Life cycle assessment and optimization of an iron making system with a combined cycle power plant: a case study from China
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In the steel industry, the iron making system deals with large quantities of materials and energy and so it can play a critical role in reducing emissions and production costs. More specifically, excess by-product gases should be used for electricity generation; otherwise, they lead to pollution. A life cycle analysis is performed to compare the environmental impact of an iron making system with a combined cycle power plant (CCPP), to a system producing the same amount of electricity in a coal power plant. The results for a Chinese steel plant show a 33% reduction in the energy conservation and emission reduction potential for the CCPP system, which is thus more environmentally friendly. A mathematical programming formulation is then proposed for optimal scheduling. It incorporates key technological constraints and is sensitive to hourly changing electricity prices. The outcome is a 19% increase in revenue from electricity sales compared to a schedule that does not dynamically adjust to the price profile. The results also show that emissions from by-product gases can be avoided completely. The paper ends with a sensitivity analysis to evaluate the impact of changes in product demand, gas storage and CCPP capacity, and emission cost.
KeywordsSteel industry Iron making system Combined cycle power plant Life cycle analysis Emission cost Mixed-integer linear programming
Lv Zhimin and Li Ting acknowledge financial support from the National Natural Science Foundation of China (Grant No. 51274043). Pedro Castro acknowledges financial support from Fundação para a Ciência e Tecnologia through the Investigador FCT Program and Project UID/MAT/04561/2013.
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