Fireside and steamside corrosion of alloys for USC plants

Natesan, K.; Park, J.H.

doi:10.1016/j.ijhydene.2006.08.038

Cited by 74 publications

(32 citation statements)

References 3 publications

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“…During that stage the process follows the linear Fig. 12 Metal loss of the analysed T23 and T92 after 1000 h exposure at 700 and 750°C dependence which is in agreement with Natesan and Park [25]. After longer time when the protective scale brakes down and the growth of magnetite is possible the rate dependence changes to parabolic; the oxidation rate remains parabolic as long as the developed scale is able to maintain adherence [26].…”

Section: Discussionsupporting

confidence: 84%

Analysis of High Temperature Steam Oxidation of Superheater Steels Used in Coal Fired Boilers

Dudziak¹,

Łukaszewicz

Simms

et al. 2015

Oxid Met

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The present work compares the behaviour of four steels: (T23, T92, T347HFG, Super304H) in the temperature range 600-750°C. This study focuses on the analysis of the oxidation kinetics in terms of mass change, metal loss and thickness change of the selected materials. In order to understand the differences in oxidation rates between the selected steels, the impact of chromium and the alloying elements were considered in this work. The obtained results show that the impact of alloying elements differs with exposure conditions and importance of the synergy effect.

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Section: Discussionsupporting

confidence: 84%

Analysis of High Temperature Steam Oxidation of Superheater Steels Used in Coal Fired Boilers

Dudziak¹,

Łukaszewicz

Simms

et al. 2015

Oxid Met

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“…Higher efficiency electricity production can be achieved by using steam systems with higher temperatures and pressures to generate electricity. Increases in steam temperatures (up to $700°C) and pressures would increase the overall efficiency of electricity generation up to $50% [3].…”

Section: Introductionmentioning

confidence: 99%

Fireside corrosion of superheaters: Effects of air and oxy-firing of coal and biomass

Syed

Simms

Oakey

2012

Fuel

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“…The maximum in the curve was first determined using base conditions of the SCM C. This temperature is higher than that found by Reid [15] and Syed [2,57] and just slightly less than that found by Natasan [19]. Tests would need to be conducted at 725 o C to confirm this.…”

Section: Temperature Effectmentioning

confidence: 95%

“…[19] Alkali iron trisulfates are the most probable cause of liquid phase corrosion, because their melting points are in the range of superheater metal temperatures, they have been found in the areas where corrosion has occurred, and they are highly reactive materials. The melting points of some alkali trisulfates are shown in Table 7.…”

Section: Alkali Iron Trisulfatesmentioning

confidence: 99%

Determination of the Initiation and Propagation Mechanism of Fireside Corrosion

2015

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A variety of deposit compositions were examined in short-term laboratory tests with the aim of determining the corrosion mechanisms of fireside corrosion for a range of chromiaforming alloys in various combustion systems. The deposits formed in boilers are complex, and despite decades of study, the propagation mechanism of fireside corrosion is not well understood. Alkali iron trisulfates, which are stabilized by SO 3 in the gas atmosphere, have been believed to be the major corrosive species for many years. The propagation mechanism for fireside corrosion was investigated using T92 (a typical ferritic boiler steel) and a model austenitic Fe-Ni-Cr alloy and synthetic coal ash deposits. The metal loss, corrosion product morphologies, and compositions were carefully characterized in order to define a propagation mechanism. The corrosive species responsible for degradation was a (Na,K) 2 SO 4 -Fe 2 (SO 4 ) 3 solution and not alkali iron trisulfates, which is contrary to what has been believed for decades.The formation of the liquid deposit is similar to Type II hot corrosion of gas turbine engines.The mechanism is a synergistic dissolution process similar to that which can occur for hot corrosion as well. Simultaneous basic and acidic dissolution of protective Cr 2 O 3 and Fe 2 O 3 disrupts protective oxide formation and locally produces negative solubility gradients at the oxide/salt interface. The dissolved Fe 2 O 3 and Cr 2 O 3 reprecipitate where there is lower solubility, creating the observed corrosion products. The effect of the deposit composition, gas atmosphere iii composition, alloy composition, temperature, and deposit thickness were examined with respect to the proposed fireside corrosion mechanism. These measurements were found to be consistent with the proposed mechanism based on synergistic fluxing.iv Oxy-fuel firing is one of three ways in which CCS can be accomplished. The other two ways are post-combustion capture, where the CO 2 is removed from the flue gas after combustion, and pre-combustion capture, where the CO 2 is removed from the fuel before combustion. Oxy-1 fuel firing is carrying out the combustion in an environment consisting of recirculated flue gases containing primarily CO 2 , steam and pure oxygen instead of air in order to create a flue gas with minimal amounts of N 2 . A schematic diagram of the oxy-fuel process is shown below in Figure 1. Figure 1: Schematic diagram of oxy-fuel combustionOxy-fuel combustion produces flue gases containing approximately 60%CO 2 -30%H 2 O-4%O 2 -5%N 2 , whereas traditional air-fired combustion produces flue gases containing 74%N 2 -[2] The flue gases in oxy-fuel systems are able to be recycled through the fuel burners leading to decreased CO 2 emissions. However, with the reduced amounts of nitrogen, the products of the oxy-fuel combustion process have increased amounts of CO 2 , steam and corrosive gases, such as SO 2 that can cause significant corrosion in superheater and reheater 2 tubes when compared to air-fired combustion. Bu...

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Fireside and steamside corrosion of alloys for USC plants

Cited by 74 publications

References 3 publications

Analysis of High Temperature Steam Oxidation of Superheater Steels Used in Coal Fired Boilers

Analysis of High Temperature Steam Oxidation of Superheater Steels Used in Coal Fired Boilers

Fireside corrosion of superheaters: Effects of air and oxy-firing of coal and biomass

Determination of the Initiation and Propagation Mechanism of Fireside Corrosion

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