Evaluation of tubular ceramic heat exchanger materials in acidic coal ash from coal-oil-mixture combustion. [Sialon; alumina; CVD, sintered, and siliconized SiC]

Technical Report · Tue Dec 01 04:00:00 EST 1981

DOI:https://doi.org/10.2172/5280230· OSTI ID:5280230

Ferber, M. K.; Tennery, V. J.

Tubes of five ceramic materials were exposed to the hot combustion gases from a coal-oil-mixture (COM) fuel in the Ceramic Recuperator Analysis Facility (CRAF) at about 1200/sup 0/C for about 500 h. Siliconized SiC, sintered ..cap alpha..-SiC, and chemically vapor deposited (CVD) SiC survived the long-term exposure with no major visible degradation. The alumina and sialon tubes were cracked extensively. Acidic coal slag deposited extensively on the upstream surface of all tubes. During cooldown, the slag did not strongly bond to any of the silicon carbide tubes, but a strong bond was developed with the alumina and sialon tubes. The silicon carbides corroded by a micropitting oxidation at the carbide-slag interface. The SiC and Si phases of siliconized SiC corroded at essentially the same rate. Exposure to hot coal slag increased the room-temperature helium permeability of all the SiC-based tubes. For KT and CVD SiC, both upstream and downstream sides exhibited expansion increases up to about 17% at 1000/sup 0/C. Sintered ..cap alpha..-SiC had much smaller increases. Al/sub 2/O/sub 3/ had an expansion increase of about 14% on the upstream side at 1000/sup 0/C but the downstream side was unchanged. 65 figures, 22 tables.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5280230
• Report Number(s): ORNL/TM-7958; ON: DE82007122
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
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36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ASHES
CARBIDES
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
COAL
COMBUSTION PRODUCTS
CRYSTAL STRUCTURE
DEPOSITION
ENERGY SOURCES
EXPANSION
FOSSIL FUELS
FOSSIL-FUEL POWER PLANTS
FUELS
HEAT EXCHANGERS
MATERIALS
MATERIALS TESTING
MECHANICAL PROPERTIES
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE TESTING
PERMEABILITY
PETROLEUM
PNICTIDES
POWER PLANTS
RESIDUES
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SLAGS
SURFACE COATING
TENSILE PROPERTIES
TESTING
THERMAL EXPANSION
THERMAL POWER PLANTS
TUBES
VERY HIGH TEMPERATURE