Multi-objective optimization applied to retrofit analysis: A case study for the iron and steel industry

Steel production is among the most energy-intensive industrial processes and is a very relevant source of CO2 emissions. Steelworks, like most process and manufacturing industries, are facing the complex challenge of minimizing CO2 emissions while improving energy efficiency and developing effective strategies for process optimization. To this end, Process Integration methods can be successfully applied to the integrated steelmaking route with the purpose of achieving a reduction in the CO2 emissions, while optimizing material and energy systems. The work presented in this paper is finalized at the development of a model for optimal exploitation of energy resources in integrated steelworks, through the application of multi-objective optimization techniques, which can be beneficial both in new design and as a retrofit. Using these techniques, a series of solutions can be found representing optimal trade-offs among different objective functions and the designer can select the best one or specify further criteria. Combining these methods, a retrofit was devised which optimized off-gas exploitation. This retrofit was then compared to the current operation.