| 1. |
- Olofsson, David, et al.
(författare)
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Optimising the operation of a district heating system
- 2013
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Ingår i: Chemical Engineering Transactions. - : Italian Association of Chemical Engineering - AIDIC. ; , s. 637-642
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Konferensbidrag (refereegranskat)abstract
- A system with several actors will increase the possibilities for collaboration and therefore, in many cases also increase the possibilities to affect the operation with economic and environmental benefits. In this paper a district heating system is studied with purpose to create economic and environmental operation guidelines in favour of the involved actors. The company LuleKraft owns a combined heat and power plant, while the four heating stations together with the DH network are owned by Luleå Energi. District heat is produced from the CHP plant and the four heating stations which are fired with process gases from an integrated steel plant, oil, wood pellets or electricity. The heat demand in the system is strongly depending on the outdoor temperature. In this paper, the system is modelled with Mixed Integer Non Linear Programming in order to optimise the profit and CO2 emission. A comparison between actual process data and modelled results is performed. A pareto front is derived to show the trade-off between economic benefits and CO2 emissions. It is found that the main suggestions, under conditions for optimised profit, are (1) to prioritize effective heat production instead of electricity production at cold outdoor temperatures and (2) redistribution of the accessible process gases between the CHP plant and one of the heating stations. This will lead to an improved operation strategy, resulting in increased profit and reduced energy consumption. Copyright © 2013, AIDIC Servizi S.r.l.
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| 2. |
- Bellqvist, David, et al.
(författare)
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Closing the loop - Processing of waste by-product from aluminum recycling into useful product for the steel industry
- 2015
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Ingår i: Chemical Engineering Transactions. - 1974-9791 .- 2283-9216. ; 45, s. 661-666
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Tidskriftsartikel (refereegranskat)abstract
- During melting of aluminum scrap a slag residue is formed. The slag residue, called black dross, has no industrial use and has to be landfilled. The work presented herein aims at developing a novel treatment process for the slag, converting it into a useful product for the steel industry and thereby replacing commercially available products made from virgin material. The concept consists of flash melting black dross and lime to form a synthetic slag former for treatment of high quality steel. Results from the modelling work indicate that the overall energy savings for an extended use of the developed product at the SSAB Europe Luleå site amounts to 31 GWh/y corresponding to 8 kt CO2/y, in addition to the process removing the need for landfill of around 20 kt of black dross per year with subsequent risk of leakage of toxic compounds.
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| 3. |
- Bellqvist, David, et al.
(författare)
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Techno-economic analysis of low temperature waste heat recovery and utilization at an integrated steel plant in Sweden
- 2014
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Ingår i: Chemical Engineering Transactions. - : Italian Association of Chemical Engineering - AIDIC. - 1974-9791 .- 2283-9216. ; 39:Special Issue, s. 67-72
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Tidskriftsartikel (refereegranskat)abstract
- Energy consumption and CO2 emissions is an ever-present issue for energy intensive industries, such as the steel industry. The work for reducing the environmental impact is a strong interest among the governments in Europe and the 20-20-20 targets, decided by the EU, set the targets for the year 2020 to increase energy efficiency by 20 %, reduce greenhouse gas emissions by 20 %, and increase the use of renewable energy to 20 %. It is therefore important for the steel industry, and other industries, to continuously be working on development of concepts for decreasing the environmental impact, which are also financially viable. This paper presents the work that has been conducted in order to evaluate the potential benefits regarding energy- & cost saving and CO2 mitigation, when recovering and utilizing low temperature waste heat at an integrated steel plant in Sweden, SSAB EMEA Lulea. In order to achieve a holistic overview of the plant a process integration approach is applied to evaluate the effects that occur when applying technologies for waste heat recovery. The results indicate a potential for energy saving of 1.9 %, and a corresponding CO2 mitigation potential of 1.5 %. The calculated payback time for the applied waste heat recovery concepts, which is based on specific methods and economic assumptions, range between 1.5 - 7.0 y.
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| 4. |
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| 5. |
- Biermann, Max, 1989, et al.
(författare)
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Scenario for near-term implementation of partial capture from blast furnace gases in Swedish steel industry
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Iron-and-steel making is a carbon-intensive industry and responsible for about 8% of global CO2 emissions. Meeting CO2 reduction targets is challenging, since carbon is inherent in the dominating production route in blast furnaces. Long-term plans to phase out carbon and change production technique are under way, such as iron ore reduction with hydrogen[1][2] won from renewable energies or electro winning[3], however unlikely to be implemented at scale before 2040 [4]. Until a transition to such technologies is completed, carbon leakage will remain to be a threat to steel industry inside EU ETS system. CCS remains an option for steel industry to comply with reduction targets and meet rising allowance (EUA) prices, currently above 20 €/t. Most studies on CCS propose a capture rate of ≥ 90 %[5–7], however, CCS could be considered as a part of a series of measures (e.g. fuel change, energy efficiency measures) that together achieve a significant reduction in CO2 emissions until a carbon-neutral production is in place. This line of thought motivates the concept of partial capture, where only the most cost effective part of the CO2 emissions are separated for storage [8]. In steel industry, high CO2 concentrations at large flows and the availability of excess heat make partial capture attractive. Previous work on the steel mill in Luleå, Sweden, emits around 3.1 Mt CO2 per year, has found that 40-45 % of site emissions can be captured fueled by excess heat alone[9]. Therein, five heat recovery technologies were assessed, ranging from back pressure operation of CHP turbine to dry slag granulation. Promising CO2 sources on site include flue gases from hot stoves and the combined-heat and power plant, and the process gas originating from the blast furnace – blast furnace gas (BFG). BFG is a pressurized, low value fuel used for heating on site. CO2 separation from BFG requires less reboiler heat for MEA regeneration, and the enhanced heating value of the CO2 lean BFG increases energy efficiency of the steel mill [9]. This work discusses the near-term (the 2020s) implementation of partial capture at a Swedish steel mill and the economic viability of such implementation dependent on the energy price, carbon price, and required reductions in CO2 emissions. Based on previous work [9][10,11] on partial capture in steel industry a cost estimation of a capture system for the BFG is conducted including CAPEX and OPEX of the MEA capture unit, gas piping, and recovering heat from the steel mill. The costs are summarized as equivalent annualized capture cost (EAC) and set into relation to transport and storage costs as well as carbon emission costs to form the net abatement cost (NAC) according to Eq. (1) ???=???+ ?????????&??????? ???? −?????? ????? [€/???2] (1) Figure 1 shows how EAC for BFG varies with the capture rate and the cost of steam for different heat recovery technologies represented by the steps in the curve ( see explanation in [9]). Note that partial capture from BFG is more economical than the full capture benchmark. The most cost-efficient case of 28 €/t CO2 captured is achieved for BFG capture fueled by steam from back-pressure operation (at the expense of electricity production), flue gas heat recovery and flare gas combustion. The transport and storage cost applied in Eq (1) represent ship transport from the Bothnian Bay to a storage site in the Baltic Sea , according to Kjärstad et el.[12]. Transport and storage cost range within 17 – 27 €/t CO2 depending on scale. These installation and operation cost for capture, transport and storage are set into relation with various scenarios on future carbon and energy (electricity) prices in Europe and Sweden. For example, Figure 2 illustrates a scenario in line with IEA’s sustainable development scenario to restrict global warming to 2°C. The carbon prices are adapted from WEO 2018 [13] and increase from 20 € to 120 € per tonne CO2 by 2040 and the electricity prices of 42-52 €/MWh (increasing with time) are based on latest results from the NEPP project [14]. In this scenario, partial capture from BFG could become economic viable in 2029, construction in 2020 with operation from 2022/23 onwards is likely to pay off within a lifetime of 20 years only. This work demonstrates the viability of partial capture as cost-efficient mitigation measure for the steel industry and illustrates conditions for an early implementation in the 2020s. This work is part of the CO2stCap project (Cutting Cost of CO2 Capture in Process Industry) and funded by Gassnova (CLIMIT programme), the Swedish Energy Agency, and industry partners.
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| 6. |
- Orre, Joel, et al.
(författare)
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Optimised integrated steel plant operation dependent on seasonal combined heat and power plant energy demand
- 2018
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Ingår i: Chemical Engineering Transactions. - 1974-9791 .- 2283-9216. ; 70, s. 1117-1122
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Tidskriftsartikel (refereegranskat)abstract
- The steel industry is energy intensive with large corresponding contributions of fossil CO2 emissions, which accounts to around 7 % of the global emissions. This presents great challenges, and continuous work is therefore done to reduce energy consumption and CO2 emissions. This work evaluates ways of decreasing the total energy demand and CO2 emissions in a system containing integrated steel plant connected to a combined heat and power plant (CHP), through optimised production operation with respect to seasonal-dependent energy demands. The studied system, which includes SSAB EMEA Lulea (integrated steel plant) and LuleKraft (CHP), is located in the municipality of Lulea in northern Sweden. The CHP produces the base demand of district heat (DH) for the community, with process gases from the integrated steel plant as its main fuel. Oil is used as an extra energy source when the amounts of process gases are insufficient to meet the DH demand, which happens mainly in the cold winter periods. Therefore, this study aims to find production guidelines to minimise the additional energy consumption of oil through matching cold winter periods with high production of process gases. Optimisation of the system is performed with a mixed integer linear programming (MILP) model based on process data for a normal year. The year is divided into periods based on varying DH demand, to give the model possibility to choose how the integrated steel plant is best operated in each period. The main variables in the integrated steel plant for the study are coke production and usage of recirculated materials, which are bound by yearly demand and availability. Optimisation of this setting is then evaluated in comparison to an optimisation where the integrated steel plant is operated in a constant manner the whole year. Results show that an optimised use of recirculated materials and coke production decreases yearly oil consumption with up to 8 GWh and increases yearly electricity production with up to 8 GWh.
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| 7. |
- Van Dijk, Erik, et al.
(författare)
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Stepwise project : Sorption-enhanced water-gas shift technology to reduce carbon footprint in the iron and steel industry
- 2018
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Ingår i: Johnson Matthey Technology Review. - 2056-5135. ; 62:4, s. 395-402
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Tidskriftsartikel (refereegranskat)abstract
- Industrial processes contribute significantly to global carbon dioxide emissions, with iron and steel manufacturing alone responsible for 6% of the total figure. The STEPWISE project, funded through the European Horizon 2020 (H2020) Low Carbon Energy (LCE) programme under grant agreement number 640769, is looking at reducing CO2 emissions in the iron and steel making industries. At the heart of this project is the ECN technology called sorption-enhanced water-gas shift (SEWGS), which is a solid sorption technology for CO2 capture from fuel gases such as blast furnace gas (BFG). This technology combines water-gas shift (WGS) in the WGS section with CO2/H2 separation steps in the SEWGS section. Scaling up of the SEWGS technology for CO2 capture from BFG and demonstrating it in an industrially relevant environment are the key objectives of the STEPWISE project, which are achieved by international collaboration between the project partners towards design, construction and operation of a pilot plant at Swerea Mefos, Luleå, Sweden, next to the SSAB steel manufacturing site.
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| 8. |
- Wang, Chuan, et al.
(författare)
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Techno-economic assessment of recovery and reuse of low temperature heat (T<350°C) in the steel industry by means of process integration
- 2014
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Ingår i: Energy Procedia. - : Elsevier Ltd. ; , s. 2188-2191
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Konferensbidrag (refereegranskat)abstract
- This article presents a techno-economic evaluation of various options for recovery and reuse of low temperature heat (LTH) with temperatures below 350°C. A process integration approach has been applied to illustrate the investment strategies for a typical European integrated steel plant towards positive energy and environmental effects. The modelling results indicate a CO2 reduction potential of 0.44-1.80% of the total CO2 emissions by recovering and reuse of LTH from the flue gas in various process units. The pay-back time depends on reuse pathways and waste heat temperature, varying from 0.5 to 7.6 years. The results are only valid for the simulated generic site. For the results implementation at real steel plants, local boundary conditions should be considered.
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