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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]

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]

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]

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]

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]

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]

Highlights • A material metabolism model on the provincial scale was established based on Substance Flow Analysis. • A comprehensive analysis of elemental metabolism was presented to explain environmental problems. • Critical nodes in metabolism was identified by establishing metabolic topologies. Abstract The three types of elements nitrogen (N), phosphorus (P) and Sulfur (S) are inextricably linked from the source to the destination throughout the system. To analyze the environmental load caused by the three elements, this study established a material metabolism model to quantify the relationships among metabolic processes on the provincial scale and examined their environmental implications based on Substance Flow Analysis (SFA). The results show that the metabolic fluxes of nitrogen, phosphorus and sulfur in the socioeconomic system of Liaoning Province in 2016 were 5.339 million tons, 0.582 million tons and 3.084 million tons, respectively. The agricultural sector caused the greatest environmental pressures on water bodies, in which nitrogen and phosphorus accounted for 61.8% and 80.2% of the total water body load. For atmospheric load, the nitrogen and sulfur elements in the industrial sector caused the largest atmospheric load, accounting for 37.8% and 91.4% of the total atmospheric load, respectively. The main source of phosphorus soil load in Liaoning Province is the agricultural production, accounting for 85.3% of the total soil load caused by phosphorus. [ABSTRACT FROM AUTHOR]