Corrosion of superheaters and reheaters of pulverized-coal-fired boilers. II
Temperature, complex sulfate composition, sulfide and carbide formation, and alloy composition were investigated for their effects on the rate of high-temperature fireside-corrosion of reheater and finishing superheater tubes in modern pulverized-coal-fired boilers. These effects were measured by firing alloys coated with synthetic deposit mixtures at various temperatures, and measuring corrosion loss, and deposit composition by chemical and x-ray diffraction methods. Complex Fe and/or Al alkali sulfate in the fireside ash deposits become molten through the temperature range of 1025-1300/sup 0/F. In the molten states these sulfates are most effective in corroding tube surfaces. Burning high S coals results in greater sulfate production and greater corrosion. The absolute amounts of Na and K in the original molten sulfate may be responsible for extensive metal loss. The metal tube are consumed. Because of the limited temperature range through which these sulfates remain molten, the recommended remedy is to protect the tubes with shields which operate at temperatures above that which molten sulfates are stable.
- OSTI ID:
- 5847301
- Journal Information:
- Trans. ASME; (United States), Journal Name: Trans. ASME; (United States) Vol. 83:4; ISSN TASMA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
014000 -- Coal
Lignite
& Peat-- Combustion
36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALKALI METALS
ALLOYS
BOILERS
CARBIDES
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COAL
COHERENT SCATTERING
CORROSION
CORROSIVE EFFECTS
DIFFRACTION
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HIGH TEMPERATURE
IRON COMPOUNDS
IRON SULFIDES
MATERIALS
METALS
OXYGEN COMPOUNDS
POTASSIUM
SCATTERING
SODIUM
SULFATES
SULFIDES
SULFUR COMPOUNDS
SUPERHEATERS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION