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Reducing CO 2 emissions of the iron and steel industry, a typical heavy CO 2 -emitting sector, is the only way that must be passed to achieve the 'dual-carbon' goal, especially in China. In previous studies, however, it is still unknown what is the difference between blast furnace-basic oxygen furnace (BF-BOF), scrap-electric furnace (scrap-EF) and hydrogen metallurgy process. The quantitative research on the key factors affecting CO 2 emissions is insufficient. There is also a lack of research on the prediction of CO 2 emissions by adjusting industrial structure. Based on material flow analysis, this study establishes carbon flow diagrams of three processes, and then analyze the key factors affecting CO 2 emissions. CO 2 emissions of the iron and steel industry in the future is predicted by adjusting industrial structure. The results show that: (1) The CO 2 emissions of BF-BOF, scrap-EF and hydrogen metallurgy process in a site are 1417.26, 542.93 and 1166.52 kg, respectively. (2) By increasing pellet ratio in blast furnace, scrap ratio in electric furnace, etc., can effectively reduce CO 2 emissions. (3) Reducing the crude steel output is the most effective CO 2 reduction measure. There is still 5.15 × 108-6.17 × 108 tons of CO 2 that needs to be reduced by additional measures. [ABSTRACT FROM AUTHOR]

Application of energy saving and consumption reduction technologies in the iron and steel industry (ISI) is an effective way to achieve sustainable development. As the highly energy‐consuming ironmaking system is an important part of steel production, reducing its exergy loss is of great significance for overall energy saving in ISI. The optimization model of the ironmaking system is established in this study based on the law of conservation of mass and the second law of thermodynamics. For the target of minimum exergy loss, material and energy systems of ironmaking are optimized and analyzed. Factors that influence the ironmaking system are further discussed. The results show that the minimum exergy loss of the ironmaking system is 4605.80 MJ t‐HM−1 by improving operation conditions. Among them, 51.15% of the total exergy loss is contributed by the blast furnace ironmaking process. [ABSTRACT FROM AUTHOR]

Summary: To promote the sustainable development of the iron and steel industry (ISI), evaluation methods and influencing factors of energy efficiency have been studied in the past decades. A systematic review of these methodologies and influencing factors is presented in this paper. Initially, this paper states the development, current situation, and energy consumption of the world's ISI. Then, the definition of energy efficiency is described. After that, the evaluation methods are categorized as single‐factor methods (including these indicators of thermodynamic, thermos‐physical, thermo‐economic, and economic) and multifactor methods (including parametric and nonparametric methods). Furthermore, typical evaluation methods are highlighted. Thermal analysis method and exergy analysis method are routinely combined to optimize the energy utilization. Data envelopment analysis (DEA) and stochastic frontier analysis (SFA) are widely concerned and well developed to gain a better economic benefit. Malmquist index method is often associated with DEA to analyze the technical process and return to scale. Some emerging methods are proposed, for example, the three‐stage DEA method together with DEA and SFA. Finally, the influencing factors of energy efficiency in the ISI are discussed, including industrial structure, technological level, energy consumption structure, price, and so on. It is suggested that optimizing energy structure and improving technology level are effective measures to improve the energy efficiency in the ISI. [ABSTRACT FROM AUTHOR]

Improving energy efficiency of the iron and steel manufacturing process (ISMP) plays a vital role in saving energy and reducing CO 2 emissions. However, there is currently a lack of research on assessment method and improvement rules of energy efficiency of the ISMP. In addition, the impact of energy efficiency on CO 2 emissions and energy consumption is rarely mentioned in previous studies. To fill this gap, this study establishes an assessment and optimization model of energy efficiency, energy consumption and CO 2 emissions in the ISMP. Taking material parameters, process parameters and reaction conditions as constraints, this study optimizes a practical ISMP with maximizing energy efficiency as the optimization goal, and further analyze energy consumption and CO 2 emissions of typical ISMP. After optimizing, energy efficiency of the ISMP is increased from 64.00% to 68.20%, energy consumption of the ISMP is reduced from 15.76 GJ/t-steel to 12.31 GJ/t-s, and the CO 2 emission of the ISMP is reduced from 1215.2 kg/t-steel to 815.3 kg/t-s. It is found that injected coal ratio of blast furnace, charge structure of blast furnace, iron-steel interface and casting-rolling interface have a greater impact on energy efficiency, energy consumption and CO 2 emission of the ISMP. • The optimization model of energy efficiency of the iron and steel making process is established. • The optimal energy efficiency of a typical steel plant is given. • Energy efficiency, energy consumption and CO 2 emissions are jointly analyzed. • The influencing factors of energy efficiency, energy consumption and CO 2 emission are discussed. • The iron-steel interface and casting-rolling interface are considered. [ABSTRACT FROM AUTHOR]

Energy efficiency is an extremely important indicator for exploring energy conservation and consumption reduction. The traditional energy efficiency assessment methods for process industry lack an in-depth thinking on energy utilization of the whole system. Based on the proposed required energy, this paper established an energy efficiency assessment method for process industry. By establishing material and energy flow networks, energy efficiency of typical iron and steel manufacturing process (ISMP) is analyzed and its influencing factors are discussed. The results found that the required energy of coking, sintering, pelletizing, blast furnace iron-making, basic oxygen furnace steel-making and steel rolling are 2626.2 MJ/t-coke, 1122.9 MJ/t-sinter, 992.3 MJ/t-pellet, 9781.5 MJ/t-hot metal, 393.95 MJ/t-molten steel and 445.3 MJ/t-steel products, respectively. The energy efficiency of typical ISMP is 66.9%. The energy efficiency of the ISMP can be effectively improved by adjusting the steel ratio, recovering waste heat and residual energy, and developing interface technologies. • Energy efficiency assessment method of process industry is proposed and established. • The material and energy flow networks of iron and steel manufacturing process are established. • The required energy of iron and steel manufacturing process is analyzed and given. • Energy efficiency of typical iron and steel manufacturing process is evaluated and given. • The influencing factor of energy efficiency is discussed. [ABSTRACT FROM AUTHOR]