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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 × 10 8 -6.17 × 10 8 tons of CO 2 that needs to be reduced by additional measures., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Due to high material density, high energy consumption density and CO 2 emission density, it is not only difficult but significant to clarify the relationship between energy consumption, the CO 2 emission and the production cost in different conditions. However, the previous researches rarely refer how to balance the energy consumption, the CO 2 emission and the production cost after the fluctuation of material, energy and carbon price as well as what will happen to them if production structure changes. Therefore, based on the conservation law of mass and energy, to study iron and steel manufacturing process (ISMP), this paper, taking carbon price into consideration, establishes a muti-optimization model of energy consumption, CO 2 emission and cost. After optimization with different objectives, the production cost per tonne of crude steel is reduced by 192.03 CNY (7.71%), the CO 2 emission per tonne of crude steel is reduced by 224.22 kg (13.37%), and the energy consumption per tonne of steel is reduced by 51.20 kgce (9.10%). Moreover, based on the optimization results under different objectives, it is ironmaking process (coal ratio and ore ratio) and steelmaking process (amount of scrap steel) that has more impact on three above as well as ore blending and coal blending have a great influence on production cost but little effect on energy consumption and CO 2 emission., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Exploring theoretical energy consumption introduces a fresh perspective for energy-saving research within the iron and steel industry, with a primary focus on the energy expended during material transformation. Building upon the theory of theoretical energy consumption, this study meticulously investigates the theoretical energy consumption associated with each stage of the iron and steel making process, including coking, sintering, pelletizing, ironmaking, steelmaking, and hot rolling. The findings reveal that, under specific conditions, the theoretical energy consumption for each process is as follows: coking (2.59 GJ), sintering (1.36 GJ), pelletizing (1.02 GJ), ironmaking (8.81 GJ), steelmaking (−0.16 GJ), and hot rolling (0.76 GJ). Additionally, this study delves into the analysis of influencing factors on theoretical energy consumption. Using the coking process as an illustrative example, it is observed that the theoretical energy consumption in coking decreases with a reduction in both moisture and volatile content in coal. Under the specified conditions, the minimum theoretical energy consumption for each process is as follows: coking (2.51 GJ), sintering (0.98 GJ), pelletizing (0.67 GJ), ironmaking (8.38 GJ), steelmaking (−0.58 GJ), and hot rolling (0.07 GJ), respectively. This comprehensive analysis serves as a valuable resource for advancing sustainable practices in the iron and steel industry. [ABSTRACT FROM AUTHOR]

Evaluating the energy efficiency of the iron and steel smelting route is of vital significance to achieve energy saving and consumption reduction. By establishing an input‐use‐end model, a new index is put forward herein to evaluate the energy utilization of the iron and steel smelting route—energy utilization efficiency. Furthermore, energy utilization efficiency of a typical iron and steel smelting route is analyzed based on the established network diagram. The results show that 1) the cleaned coal is the largest energy input in the whole route, which is 14 460.4 MJ, followed by injected coal. 2) About 57.6% of primary energy is converted into byproduct gases and 31.7% of that is converted into various waste heats. 3) The energy loss of the whole route is 9583.8 MJ, of which the direct loss, indirect loss, and internal loss are 2630.8, 5366.9, and 1586.1 MJ, respectively, accounting for 14.5%, 29.5%, and 8.7% of the total purchased energy. 4) The energy utilization efficiency of the whole process is 47.6%. 5) Improving energy recovery is the most effective measure to improve energy utilization efficiency instead of degrading energy input and changing product structure. [ABSTRACT FROM AUTHOR]

The integrated optimization and analysis of material and energy flows are effective ways to reduce energy consumption and costs in the iron and steel sector. There is still a lack of research on the multi-objective optimization of the integrated steel production process and the auxiliary energy process. To fill this gap, this paper presented a single- and multi-objective optimization model for material and energy scheduling and utilization of the steelworks. This model considered physical and chemical conversion mechanisms in the production process, as well as operating characteristics and production-consumption relations of equipment in the gas-steam-electricity network. The objective function was constructed using comprehensive energy consumption (CEC) and economic cost (EC), and fuzzy sets were used to find a compromise solution and the trade-off operation strategies between the two goals. The CEC and EC effectively dropped by 5.09% and 7.29%, respectively, in comparison to the actual enterprise value, through the optimization of the material ratio, product structure, energy utilization, and other parameters of the steelworks. Additionally, a quantitative analysis of the effects of variables such as the ratio of pellets, the ratio of scrap, the hot charging temperature of the slab, and the utilization of surplus gases was conducted. • A single- and multi-objective optimization model for material and energy scheduling and utilization is proposed. • The compromise solution of energy consumption and economic multi-objective optimization is found. • Influence of material and energy flows on variation in multi-objective is discussed. • Highly efficient and cost-effective modes of using surplus gases are explored. [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]

• A novel assessment method is proposed to increase benefits of manufacturing systems. • Networks of material, energy, environment and economic are thoroughly considered. • The comprehensive value flow is presented considering the exergy of energy. • Feasible suggestions are therefore proposed to improve the performance in energy and economic. • It is confirmed efficient in following case study with dramatic improved comprehensive benefits. The comprehensive assessment of the performance of production system is a crucial activity for the implementation of sustainable production practices for the manufacturing industry. The existing relevant assessment methods are not comprehensive enough, especially in terms of material, energy, environment and economics. They lack specific economic performance indicators based on industrial systematic analysis, and couldn't give a clear explanation for the comprehensive value flow in the production process. This paper proposes a novel assessment method, called Comprehensive Value Flow Analysis, which aims to describe and classify activities in the network of material, energy, environment and economics according to systematic energy saving and lean production theory. The drawing method of comprehensive value flow and a new cost-benefit indicator named advanced cost-profit ratio are proposed for identifying quantitatively the criticalities related to activities, processes, systems, technologies, etc. And significant suggestions for the improvement strategies implementation are given. A case study of a typical iron and steel enterprise has been evaluated using this method. Moreover, it successfully identifies the issues about energy structure, production structure and technologies application with a global perspective by explicating the comprehensive value flow and analyzing the relevant indicators, and then offering some valuable suggestions for sustainable development. The analysis highlighted that every enterprise has its own marginal benefits according to the production status and market economy. In summary, it is favorable to make real and effective decisions on improvement for the comprehensive benefits of enterprises. [ABSTRACT FROM AUTHOR]