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Titel:
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A mechanistic study of the slag formation from iron-rich coals
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Auteur(s):
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Gepubliceerd door:
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Publicatie datum:
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ECN
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1995
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ECN publicatienummer:
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Publicatie type:
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ECN-RX--95-041
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Overig
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Aantal pagina's:
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Volledige tekst:
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27
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Niet beschikbaar.
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Samenvatting:
Near-burner slag formation of minerals from two iron rich coals wasinvestigated in the reproducible environment of a laboratory burner. Alumina
deposit plates were placed in the flow with the thin edge facing the particle
stream. Tests were performed in an environment simulating a low-NOx burner
flame and in a sharply reducing atmosphere simulating cyclone-type
combustion. In the latter simulation the deposit surface was at approximately
1400 deg C. The burner was fired with large excess CO for this simulation. In
this highly reducing atmosphere, the pyrite (FeS2) rich coal produced a
low-viscosity slag from which the sulphur rapidly volatilized. In the
simulated slag from a coal rich in iron oxide, the slag was also of low
viscosity. During cooling the iron crystallized out as dendrites or
triangular crystals. These consisted of iron oxide, while reduction of the
iron oxide to elemental iron by the carbon monoxide had been expected. In the
low-NOx combustion simulation the probe temperature was 1100C. The coal rich
in iron oxide did not produce an adherent deposit. Pyrite was found to
produce a viscous surface layer of pyrrhotite (FeS) on which other minerals
adhered, for the first time showing in fundamental form the slag induction by
pyrite in progress. With the probe at a position where the secondary air
mixed in, the deposit solidified because of the in-situ oxidation of the
pyrrhotite to solid iron oxide. 5 figs., 1 tab., 13 refs.
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