Evaluation of tubular ceramic heat-exchanger materials in basic coal ash from coal-oil-mixture combustion. [Sialon]
Tubes of ten different structural ceramic materials were exposed to the hot combustion gases from a coal-oil-mixture (COM) fuel in the Ceramic Recuperator Analysis Facility (CRAF) at an outer tube wall temperature of about 1240/sup 0/C for about 240 h. Air flow through each tube simulated the conditions in a tubular heat exchanger element. As-received and exposed materials and solidified coal slag were examined. Several important properties of the ceramics, including room-temperature helium permeability, room-temperature C-ring fracture strength, and thermal expansion from room temperature to 1100/sup 0/C were measured for both as-received and exposed specimens. The ten structural ceramics included six types of silicon carbide, a high-purity alumina, and three types of newly available sialons. Highly fluid basic coal slag deposited on the outer surfaces of the structural ceramic tubes during the coal combustion and all of the tubes lost significant fractions of their wall thickness. Exposure to the hot coal slag increased permeability of all the surviving tubes by about one order of magnitude. The room-temperature C-ring fracture strength for the five types of SiC and one type of Al/sub 2/O/sub 3/ ceramic decreased by about 3 to 60%. Siliconized types of SiC had strength reductions of 38 to 61%. Sintered ..cap alpha..-SiC showed the smallest strength reduction of 3%. The high purity Al/sub 2/O/sub 3/ had a strength loss of about 28%. The thermal expansion of these materials did not change significantly. 46 figures, 12 tables.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6726692
- Report Number(s):
- ORNL/TM-8385; ON: DE83001700
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CORROSION
CERAMICS
HEAT EXCHANGERS
MATERIALS TESTING
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
WASTE HEAT UTILIZATION
ASHES
COMBUSTION PRODUCTS
EXPERIMENTAL DATA
FRACTURE PROPERTIES
FUEL OILS
FUEL SLURRIES
PERMEABILITY
SLAGS
THERMAL EXPANSION
TUBES
ALUMINIUM COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DISPERSIONS
EXPANSION
FUELS
INFORMATION
LIQUID FUELS
MECHANICAL PROPERTIES
MIXTURES
NITRIDES
NITROGEN COMPOUNDS
NUMERICAL DATA
OILS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PETROLEUM PRODUCTS
PNICTIDES
RESIDUES
SLURRIES
SUSPENSIONS
TESTING
WASTE PRODUCT UTILIZATION
320304* - Energy Conservation
Consumption
& Utilization- Industrial & Agricultural Processes- Waste Heat Recovery & Utilization
360205 - Ceramics
Cermets
& Refractories- Corrosion & Erosion