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- Folkeson, Nicklas, 1981, et al.
(författare)
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Fireside corrosion of stainless and low alloyed steels in a waste-fired CFB boiler; The effect of adding sulphur to the fuel
- 2008
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Ingår i: Materials Science Forum. ; 595-598, s. 289-297
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion field tests have been carried out in the superheater region of a commercial waste-fired 75MW CFBC boiler using air cooled probes. Exposure time was 24 and 1000 hours. The effect of adding sulphur to the fuel on the corrosion of two high alloyed steels and a low alloyed steel was studied. The fuel consisted of 50% household waste and 50% industrial waste. The exposed samples were analyzed by ESEM/EDX and XRD. Metal loss was determined after 1000 hours. Both materials suffered significant corrosion in the absence of sulphur addition and the addition of sulphur to the fuel reduced corrosion significantly. The rapid corrosion of the high alloyed steel in the absence of sulphur addition is caused by the destruction of the chromium-containing protective oxide by formation of calcium chromate. Adding sulphur to the fuel inhibited chromate formation and increased the sulphate/chloride ratio in the deposit. Iron(II) chloride formed on the low alloyed steel regardless of whether sulphur was added or not.
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| 2. |
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| 3. |
- Pettersson, Carolina, 1980, et al.
(författare)
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KCl-Induced High Temperature Corrosion of the Austenitic Fe-Cr-Ni Alloys 304L and Sanicro 28 at 600 °C
- 2006
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Ingår i: Corrosion Science. ; 48:6, s. 1368-1378
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Tidskriftsartikel (refereegranskat)abstract
- The influence of KCl(s) on the high temperature oxidation of the austenitic alloys 304L and Sanicro 28 at 600 °C in O2 + H2O environment is reported. 0.10 mg/cm2 KCl(s) was added before exposure. The samples are investigated by grazing angle XRD, SEM/EDX, and AES. In the absence of KCl, both alloys show protective behaviour in dry O2. In O2 + H2O environment, alloy 304L suffers local breakaway corrosion while Sanicro 28 still shows protective behaviour. The oxidation of both alloys is strongly accelerated by KCl. KCl reacts with chromium in the normally protective corundum-type oxide, forming K2CrO4. This depletes the scale in chromia and leads to the formation of a non-protective, iron-rich scale. The significance of KCl-induced corrosion in real applications is discussed and the oxidation behaviour of the two steels is compared.
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| 4. |
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| 5. |
- Pettersson, Jesper, 1978, et al.
(författare)
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The influence of sulphur additions on the corrosive environment in a waste-fired CFB boiler
- 2005
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Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 522-523, s. 563-570
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion/deposition field tests have been carried out in the superheater region of a commercial waste-fired 75MW CFBC boiler using air cooled probes. The influence of material temperature (450-500 degrees C), flue gas temperature, temperature variations (i.e. thermal cycling) and additives to the fuel (elemental sulphur and dolomite) on deposition and corrosion was studied. The results presented here mainly consider the influence of sulphur additions to the fuel. The fuel was a mixture of 50% household waste and 50% industrial waste. After exposure the samples were analyzed by ESEM/EDX, XRD, AAS, FIB and IC. With no additional sulphur, alkali chlorides made up a large part of the deposit/corrosion product layer and in some cases chromate (VI) was detected. It is suggested that the chromate (VI) has formed by reaction of the protective oxide with alkali chlorides in the deposit. Adding sulphur to the fuel changed the composition of the deposits, alkali chlorides being largely replaced by alkali sulphates. No chromates(VI) were detected in the sulphur-added runs. It is suggested that adding sulphur to the fuel may decrease fireside corrosion because it changes the composition of the deposit. Alkali sulphates are much less corrosive than alkali chlorides partly because they do not form chromate(VI).
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| 6. |
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| 7. |
- Enquist, Karl, et al.
(författare)
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Membrane-integration characteristics of two ABC transporters, CFTR and P-glycoprotein
- 2009
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 387:5, s. 1153-1164
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Tidskriftsartikel (refereegranskat)abstract
- To what extent do corresponding transmembrane helices in related integral membrane proteins have different membrane-insertion characteristics? Here, we compare, side-by-side, the membrane insertion characteristics of the 12 transmembrane helices in the adenosine triphosphate-binding cassette (ABC) transporters, P-glycoprotein (P-gp) and the cystic fibrosis transmembrane conductance regulator (CFTR). Our results show that 10 of the 12 CFTR transmembrane segments can insert independently into the ER membrane. In contrast, only three of the P-gp transmembrane segments are independently stable in the membrane, while the majority depend on the presence of neighboring loops and/or transmembrane segments for efficient insertion. Membrane-insertion characteristics can thus vary widely between related proteins.
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| 8. |
- Pettersson, Carolina, 1980, et al.
(författare)
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Corrosivity of KCl(g) at Temperatures Above its Dew Point - Initial Stages of the High Temperature Corrosion of Alloy Sanicro 28 at 600°C
- 2006
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Ingår i: Materials Science Forum. ; 522-523, s. 539-546
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Tidskriftsartikel (refereegranskat)abstract
- The influence of gaseous KCl on the high temperature oxidation of alloy Sanicro 28 (27Cr31Ni) at 600°C in 5% O2 (N2 in balance) is reported. The samples were exposed isothermally in flowing gas, the dew point of KCl being 590°C corresponding to a partial pressure of KCl of about 2∙10-6 atm. The exposure time was 24, 72 and 168 hours. The samples were investigated by gravimetry, grazing incidence XRD, SEM/EDX and AES. The results show that the oxidation of Sanicro 28 at 600°C is accelerated by KCl(g) at metal temperatures above the dew point of the salt. KCl(g) reacts with the protective chromium rich oxide ((Fe1-xCrx)2O3) forming K2CrO4. The resulting chromium depletion of the oxide gives an increasing oxidation rate but does not trigger breakaway corrosion. The distribution of potassium chromate on the sample surface is strongly flow-dependent, showing that the rate of formation of potassium chromate is limited by the rate of transport of KCl(g) to the surface. No evidence for chlorine was found on the corroded samples by AES profiling or EDX.
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| 9. |
- Pettersson, Carolina, 1980, et al.
(författare)
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Corrosivity of KCl(g) at temperatures above its dew point - Initial stages of the high temperature corrosion of alloy Sanicro 28 at 600 degrees C
- 2005
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Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 522-523, s. 539-546
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Tidskriftsartikel (refereegranskat)abstract
- The influence of gaseous KCl on the high temperature oxidation of alloy Sanicro 28 (27Cr31Ni) at 600 degrees C in 5% O-2 (N-2 in balance) is reported. The samples were exposed isothermally in flowing P as, the dew point of KCl being 590 degrees C corresponding to a partial pressure of KCl of about 2(.)10(-6) atm. The exposure time was 24, 72 and 168 hours. The samples were investigated by gravimetry, grazing incidence XRD, SEM/EDX and AES. The results show that the oxidation of Sanicro 28 at 600 degrees C is accelerated by KCl(g) at metal temperatures above the dew point of the salt. KCl(g) reacts with the protective chromium rich oxide ((Fe1-xCrx)(2)O-3) forming K2CrO4. The resulting chromium depletion of the oxide gives an increasing oxidation rate but does not trigger "breakaway" corrosion. The distribution of potassium chromate on the sample surface is strongly flow-dependent, showing that the rate of formation of potassium chromate is limited by the rate of transport of KCl(g) to the surface. No evidence for chlorine was found on the corroded samples by AES profiling or EDX.
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| 10. |
- Pettersson, Carolina, 1980
(författare)
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High Temperature Corrosion of Some Stainless Steels
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The high temperature corrosion of the alloy Sanicro 28 (35Fe27Cr31Ni) is addressed in this thesis. The influence of water vapour and two potassium-containing salts was investigated. In addition, three other alloys were studied. Polished steel coupons were isothermally exposed in tube furnaces at 600–800°C in 5% O2 and in 5% O2 + 40% H2O. Exposure time was 1–672 hours. Some samples were coated with salt prior to exposure (0.1 mg/cm2 KCl(s) or K2CO3(s)). Other samples were exposed in situ to KCl(g), using a crucible containing KCl(s) positioned upstream of the samples. Besides laboratory studies, field exposures were conducted in full-scale power plants. The samples were investigated by gravimetry, XRD, SEM, EDX, FIB, TEM, AES and IC. Alloy Sanicro 28 forms a protective, duplex scale consisting of a corundum type chromium-rich oxide, (CrxFe1-x)2O3, and a spinel type oxide, in O2 and in O2 + H2O environments. In the presence of water vapour, chromic acid, CrO2(OH)2, is vaporized. However, the resulting chromia depletion of the outer part of the oxide does not lead to breakaway corrosion, due to the high chromium to iron ratio in the alloy. Potassium chloride strongly accelerates the high temperature corrosion of alloy Sanicro 28. Corrosion is initiated by the formation of potassium chromate, K2CrO4, through the reaction of KCl with the protective, chromium-rich oxide. Chromate formation acts as a sink for chromium in the oxide and leads to a deterioration of its protective properties. No evidence was found to support the formation of transition metal chlorides. Once the protective chromium-rich oxide has been depleted in chromium by chromate formation, the alloy becomes susceptible to direct attack by the remaining KCl(s). The KCl-induced corrosion of alloy Sanicro 28 is the same in principle regardless of whether KCl is in solid or gaseous form. Moreover, the reaction with K2CO3(s) is analogous to that with KCl(s). Alkali-induced corrosion of chromia-forming alloys is important, e.g. in fireside corrosion in biomass and waste fired power plants. The present results imply that the corrosivity in boilers can be mitigated by changing the fuel mix so as to convert alkali chlorides and carbonates, in the flue gas and in deposits, into compounds that do not react with chromia. This can be achieved by adding sulphur to the fuel, which converts alkali chlorides and carbonates to the corresponding sulphates.
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