Characterization of submicron fly-ash in cyclone-fired boilers
This study contains information concerning the submicron fraction of fly-ash produced by cyclone-fired boilers. Experimental activities involved size fractionation and chemical analyses of separated ash particles. Approximately 10% of the fly-ash under investigation consists of particles in the submicron range. The chemical composition of the submicron fraction is considerably different from that of the bulk. In particular, silicon and sulfur are enriched while iron and aluminum are depleted. Calcium shows slight possible enrichment trends while sodium, potassium and magnesium exhibit constant concentrations for all size ranges. Silicon enrichment is consistent with equilibrium predictions which indicate significant vaporization of this element under reducing conditions. The sulfur trends are attributed to the surface adsorption of gaseous sulfur-containing species. Enrichment of iron is also predicted whereas the opposite is found experimentally. The morphology of submicron ash was examined extensively with the aid of the scanning electron microscope. Submicron ash can be approximately visualized as aggregates, each containing an average of 10 or so primary particles. The primary particles themselves are about 0.06 micron in diameter. This study, intended as an aid to the theoretical development, has provided basic data on the particle size versus enrichment characteristics of fly-ash in a cyclone-fired boiler. In general, the vaporization condensation mechanism is further confirmed as a major source of submicron fly-ash.
- Research Organization:
- New Hampshire Univ., Durham (USA). Dept. of Chemical Engineering
- OSTI ID:
- 6558488
- Report Number(s):
- FE-2205-13
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010600* -- Coal
Lignite
& Peat-- Properties & Composition
ABSORPTION SPECTROSCOPY
AEROSOL WASTES
BOILERS
CARBONACEOUS MATERIALS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COAL
COMBUSTION
ELECTRON MICROSCOPY
ENERGY SOURCES
ENRICHMENT
FLY ASH
FOSSIL FUELS
FOSSIL-FUEL POWER PLANTS
FRACTIONATION
FUELS
IRON COMPOUNDS
MICROSCOPY
OXIDATION
PARTICLE SIZE
POWER PLANTS
SEPARATION PROCESSES
SILICON COMPOUNDS
SIZE
SPECTROSCOPY
SULFUR COMPOUNDS
THERMAL POWER PLANTS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
WASTES