Phase relationships in coal ash corrosion products

Conference · Tue Oct 01 04:00:00 EDT 1996

OSTI ID:370393

Kalmanovitch, D ^[1]

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1. Consultant Materials Engineering, Worcester, MA (United States)

The corrosion of heat transfer surfaces in coal-fired utility boilers is a major concern to the efficient operation of these units. Despite the importance of the corrosion there has been limited research on the relationship between the ash components on the tube surface and the interactions and reactions between the various components and the steel surface. Mechanisms such as molten phase corrosion, sulfidation, and high temperature oxidation have been identified as leading to extensive wastage of tube metal. This paper describes research into the formation of molten or semimolten phases within ash deposits which are associated with corrosion of superheater and reheater fireside surfaces. For example, the phases potassium pyrosulfate (K{sub 2}S{sub 2}O{sub 7}) and potassium aluminum sulfate (K{sub 2}Al{sub 2}SO{sub 7}) have been determined by x-ray diffraction to be present in deposits where fireside corrosion has occurred. However, both these phases are not directly derived from coal minerals or the common matrix observed in ash deposits. The examination of the reactions and interactions within deposits which result a the formation of these and other phases associated with corrosion will be discussed in the paper.

• OSTI ID: 370393
• Report Number(s): CONF-960376--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
ASHES
COAL
COMBUSTORS
CORROSION
CORROSION PRODUCTS
DEPOSITS
MINERALS
OXIDATION
PHASE TRANSFORMATIONS
POTASSIUM SULFATES
SULFIDATION
X-RAY DIFFRACTION