Modeling of Electric Arc Furnaces ( EAF ) with electromagnetic stirring
Electromagnetic stirring can play an important role in modern Electric Arc Furnaces (EAF), as they often operate far from equilibrium conditions, with tap-to-tap times of 45 minutes or less, high electric power input and significant energy additions from fuel and oxygen. Numerical modeling is used extensively in ABB’s current efforts to optimize the EAF process with electromagnetic stirring. The modeling approach uses a Finite-Element method (FEM) for computing the forces generated by the electromagnetic stirrer, whereas the resulting flow properties, heat and mass transfer in the system is computed using a Finite-Volume (FVM) flow solver. The paper presents the numerical model in greater detail and discusses some important results. We show that electromagnetic stirring gives a more than ten-fold increase of flow velocities and circulation, compared with a flow driven by natural convection alone. The global circulation created by electromagnetic stirring dramatically reduces temperature differences in the melt, thus reducing super-heating of the melt surface and risks for cold regions. Efficient mixing of chemical species, together with even temperatures, is beneficial for efficiency and controllability of the chemical reactions in the slag-metal interface.
Pragmatic analysis of the electric submerged arc furnace continuum
A transient mathematical model was developed for the description of fluid flow, heat transfer and electromagnetic phenomena involved in the production of ferronickel in electric arc furnaces. The key operating variables considered were the thermal and electrical conductivity of the slag and the shape, immersion depth and applied electric potential of the electrodes. It was established that the principal stimuli of the velocities in the slag bath were the electric potential and immersion depth of the electrodes and the thermal and electrical conductivities of the slag. Additionally, it was determined that, under the set of operating conditions examined, the maximum slag temperature ranged between 1756 and 1825 K, which is in accordance with industrial measurements. Moreover, it was affirmed that contributions to slag stirring due to Lorentz forces and momentum forces due to the release of carbon monoxide bubbles from the electrode surface were negligible.
Analysis of Velocity and Temperature Fields of Molten Metal in DC Electric Arc Furnace
Recently some small scale industries have started using DC electric arc furnace to recycle scrap materials, however modelling and simulation data are very limited in the literature. Therefore, it appears that a numerical simulation could provide many important components for predicting suitable operating conditions, better design and efficient control of the process. With this objective, a numerical simulation model is developed under certain simplifying assumptions. A SIMPLER algorithm is used to solve the model equations.Computed results show that the circulating patterns and the patterns of increasing the temperature of the melt are significantly affected by the change in bottom electrode diameter and these calculated results present very important information. For example, a furnace can be designed in such a way that the melt temperature can be increased uniformly throughout the bath which is very important for making homogeneous alloys. It is also found that the effect of natural convection on melt circulation is negligible, that is, circulation is totally controlled by the electromagnetic force field. In addition to the flow field data, data obtained from the electromagnetic field computations are also presented.