OXY-COMBUSTION ENVIRONMENT CHARACTERIZATION: FIRE-AND STEAM-SIDE CORROSION IN ADVANCED COMBUSTION (original) (raw)
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Fireside Corrosion of Applied and Modern Superheater-alloys Under Oxy-fuel Conditions
Energy Procedia, 2013
Operation of oxy-fuel power plants under ultra-supercritical parameters would help to overcome, to a certain extent, efficiency penalties from air separation and CO 2 -compression units. To improve the knowledge on material behavior under oxy-fuel combustion six candidate superheater alloys, varying from martensitic via iron-base austenitic to nickel-base were chosen and exposed at metal temperature of 580°C and 650°C to real oxy-fuel combustion conditions in 3MW combustion test rig of Enel and subsequently moved for further tests to laboratory corrosion test set-up at IFK. Exact definition of combustion conditions was based on measurements performed by IFRF.
Fireside Corrosion in Oxy Fuel Combustion of Coal/Biomass
This research work is focused on the fireside corrosion in oxy fuel combustion of coal/biomass. An experiment was conducted in a laboratory, simulating an environment similar to that in power station boilers. Four stainless steel specimen coated separately with biomass ash and coal ash were inserted on a cooling bomb in a 2.4KW furnace and five gases; N2, O2, CO2, HCl and SO2 were passed through mass flow controllers into the corrosion furnace at set temperature 800 o C±5 o C and metal specimen at set temperatures of 529 o C to 546 o C for the cold side and hot side of the stainless steel respectively. An SEM/EDX analysis carried out on the metal specimen shows the extent of corrosion that has occurred on their surface. Which shows the rate of corrosion of the biomass coated stainless steel is greater than the rate of corrosion of the 50/50 mixture biomass/coal coated stainless steel which is also greater than the rate of corrosion of the uncoated stainless steel. Thermo-gravimetric analysis was conducted on the biomass/coal sample. Ultimate analysis was completed for the biomass/coal sample. An ash fusion test was conducted on the biomass/coal ash sample, which generated the four ash fusion temperatures. SEM/EDX analysis was conducted on the biomass ash and coal Ash.
Performance of superheater materials in simulated oxyfuel combustion conditions
Materials and Corrosion, 2013
This report is based on the results from laboratory testing performed at VTT. The goal of the VTT part in the project was to estimate the oxidation/corrosion behaviour of selected alloys exposed to moist CO 2 rich simulated flue gas with and without CaCO 3-CaSO 4 deposit at high temperatures relevant to oxyfuel combustion. The results of gas exposure testing without deposit were compared to corresponding results from simulated air-fired coal combustion conditions. This work was a part of the HICOR project (Tekes contract 40118/08). The authors wish to thank Tekes, Fortum Oyj, Foster Wheeler Energy Oy and VTT for the financial and other support during the project.
Journal of Physics: Conf. Series, 2017
Corrosion studies are key elements that ensure the correct functioning of equipment in the industrial sector. The oxidation phenomena were evaluated, taking as a case study steel ASTM A335 P91 (P91), steel of typical use in equipment that works at high temperatures. Five (5) exposure times were selected for the experimental development: 1, 20, 50, 100, and 200h; as well as four (4) analysis temperatures: 450, 550, 650, and 750°C. Through the metallographic analysis was possible to evidence the presence of multiple carbide precipitates and a terrific structure, after all the temperatures tested. On the other hand, the analysis of hardness and microhardness showed an increase for all the evaluated temperatures. These increases were mainly related to the precipitation of carbides in the coupons of P91. Regarding the chemical analysis, it was possible to conclude that after 200h of experimentation at each temperature, a layer of duplex oxide, composed mainly of hematite, magnetite, and spinel iron-chromium, was formed in the O2/H2O atmosphere. Finally, the kinetic study demonstrated that the oxide layer formed on each coupon of P91 was of protective character.
Chemical Engineering Transactions, 2018
The current energy production processes go hand in hand with corrosive phenomena; which is the case of the combustion process in a refinery, where the presence of compounds such as CO2 and H2O, result in alloy catastrophic carburization and oxidation respectively. This research work was evaluated the corrosive effect that can be generated in a real combustion environment, for which, it was necessary to select a model mixture of refinery gases and simulate its theoretical combustions products. The main results showed the formation of a semi-protective duplex oxide layer; whose inner layer was composed mainly of chromium, while the outer layer was much richer in iron. On the other hand, the carburizing effect of CO2 was suppressed by the high oxygen potential in the combustion environment; leading to the conclusion that in real conditions, at 750 ºC and after 200 h of testing, steels such as ferritic alloy ASTM A335 P91, could not present appreciable damages during their operation in refinery boilers and furnaces.
IJERT-Fireside Corrosion in Oxy Fuel Combustion of Coal/Biomass
International Journal of Engineering Research and Technology (IJERT), 2016
https://www.ijert.org/fireside-corrosion-in-oxy-fuel-combustion-of-coalbiomass https://www.ijert.org/research/fireside-corrosion-in-oxy-fuel-combustion-of-coalbiomass-IJERTV5IS010369.pdf This research work is focused on the fireside corrosion in oxy fuel combustion of coal/biomass. An experiment was conducted in a laboratory, simulating an environment similar to that in power station boilers. Four stainless steel specimen coated separately with biomass ash and coal ash were inserted on a cooling bomb in a 2.4KW furnace and five gases; N2, O2, CO2, HCl and SO2 were passed through mass flow controllers into the corrosion furnace at set temperature 800 o C±5 o C and metal specimen at set temperatures of 529 o C to 546 o C for the cold side and hot side of the stainless steel respectively. An SEM/EDX analysis carried out on the metal specimen shows the extent of corrosion that has occurred on their surface. Which shows the rate of corrosion of the biomass coated stainless steel is greater than the rate of corrosion of the 50/50 mixture biomass/coal coated stainless steel which is also greater than the rate of corrosion of the uncoated stainless steel. Thermo-gravimetric analysis was conducted on the biomass/coal sample. Ultimate analysis was completed for the biomass/coal sample. An ash fusion test was conducted on the biomass/coal ash sample, which generated the four ash fusion temperatures. SEM/EDX analysis was conducted on the biomass ash and coal Ash.
Fireside corrosion of selected alloys by ash recovered from coal-water slurry combustion
Fuel Processing Technology, 1997
The corrosion behavior of five selected stainless steels was evaluated in a simulated fireside corrosion atmosphere for a coal-water slurry system. Two types of ash, generated from actual combustion tests of coal-water slurries, were used as the fireside test deposits. The ashes differed in the amount of unburned carbon in each. The alloys selected were Types 304, 316, 321. 347 stainless steels and high-nickel 800 M. Tests were conducted for 48 h at temperatures of 600, 700, 800°C in a simulated flue gas, representative of the atmosphere expected in coal-water slurry combustion, and at 1000°C in inert atmosphere. Analyses of the test coupons after removal from the furnace included scanning electron microscopy, optical microscopy, and weight-loss measurements. Scanning electron microscopy showed the presence of fused corrosion deposits, proving that liquid phases were involved in the corrosion process. Microprobe analysis of selected samples detected no sulfur in the corrosion products, suggesting that complex sulfates were not being formed. The low-carbon ash was more corrosive toward the alloys than the high-carbon ash. The high-carbon ash tended to shift the temperature of maximum corrosion toward higher temperatures. Type 316 stainless steel showed the highest corrosion losses among the five alloys tested with the low-carbon ash at 600-800°C. For tests with the high-carbon ash, the corrosion losses for all the alloys, except for Type 347, were low. The differences in corrosion losses between the types of ashes relate to the differences in carbon and calcium contents of the two ashes. The overall corrosion losses were small when compared to literature values for fireside corrosion losses in pulverized coal combustion. Published by Elsevier Science B.V.
Chemical Engineering Transactions, 2018
The corrosive effects developed on Fe-9Cr-1Mo steel in a typical combustion environment were evaluated. For this, steel samples were submitted in a peritubular horizontal boiler, through the design of a coupon holder. With the experimental conditions characterized, the theoretical corrosion products were simulated; which showed similarity with SEM-EDS and DRX analysis, in the formation of hematite, magnetite, and chromite. On the other hand, the oxide layers' morphology deposited on the substrate, indicated the appearance of multiple efforts in them: cracks, pores, voids, and detachments were observed. To complement these observations, the kinetic study was carried out, which allowed determining a semi-protective behavior from the oxide layers formed on Fe-9Cr-1Mo steel; where the diffusive processes are partially reduced. Finally, only oxidation and some localized nitridation could be identified. Carburization could not be identified due to the high oxygen potentials in the environment, and the short-selected exposure times.