Abstract
The goal of carbon dioxide (CO2) reduction in energy production has lead power plant operators to increase the efficiency by higher process parameters and to use alternative fuels instead of fossil fuels. Maintenance of power plant boilers experience great challenges due to use of difficult biomass and recycled fuels, which can cause severe corrosion damage to different boiler components and decrease lifetime of the metallic components. Investigation on suitable material solution to encounter the corrosion problems in even higher process temperatures is thus needed. Thermal spray coatings to be applied up to 750 °C in biomass boiler conditions were sprayed and their high temperature corrosion resistance was validated in a 550 MWth circulating fluidized bed (CFB) burning mainly biomass. Three test campaigns were performed with controlled probe measurements, their duration varying from 1300 hours to 5900 hours.
Two material test temperatures were set by the water and air controlled probe: 550 °C and 750 °C. The coatings were high velocity oxy-fuel (HVOF) sprayed nickel- and iron-based NiCr, Ni-21Cr, IN625, NiCrAlY, FeCr and arc sprayed NiCrTi. Two spray guns were applied to spray the metallic HVOF coatings in order to compare the effect of coating structure and oxygen content on the corrosion resistance. Applicability and performance of one ceramic coating Al2O3 with bond coat NiCrAlY was also tested. Reference tube materials were ferritic steel T92 and nickel super alloys A263 and A740. Most of the coatings showed excellent corrosion performance both at lower and higher test temperature.
However, Ni-21Cr and IN625 corroded strongly at higher temperature and cannot be applied with high chlorine containing fuels such as biomass at temperatures as high as 750 °C. According to this study, corrosion performance validation of materials suitable for advanced power plants with higher steam and material temperatures is possible with temperature controlled probe exposure in real boiler conditions.
Two material test temperatures were set by the water and air controlled probe: 550 °C and 750 °C. The coatings were high velocity oxy-fuel (HVOF) sprayed nickel- and iron-based NiCr, Ni-21Cr, IN625, NiCrAlY, FeCr and arc sprayed NiCrTi. Two spray guns were applied to spray the metallic HVOF coatings in order to compare the effect of coating structure and oxygen content on the corrosion resistance. Applicability and performance of one ceramic coating Al2O3 with bond coat NiCrAlY was also tested. Reference tube materials were ferritic steel T92 and nickel super alloys A263 and A740. Most of the coatings showed excellent corrosion performance both at lower and higher test temperature.
However, Ni-21Cr and IN625 corroded strongly at higher temperature and cannot be applied with high chlorine containing fuels such as biomass at temperatures as high as 750 °C. According to this study, corrosion performance validation of materials suitable for advanced power plants with higher steam and material temperatures is possible with temperature controlled probe exposure in real boiler conditions.
| Original language | English |
|---|---|
| Title of host publication | Materials for Advanced Power Engineering 2014 |
| Editors | Jacqueline Lecomte-Beckers, Olivier Dedry, John Oakey, Bernd Kuhn |
| Pages | 727-736 |
| Publication status | Published - 2014 |
| MoE publication type | A4 Article in a conference publication |
| Event | 10th Liège Conference on Materials for Advanced Power Engineering - Palais des Congrès, Liège, Belgium Duration: 14 Sept 2014 → 17 Sept 2014 Conference number: 10 |
Publication series
| Series | Schriften des Forschungszentrums Jülich: Reihe Energie & Umwelt/Energy & Environment |
|---|---|
| Volume | 234 |
| ISSN | 1866-1793 |
Conference
| Conference | 10th Liège Conference on Materials for Advanced Power Engineering |
|---|---|
| Country/Territory | Belgium |
| City | Liège |
| Period | 14/09/14 → 17/09/14 |
Keywords
- biomass
- boiler
- co-firing
- thermal spray
- coating
- high temperature corrosion