Identification of main influencing factors of life cycle CO_2 emissions from the integrated steelworks using sensitivity analysis

摘要

The amount of CO_2 emissions from steelworks accounts for a great share of the total CO_2 emissions from industry in China. Thus, reducing CO_2 emissions from steelworks is urgent for China's environmental protection and sustainable development. This study aims at identifying factors that influence CO_2 emissions from steelworks and proposing measures to reduce CO_2 emissions. The life cycle inventory (LCI) of iron and steel products implies the relationship between the CO_2 emissions of the steelworks and the input variables of the LCI. The Tornado Chart Tool is utilized to calculate the variation of CO_2 emissions caused by the change of each input variables of LCI. Then, mean sensitivity of each input variable is calculated and the ranking criterion developed is used to identify the main factors influencing the integrated steelworks. Subsequently, measures for reducing CO2 emissions are proposed. The results indicate that the very important influencing factors of CO_2 emissions in steelworks are the CO_2 emission factor of Blast Furnace Gas (BFG), liquid steel unit consumption of continuous casting, continuous casting slab unit consumption of hot rolling and hot metal ratio of steel making. Consequently, many efficient measures for reducing CO_2 emissions have been proposed, such as removing CO_2 contained in BFG, decreasing the hot metal ratio of Basic Oxygen Furnace (BOF), recycling BFG, optimizing the products' structure, etc.