| 1. |
- Henderson, Pamela, et al.
(författare)
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A steam loop for materials testing at 600C in a biomass and waste fired boiler : results of corrosion testing
- 2010
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Ingår i: 9th Liege conference on Materials for Advanced Power Engineering 2010. - : Forschungszentrum Jülich GMbH. - 9783893366859 ; , s. 1140-1149
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Konferensbidrag (refereegranskat)abstract
- A steam loop for corrosion testing was constructed in Esshete 1250 and attached to one of the superheaters in a 100 MWth bubbling fluidised bed (BFB) boiler. The loop raised the final steam temperature to about600°Cat 140 bar. A number of different test materials were welded into the loop for evaluation at low temperature (500°Csteam) and high temperature (600°Csteam). Their wall thicknesses were measured with a high resolution ultrasonic probe before and after exposure. A number of sections were examined metallographically after exposure. The steam loop was in service for one firing season (about 5500 h) and the fuel mixture was initially a biomass mix co-firing with 15% coal. However halfway though the firing season the coal was replaced with 15% packaging waste containing plastic and aluminium. The latter mixture (biomass and waste) was highly corrosive and accounted for most of the corrosion. The alloys with the highest Ni and Cr contents, Haynes230, AC66 and HR11N, showed negligible steam-side corrosion. The 11% chromium steel X20 and the nickel-base alloy HR11N were not tested at the higher steam temperature because of strength considerations. Regarding fireside corrosion at500°Csteam the alloys with the best corrosion resistance were Haynes 230, HR11N, AC 66 and HR3C followed by Esshete 1250 and TP347HFG. The corrosion rate of X20 was unacceptably high and is totally unsuitable for this fuel mix. At 600°C Haynes 230 showed the lowest corrosion rates, followed by TP 347 HFG, HR3C, AC66, and Esshete 1250. Large amounts of internal corrosion were seen.
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| 2. |
- Henderson, Pamela, et al.
(författare)
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Combating corrosion in biomass and waste-fired plant
- 2010
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Ingår i: 9th Liege conference on Materials for Advanced Power engineering 2010. - : Forschungszentrum Jülich GmbH. - 9783893366859 ; , s. 986-999
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Konferensbidrag (refereegranskat)abstract
- Many biomass- or waste-fired plants have problems with high temperature corrosion especially if the steam temperature is greater than500°C. An increase in the combustion of waste fuels means that an increasing number of boilers have had problems. Therefore, there is great interest in reducing the costs associated with high temperature corrosion and at the same time there exists a desire to improve the electrical efficiency of a plant by the use of higher steam temperatures. Assuming that the fuel is well-mixed and that there is good combustion control, there are in addition a number of other measures which can be used to reduce superheater corrosion in biomass and waste fired plants, and these are described in this paper. These include the use of fuel additives, specifically sulphur-containing ones; design aspects like placing superheaters in less corrosive positions in a boiler, using tube shielding, a wider pitch between the tubes; operational considerations such as more controlled soot-blowing and the use of better materials.
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| 3. |
- Henderson, Pamela, et al.
(författare)
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Preliminary experience with material testing at the oxyfuel pilot plant at Schwarzepumpe
- 2010
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Ingår i: 9th Liege conference on Materials for Advanced Power engineering 2010. - : Forschungszentrum Jülich GmbH. - 9783893366859 ; , s. 1244-1259
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Konferensbidrag (refereegranskat)abstract
- Several material related issues may arise from oxyfuel combustion of coal due to the presence of CO2 but also as an effect of the partial recirculation of the flue gas. Two examples are increased corrosion and carburisation which may limit steam data, hence limiting the efficiency.A number of corrosion tests, in both conventional air-firing and oxyfuel mode, have been made in Vattenfalls 30 MW oxyfuel pilot plant located in Schwarze Pumpe, Germany. Internally cooled corrosion probes, equipped with ferritic, austenitic, super austenitic steels as well as Ni-based and FeCrAl alloys, simulating superheaters, economisers and air preheaters were exposed for up to 1500 hrs.The analyses show an indication of higher material wastage in oxyfuel compared to air combustion especially at the lower exposure temperatures. This may be due to increased sulphur concentration in corrosion front, increased heat flux, carburisation or other preciptate formations on austenitic steels and Ni-based alloys.
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