| 1. |
- Andersson, S., et al.
(author)
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Sulfur recirculation for increased electricity production in Waste-to-Energy plants
- 2014
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 34:1, s. 67-78
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Journal article (peer-reviewed)abstract
- Sulfur recirculation is a new technology for reducing boiler corrosion and dioxin formation. It was demonstrated in full-scale tests at a Waste to Energy plant in Goteborg (Sweden) during nearly two months of operation. Sulfur was recirculated as sulfuric acid from the flue gas cleaning back to the boiler, thus creating a sulfur loop. The new technology was evaluated by extensive measurement campaigns during operation under normal conditions (reference case) and operation with sulfur recirculation. The chlorine content of both fly ash and boiler ash decreased and the sulfur content increased during the sulfur recirculation tests. The deposit growth and the particle concentration decreased with sulfur recirculation and the dioxin concentration (I-TEQ) of the flue gas was reduced by approximately 25%. Sulfuric acid dew point measurements showed that the sulfuric acid dosage did not lead to elevated SO3 concentrations, which may otherwise induce low temperature corrosion. In the sulfur recirculation corrosion probe exposures, the corrosion rate decreased for all tested materials (16Mo3, Sanicro 28 and Inconel 625) and material temperatures (450 degrees C and 525 degrees C) compared to the reference exposure. The corrosion rates were reduced by 60-90%. Sulfur recirculation prevented the formation of transition metal chlorides at the metal/oxide interface, formation of chromate and reduced the presence of zinc in the corrosion products. Furthermore, measured corrosion rates at 525 degrees C with sulfur recirculation in operation were similar or lower compared to those measured at 450 degrees C material temperature in reference conditions, which corresponds to normal operation at normal steam temperatures. This implies that sulfur recirculation allows for higher steam data and electricity production without increasing corrosion.
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| 2. |
- Cantatore, Valentina, 1986, et al.
(author)
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Oxidation Driven Permeation of Iron Oxide Scales by Chloride from Experiment Guided First-Principles Modeling
- 2019
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In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:42, s. 25957-25966
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Journal article (peer-reviewed)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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| 3. |
- Eklund, Johan, 1991, et al.
(author)
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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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In: Materials and Corrosion. - : Wiley. - 0947-5117 .- 1521-4176. ; 70:8, s. 1476-1485
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Journal article (peer-reviewed)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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| 4. |
- Eklund, Johan, 1991, et al.
(author)
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High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications
- 2019
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In: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 91:5-6, s. 729-747
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Journal article (peer-reviewed)abstract
- The present study investigates the initial corrosion behaviour of HVAF-sprayed NiCr, NiAl and NiCrAlY coatings in two different environments, O 2 + H 2 O and O 2 + H 2 O + KCl at 600 °C for up to 168 h in order to evaluate the possibility of utilizing such coatings in biomass- and waste-fired boilers. SEM/EDX analysis showed that all coatings displayed a protective behaviour in O 2 + H 2 O. Upon addition of KCl (O 2 + H 2 O + KCl), the corrosion behaviour of the NiCr coating drastically changed as it formed a thick oxide layer and displayed major chlorine diffusion down to the substrate. The NiCrAlY coating displayed a significantly better corrosion resistance with only minor oxide formation. The NiAl coating exhibited a protective behaviour similar to when exposed in the absence of KCl indicating that a thin protective oxide has formed on the coating surface. The performance of the NiAl and NiCrAlY coatings is promising for future studies with long-term exposures in more corrosive environments such as in a biomass- and waste-fired boiler.
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| 5. |
- Eklund, Johan, 1991, et al.
(author)
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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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In: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 144, s. 266-276
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Journal article (peer-reviewed)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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| 6. |
- Guiglion, G., et al.
(author)
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4MOST Survey Strategy Plan
- 2019
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In: Messenger. - 0722-6691. ; 175, s. 17-21
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Journal article (other academic/artistic)abstract
- The current status of and motivation for the 4MOST survey strategy, as developed by the Consortium science team, are presented here. Key elements of the strategy are described, such as sky coverage, number of visits and total exposure times in different parts of the sky, and how to deal with different observing conditions. The task of organising the strategy is not simple, with many different surveys that have vastly different target brightnesses and densities, sample completeness levels, and signal-to-noise requirements. We introduce here a number of concepts that we will use to ensure all surveys are optimised. Astronomers who are planning to submit a Participating Survey proposal are strongly encouraged to read this article and any relevant 4MOST Survey articles in this issue of The Messenger such that they can optimally complement and benefit from the planned surveys of the 4MOST Consortium.
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| 7. |
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| 8. |
- Hoseini Hooshyar, Hamed, 1986, et al.
(author)
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Initial corrosion attack of 304L and T22 in 2 MW biomass gasifier: a microstructural investigation
- 2015
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In: Materials at High Temperatures. - 0960-3409. ; 32:1-2, s. 197-204
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Journal article (peer-reviewed)abstract
- The work investigates the initial corrosion attack on a low alloyed steel and a stainless steel in a 2 MW test gasifier. The gasifier environment generates homogenous deposits that consist mainly of carbon containing species, potassium sulphate, potassium chloride and zinc sulphide. The stainless steel exhibits better corrosion resistance compared to the low alloyed steel and the analysis indicates a protective thin scale covering parts of the surface after 4 h exposure. However, in some areas the oxide scale has lost its protective properties and thicker oxide scales are seen. The thick oxide islands consist of an inward growing Fe,Cr,Ni oxide and an outward growing iron oxide. The low alloyed steel shows a more homogenous and faster initial corrosion attack. The thick scales exhibit a sharp straight line in the middle of the scale that separates the bottom spinel oxide from the outer iron rich parts of the scale. It is considered that this flat interface corresponds to the original sample surface
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| 9. |
- Hoseini Hooshyar, Hamed, 1986, et al.
(author)
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The Effect of H-2 and H2O on the Oxidation of 304L-Stainless Steel at 600 A degrees C: General Behaviour (Part I)
- 2016
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In: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 85:3-4, s. 321-342
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Journal article (peer-reviewed)abstract
- The effect of p(H2O) and p(H-2) on the oxidation of 304L stainless steel at 600 A degrees C has been investigated in the present study. The samples were analysed by means of X-ray diffraction, Auger spectroscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy. The results showed that at fixed p(H-2), the corrosion rate increased considerably with increasing p(H2O). At fixed p(H2O), the corrosion rate decreased slightly with increasing p(H-2). Duplex oxide scales formed during the exposure in all environments. The outer and inner layer consisted of Fe3O4 and (Fe, Cr)(3)O-4, respectively. The latter was mainly in the form of internal oxidation. The Cr-rich oxide formation was observed at the initial oxidation process before oxide breakdown. The Auger analysis also suggested the presence of Cr-rich oxide layer just after the breakaway oxidation. The results indicated that the rate-determining step in the corrosion attack is surface controlled or diffusion controlled through an oxide layer with fixed thickness over time.
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| 10. |
- Jonsson, Torbjörn, 1970, et al.
(author)
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High-Temperature Oxidation of FeCr(Ni) Alloys : The Behaviour After Breakaway
- 2017
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In: Oxidation of Metals. - : Springer Nature. - 0030-770X .- 1573-4889. ; 87:3-4, s. 333-341
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Journal article (peer-reviewed)abstract
- The oxidation of an austenitic FeCr(Ni) steel at 600 C in H2O ?KCl ? O2/H2 ? H2O ? Ar environments is studied up to 168 h. The oxidationbehaviour after ‘‘breakaway’’ is investigated by microstructural investigations, andthermodynamic calculations (Thermo-Calc) on the FeCr(Ni)–O system are used tointerpret the results. The characteristic ‘‘breakaway’’ scale morphology exhibits anoutward-growing iron oxide and a bottom layer consisting of inward-growing spineloxide and reaction zones containing Cr-rich oxide precipitates and Cr-depletedmetal. The equilibrium calculations show that a miscibility gap appears in the FeCrspinel oxide below 665 C influencing the microstructure of the inward-growingscale. Equilibrium calculations on the FeCrNi–O system show that Ni is notexpected to enter the spinel oxide in low oxygen activity conditions, in accordancewith observations
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