S5 · Wet FGD Desulfurization

Wet FGD Desulfurization (List of Media, Grades, and Boundary Conditions for 2507/904L Mediums)

Sort the media, grades, and boundary conditions related to wet FGD desulfurization: List three typical components/processes with recommended grades, specifications, failure reasons, and standards.

Stainless Steel Flues and Absorbers for Power Plant Desulfurization Systems
Power and Environment: Flues, absorbers, heat exchangers (Illustration; actual selection based on media, temperature, and drawings)

Three parts and material lists

Part / ComponentRecommended GradeSpecifications / ThicknessSurfaceMain Failure ModesReference Standards
FGD Outlet Flue Gas Condensate2507/2205/316L/304LWater Saturation + Solid-Liquid Droplets + Cl⁻/SO₄²⁻Corrosion Rate Ranking: 2507 < 2205 < TA2 < 316L; 2205/2507 insignificantly different; 304L/316L significant corrosionSpray Tower / Mist Chamber / Flue Liner prefer 2205/2507; select 254NM/AL-6XN in extreme local areasASTM A240;DL/T 5196
Sulfuric Acid Environment (not FGD but often confused)2507/904L/254SMOH₂SO₄ 20–40%Corrosion rate of 2507 at 40% H₂SO₄ > 50 mm/a; 904L/254SMO better with 904L/254SMOWhen sulfuric acid concentration or temperature exceeds the 2507 boundary, upgrade to 904L/254SMO and do not use duplex steel as a workaroundASTM A240; Corrosion Maps
FGD Absorber / Dry-Wet Alternation Entry Flue254NM/AL-6XN/904L/C276/C22High Cl⁻ concentration + pH 2–5 + 50–160°C316L perforates quickly at the wet-dry boundary; localized pitting and SCC in high alloy areasHigh alloys used only for most severe local conditions, not throughout the entire tower uniformlyASTM A240/B575;DL/T 5196
Table isStandard ConfigurationMaterial selection

Consider usage conditions rather than specifying grades

  • The most common grades in this industry are 2507 (2), 904L (2), and 304L (1) — parentheses indicate the number of parts involved, useful for quoting and material ordering.
  • Thickness range: 2–160 mm. Thin plates are often formed pieces (considering bend back and deep drawing cracking), thick plates are typically welded structures (considering heat input and sensitization).

What are common questions?

Wet FGD desulfurization: 2205/2507/254NM/904L Which stainless steel is used the most for sorting corrosion rates?
Total pages: Counting these 3 parts, the most frequent is 2507 (2), 904L (2), and 304L (1). Specific to a part still depends on the medium and temperature, such as stainless countertops that contact salt water should switch from 304 to 316L.
Which parts are most prone to problems?
Failure description, typically "FGD condensate from flue gas": Spray tower/scrubber/cloth lining priority 2205/2507; extreme local selection 254NM/AL-6XN; recommended grades 2507/2205/316L/304L, specification water-saturated + solid-liquid droplets + Cl⁻/SO₄²⁻. This type of condition recommends specifying medium concentration, temperature, and cleaning method during the design phase.
What thickness should I select?
Thickness range in the list is 2–160 mm. For thin sections, consider bending and surface finish; for thick sections, welding and structural strength. Values may vary by manufacturer for the same location, review your drawing or operating conditions.

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