| 11. |
- Köhler, Anna, 1989, et al.
(author)
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Experimental characterization of axial fuel mixing in fluidized beds by magnetic particle tracking
- 2016
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Conference paper (other academic/artistic)abstract
- A Magnetic Particle Tracking (MPT) system is applied to a bubbling fluidized bed to study how axial mixing and segregation of fuel are influenced by the fuel density and operational conditions (fluidization velocity, bed height and pressure drop across the gas distributor). The MPT system is used to determine the vertical distribution of the tracer particle in a fluid-dynamically down-scaled cold unit resembling a 0.74×0.74 m2 fluidized bed reactor operating at 800 °C. This work uses a tracer particle of 10 mm in diameter, corresponding to a fuel particle of 44 mm. Different tracer particles are applied with solids density representing biomass, biomass char and that of the average bulk. The MPT system yields a spatial accuracy in the order of 10-3 m and a time resolution of 10-3 s. For the operational range investigated, three fuel segregation regimes can be identified from the MPT measurements: 1) A flotsam regime which occurs at low fluidization velocities and for low density tracer particles, 2) A transition regime over which an increase in fluidization velocity results in that the presence of fuel particles at the bed surface decreases rapidly, and 3) A fully developed mixing regime in which the presence of tracer particle at the bed surface and the splash zone remains constant with fluidization velocity. The transition velocities between the regimes depend on bed height and density of the tracer particle.
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| 12. |
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| 13. |
- Mata Las Heras, Erika, 1980, et al.
(author)
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Cost-Effectiveness of Retrofitting Swedish Buildings
- 2017
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In: Cost-Effective Energy Efficient Building Retrofitting: Materials, Technologies, Optimization and Case Studies. - 9780081011287 ; , s. 343-362
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Book chapter (other academic/artistic)abstract
- This chapter presents potentials for energy conservation through energy retrofitting of existing Swedish buildings, including residential and nonresidential buildings. The Swedish building stock is described with 1800 representative buildings, in a combination of sample and archetype buildings, and is modeled with a dynamic and detailed building-stock model. Ten individual energy conservation measures and 6 packages of measures are considered. The chapter also presents how the cost-effectiveness of the measures depends on energy prices, discount rates, and the assumed investment costs for the different measures. The results are presented and discussed separately for residential buildings, divided into single-family dwellings and multifamily dwellings, and nonresidential buildings.
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| 14. |
- Mocholí Montañés, Rubén, 1990, et al.
(author)
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Large-scale Torrefaction of waste wood for pulverized-coal substitution in blast furnaces: Torero project
- 2018
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Conference paper (other academic/artistic)abstract
- The overall aim of the Torero project is to be the world-first large scale implementation of the waste wood torrefaction for substitution of pulverized coal in blast furnaces. Steel making is highly dependent on coal for reduction of the iron ore in the blast furnace and for energy supply. Substitution of coal with biomass could effectively reduce CO2 emission in steelmaking. However, the steel making process has strict constrains on the properties of the fuel, making it difficult to use a heterogeneous fuel like biomass. In addition, the price of biomass, especially in a carbon constrained energy system, is higher than for coal. The Torero-project considers substitution of the pulverized coal used in the blast furnace with torrefied waste wood. The torrefaction process produces a bio-coal that is possible to mill and use in the present blast burners. Although waste wood is considered as a difficult, due to the high content of contaminants, which limits the alternative uses and, thus, makes it cost-effective in processes where it can be used. The process will be implemented at the ArcelorMittal site in Gent (Belgium), together with the sister project Steelanol, for microbiological fermentation of the carbon monoxide in blast furnace exhaust fumes to bioethanol. The combination of the two projects aims to convert waste wood to produce 80 million litres per year of bioethanol. This work is a first assessment of the Torero project concept. Process simulations are performed in Aspen Plus to evaluate the heat and mass balances of the integrated torrefaction process. The reaction mechanism of the torrefication process of the waste wood are based on small scale experiments and implemented into the reactor model. The ArcelorMittal plant in Ghent is used as a reference in the evaluation. The results of this investigation highlight performance, emissions and technical barriers including the effects of fuel properties and presence of trace species in the fuel.
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| 15. |
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| 16. |
- Òsk Gardarsdòttir, Stefanìa, 1987, et al.
(author)
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Challenges for coal based electricity generation in energy systems with high capacity of variable renewable energy sources
- 2016
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In: Proceedings of the 41st International Technical Conference on Clean Coal & Fuel Systems.
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Conference paper (other academic/artistic)abstract
- The market conditions for thermal power plants in Europe are changing rapidly with ever increasing share of the supply provided by variable renewable energy sources. Operators are struggling to keep up with the new conditions in a system where power plant flexibility has historically been of less importance. This is however starting to change and in line with this development, the power industry is increasingly interested in R&D work on improving plant flexibility. Based on interviews with several experts within the power industry, a literature review and dynamic power plant modelling this work highlight and discusses important areas of development for flexible coal-based power generation. Four flexibility aspects were specifically emphasized by the experts interviewed; turn-down, part-load efficiency, start-up times and ramp rates. All experts interviewed regarded retrofits of existing plants to be a more likely development than building of new flexible plants and at present, it seems as the focus is mainly to use all low-cost options for increasing plant flexibility. The extent of beneficial effects from increased plant flexibility for both the plant operator, and the electricity system is still unclear. A techno-economic modeling study of power systems combined with dynamic power plant modeling, taking into account the possible development in plant flexibility as highlighted in this work, could further provide valuable insight and underline which flexibility aspects are of most importance to develop.
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| 17. |
- Sette, Erik, 1984, et al.
(author)
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3-dimensional particle tracking in a fluid-dynamically downscaled fluidized bed using magneto resistive sensors
- 2015
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In: The 8th International Symposium on Coal Combustion.
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Conference paper (other academic/artistic)abstract
- This paper presents a measurement technique for continuous tracking of particles in 3-dimensional bubbling fluidized beds operated according to scaling laws. By applying Glicksman’s full set of scaling laws to both bulk solids and tracer particle the bed is assumed to be fluid-dynamically similar to a combustor operated at 900 °C with the tracer particle corresponding to a fuel particle with properties similar to anthracite coal. Two different gas distributors with varying pressure drop are used to investigate the influence of bed design on fuel mixing.Flow structures formed around rising gas bubbles, so called bubble paths, are identified and the tracer particle traverses the entire bed for a gas distributor yielding a high pressure drop. For a gas distributor yielding a low pressure drop flow structures are less pronounced and the tracer particle is not circulating the entire bed.
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| 18. |
- Taljegård, Maria, 1988, et al.
(author)
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Electric vehicles as power and energy provider for the European electricity system - an electricity systems modelling study
- 2019
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Conference paper (other academic/artistic)abstract
- This study analysis the potential for electric vehicles (EVs) to contribute with power and energy to the electricity system by means of demand response, storage of electricity and contribution to the power reserve. The work applies real-time measurements of driving patterns and a cost-minimisation model of the electricity system assuming zero CO2 emission and run for selected European regions. The results shows that EVs can (i) substantially reduce investments in peak power capacity, (ii) replace investments in other both short-term and long-term storage technologies (e.g., stationary batteries and hydrogen storage), and (iii) participate in the power reserve with large additional power capacity.
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| 19. |
- Österbring, Magnus, 1986, et al.
(author)
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Metod för omställning av urbana byggnadsbestånd
- 2018
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Reports (other academic/artistic)abstract
- Även om den teoretiska och tekniska potentialen för att minska energianvändningen i befintliga byggnader är stor, är den faktiska besparingspotentialen mindre känd. Syftet med projektet är att utveckla en metodik för att identifiera renoverings-, tillbyggnads- och nybyggnadsalternativ för urbana byggnadsbestånd som är miljömässigt och ekonomiskt gynnsamma och där energibesparingsåtgärder ligger i centrum. Projektet utgår från existerande beräkningsmodeller men kombinerar dessa på nytt sätt. En tidigare utvecklad byggnadsbeståndsmodell integrerad i geografiska informationssystem kombineras med en byggnadsfysikalisk modell för större byggnadsbestånd (ECCABS modellen - Energy, Carbon and Cost Assessment for Building-Stocks) samt livscykelanalys. Genom att använda byggnadsspecifik information och hantera byggnader i deras lokala kontext kan en mer holistisk syn uppnås. Tillgängliga databaser med byggnadsspecifika data har samlats och processats för flerbostadsbeståndet i Göteborg. Data används för beskrivningar av flerbostadshusbeståndets energiprestanda och framtida renoveringsbehov som i sin tur används som input för beräkningar av energibehoven. Beskrivningen och analysen tar hänsyn till byggnadens ålder, värdeår, ägare, geometri som länkas till ett geografiskt läge, och används för modelleringen av byggnadernas energiprestanda. Byggnadsbeståndsbeskrivningen hanterar varje byggnad som unik och tillåter på så sätt differentierade beskrivningar av byggnadsbestånd, dvs resultaten kan aggregeras på önskad skala för att passa olika intressenters behov. Bland annat har olika renoveringsscenarios tagits fram för att undersöka energisparpotentialen fram till år 2035. Resultaten visar att trots potential att minska den specifika energianvändningen i det befintliga beståndet så förblir den totala energianvändningen i flerbostadshusbeståndet i det närmaste oförändrad på grund av den tillkommande energianvändningen i nybyggnationen. I detta projekt har flerbostadshusbeståndet i Göteborg studerats men metodiken är generellt tillämpbar oavsett geografiskt område. Metodiken kan användas för prioritering av olika energieffektiviseringsåtgärder vid renovering där fastighetsförvaltare, i nuläget främst bostadsbolag, är den huvudsakliga målgruppen. Även andra beslutfattare såsom kommunala energiplanerare och stadsplanerare kan stödjas i sitt beslutsfattande för att uppnå en hållbar transformation av urbana byggnadsbestånd. Genom implementeringen av metoden i ett geografiskt informationssystem ges inte bara möjlighet att undersöka vilka besparingsåtgärder som är gynnsamma för en effektivare energi- och resursanvändning utan också att prioritera vilka geografiska områden som får mest ut av dessa åtgärder. Den framtagna metodiken kan ses som ett första steg i ett försök att formalisera och strukturera modellering, visualisering och kommunikation av resultat. Ytterligare forskning behövs för att kunna bedöma och utvärdera potentialen genom kvalitativa, fördjupade behovsstudier riktade till bostads- och fastighetsbolag. Ett annat spår är att utvidga beståndet som
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