Bed material agglomeration during fluidized bed combustion. Technical progress report, October 1, 1993--December 31, 1993
During this quarter, agglomerates which formed in the FBC at Montana-Dakota Utilities (Heskett Station Unit 2 located in Bismarck, ND) were analyzed by x-ray diffraction analyses (XRD) for mineral determination; bulk chemical composition was determined by inductively coupled plasma spectroscopy; and polished sections were made for optical and scanning electron microscopy. Polarized-light microscopy was performed using a Zeiss research microscope. Individual mineral grains were analyzed using an ARL electron microprobe and a JOEL 840 scanning electron microscope. The agglomerate was found in the mechanical dust collector and was about ten centimeters in diameter with a dark-colored core and a greenish rim. The sample had voids up to ten millimeters in size; however, the agglomerate was hard to break apart. Bulk compositionally, the agglomerate consists primarily of calcium, silica, and alumina with relatively high abundances of iron (8 to 9 wt %), magnesium (5 to 9 wt %) and sodium (3 to 4 wt %). It is likely that the ``root`` cause of this agglomerate originated in the dense phase of the FBC bed. Because fluidized bed combustors work below the ash fusion temperature of coal ash, aluminosilicates (clays) in the ash probably became ``sticky`` due to fluxing reactions with pyrite (FeS{sub 2}) and perhaps alkalies (Na). This is indicated by the high amounts of iron, silica, and alumina in the agglomerate. Because of the size of the deposit, the bed particles probably agglomerated in the dust collector.
- Research Organization:
- Ames Lab., Ames, IA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-92PC92530
- OSTI ID:
- 10143848
- Report Number(s):
- DOE/PC/92530-T6; ON: DE94010257; BR: AA1525050
- Resource Relation:
- Other Information: PBD: Jan 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COAL
FLUIDIZED-BED COMBUSTION
AGGLOMERATION
X-RAY DIFFRACTION
EMISSION SPECTROSCOPY
OPTICAL MICROSCOPY
SCANNING ELECTRON MICROSCOPY
ELECTRON MICROPROBE ANALYSIS
DEPOSITS
PROGRESS REPORT
014000
400102
COMBUSTION
CHEMICAL AND SPECTRAL PROCEDURES