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@ARTICLE{Sefidari:863658,
author = {Sefidari, H. and Wiinikka, H. and Lindblom, B. and Nordin,
L. O. and Wu, G. and Yazhenskikh, E. and Müller, Michael
and Ma, C. and Öhman, M.},
title = {{C}omparison of {H}igh-{R}ank {C}oals {W}ith {R}espect to
{S}lagging/{D}eposition {T}endency at the {T}ransfer-{C}hute
of {I}ron-{O}re{P}pelletizing {G}rate-{K}iln {P}lants: {A}
{P}ilot-{S}cale {E}xperimental {S}tudy {A}ccompanied by
{T}hermochemical {E}quilibrium {M}odeling and {V}iscosity
{E}stimations},
journal = {Fuel processing technology},
volume = {193},
issn = {0378-3820},
address = {New York, NY [u.a.]},
publisher = {Science Direct},
reportid = {FZJ-2019-03664},
pages = {244 - 262},
year = {2019},
abstract = {Iron-ore pelletizing plants use high-rank coals to supply
the heat necessary to process ores. Ash material from coal,
in combination with iron-ore dust originating from the
disintegration of the pellets, can cause deposition/slagging
which often leads to severe production losses and damage.
Deposition/slagging is most prominent in the hot areas of
the grate-kiln setup and is more severe at the inlet of the
rotary-kiln, i.e., the transfer-chute. Following on from our
previous work, high-rank bituminous coals with potential for
use in the pelletizing process were combusted in a
pilot-scale (0.4 MW) pulverized-coal fired experimental
combustion furnace (ECF). The fly-ash particles and
short-term deposits were characterized to shed light on the
observed difference in slagging/deposition tendencies of the
coals. Global thermodynamic equilibrium modeling, in
combination with viscosity estimates, was used to interpret
the experimental findings and investigate the effect of the
coal-ash composition upon deposition/slagging. This approach
was carried out with and without the presence of Fe2O3-rich
pellet-dust under oxidizing conditions within the
temperature range at the transfer-chute of iron-ore
pelletizing rotary-kilns. Based on the findings, a
Qualitative Slagging Indicator (QSI) was proposed that can
help pre-screen new solid fuels for potential slagging
issues. The proposed QSI highlights the following: (1) an
inverse relationship between viscosity and
slagging/deposition tendency of the coals was observed (2)
as viscosity decreases (either with increasing temperature
or due to the change in the coal-ash composition), stronger
deposits will form that will complicate the mechanical
removal of the deposited layer. It was therefore inferred
that low viscosity molten phases facilitate
deposition/slagging, which is exacerbated by the presence of
fluxing agents (e.g., CaO, MgO, K2O, Na2O, and Fe2O3) in the
deposits. The low viscosity coal-ash-induced molten phases
are also more likely to interact with the Fe2O3-rich
pellet-dust that results in further decreases in viscosity,
thereby intensifying depositions. The results from this work
complement the on-going research by our group to elucidate
and alleviate ash-related problems in industrial grate
kilns.},
cin = {IEK-2},
ddc = {660},
cid = {I:(DE-Juel1)IEK-2-20101013},
pnm = {113 - Methods and Concepts for Material Development
(POF3-113)},
pid = {G:(DE-HGF)POF3-113},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000473842100026},
doi = {10.1016/j.fuproc.2019.05.026},
url = {https://juser.fz-juelich.de/record/863658},
}