A. V. Lapteva

Graph model for carbon dioxide emissions from metallurgical plants

Mathematical models are presented for estimating carbon dioxide emissions from metallurgical processes. The article also presents a new mathematical model in graph form to calculate transit and net emissions of carbon dioxide based on the estimates obtained for the individual processes. The graph model is used to compare the blast-furnace–converter process with the blast-furnace–EAF process.

EVALUATING THE CARBON FOOTPRINT FROM THE PRODUCTION OF STEEL IN AN ELECTRIC-ARC FURNACE

Data reported by a specific factory in the Urals are used to calculate the net emission of carbon dioxide from steel production in an electric-arc furnace with allowance for the steel’s deoxidation. The calculation is performed with the use of graph models of carbon-dioxide emissions.

Greenhouse-gas (CO2) emissions in the steel industry

The greenhouse gas CO2 is produced copiously in the steel industry. Three types of carbon-dioxide emissions may be distinguished: emissions in the technological processes, emissions in transit, and the overall emissions. The overall CO2 emissions characterize the sum of the process and transit emissions. A classification of processes in the iron and steel industry is proposed, in terms of the mechanism by which the CO2 is formed. Five major sources are identified: furnaces, converters, open-hearth furnaces, blast furnaces, and coke batteries. The overall CO2 emissions are determined for six combinations of processes whose final product is steel.

Application of the triad of blast furnace, oxygen converter, and electric arc furnace for reducing of carbon footprint

Carbon footprint is the mass of carbon formed in the full cycle of manufacturing one kind or another product. This carbon is included in greenhouse gases. During production of iron and steel are generated carbon monoxide and greenhouse gases: methane, and carbon dioxide. Methane and carbon monoxide burn to carbon dioxide by secondary energy resources. By this means, the carbon footprint by the production of iron and steel has determined by the weight of carbon dioxide formed in this production. As results of analysis of the processes of manufacture of iron and steel, it has revealed that the tandem of blast furnace with electric arc furnace is characterized by a lower value of integrated emissions of CO2 than the tandem of blast furnace with an oxygen converter. It was proposed to process of the cast iron made by one blast furnace, then in the oxygen converter, and, at last, in one or more electric arc furnaces. Moreover, the electric arc furnace is loaded by 30% of iron produced in blast furnace, and the remaining 70% are complemented by metal scrap. In the oxygen converter is loaded, the part of cast iron (75–85%), that remained after processing in the arc furnace. The converter is applied the metal scrap for full loading. Calculations of total emission of carbon dioxide for different triads of these units are made. Simultaneous use of oxygen converter with electric arc furnaces for cast iron smelting (obtained from one blast furnace) helps to reduce reliably the emission of carbon dioxide to 20% as it is follows from these calculations. This suggests that such a triad of used units conforms to green technology. Example of the use of mentioned triad is for a full load of the converter applied to metal scrap. The calculations total emissions of carbon dioxide for different triads of these units were performed. From these calculations it follows that the simultaneous use of oxygen converters after electric arc furnaces for smelting iron (obtained from one blast furnace), it helps to reduce the emission of carbon dioxide to 20%. This suggests that this triad of used units conforms to green technology. An example of using this triad is in the Magnitogorsk Iron and Steel Works, where along with the oxygen converter, electric arc furnaces with the use of locally produced electricity at burning fuel of secondary energy resources from units, in which the fuel is burnt. This practice can be recommended for a number of other metallurgical enterprises.

Comparative Analysis of the Influence of Fuel Injection on the Energy Intensity and Carbon Footprint of the Blast-Furnace Process

The data on the energy intensity, carbon dioxide emission, and end-to-end emission (carbon footprint) for the production of vanadium iron in coke-fired blast furnaces with injection of either natural gas or both natural gas and pulverized coal are presented. Energy intensity is represented by end-to-end process fuel number. Mean values, variance, standard deviation, range of variation of process fuel number, emission, and end-to-end emission of carbon dioxide are calculated using published data on the consumption of coke, natural gas, and pulverized coal in a blast furnace. It is shown that the process with injection of pulverized coal has better performance in terms of energy intensity. Carbon footprint is minimum when injecting natural gas only.

Types of greenhouse gas emissions in the production of cast iron and steel

Types of carbon dioxide emissions in iron and steel production are indicated. Production processes have been classified according to mechanisms of carbon dioxide formation. Mathematical models for calculation of carbon dioxide emissions for each type of process are found. Calculations results of carbon dioxide emissions of coke (BF + EAF) and cokeless processes (Corex, Midrex, HyL-3, Romelt) in combination with EAF are provided.

Analysis of Energy Content and CO2 Emissions in Different Combinations of Coke-Using and Coke-Less Processes for Steel Production

Comparative estimates are made of energy content and emissions of carbon dioxide – a greenhouse gas – for different combinations of coke-using processes (blast-furnace – BOF, blast-furnace – electric-arc-furnace (EAF)) and coke-less processes (HyL-3 – EAF, MIDREX – EAF; ROMELT – EAF, COREX – EAF, direct alloying with vanadium (DAV), EAF operation on scrap) that are performed in the course of producing steel. These processes were compared as part of an energy-environmental analysis by examining both energy content and a parameter that characterizes the emission of the greenhouse gas CO2 – the technological greenhouse number (TGN). It was determined that the advantages in terms of energy content and CO2 emissions belong to EAF steelmaking with the use of scrap, the DAV process, the HyL-3 – EAF process, and the Midrex – EAF process. It should be noted that the steel obtained in the DAV process is alloyed with vanadium. In each case, the processes that do not involve the use of molten pig iron in steel production should be given the highest priority based on their ratings for energy content and greenhouse-gas emissions.

Analysis of the feasibility of reducing fuel consumption and carbon-dioxide emissions and obtaining carbon credits with the use of sverdlovskaya-oblast factories as an example

This article discusses aspects of improving the efficiency of heating and heat-treatment furnaces from the standpoint of the fuel savings that can be realized by the use of different methods to modernize such furnaces.