Evaluation of tubular ceramic heat exchanger materials in acidic coal ash from coal-oil-mixture combustion. [Sialon; alumina; CVD, sintered, and siliconized SiC]
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. (ORNL), Oak Ridge, TN (United States)
- 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
Similar Records
High temperature behaviour of silicon carbide and aluminium oxide ceramics in coal and residual-oil slags
High-temperature behavior of silicon carbide, sialon, and aluminum oxide ceramics in coal and residual-oil slags
Related Subjects
36 MATERIALS SCIENCE
ALUMINIUM OXIDES
PERFORMANCE TESTING
FOSSIL-FUEL POWER PLANTS
HEAT EXCHANGERS
MATERIALS TESTING
SILICON CARBIDES
SILICON NITRIDES
ASHES
CHEMICAL VAPOR DEPOSITION
COAL
COMBUSTION PRODUCTS
MICROSTRUCTURE
PERMEABILITY
PETROLEUM
SLAGS
TENSILE PROPERTIES
THERMAL EXPANSION
TUBES
VERY HIGH TEMPERATURE
ALUMINIUM COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL COATING
CRYSTAL STRUCTURE
DEPOSITION
ENERGY SOURCES
EXPANSION
FOSSIL FUELS
FUELS
MATERIALS
MECHANICAL PROPERTIES
NITRIDES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PNICTIDES
POWER PLANTS
RESIDUES
SILICON COMPOUNDS
SURFACE COATING
TESTING
THERMAL POWER PLANTS
200101* - Fossil-Fueled Power Plants- Cooling & Heat Transfer Equipment & Systems
360105 - Metals & Alloys- Corrosion & Erosion