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Analysis of atmospheric fluidized bed combustion agglomerates. Final report

Author
Perkins, D. III
Published
United States : [publisher not identified], 1984
Springfield, Va.: National Technical Information Service, [approximately 1984]
Physical Description
microfiche : negative ; 11 x 15 cm
Additional Creators
Brekke, D. W. and Karner, F. R.

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Summary
Chemical and textural studies of AFBC agglomerates have revealed detailed information regarding the mechanisms of agglomeration. The formation of agglomerates in a silica sand bed can be described by a four step process: initial ash coatings of quartz grains; thickening of ash coatings and the formation of nodules; cementation of nodules to each other by a sulfated aluminosilicate matrix; and partial or complete melting of eutectic compositions to produce a sticky glass phase between grains and along fractures. Once agglomeration has begun, large scale solidification and restricted flow within the bed will lead to hot spots, wholesale melting and further agglomeration which ultimately forces a shutdown. Standard operating temperatures during normal AFBC runs come quite close to, or may actually exceed, the minimum temperatures for eutectic melting of the silicate phases in the coal and standard bed materials. The partially melted material may be expected to lead to the formation of dense, sticky areas within the bed, and the formation of hot spots which further exacerbate the problem. Ultimately, large scale bed agglomeration will result. Attempts to eliminate agglomeration by removal of sodium via an ion exchange process have yielded encouraging results. A second approach, used to raise melting temperatures within the bed, has been to use bed materials that may react with low-temperature minerals to produce high-temperature refractory phases such as mullite or other alkali and alkali-earth alumino-silicates.
Report Numbers
DE84016148; DOE/FC/10120-1608
Other Subject(s)
Collection
NTIS collection.
Note
DOE contract number: AB18-80FC10120
OSTI Identifier 6678387
Research organization: North Dakota Univ., Grand Forks (USA). Engineering Experiment Station.
View MARC record | catkey: 47344237