Enhanced Heat Recovery From Electric Arc Furnaces: Optimization and Comparative Analysis of Steam and Organic Rankine Cycles

Abstract

In this study, two distinct approaches were proposed for recovering heat from the exhaust gases of electric arc furnaces (EAFs)—the steam cycle and the organic Rankine cycle (ORC). These methods were evaluated based on various criteria, including energy and exergy efficiency, economic feasibility, and environmental impacts. To identify optimal performance parameters, the effects of different working fluids in the ORC were examined, revealing significant variations in cycle behavior depending on the fluid used. Consequently, the most effective operational conditions for each specific fluid were identified and recorded based on temperature and pressure fluctuations. The analysis led to the selection of acetone as the optimal working fluid due to its favorable performance despite its high flammability, characterized by its isentropic nature. The energy and exergy efficiencies of the cycle using this fluid reached 21% and 61%, respectively, with a power output of 597.4 kW under maximum conditions. Additionally, the study demonstrated that, given the high temperature of the heat source, the steam cycle is more justifiable than the combined steam and ORC with the proposed configuration. The exergy efficiency of the steam cycle reached a maximum of 57%, with a net power output of 2897 kW and a total cost rate of $0.041/s under these conditions. Finally, by optimizing the steam cycle using a genetic algorithm, the ideal values for exergy efficiency were slightly reduced to 53%, with a significant decrease in the total cost rate to $0.036/s.