Scholarlink

<p>Sanicro 25, a high-Cr austenitic stainless steel (22.5Cr–25Ni–3.4W–3Cu–0.5Nb), is a cost-effective candidate for superheater piping for Advanced Ultra-Supercritical (AUSC) coal thermal power plants. High steam operating temperatures (&gt; 710&#xa0;°C) and pressures (~ 31&#xa0;MPa) for enhanced thermal efficiency (&gt; 46%) necessitate materials with superior creep and corrosion resistance. Long operations under unwarranted transients that might undermine the structural integrity of superheater tubes due to increased material degradation caused by fireside corrosion attack (FSC) in real Indian coal ash environments remain underexplored. This study provides the first integrated long-term (2000&#xa0;h) FSC assessment of Sanicro 25 at 750&#xa0;°C using Indian coal ash/flue gas, employing the deposit-recoat method to mimic slagging/deslagging at the laboratory scale relevant to the Indian AUSC program. The oxide characteristic and surface characterization by XRD, Raman spectroscopy, and SEM/EDS analysis reveal the initial formation of a Cr<sub>2</sub>O<sub>3</sub> passive film, followed by localized fluxing, leading to non-uniform chromia breakdown. The results reveal a distinct time-dependent degradation sequence, creating a stratified oxide scale with a Fe-rich outer layer, a probable mixed spinel layer in the middle, and a chromia inner layer. The penetration depth accelerated after 1500&#xa0;h, driven by sulfur ingress forming a S-rich band undermining protection. By 2000&#xa0;h, the inner chromia layer dominates and the total oxide scale ranged from 53 ± 4 to 112 ± 28&#xa0;μm, as time progressed from 500 to 2000&#xa0;h. Parabolic kinetic fitting reveals a corrosion rate of ~ 0.27 mm/y at 2000&#xa0;h. A detailed fireside corrosion mechanism tailored to Indian coal ash is proposed to aid in the design of sulfur-tolerant AUSC superheaters.</p> Graphical Abstract <p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Evaluation of Fireside Corrosion of Super Austenitic Stainless Steel Sanicro 25 at 750 °C Under Simulated Advanced Ultra Super Critical Fireside Conditions

  • 期刊论文

  • 发表日期：

    2026年5月25日

查看全文
  • C. Anushree,
  • Koustuv Ghosh,
  • E. Vetrivendan,
  • S. Ningshen,
  • Anish Kumar

摘要

Sanicro 25, a high-Cr austenitic stainless steel (22.5Cr–25Ni–3.4W–3Cu–0.5Nb), is a cost-effective candidate for superheater piping for Advanced Ultra-Supercritical (AUSC) coal thermal power plants. High steam operating temperatures (> 710 °C) and pressures (~ 31 MPa) for enhanced thermal efficiency (> 46%) necessitate materials with superior creep and corrosion resistance. Long operations under unwarranted transients that might undermine the structural integrity of superheater tubes due to increased material degradation caused by fireside corrosion attack (FSC) in real Indian coal ash environments remain underexplored. This study provides the first integrated long-term (2000 h) FSC assessment of Sanicro 25 at 750 °C using Indian coal ash/flue gas, employing the deposit-recoat method to mimic slagging/deslagging at the laboratory scale relevant to the Indian AUSC program. The oxide characteristic and surface characterization by XRD, Raman spectroscopy, and SEM/EDS analysis reveal the initial formation of a Cr2O3 passive film, followed by localized fluxing, leading to non-uniform chromia breakdown. The results reveal a distinct time-dependent degradation sequence, creating a stratified oxide scale with a Fe-rich outer layer, a probable mixed spinel layer in the middle, and a chromia inner layer. The penetration depth accelerated after 1500 h, driven by sulfur ingress forming a S-rich band undermining protection. By 2000 h, the inner chromia layer dominates and the total oxide scale ranged from 53 ± 4 to 112 ± 28 μm, as time progressed from 500 to 2000 h. Parabolic kinetic fitting reveals a corrosion rate of ~ 0.27 mm/y at 2000 h. A detailed fireside corrosion mechanism tailored to Indian coal ash is proposed to aid in the design of sulfur-tolerant AUSC superheaters.

Graphical Abstract