| 1. |
- Davidsson, Kent, 1967, et al.
(författare)
-
Potassium, chlorine, and sulfur in ash, particles, deposits, and corrosion during wood combustion in a circulating fluidized-bed boiler
- 2007
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 21:1, s. 71-81
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of the addition of chlorine and/or sulfur to the fuel on fly ash composition, deposit formation, and superheater corrosion has been studied during biomass combustion in a circulating fluidized-bed boiler. The chlorine (HCl (aq)) and sulfur (SO2 (g)) were added in proportions of relevance for the potassium chemistry. The composition of the bottom and the fly ashes was analyzed. Gas and particle measurements were performed downstream of the cyclone before the convection pass and the flue gas composition was recorded in the stack with a series of standard instruments and an FTIR analyzer. At the position downstream of the cyclone, a deposit probe was situated, simulating a superheater tube. Deposits on the probe and initial corrosion were examined. It is concluded that addition of sulfur and chlorine increases the formation of submicron particles leading to deposition of potassium sulfate and chloride. The results compare well with earlier work based on laboratory-scale experiments concerning effects of chlorine and sulfur on potassium chemistry.
|
|
| 2. |
- Folkeson, Nicklas, 1981, et al.
(författare)
-
Fireside corrosion of stainless and low alloyed steels in a waste-fired CFB boiler; The effect of adding sulphur to the fuel
- 2008
-
Ingår i: Materials Science Forum. ; 595-598, s. 289-297
-
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.
|
|
| 3. |
- Froitzheim, Jan, 1981, et al.
(författare)
-
Chromium evaporation of Coated and uncoated FE-22CR steels investigated by a novel denuder technique
- 2009
-
Ingår i: 3rd European Fuel Cell Technology and Applications - Piero Lunghi Conference, EFC 2009; Rome; Italy; 15 December 2009 through 18 December 2009. - 9788882862114 ; , s. 77-78
-
Konferensbidrag (refereegranskat)abstract
- The formation of volatile chromium species is a major problem concerning metallic interconnects for Solid Oxide Fuel Cells (SOFC). This problem is known and a number of routes, usually in the form of coatings, has been presented to overcome this problem. This paper investigates the influence of thin metallic films which can be applied by a low cost process. The measurements are carried out by a novel denuder technique where volatile chromium species are collected as sodium chromate. This technique allows the quantification of chromium evaporation in a time resolved manner. Coated and uncoated samples of ferritic steels developed for SOFC applications are investigated at 850°C in a N2-O2-H2O environment.
|
|
| 4. |
- Froitzheim, Jan, 1981, et al.
(författare)
-
Cr evaporation of metallic interconnects: A novel method for quantification
- 2009
-
Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781566777391 ; 25:2 PART 2, s. 1423-1428
-
Konferensbidrag (refereegranskat)abstract
- Chromium evaporation from metallic interconnects in SOFCs is commonly poisoning the cathode of SOFCs. To reduce chromium evaporation, rather thick coatings have been deposited using various coating techniques. In this study, a 22% Cr ferritic steel has been coated with thin films (
|
|
| 5. |
- Froitzheim, Jan, 1981, et al.
(författare)
-
Investigation of Chromium Volatilization from FeCr Interconnects by a Denuder Technique
- 2010
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 157:9, s. B1295-B1300
-
Tidskriftsartikel (refereegranskat)abstract
- A technique is presented for accurate and time-resolved quantification of chromium volatilization from alloys at high temperature. A denuder tube which is coated with Na2CO3 is placed downstream of the samples. CrO2(OH)(2) that evaporated from the samples is collected on the denuder and converted to the thermally stable Na2CrO4. The chromate is then dissolved in water and determined quantitatively. Three commercially available ferritic 22% Cr steels intended for use as solid oxide fuel cell interconnect materials (Sanergy HT, Crofer 22 APU, and ZMG 232) have been investigated with respect to chromium volatilization and oxidation rate. The effect on chromium volatilization of a submicrometer cobalt coating on the steel surface is reported. Comparisons are made with a conventional thick ceramic coating. The experiments are carried out at 850 degrees C in N-2 - 20% O-2 - 3% H2O atmosphere. The submicrometer Co coatings proved to be very efficient, reducing Cr volatilization by 1 order of magnitude. Microscopic studies show that both uncoated steel and steel coated with a submicrometer cobalt film develop two-layered oxide scales with the bottom part consisting of a Cr-rich corundum-type oxide. The uncoated samples develop a top layer consisting of (Cr, Mn)(3)O-4 oxide, whereas the Co-coated samples exhibit a top layer consisting of Co-rich spinel oxide. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3462987] All rights reserved.
|
|
| 6. |
|
|
| 7. |
- Larsson, Erik, 1983, et al.
(författare)
-
The Influence of KCl and HCl on the High-Temperature Oxidation of a Fe-2.25Cr-1Mo Steel at 400 °C
- 2020
-
Ingår i: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 93:1-2, s. 29-52
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of alkali- and chlorine-containing compounds on the corrosion of superheater alloys has been studied extensively. The current paper instead investigates the corrosive effects of KCl and HCl under conditions relevant to waterwall conditions. A low-alloy (Fe-2.25Cr-1Mo) steel was exposed to KCl(s), 500 vppm HCl(g) and (KCl + HCl) in the presence of 5%O2 and 20% H2O at 400 °C. The results indicate that alloy chlorination by KCl occurs by an electrochemical process, involving cathodic formation of chemisorbed KOH on the scale surface and anodic formation of solid FeCl2 at the bottom of the scale. The process is accompanied by extensive cracking and delamination of the iron oxide scale, resulting in a complex, convoluted scale morphology. Adding 500 vppm HCl to the experimental environment (KCl + HCl) initially greatly accelerated the formation of FeCl2 at the scale/alloy interface. The accelerated alloy chlorination is attributed to HCl reacting with KOH at the scale surface, causing the cathodic process to be depolarized. A rapid slowing down of the rate of chlorination and corrosion in KCl + HCl environment was observed which was attributed to the electronically insulating nature of the FeCl2 layer which forms at the bottom of the scale, disconnecting the anodic and cathodic regions.
|
|
| 8. |
|
|
| 9. |
- Pettersson, Jesper, 1978, et al.
(författare)
-
The influence of sulphur additions on the corrosive environment in a waste-fired CFB boiler
- 2005
-
Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 522-523, s. 563-570
-
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).
|
|
| 10. |
|
|
