Keywords: exergy analysis, steel electric arc furnaces, preheating, energy analysis, furnace efficiency, air infiltration, energy consumption, energy waste, stack gases, heat transfer, cooling water, exergy destruction, combustion
Exergy and energy analysis of an AC steel electric arc furnace under actual conditions
The energy and exergy analyses of an existing steel Electric Arc Furnace (EAF) are performed to estimate the potential for increasing the furnace efficiency. To obtain realistic results, the effect of air infiltration into the furnace was taken into account. The results of the analyses revealed that the energy and exergy efficiencies of the furnace are low and should be increased. The main sources of energy waste are stack gases followed by heat transfer to the cooling water, while the main sources of exergy destruction are combustion and heat transfer. Hot stack gases contain 18.3% and 12.2% of the total input energy and exergy, respectively. Increasing the air infiltration reduces the energy and exergy efficiencies of the EAF. By using the energy of flue gas to preheat the sponge iron, the electrical energy consumption of the furnace can be reduced by 89 GJ, dictating a 21.4% reduction in electrical energy consumption and a 13.6% increase in steel production.