Search

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]

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]

To solve the unreasonable energy distribution and excessive energy waste in the steam system of iron and steel (I&S) industry, a mixed integer linear programming model based on the theory of exergy and energy level is developed in this study to optimize the steam system. After optimization, the utilization potential of waste energy is found. Then, several waste energy recovery technologies are compared according to their application results. The results show that the exergy efficiency of steam system is 74.065%. After optimization, the exergy efficiency of steam system is increased by 10.568%, the energy input of the I&S enterprise is reduced by 84.30 MJ t−1‐CS−1, and waste energy potential is found at hot rolling, sintering, and converter. Herein, flue gas waste heat from hot rolling and sintering is recovered using series two‐stage Organic Rankine Cycle with cyclopentane as the working fluid, and steam waste energy from converter is recovered using saturated steam power generation. These waste energy technologies increase the electricity generation of I&S enterprise by 15.25 kWh t−1‐CS−1. Overall, combining the optimization model with the use of waste energy recovery technologies is necessary and effective for I&S enterprise to increase their energy efficiency. [ABSTRACT FROM AUTHOR]

Improving energy efficiency has been widely recognized as a direct, efficient, and cost-effective approach to advancing energy conservation, reducing emissions, and achieving sustainable development. While there are numerous and effective methods to enhance energy efficiency in a typical steel manufacturing system, they are relatively scattered and independent, lacking a systematic review for multi-level, comprehensive and scientific evaluation and improvement of energy efficiency within the steel industry. To fill this gap, this work initially presents an overview of the component units and energy networks within steel production system. Subsequently, a comprehensive review and analysis are conducted from multiple perspectives, such as energy evaluation, diagnosis, benchmarking analysis, optimization, and energy-saving measures. Each part meticulously selects the literature through content evaluation analysis to discuss methods, technologies, and models for improving energy efficiency, along with potential challenges that need to be overcome for future advancements. Furthermore, the paper examines the diverse challenges encountered by steel manufacturing in realizing energy efficiency improvements and exploring energy-saving potential. It also underscores the corresponding future developmental direction, including the construction of multi-level evaluation systems, implementation of intelligent energy efficiency improvement methods and technologies, and adoption of intelligent energy systems crucial for intelligent analysis and manufacturing in steel sector. • Energy efficiency improvement methods within the steel production sector are comprehensively reviewed. • Multi-level energy efficiency evaluation methods for the steel production are summarized. • Advances in energy efficiency diagnosis, benchmarking analysis, optimization and energy-saving technologies are summarized. • Challenges and prospects for energy efficiency improvement in steel sector are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exergy loss of enterprise is optimized by building mathematical programming model. • Influences of 9 key factors on system's total exergy loss and cost are discussed. • Recovery and utilization of waste heat are optimized by detailed technical models. • Waste heat potential and heating capacity of enterprise are evaluated. • Interface loss between upstream & downstream processes is quantified by exergy. A substantial quantity of waste heat resources generated in iron and steel manufacturing process (ISMP) can fulfill certain demand for urban heating. However, the waste heat utilization level of different iron and steel enterprises varies a lot and few studies have combined the upstream enterprise's production with downstream waste heat utilization for discussion. By establishing an optimization model based on material balance, thermodynamic laws and reaction mechanism of the ISMP, this study firstly obtain the minimum exergy loss and the corresponding production cost ＆ exergy efficiency. The total exergy loss of ISMP is reduced from 8413.19 MJ/t-MS to 7669.27 MJ/t-MS. The exergy efficiency of the whole process is increased from 63.75 % to 65.46 % and the total waste heat potential reaches 1471.25 MJ/t-MS. It is found that coke ratio, air leakage rate, scrap steel ratio, etc. have great impact on exergy loss of ISMP. Then, the optimization and evaluation of the waste heat utilization are carried out by establishing models with taking urban heating into consideration. The available external heat supply is 813.15 to 853.55 MJ/t-MS and the enterprise's heating load can reach 229.23–251.47 MW, which allow to supply heat for an area of 5.46–5.93 million m2. Finally, the problem of waste heat instability in the heating process is briefly discussed and some solution strategies are proposed to overcome this defect. [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]

Abstract As one of the energy-intensive and high-polluted industries, steel industry is facing great challenges of energy-saving and emission reduction. In this study, a bottom-up approach is used to build the inventory of air pollutants in China's steel industry. We analyzed the temporal and spatial characteristics of the atmospheric emission inventory of China's steel industry. The results show that: (1) In 2015, the total amount of SO 2 , NOx, PM, PM 2.5 , PM 10 and PCDD/Fs emissions from Chinese steel industry were 1697.58kt, 1017.24kt, 4028.01kt, 849.02kt, 1330.53kt and 1216.83g I-TEQ, respectively. SO 2 , NOx, PM, PM 10 and PCDD/Fs emissions mainly came from the sintering process, and PM 2.5 came from the converter process. (2) NOx emissions show an "upward" trend, while SO 2 emissions depict a "slowdown" trend. PM, PM 2.5 , PM 10 and PCDD/Fs emissions present inverse U-shape trends. (3) The air pollutant inventory of Chinese steel industry indicates obviously spatial characteristics. Taking SO 2 emissions in 2015 as an example, SO 2 emissions from steel industry in North China and East China reached 1006.63kt, accounting for 65.2% of the total emissions. Hebei, Jiangsu and Shandong provinces where locate intensive traditional steel enterprises with majority of steel products generated SO 2 emissions of approximately 404.04kt, 171.83kt and 156.28kt respectively, accounting for 23.80%, 10.12% and 9.20% total emissions of China's steel industry. (4) The simulation model of air pollutants (SO 2 , PM) was established taking adjusted production capacity and layout of steel industry into consideration, the simulation suggests that SO 2 and PM emissions are projected to decrease by 1Mt, 2 Mt, respectively. [ABSTRACT FROM AUTHOR]

Steel industry is an important mainstay industry and key greenhouse gas emitter of China. Employing life cycle assessment method of cradle-to-gate and establishing material flow model for steel production processes, this paper analyzed carbon footprints of steel enterprises to reduce carbon emission efficiently. Taking the function of forest to capture carbon into account, carbon footprint was expressed as the forest area instead of carbon dioxide equivalent (CO 2 e). Taking five typical steel enterprises (J, A, T, N, B) in China as examples, the carbon footprint per ton of steel in each process was calculated and its influence factors were analyzed. Results show that (1) from the perspective of process, the carbon footprint of iron-making, in which a large amount of coke and coal is consumed, is the largest, followed by the process of coking and sintering; (2) analyzing the type of gas, CO 2 contributes over 70% of the total carbon footprint in the whole production process; (3) the average carbon footprint per ton of steel was 0.325 hm 2 /t. Among five companies, carbon footprints of company N were up to 0.342 hm 2 /t, while company B had the lowest carbon footprint, at only 0.291 hm2/t. The gaps of carbon footprint are mainly due to geographical differences, energy consumption construction and product equipment and technology. The carbon footprint of enterprises was compared with the local carbon capacity, and analysis results show that the steel output and local forest areas could be significant factors determining whether the carbon emissions discharged by steel mills exceed the local carbon capacity and cause environment problems. According to analysis results, corresponding opinions and policies were proposed. [ABSTRACT FROM AUTHOR]

Intensive energy consumption and high pollutant emission have always been the obstacles for achieving the sustainable development of the iron and steel (I&S) industry. The complex material flows, energy flows and emission flow of I&S industry require better assessment to implement comprehensive governance and impact analysis. The 48-month data of a typical I&S enterprise is used for evaluating intensities and analyzing influencing factors from the perspective of material, exergy and emission networks. The results show that the exergy intensity and carbon emission intensity of the whole site including main processes and auxiliary processes are 23.804 GJ/t-CS and 1642.7 kg/t-CS, respectively. In particular, auxiliary process plays a critical role, whose exergy loss accounts for about 28.85% of the total. The terms of energy structure, technology capacity, product structure and environmental conditions are considered to analyze on the influencing factors of the case, and then providing relevant suggestions. On the whole, integration assessment of material-exergy-emission networks of I&S industry is necessary and helpful to find their changes and migration, and to further implement energy management and emission reduction. • Material-exergy-emission network is analyzed for the whole iron & steel enterprise. • The data of main and auxiliary processes with time granularity are analyzed. • The intensities of energy, exergy and emission of various products are presented. • The influencing factors for the material-exergy-emission network are discussed. [ABSTRACT FROM AUTHOR]

The development of hydrogen metallurgy holds enormous significance in facilitating the low-carbon and environmentally sustainable transition of iron and steel industries. However, there is a lack of research on the impact of implementing hydrogen metallurgy on the downstream process and even the whole process. To fill this research gap, a model that considers specific internal reactions of steelmaking process was developed utilizing the bottom-up approach. Subsequently, by integrating the hydrogen metallurgy process with the traditional long process and short process, the energy intensity, exergy intensity and carbon emission intensity were quantitatively analyzed from multiple viewpoints. The results of the basic oxygen furnace (BOF) and electric arc furnace (EAF) exhibit a degree of similarity, with an increase in directly reduced iron (DRI) addition, resulting in an insufficient heat and an increase in process energy consumption, exergy loss, and carbon emissions. But there are also some subtle differences, such as oxygen consumption. Following the integration of hydrogen metallurgy, the energy intensity and exergy intensity of the BF-BOF process increase 11.984 kgce/t-CS and 3.083 × 102 MJ/t-CS, respectively. However, the carbon emission intensity decreased by 46.514 kg/t-CS. The integrated Chinese-style short process has the lowest carbon emission intensity of 879.664 kg/t-CS at 40% DRI and 60% scrap. Nevertheless, the energy intensity and exergy intensity have increased by 27.383 kgce/t-CS and 42.012 × 102 MJ/t-CS respectively compared to their initial values. It is noteworthy that the process of hydrogen production plays a significant role in mitigating the exergy intensity and carbon emission intensity. [Display omitted] • The white box model based on material-energy-exergy flow of furnace are created. • The material–energy–emission nexus model of integration processes is proposed. • Energy intensity, exergy intensity and carbon emission intensity are introduced as indicators. • Impacts of direct reduced iron addition on variation in indicators are discussed. • Hydrogen production process has an important impact on the indicators. [ABSTRACT FROM AUTHOR]

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. • The muti-objective optimization model of iron and steel industry is established. • The carbon price is considered during model establishment and analyzing. • The objective with energy consumption, CO 2 emissions and cost are optimized. • The factors affecting cost, energy consumption and CO 2 emission are discussed. [ABSTRACT FROM AUTHOR]

Towards the target of carbon neutrality, the need for deep decarbonization in iron and steel industry is increasingly recognized. Existing studies rarely mention the effects of collaboration with its source industries for carbon emission reduction in ISI. Furthermore, the fundamental laws of CO 2 emission reduction capacity with cost change of source substitutions for various steel production routes under market economics are unclear. To avoid the blind substitution of clean sources for meeting the urgent requirements for decarbonization in China's steel industry, which may result in increased carbon emissions and uneconomical carbon reduction from a lifecycle perspective. This paper integrates the production and utilization processes of source resources into the steel production process, establishes coupling models of carbon and value flows for four main types of steel production routes, and aims to quantitatively analyze the specific CO 2 emission reduction potential and costs. Three economic market development scenarios from 2021 to 2060 are set, and the marginal carbon prices of various source substitutions are determined. Subsequently, decarbonization pathways with the goal of minimizing production costs are developed. Finally. The future resource demand and the carbon emission reduction contributions of source industries collaborated are predicted. The results show that (1) about 81.7–89.9 % of CO 2 emissions could be reduced in the scenarios; (2) the demands of electric power and hydrogen energy will reach 54.48–511.90 BkWh and 7.47–10.31 Gt in 2060, respectively; and (3) collaboration with source industries could make 18.3–18.3% of CO 2 emission reduction contributions. All in all, this study could provide scientific support for the low-carbon transformation of China's steel industry. • Carbon and value flows of BF-BOF, Scrap-EAF, DRI-EAF, MOE-EAF routes are analyzed. • CO 2 emission reduction potential with marginal carbon price is determined. • Decarbonization paths during 2021–2060 for China's steel industry are developed. • Quantify the contribution of collaborative carbon reduction with source industries. [ABSTRACT FROM AUTHOR]

Abstract The production of iron and steel is energy-intensive that motivated the emergence of various energy-saving technologies to reduce energy consumption. However, the effects of water-saving brought by these energy-saving technologies are rarely examined which can lead to misevaluation of their economic feasibility. In this regard, material flow analysis (MFA) was used in this study to establish the water-energy nexus and examine the potential of water-saving and energy-saving effects in the condition of applying various mixes of the 16 technologies (Ministry of Industry and Information Technology, 2015–2016) in iron and steel industry. Meanwhile, this study classified the selected 16 energy-saving technologies into three groups: direct water-saving technology, indirect water-saving technology, and water consumption technology. The low-temperature steel rolling technology is the only water-consuming energy-saving technology in this study; its indirect specific water computation reaches 0.06 m3/t. The remaining 15 energy-saving technologies have the potential of saving water indirectly, with averaged indirect specific water-saving amounting to 0.28 m3/t. This study also built an evaluation scheme of cost-benefit analysis for energy-saving technologies. With consideration of benefits brought by water saving, eleven technologies have the potential to achieve economic feasibility compared to nine in which mere energy-saving effects being considered. The results show that if the studied 16 technologies are implemented simultaneously, the comprehensive specific energy consumption will be reduced by 4.28 MJ, and the specific fresh water consumption will be reduced by 0.68 m3. Meanwhile, this research found that the cost of most energy-saving technologies will be decreased by an average of 5.52 CNY/GJ, despite the cost of low-temperature steel rolling technology increased by 0.68 CNY/GJ. This study evaluated the cost-effectiveness of energy-saving technologies taking the benefits of water conservation into consideration. It could provide references for decision-makers to develop commercialization strategies on energy saving technologies in the steel industry. [ABSTRACT FROM AUTHOR]