapping process, and making it compatible with subsequent refining The equipment is kept synchronized; the difference between the actual tapping temperature and the target temperature is reduced, thereby improving the ladle refining process.