Stirring improves the heat and mass transfer, which significantly benefits the furnace operation in a number of different ways. It accelerates the dissolution rate of scrap and alloy additives, which reduces the furnace cycle time. In addition, stirring decreases the temperature stratification between the liquid metal surface and the bottom, thereby improving the ability to introduce more heat into the furnace. The energy efficiency is improved, giving a potential for energy savings. The surface temperature is lowered, which reduces the dross formation. Considerable improvements in productivity and large cost savings can be achieved, giving a short payback time.
Increased productivity
Plant results show productivity improvements of up to 40 percent.
Figure: Reduced cycle time for a 90-ton melting furnace.
Reduced dross formation
Plant data show dross reductions of between 15 and 50 percent
Reduced energy consumption
AL-EMS improves the energy efficiency by increasing the ability to introduce more heat into the furnace and by allowing for reduced door openings for manual stirring.
Improved chemical and hermal homogeneity
AL-EMS gives perfect chemical and thermal homogeneity in the liquid metal.
Reference measurements made on a 32-ton rectangular furnace with bottom- mounted stirrer.
AL-EMS gives:
- Complete homogenization of temperature stratification within 2-3 minutes
- Lower surface temperature, which reduces the dross formation
Reduced maintenance
The AL-EMS stirring coil does not contain any movable parts. Nor is it exposed to liquid metal. These two features give a very reliable system and a low maintenance. In addition, the reduced need for mechanical stirring or the replacement of a heavy mechnical stirring system with its associated maintenance needs with an AL-EMS system, can further reduce the overall maintenance.