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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]

[Display omitted] • [TND-C][Tf 2 N]/DFP exhibits the H 2 S uptake of 3.65 mol/mol at 30 °C and 1 bar. • [TND-C][Tf 2 N]/DFP exhibits good selectivity for H 2 S/CO 2 (25) and H 2 S/CH 4 (8 3 6). • The yield of thiols reaches 99 % within 30 min under mild conditions. • The reaction regeneration of the absorbent is carried out at room temperature. • Reaction regeneration strategy eliminates high energy losses during desorption of H 2 S. In this work, we developed a composite solution (FILs/DFP) using ionic liquids (FILs) and 4-formylmorpholine (DFP) for natural gas desulfurization. Among these, [TND-C][Tf 2 N]/DFP exhibited an impressive H 2 S uptake of 3.65 mol/mol and H 2 S/CO 2 selectivity of 25 at 30 °C and 1 bar. The 1H NMR, FTIR, and DFT calculations revealed that the dense hydrogen bonding network and the active sites of tertiary amines in FILs/DFP were the main factors for the efficient uptake of H 2 S. Furthermore, we propose a viable reaction regeneration strategy at room temperature, successfully addressing the challenges of absorber regeneration, the catalytic activity of the FILs remained above 95 % even after six cycles. Overall, this strategy eliminates the high energy losses of H 2 S desorption and allows for the recycling of FILs with minimal energy consumption. This simultaneously achieving dual objectives of H 2 S conversion and absorbent regeneration process shows promising applications in natural gas desulphurization. [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]

In this paper, we present a novel variational wavelet inpainting based on the total variation (TV) regularization and the l1-norm fitting term. The goal of this model is to recover incomplete wavelet coefficients in the presence of impulsive noise. By incorporating the Moreau envelope, the proposed model for wavelet inpainting can better handle the non-differentiability of the l1-norm fitting term. A modified primal dual fixed-point algorithm is developed based on the proximity operator to solve the proposed variational model. Moreover, we consider the existence of solution for the proposed model and the convergence analysis of the developed iterative scheme in this paper. Numerical experiments show the desirable performance of our method. [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]

[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]

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]

In the context of carbon neutrality, energy conservation and carbon reduction in the heating industry have become the focus of attention. However, severe heat loss is currently occurring in the secondary heating system due to hydraulic imbalance, which is unable to supply heat according to users' needs. In view of this, a thermodynamic-hydraulic model of users' demand for heat and flow rate for the heating system is established. Then, a novel method to regulate hydraulic imbalance is proposed, with the dynamic heat demand satisfied by regulating the valve opening based on NSGA-II. The optimization results show that the comprehensive hydraulic imbalance coefficient has been reduced from 23.08 to less than 0.019, which means that almost 100% of users can get heat supplies corresponding to their needs, while the energy consumption is reduced by about 30%. Additionally, when there are 1000 population and iteration steps, good convergence and high speed are presented using this method. In summary, an on-demand optimized model of hydraulic balance for the secondary heating network is put forward, which provides powerful engineering support and guidance for intelligent heating construction. • This paper presents a method to regulate the hydraulic balance of network using NSGA-II according to the heat demand. • This paper combines the demand flow regulation of users with the resistance analysis of the heating network. • The hydraulic balance can be implemented greatly by using the hydraulic imbalance coefficient as the optimization goal. • The number of iteration steps in the algorithm has an effect on the optimization results. [ABSTRACT FROM AUTHOR]

As one of the largest countries with sound industrial systems in the world, China is a major emitter of greenhouse gases. In order to achieve sustainable development, the analysis of greenhouse gas emissions from industry is of great significance. This research evaluates the greenhouse gas emission efficiency (GHG efficiency) at industry level in 26 sectors of China and analyzes the impacts of its determinants using stochastic frontier approach. Furthermore, the correlations for GHG efficiency with its determinants and other proxies are estimated by Kendall's rank analysis. Industry level data from Chinese processing and manufacturing industries spanning over the period 2000–2016 are used for this analysis. Results show that there has little potential to improve GHG efficiency, then technology progress is necessary. The GHG efficiency performance responds both to changes in the proportion of net electricity use and the ratio of electricity price to coal price; meanwhile the technology capacity also has a positive impact. Besides, three main proxies of GHG intensity, energy efficiency and energy intensity have their own significance respectively, but could not represent GHG efficiency. Unlabelled Image • China's GHG efficiency at industry level is assessed by stochastic frontier analysis. • At night, net electricity is better than small-scale on-site coal-fired power plant. • Technology advance is better to improve efficiency and mitigate GHG emissions. • Energy efficiency and GHG efficiency are dependent but loosely related indexes. [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]

The traditional iron and steel industry (ISI) began to implement technological innovations aimed at lowering carbon footprint and emissions, resulting in hydrogen metallurgy gradually becoming a new trend of green development in ISI. However, there is a lack of comprehensive and in-depth analysis of energy-exergy based on the second law of thermodynamics in the current research of hydrogen metallurgy. To address these issues, a numerical calculation model of hydrogen metallurgy based on material-energy-exergy is established. Two novel evaluation indexes are introduced to better evaluate the impact of various parameters on hydrogen metallurgy. It was found that the exergy intensity is mainly affected by the amount of reducing gas, and increasing the preheating temperature of the ore cannot always reduce the exergy intensity due to the influence of element conservation. And when the ore preheating temperature is higher than 623 K, the exergy utilization efficiency decreases. After calculation, the lowest exergy intensity is 1.23 × 107 kJ/t-DRI when the H 2 content is 41.37% and the ore temperature is 773 K. Furthermore, a simple process is designed to recover a substantial volume of unreacted gas from the furnace top gas. Overall, this study can serve as a reference for actual hydrogen metallurgy production. [Display omitted] • A material-energy-exergy model based on the second law of thermodynamics is created. • In addition to the traditional evaluation indexes, two novel ones are also introduced. • Preheating ore temperature above 623 K reduces the exergy utilization efficiency. • Rising ore preheating temperature does not decrease exergy intensity continuously. • A simple waste energy recovery process is proposed. [ABSTRACT FROM AUTHOR]

For the objective of carbon neutrality stated by the global climate conference, the iron and steel industry, a major carbon emitter, must transition to green and low-carbon development as quickly as feasible. Hydrogen metallurgy direct reduction technology has attracted much attention because of its low emission. However, the current study on hydrogen metallurgy shaft furnace lacks a comprehensive in-depth analysis of gas consumption, gas utilization, and exergy intensity. To tackle these problems, a material and energy optimization model including intermolecular chemical reaction is established. The original process is optimized by this model, the gas utilization is enhanced by 26.7%, gas consumption is decreased by 906.34 m3/t-DRI, and exergy intensity is reduced by 8.8 GJ/t-DRI. Furthermore, the impacts of gas composition, gas temperature, and ore temperature on gas consumption, gas utilization, exergy structure, and exergy intensity, as well as their interactions, are investigated thoroughly. The analysis highlighted that properly reducing hydrogen content and increasing gas and ore temperature can improve gas utilization and reduce gas consumption. Simultaneously, lowering gas consumption can effectively lower exergy intensity. And furnace top gas exergy is closely related to gas utilization. On the whole, it is advantageous to promote the development of hydrogen metallurgy by conducting in-depth and systematic analyses. [Display omitted] • An NLP model including intermolecular chemical reactions is established. • The accuracy of the model is verified by actual production data. • The material and energy assessments are presented considering the exergy of energy. • Relationships of gas utilization, exergy intensity are thoroughly considered. • Suggestions are proposed to improve the energy utilization in actual production. [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]

The properties of vitrified bond abrasive tools, which are composed of diamond grains and Li 2 O–ZnO–Al 2 O 3 –SiO 2 (LZAS) vitrified bond with and without B 2 O 3 were comprehensively investigated. The results show that the vitrified bond incorporating 10 mol% B 2 O 3 exhibits a lower refractoriness and a higher fluidity compared with that of vitrified bond without B 2 O 3 . Moreover, the thermal expansion coefficient (TEC) of vitrified bond containing 10 mol% B 2 O 3 is very close to the TEC of diamond grains. Meanwhile, the open porosity of diamond composite is decreased from 41% to 29% by incorporating 10 mol% B 2 O 3 , which was 28.5% lower than that of vitrified bond without B 2 O 3 . The bending strength and Rockwell hardness of the diamond composite are significantly improved when the content of B 2 O 3 reached 10 mol%. SEM observation revealed that the diamond grains were closely overlaid by vitrified bond and diamond composite containing 10 mol% B 2 O 3 exhibited a relatively denser structure. The relation between the structural change and compositional variation by introducing B 2 O 3 was analyzed by Fourier transform infrared spectroscopy (FTIR). [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]

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]

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]