| 1. |
- Eklund, Johan, 1991, et al.
(författare)
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Field exposure of FeCrAl model alloys in a waste-fired boiler at 600°C: The influence of Cr and Si on the corrosion behaviour
- 2019
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Ingår i: Materials and Corrosion. - : Wiley. - 0947-5117 .- 1521-4176. ; 70:8, s. 1476-1485
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Tidskriftsartikel (refereegranskat)abstract
- Materials and Corrosion WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The aim of this study was to examine the performance of FeCrAl model alloys in a waste-fired boiler and investigate the influence of chromium and silicon content on the corrosion behaviour. The investigation was executed by utilising an air-cooled probe, giving a material temperature of 600°C throughout a 672 hr exposure. The material loss measurements were performed by utilizing an ultrasonic thickness gauge in combination with scanning electron microscopy analysis. It was found that increasing the chromium content significantly reduced the overall material loss of the FeCrAl model alloys but further accelerated the corrosion attack on the windward side. Simultaneously, the increased chromium content caused embrittlement of the material. Minor additions of silicon drastically reduced the material loss of the FeCrAl model alloys, whereas the sample ring with no silicon present was completely deteriorated. The trends observed in this field study correlated well with what has been observed in previous laboratory studies. A state-of-the-art alloy in the present environment, Inconel 625, was simultaneously exposed and showed similar performance to the silicon-containing FeCrAl model alloys with ≥10 wt% Cr.
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| 2. |
- Eklund, Johan, 1991, et al.
(författare)
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The influence of silicon on the corrosion properties of FeCrAl model alloys in oxidizing environments at 600 °C
- 2018
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 144, s. 266-276
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the influence of Si on the high temperature corrosion behaviour of FeCrAl model alloys in O2, O2+H2O and O2+H2O + KCl at 600 °C for up to 168 h. The investigation by SEM/EDX showed that all alloys displayed a protective behaviour in dry O2. In the more corrosive environments (O2+H2O and O2+H2O + KCl) the addition of Si affected the oxidation properties in two ways; Alloys containing Si resisted breakaway oxidation caused by Cr-evaporation (O2+H2O) and the thickness of the oxide formed after breakaway oxidation decreased with increasing amount of Si (O2+H2O + KCl).
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| 3. |
- Andersson, Sven, 1968, et al.
(författare)
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High Temperature Corrosion and Dioxin Abatement Using Sulfur Recirculation in a Waste-to-Energy Plant
- 2019
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Ingår i: Detritus. - : Eurowaste SRL. - 2611-4127 .- 2611-4135. ; 5:Mars, s. 92-98
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur Recirculation is a novel technique for reducing the high temperature corrosion and dioxin formation in Waste-to-Energy plants by recirculating sulfur from the wet flue gas cleaning back to the boiler. This is achieved by separating SO2 from the flue gas in a wet scrubber downstream of a HCl scrubber. H2O2 dosed into the scrubber reacts with SO, in the gas and produces a 15-25 wt% H2SO4 solution, which is injected into the boiler producing SO2, thus creating a sulfur loop. The first permanent full-scale installation has been in operation in one of the two commercial full-scale Waste-to Energy boilers at Maabjerg Energy Center (MEC) in Denmark since October 2016. The recirculated sulfur increased the gas concentration of SO2 by a factor of 2-3 in the boiler, thereby enhancing the sulfation of corrosive alkali chlorides to non-corrosive alkali sulfates. The chlorine content of the superheater deposits decreased by 85%, and the superheater corrosion rate decreased by 40-90% during the first year of operation. The dioxin concentrations upstream of the dioxin removal system decreased by 75% and the dioxin emissions decreased by 72% with Sulfur Recirculation in operation. Furthermore, the sulfate containing effluent water was almost eliminated due to the increased sulfation of the ashes and deposits.
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| 4. |
- Asokan, Vijayshankar, 1984, et al.
(författare)
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The influence of Si on the primary protection of lean FeCrAl model alloys in O2 and O2+H2O at 600 °C: A microstructural investigation
- 2021
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 179
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the influence of Si on the high-temperature corrosion behavior of lean FeCrAl model alloys in O2 and O2+H2O at 600 °C. The addition of Si prevented breakaway oxidation in O2+H2O which may be explained by the increased Al-content and reduced Cr-content in the oxide (O2) as well as the Si-enrichment in the outer part of the scale (O2+H2O). A proposed explanation for the impact of Si-addition on the Cr- and Al-content was given by thermodynamic calculations which showed that the presence of Si increases the activity of Al in the alloy while reducing the activity of Cr.
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| 5. |
- Balachandran, Arvind, 1994-
(författare)
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Battery Integrated Modular Multilevel Converter Topologies for Automotive Applications
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electric vehicles are rapidly developing in response to the need for increasing sustainable energy sources. The range and lifetime of an electric vehicle are limited by the battery pack. A pack comprises modules with several parallel and/or series-connected cells. Differences in leakage currents and cell in-homogeneities cause individual cell voltage and state-of-charge distribution among the cells to be non-homogeneous. As a result, over time, some cells discharge faster than other cells, thus limiting the total energy delivered by the pack. In order to maximize the energy delivered by the pack, individual cell control is desirable. As a solution, battery-integrated modular multi-level converter (BI-MMC) topologies are proposed, presented, and evaluated. BI-MMC topology consists of either one or two arms per phase, and each arm comprises several cascaded stages of DC–AC converters and is commonly referred to as submodules. BI-MMCs provide increased controllability and potential improvement in the lifetime of the battery pack. Furthermore, BI-MMCs have low output total harmonic distortion, further improving the powertrain efficiency.The first contribution is the design and evaluation of 3-phase and 6-phase BI-MMCs; comparisons are made against a conventional 2-level inverter for a 40-ton 400 kW commercial vehicle. The evaluation considers the total number of submodules, energy rating of the DC-link capacitors, battery losses, capacitor losses, and semiconductor losses. The evaluation showed that the BI-MMCs have lower semiconductor losses than the conventional 2-level inverter. However, the BI-MMCs have higher capacitor and battery losses. The second contribution is the investigation of the impact that the number of series connected cells per submodule has on the total losses of the BI-MMC. The study showed that 5- to 6-series connected cells have the lowest losses. The third contribution is the design principles for optimization of the DC-link capacitors and the MOSFET switching frequency; this is supported by experimental validation for the loss distribution within a submodule. The fourth contribution is a methodology for determining the battery impedance using the full-load converter current. In a conventional battery pack, the battery is connected directly to the fast charger’s DC supply. However, in a BI-MMC, the battery and the inverter are integrated, potentially increasing the DC charging capabilities because higher voltages can be achieved during charging than during operation. The fifth contribution is thus the derivation and investigation of the maximum DC charging power of BI-MMCs assuming the same submodule semiconductor losses during traction. The analysis showed that most BI-MMCs have a maximum DC charging power of about 1MW.
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| 6. |
- Bigdeli, Sedigheh, 1984, et al.
(författare)
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Strategies for High-Temperature Corrosion Simulations of Fe-Based Alloys Using the Calphad Approach : Part I
- 2021
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Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 42:3, s. 403-418
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Tidskriftsartikel (refereegranskat)abstract
- The environmental degradation of materials at high temperatures limits the useful life of different industrial components and hinders the development of more economical and environmentally friendly processes for the energy production. Despite the importance of this phenomena, a model to predict lifetime of materials that degrade due to high-temperature corrosion has up till now been lacking due to limitations of the computational possibilities and the complex nature of oxidation. In the present work we develop some strategies to model high-temperature corrosion in Fe-based alloys using the Calphad (Calculation of Phase Diagrams) approach. It is proposed that kinetic-based simulations for oxidation of Al and Cr can accurately represent the lifetime of the protective layers in FeCrAl and FeCr alloys at different temperatures in air. The oxide systems are in addition investigated by equilibrium calculations. The corrosion mechanisms of FeCr and FeCrAl alloys are discussed based on theoretical and experimental knowledge.
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| 7. |
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| 8. |
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| 9. |
- Cantatore, Valentina, 1986, et al.
(författare)
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Oxidation Driven Permeation of Iron Oxide Scales by Chloride from Experiment Guided First-Principles Modeling
- 2019
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:42, s. 25957-25966
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Tidskriftsartikel (refereegranskat)abstract
- In this comprehensive investigation, it is demonstrated how chloride ions may permeate a crack-free oxide scale, thus providing hitherto missing mechanistic insight as to the impacts of KCl(s) or HCl(g) exposures on the high-temperature corrosion of biomass- and waste-fired boilers. Guided by dedicated experimental analyses, mechanistic understanding is gained by means of density functional theory. Chloride ions, being accommodated in oxygen anion vacancies that are generated at the receding magnetite/alloy interface, are driven through the oxide scale by the oxidation process. Intermediate stabilities of quasi-homogeneous transient iron oxychloride species are found, employing potassium ferrite and goethite as complementary cation sinks for the KCl(s) and HCl(g) reactants, respectively. Spontaneous disproportionation of the supersaturated oxychlorides into two different types of chloride decorated magnetite grain boundaries is demonstrated. These motifs are proposed to explain loss of scale integrity as well as accelerated oxidation by offering short-circuiting transient pathways for ion diffusion.
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| 10. |
- Dahl, K. V., et al.
(författare)
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Characterization of pack cemented Ni(2)Al(3 )coating exposed to KCl(s) induced corrosion at 600 degrees C
- 2018
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Ingår i: Materials at High Temperatures. - : Informa UK Limited. - 0960-3409 .- 1878-6413. ; 35:1-3, s. 267-274
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation of Ni2Al3 produced by pack aluminizing of pure nickel was studied with and without 0.10 mg cm(-2) KCl(s) deposit in an environment containing 5% O-2, 40% H2O and 55% N-2 at 600 degrees C for up to 168 h. Oxide microstructure and composition was investigated by SEM/EDX, BIB, TEM and GDOES. Oxidised Ni2Al3 shows minimal weight gain, while adding KCl results in a small weight loss consistent with evaporation of KCl. On the surface of samples exposed to the gas environment only, a 30 nm oxide of Al oxide was present, but where KCl was present as deposit, 50-250 nm thick nodules form that are enriched in K, O and Al.
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