AUTOMATED CALCULATIONS IN THE DEVELOPMENT OF ENERGY-EFFICIENT DESIGNS OF FURNACES FOR ALUMINUM SCRAP REMELTING

Abstract

The analysis of operational thermal conditions of the furnaces for aluminum scrap remelting is given. It was established that it is necessary to choose refractory materials with aluminum oxide content more than 85 % and the thickness of the thermal insulation should ensure the temperature of the external surfaces not higher than 50 °C when designing the furnaces for lining. On the basis of relevant methods packages of application programs have been developed for design calculations of lining and thermal insulation considering thermal conductivity change of individual layers as a result of their complete or partial impregnation with molten aluminum; calculations of energy balances; the selection of external heating devices with electric or flame heating. The power of the external heat source, the amount of heat spent on heating the scrap to the melting temperature, melting and overheating the melt to the working temperature and heat loss have been taken into account in the energy balance. The heat balance equation is used for determination of the melting time for electrically heated furnaces or the power of burner devices at the desired melting time. In the design calculations, the necessary thicknesses of lining and heat-insulating materials are chosen for all elements of enclosure. With appropriate calculations in dialog mode, it is also possible to change materials and their thickness quickly in case of exceeding the allowable operating temperatures of these materials. Options of using electric tape or wire heaters made of nichrome or EI-626 steel were considered during external heating devices calculations. Flame heating can be implemented using gas burners or liquid fuel nozzles. Further variant calculations based on the developed methods and software made it possible to create a furnace design with a capacity of 600 kW with reduced energy and operating costs for the melting process. Bibl. 14, Fig. 1, Tab. 1.