Interaction between electromagnetic, heat and mass transfer in metalurgical machinery
The electro-metalurgical devices are oftenly used for obtaining various kinds of metal alloys with given composition. The electromagnetic interaction, heat and mass transfer processes occur simultaneously in these devices during treatment and keeping the metal melted for further processing. The following kind of such type devices can be mentioned
- induction crucible furnaces;
- induction channel furnaces;
- induction furnaces with separated coolable crucible.
The electromagnetic interaction created by the inductor is mainly provided for transfer of heat energy to the melt. The heat energy appears by means of induced current. Simultaneously, the electromagnetic forces are acting on melt and conducting elements of device. These forces creates intense and turbulent melt motion with tendency to force back the conducting elements from the inductor. Therefore, the shape of conducting region can change in high power equipment:
- deformation of free surface of metal in crrucible furnaces;
- pinch effect in channel furnaces;
- the forcing back of melt in crucible furnaces with coolable crucible, etc.
The form of electromagnetic field cahnges essentially at the transformation of conducting material. Usually, it reduces the expedient coefficient. It also change the conditions for heat exchange with constructive elements od furnace. Hence, the intensity and character of melt flux of vary. Both the motion of conducting melt in magnetic field and change of conductivity caused by temperature revercibly influences in some extent the distribution of electromagnetic field and characteristic parameters of the equipment. The direct impingment of the exploitation is possible in high power furnaces, e.g.:
- outspoken deformation of free surface that creates instabilities;
- because of high velocities of turbulent flux of melt;
- because of pinch effect in channels of channel furnace.
Various other factors of this electromagnetic interaction can significantly reduce the lifetime of equipment, e.g.:
- because of chemical and mechanical erosion of refractory, that influences the flux intensity, temperature and melt contribution;
- deposition of various kinds of oxides that occurs due to previously mentioned factors.
Therefore, the analysis of electromagnetic, temeperature and velocity fields in these equipments plays significant role for development of technological processes, increasing of lifetime and efficiency. It is complicated to make experimental measurements at such a temperature and with high chemical activity of materials. Hence, the mathematical modelation could play a significant role. The laboratory has high experience and original methodics, and software are elaborated for electromagnetic, heat and mass transfer processes and their interaction. The mai n part of research consists of the formulation of essential factor for a given problem, and analysis of interaction type. The formulation must be such that the model accuratelly describes the interaction and is carryable for present hardware. The commercial packages (e.g., ANSYS, FLUENT) are used, too.
The results of research allows to give recomendations for projectation of high power effective metalurgical devices. Moreover, the model helps to understand the physical processes inside them.