MSc Thesis: Waste Heat Recovery from Aluminum Production
Miao Yu successfully defends his master's thesis
REYKJAVIK, February 9 – At the end of last month, MSc of Sustainable Energy Engineering and dual-degree student from Tianjin University, Miao Yu successfully defended his master’s thesis project on waste heat recovery from aluminum production. Throughout his work, Miao Yu was supervised by Dr. Guðrún Sævarsdóttir, Dr. María S. Guðjónsdóttir and Dr. PállValdimarsson from Reykjavik University, along with Dr. Jiansheng Wang from Tianjin University. Mr. Gestur Valgarðsson from EFLA engineering company was present as an examiner. The thesis work was funded by Alcoa Foundation .
According to Miao Yu, half of the energy consumed in aluminum production is lost as waste heat and approximately 30-45% of the total heat is eliminated with the exhaust gas. Alcoa Fjardaal, an aluminum production plant located in east of Iceland is one of the most modern and technologically advanced plants in the world with 350 000 tons per annum production capacity. However, such production comes with a 110 °C exhaust gas with 88.1 MW of heat.
Miao Yu’s project focuses on devising and comparing waste heat recovery models from the aluminum smelter exhaust gas. He proposed three scenarios: organic Rankine cycle (ORC) system for electric power production, heat supply system, and combined heat and power (CHP) system. For the ORC model, Miao Yu estimated that the maximum power output was 2.57 MW with an evaporation temperature of 61.22°C. For the same temperature drop, 42.34 MW was generated with the heat supply model. Additionally, the heat supply model could serve a dual purpose of district heating. The CHP system, on the other hand could provide 1.156 MW power and 23.55 MW heating capacity. From these results, Miao Yu then concluded that the highest energy efficiency was achieved by the heat supply model, while the maximum power output was obtained with the ORC model.
Miao Yu explained that the low temperature of the exhaust gas limits the efficiency of the ORC model. However, increasing the heat source temperature could solve such limitation. At 150 °C exhaust gas temperature, 9.17 MW power could be generated. Miao Yu’s work established that it is feasible to achieve an efficient waste heat recovery from aluminum smelters. To read more about his work, click on the following link.
Congratulations Miao Yu on an excellent thesis!