Evaluation of the efficiency of a ferrochrome plant with exergoeconomic analysis method

The iron and steel industry is the world's largest energy consuming manufacturing industry. Dependence on monopoly suppliers in natural gas and electricity is among the weaknesses of the sector. More efficient use of energy in this sector is very important to strengthen the competitiveness of the industry and to minimize environmental impacts such as greenhouse gas emissions. Within the scope of this thesis, cost-based mass optimization was carried out by thermodynamic analyzes of the electric arc furnace in which the metal smelting processes are carried out in a plant producing high carbon ferrochrome. Energy, exergy and exergoeconomic analysis methods were applied to the electric arc furnace in the mentioned facility. In addition to these analyzes, environmental impact analyzes of the electric arc furnace were also carried out. The energy efficiency of the electric arc furnace in the facility was calculated as 50,69% and the exergy efficiency as 46.49%. The energy losses in the electric arc furnace constitute 5.85% of the total energy entering the control volume, and the exergy losses constitute 20.39% of the total exergy input. Similar studies in the literature applied to the ferrochrome production process show that the exergy efficiency of this type of furnace varies between 40% and 60%. The unit exergy cost of ferrochrome was determined as 125.74 $/GJ, and the unit exergy cost of lost exergy was determined as 69.32 $/GJ. As a result of the environmental impact analysis, the resource reuse rate was 84.26%, the carbon dioxide production rate was 958.12 kg per ton of ferrochrome, and the sustainability index was 1.86. The results obtained from the exergy analyzes of the electric arc furnace were also supported by the results obtained from the exergoeconomic analysis and the results of the environmental impact analysis. By combining the exergoeconomic analysis and the exergy and cost concepts of the electric arc furnace, an idea is presented about which area the improvement studies should focus on. When the electric arc furnace is considered in terms of energy efficiency, it is clearly seen that there are areas for improvement as a result of the analyzes made.