| 1. |
- Arzpeyma, Niloofar, et al.
(författare)
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Development of a Mass and Energy Balance Model and Its Application for HBI Charged EAFs
- 2020
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- A static mass and energy balance model combined with a MgO saturation slag model is developed for electric arc furnaces. The model parameters including distribution ratios and dust factors are calibrated for a specific furnace using experimental data. Afterward, the model is applied to study the effect of charging different amounts of hot briquetted iron (HBI) on energy consumption, charged slag former amount, and slag composition. The following results were obtained per each 1% increase of HBI additions: (i) a 0.16 Nm(3)/t decrease in the amount of injected oxygen for metal oxidation, (ii) a 1.29 kWh/t increase in the electricity consumption, and (iii) a 34 kg increase in the amount of the slag.
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| 2. |
- Arzpeyma, Niloofar, et al.
(författare)
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Model Development to Study Uncertainties in Electric Arc Furnace Plants to Improve Their Economic and Environmental Performance
- 2021
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- A statistical model is developed in order to simulate the melt composition in electric arc furnaces (EAFs) with respect to uncertainties in (1) scrap composition, (2) scrap weighing and (3) element distribution factors. The tramp element Cu and alloying element Cr are taken into account. The model enables simulations of a charge program as well as backwards estimations of the element concentrations and their variance in scrap. In the backwards calculation, the maximum likelihood method is solved by considering three cases corresponding to the involved uncertainties. It is shown that the model can estimate standard deviations for elements so that the real values lie within the estimated 95% confidence interval. Moreover, the results of the model application in each target product show that the estimated scrap composition results in a melt composition, which is in good agreement with the measured one. The model can be applied to increase our understanding of scrap chemical composition and lower the charged material cost and carbon footprint of the products.
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| 3. |
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| 4. |
- Compañero, Reinol Josef, et al.
(författare)
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Appraising the value of compositional information and its implications to scrap-based production of steel
- 2023
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Ingår i: Mineral Economics. - : Springer Nature. - 2191-2203 .- 2191-2211.
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Tidskriftsartikel (refereegranskat)abstract
- The current nature of steel design and production is a response to meet increasingly demanding applications but without much consideration of end-of-life scenarios. The scrap handling infrastructure, particularly the characterization and sorting, is unable to match the complexity of scrapped products. This is manifested in problems of intermixing and contamination in the scrap flows, especially for obsolete scrap. Also, the segmentation of scrap classes in standards with respect to chemical compositions is based on tolerance ranges. Thus, variation in scrap composition exists even within the same scrap type. This study applies the concept of expected value of perfect information (EPVI) to the context of steel recycling. More specifically, it sets out to examine the difference between having partial and full information on scrap composition by using a raw material optimization software. Three different scenarios with different constraints were used to appraise this difference in terms of production and excess costs. With access to perfect information, production costs decreased by 8–10%, and excess costs became negligible. Overall, comparing the respective results gave meaningful insights on the value of reestablishing the compositional information of scrap at the end of its use phase. Furthermore, the results provided relevant findings and contribute to the ongoing discussions on the seemingly disparate prioritization of economic and environmental incentives with respect to the recycling of steel.
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| 5. |
- Gyllenram, Rutger, et al.
(författare)
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Blast furnace control after the year 2000
- 1996
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Ingår i: Steelmaking Conference Proceedings. - : Iron & Steel Soc of AIME, Warrendale, PA, United States. ; , s. 685-692
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Konferensbidrag (refereegranskat)abstract
- Rapid technical development together with developments in work organization makes it important to investigate possible ways to achieve a cost efficient process control of different metallurgical processes. This paper describes a research project, and proposes a human oriented Information Technology Strategy, ITS, for control of the Blast Furnace process. The method used is that of deductive reasoning from a description of the prevailing technological level and experiences from various development activities. The paper is based on experiences from the No. 2 Blast Furnace at Lulea Works but the conclusions do not at this stage necessarily reflect the opinion of the management and personnel or reflect their intentions for system development at SSAB.
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| 6. |
- Gyllenram, Rutger, et al.
(författare)
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Driving investments in ore beneficiation and scrap upgrading to meet an increased demand from the direct reduction-EAF route
- 2021
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Ingår i: Mineral Economics. - : Springer Science and Business Media Deutschland GmbH. - 2191-2203 .- 2191-2211.
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Tidskriftsartikel (refereegranskat)abstract
- The pressure on the steel industry to reduce its carbon footprint has led to discussions to replace coke as the main reductant for iron ore and turn to natural gas, bio-syngas or hydrogen. Such a major transition from the blast furnace-basic oxygen furnace route, to the direct reduction-electric arc furnace route, for steel production would drastically increase the demand for both suitable iron ore pellets and high-quality scrap. The value for an EAF plant to reduce the SiO2 content in DRI by 2 percentage points and the dirt content of scrap by 0.3 percentage points Si was estimated by using the optimization and calculation tool RAWMATMIX®. Three plant types were studied: (i) an integrated plant using internal scrap, (ii) a plant using equal amounts of scrap and DRI and (iii) a plant using a smaller fraction of DRI in relation to the scrap amount. Also, the slag volume for each plant type was studied. Finally, the cost for upgrading was estimated based on using mainly heuristic values. A conservative estimation of the benefit of decreasing the silica content in DRI from 4 to 2% is 20 USD/t DRI or 15 USD/t DR pellets and a conservative figure for the benefit of decreasing the dirt in scrap by 0.3 percentage points Si is 9 USD/t scrap. An estimate on the costs for the necessary ore beneficiation is 2.5 USD/t pellet concentrate and for a scrap upgrade, it is 1-2 USD/t scrap.
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| 7. |
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| 8. |
- Gyllenram, Rutger, et al.
(författare)
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Lubricating the recycling machine
- 2012
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Ingår i: Revue de métallurgie (Imprimé). - : EDP Sciences. - 0035-1563 .- 1156-3141. ; 109:5, s. 349-358
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Tidskriftsartikel (refereegranskat)abstract
- When introducing a new control paradigm in industry or society one has to accept that it is an evolutionary process where people, methods and processes must develop simultaneously, and this takes time. The recycling of material has been studied intensely for the last ten years using different approaches to material flow analyses, MFAs. They have given a good view of the magnitude of material flows but their use has been limited by lack of relevant data. In the case of recycling, data must be acquired from the practitioners of the trade and in order to get it, the value of the output for them and for society must be proved and visualized. This paper is based on a MFA model developed at KTH for steel flows in Sweden (part of the Swedish environmental research program, the "Steel-Eco-Cycle"). The aim of the work reported on here was to initiate the process of motivating better sampling of data in industry and society for performing MFAs. The KTH model is based on a product-to-product approach for steel, describing the recycling machine. Data is presented in a simplified model for Sweden with total figures and figures per capita. Areas where improvements can be made are identified and ways to "lubricate" the recycling machine are discussed. The main idea is to provide a way of describing flows that can be of use to recyclers and steel producers and form a basis for discussions on improvements. Finally, the underlying model is briefly described and the uncertainties of data are discussed.
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| 9. |
- Gyllenram, Rutger, et al.
(författare)
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User friendliness : why are some beautiful models used while others are thrown in the wastepaper basket?
- 2008
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Ingår i: SCANMET III. - Luleå : MEFOS. - 9789163322693 ; , s. 315-322
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Konferensbidrag (refereegranskat)abstract
- Development and implementation of models in steel companies represent large values and will be even more important in the future. There are many pitfalls to step into in the process of modelling and implementation of systems. In this paper pitfalls and success factors experienced in six different projects are presented and discussed. Experiences like these are hard to earn and easily forgotten and it is concluded that this kind of knowledge management ought to be on the agenda for top management like the Corporate Technology Officer, CTO.
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| 10. |
- Nurdiawati, Anissa, et al.
(författare)
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Towards fossil-free steel : Life cycle assessment of biosyngas-based direct reduced iron (DRI) production process
- 2023
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 393
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Tidskriftsartikel (refereegranskat)abstract
- Given the urgent need for transitions towards global net zero emissions, decarbonisation of the iron and steel industry is critical. Deep decarbonising this sector requires a breakaway from current blast furnace-basic oxygen furnace (BF-BOF) technologies that largely depend on fossil resources. Biosyngas is considered to be a promising alternative to fossil energy and reductants used in existing ironmaking due to its renewability, technological maturity and compatibility for use in existing furnaces. The present work assesses the environmental impacts of biosyngas-based direct reduced iron production followed by electric arc furnace (DRI-EAF) routes for crude steel production. Further, the proposed routes are compared with the other steelmaking routes, including BF-BOF, natural gas (NG)-based and hydrogen-based direct reduction routes by performing life cycle assessment (LCA). The results indicate that the global warming potential (GWP) value for the biosyngas-based DRI-EAF system is 75% lower than the existing NG-based DRI-EAF route and 85% lower than the BF-BOF route. Moreover, the proposed system possibly has lower GWP values than the renewable hydrogen-based DRI-EAF route. The pro-posed system has an estimated cradle-to-gate GWP of 251 kg CO2 eq./t crude steel, of which 80% is from up-stream emissions. Combined with CO2 storage, the GWP of the proposed system is a net negative, estimated at-845 kg CO2 eq./t crude steel for the selected system boundary. In addition to GWP, other non-climate impact indicators are also evaluated to identify potential burden shifting. The results highlight the emissions reduction potential of the novel biosyngas DRI production route. Large-scale deployment, however, requires sustainable forest management and adequate CCS infrastructure, along with a strong, long-term policy framework to incentivise the transitions.
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| 11. |
- Ternstedt, PAtrik, 1979-, et al.
(författare)
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Using an AOD simulator workbench to support process control development
- 2011
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Ingår i: METEC InSteelCon 2011, Düsseldorf, Germany, 27 June - 1 July, 2011.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The AOD (Argon Oxygen Decarburization) process is simulated with a model developed within the RFCS project OPCONSTAINLESS. The focus on the project has been on the influence of slag on the decarburization process. Here, a slag property is usually a parameter that is not used for process control, often due to the complexity of the slag system. The workbench, TimeAOD2, has been coupled with the Thermo-Calc software [1], giving the ratios of different slag phases and amount of liquid slag throughout the operation. The workbench gives the process manager an opportunity to see the outcome of different process layouts, control paradigms and raw material choices under different production conditions. A number of scenarios are outlined and different solutions evaluated. The simulation data is for some cases compared to operational data from AOD plants in Sweden.
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| 12. |
- Wei, Wenjing, et al.
(författare)
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Assessment of Scrap-based Production for Low Phosphorus Stainless Steel
- 2018
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Konferensbidrag (refereegranskat)abstract
- Low phosphorous contents in austenitic stainless steels favours a resistance to stress corrosion cracking and reduces the susceptibility to hot cracking. An industrial problem is that phosphorous cannot be removed from chromium alloyed steels, since oxidation of chromium occurs before phosphorous oxidation. This brings a challenge for scrap-based stainless steelmakers since an accumulation of phosphorous in the steel cycle should be avoided. In this paper, the effects of the phosphorus content in stainless steel scrap have been studied when producing AISI 304-type of stainless steel with low phosphorus level demands. These steels are often produced by melting scrap by using the EAF-AOD route. The influence of scrap with varied phosphor contents on steels has been assessed by using RAWMATMIX®, which is a web-based raw material optimization software.
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| 13. |
- Wei, Wenjing, et al.
(författare)
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Energy Consumption and Greenhouse Gas Emissions During Ferromolybdenum Production
- 2020
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; 6:1, s. 103-112
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Tidskriftsartikel (refereegranskat)abstract
- Molybdenum is mainly used as an alloy material in the iron and steel industry and typically in the form of ferromolybdenum (FeMo). The current study aims to evaluate the energy consumption and greenhouse gas emissions (GHG) of four ferromolybdenum production cases using inventory inputs from a process model based on mass and energy conservations. The total energy required for producing 1 tonne of FeMo can vary between 29.1 GJ/t FeMo and 188.6 GJ/t FeMo. Furthermore, the corresponding GHG emissions differ from 3.16 tCO2-eq/t FeMo to 14.79 tCO2-eq/t FeMo. The main variances are from the mining and beneficiation stages. The differences in these stages come from the beneficiation degree (ore grade) and the mine type (i.e., co-product from copper mining). Furthermore, the mine type has a larger impact on the total energy consumption and GHG emissions than the beneficiation degree. More specifically, FeMo produced as co-product from copper mining has a lower environmental impact measured as the energy consumption and GHG emission among all the four cases. The inventory, consumed energy or associated GHG emission is independent on the initial ore grade and mine type in the downstream production stages such as roasting and smelting. Also, transport has the least impact on the energy consumption and GHG emission among all production stages.
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| 14. |
- Wei, Wenjing, et al.
(författare)
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Energy Consumption and Greenhouse Gas Emissions of High-Carbon Ferrochrome Production
- 2023
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Ingår i: JOM. - : Springer Nature. - 1047-4838 .- 1543-1851. ; 75:4, s. 1206-1220
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- This work presents a process model developed based on mass and energy conservation to assess high carbon ferrochrome production from cradle to gate through four supply routes: (1) a conventional submerged arc furnace (SAF), (2) a closed submerged arc furnace with preheating (CSAF+PH), (3) a closed submerged arc furnace with 60% prereduction (CSAF+PR60%) and (4) a direct-current arc furnace (DCAF). The energy requirements are between 40 and 59 GJ/t FeCr (74–111 GJ/t Cr), and the greenhouse gas (GHG) emissions range between 1.8 and 5.5 tCO2-eq/t FeCr (3.3–10.3 tCO2-eq/t Cr). The upgrading of coal-powered SAF process to a closed furnace CSAF+PH and CSAF+PR60% contributes to an emission reduction of 23% and 18%, respectively. Moreover, the use of hydro-powered electricity leads to a further emission reduction of 68% and 47%, respectively. For CSAF+PR process, the GHG emissions can be reduced by 14% when increasing the pre-reduction ratio from 30% to 80% and decreased by 10% when charging hotter feed from 100 °C to 1000 °C. The proposed process model is feasible in generating site-specific inventory data and allowing for parameter studies as well as supporting companies to improve the transparency of the environmental performance in the FeCr value chain.
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| 15. |
- Wei, Wenjing, et al.
(författare)
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Energy Consumption and Greenhouse Gas Emissions of Nickel Products
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13:21
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Tidskriftsartikel (refereegranskat)abstract
- The primary energy consumption and greenhouse gas emissions from nickel smelting products have been assessed through case studies using a process model based on mass and energy balance. The required primary energy for producing nickel metal, nickel oxide, ferronickel, and nickel pig iron is 174 GJ/t alloy (174 GJ/t contained Ni), 369 GJ/t alloy (485 GJ/t contained Ni), 110 GJ/t alloy (309 GJ/t contained Ni), and 60 GJ/t alloy (598 GJ/t contained Ni), respectively. Furthermore, the associated GHG emissions are 14 tCO(2)-eq/t alloy (14 tCO(2)-eq/t contained Ni), 30 t CO2-eq/t alloy (40 t CO2-eq/t contained Ni), 6 t CO2-eq/t alloy (18 t CO2-eq/t contained Ni), and 7 t CO2-eq/t alloy (69 t CO2-eq/t contained Ni). A possible carbon emission reduction can be observed by comparing ore type, ore grade, and electricity source, as well as allocation strategy. The suggested process model overcomes the limitation of a conventional life cycle assessment study which considers the process as a 'black box' and allows for an identification of further possibilities to implement sustainable nickel production.
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| 16. |
- Wei, Wenjing, et al.
(författare)
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Prediction of nitrogen behaviour in the AOD process by a time-dependent thermodynamic model
- 2022
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Ingår i: Ironmaking & steelmaking. - : Taylor and Francis Ltd.. - 0301-9233 .- 1743-2812. ; 49:1, s. 70-82
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a time-dependent thermodynamic AOD process model, TimeAOD3™, is proposed to be used as a prediction model at practice to reach the desired nitrogen level to lower the cost and carbon footprint. The model is developed from an existing model and integrated with Thermo-Calc®. The modelling results suggest a fairly good prediction when compared with production-scale heats. The relative error of dissolved nitrogen content during and after decarburisation is −0.05 < RE < 1.36 and −0.23 < RE < 0.29, respectively. Besides, most modelled dissolved N% are higher than the measurement during decarburisation. This is probably owing to the formation of high turbulence flow and CO gas bubble which can flush the dissolved nitrogen out of the bath at practice. Moreover, dissolved C%, Cr% in bath and Cr2O3%, CaO%, MgO% in slag, as well as bath temperature are also compared and studied.
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| 17. |
- Westerberg, O., et al.
(författare)
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Improving steel quality and decreasing production cost and carbon footprint through raw material management
- 2012
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Ingår i: 70th World Foundry Congress 2012, WFC 2012. - 9781622763825 ; , s. 515-518
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Konferensbidrag (refereegranskat)abstract
- A thorough raw material selection and blending is essential for achieving a high quality melt at a minimum cost. Residual material from previous production constitute a large part of the material input and a practice where residuals from one steel type is used for producing the same steel type often lead to big stocks of internal scrap. The value of internal scrap is high due to its known alloy content and can, if used optimally, reduce overall production costs Global Warming has put the emissions of CO2 as a main focus point in product ecology. The choice of alloy source and electricity (if possible) is vital for reducing the carbon footprint for stainless steel. This paper discusses possible ways to decrease the capital bound in stock for a stainless steel foundry. Ways to improve quality control of scrap are outlined in order to be able to buy cheaper scrap and reduce the fraction of alloying elements coming from primary alloys.
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| 18. |
- Widlund, Daniel, et al.
(författare)
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Towards Model-Based Closed-Loop Control of the Basic Oxygen Steelmaking Process
- 1998
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - 1474-6670. ; 31:23, s. 69-74
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Tidskriftsartikel (refereegranskat)abstract
- Model-based closed-loop control of the basic oxygen steelmaking process will give an opportunity to increase process operation performance. By using control algorithms that interact with thermodynamical and physical models capable of making real-time predictions of the effects of control actions, the time delays in order to wait for process response will be eliminated. Existing limitations like pre-set lance programs can be avoided. This paper outlines the concept of a recently started project aiming at model-based closed-loop control as well as present the initial work that has been made on the subject.
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| 19. |
- Zaini, Ilman Nuran, et al.
(författare)
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Decarbonising the iron and steel industries: Production of carbon-negative direct reduced iron by using biosyngas
- 2023
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 281
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Tidskriftsartikel (refereegranskat)abstract
- Bioenergy with carbon capture and storage (CCS) in iron and steel production offers significant potential for CO2 emission reduction and may even result in carbon-negative steel. With a strong ambition to reach net-zero emissions, some countries, such as Sweden, have recently proposed measures to incentivise bioenergy with CCS (BECCS), which opens a window of opportunities to enable the production of carbon-negative steel. One of the main potential applications of this route is to decarbonise the iron reduction processes that account for 85 % of the total CO2 emission in the iron and steel plants. In this study, gasification is proposed to convert biomass into biosyngas to reduce iron ore directly. Different cases of integrating the biomass gasifier, Direct Reduced Iron (DRI) shaft furnace, and CCS are evaluated through process simulation work. Based on the result of the work, the proposed biosyngas DRI route has comparable energy demand compared to other DRI routes, such as the well-established coal gasification and natural gas DRI route. The proposed process can also capture 0.65–1.13 t of CO2 per t DRI depending on the integration scenarios, which indicates a promising route to achieving carbon-negative steel production.
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