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By Knut Bech and Harald Laux, SINTEF, Trondheim, Norway
SINTEF Materials Technology has used Fluent software to improve metallurgical
and chemical processes since 1985. In 2001, Fluent and SINTEF formalized
their long-standing relationship via a partnership agreement, under which
SINTEF may develop and deliver modeling enhancements to Fluent clients.
The cooperation provides Fluent clients improved access to SINTEF’s
expertise and to new models, developed under non-commercial research projects,
that improve the prediction of combustion, pollutant formation, radiation,
solidification, magnetohydrodynamics, electrochemistry, and multiphase
flows encountered in the metallurgical and oil/gas industries.
The final macrosegregation percentage in a fully solidified Sn-5wt%Pb
alloy, which was solidified by cooling at the left hand wall; the mixture
was depleted of lead at the top surface and enriched with it at the bottom;
red regions have the highest positive macrosegregation, or highest lead
content; blue regions have the highest negative macrosegregation, or lowest
lead content
“SINTEF was a pioneer in multiphase CFD modeling, developing
Eulerian multifluid modeling of gas-solid flows as early as
1988 using FLUENT 2.97,” says Stein Tore Johansen, Research Director
of the Department of Flow Technology at SINTEF. “In cooperation
with the ferro-alloy and incineration industries, we are now
extending the capacity for detailed modeling of reactive flows,
in particular with respect to NOx and pyrolysis.”
Recently, design studies of ferrosilicon plants were performed.
The project began with a combustion simulation in FLUENT of
the old furnace hood and off-gas channel at an Elkem ferrosilicon
plant. FLUENT was then used to support the design of a new
off-gas system that fulfills Elkem’s requirements for plant operation
performance. With the new off-gas system, the furnace is now
operating at higher loads, the clogging danger is considerably
reduced, gas leakages from the hood to the environment are prevented,
and the new cooling system is able to recover several
GWhs/year of electric energy.
SINTEF has also developed within FLUENT advanced solidification models
for metallurgical applications, based on the multifluid approach. Macrosegregation,
or variations in composition during solidification caused by melt convection
and moving crystals, can be simulated with these tools. The solidification
routines are coupled to micromodels for the growth kinetics of dendrites,
branch-like structures formed by nonuniformities in the melt.
Pathlines in an old design of the furnace hood and the off-gas channels
of a ferrosilicon plant; at the base of the furnace, contours of temperature
are plotted on an iso-surface of constant reaction rate
During the last decades, the Norwegian aluminum industry has focused
heavily on increased current efficiency and improved energy efficiency
in reduction cells, used for aluminum processing. Quantitative knowledge
of the flow pattern in the liquid metal and electrolyte of aluminum reduction
cells has been important for guiding the performance improvements. Engineers
at SINTEF implemented a solver for the electromagnetic field in early
versions of FLUENT, enabling the study of magnetohydrodynamic flow in
these cells. During the last two years, electrochemical models have been
added to FLUENT and combined with a mixture multiphase flow model to produce
a special code for electrolysis cell design.
Prediction of flow in aluminum electrolysis cells, showing gas concentration,
lines of constant electric potential, and velocity vectors in the electrolyte
Bubbly flows occurring in metallurgical applications have also
been a focus of research and development at SINTEF. Recently,
FLUENT has been used to calculate mixing in a gas-stirred ladle
for steel alloying and particle flotation for cleaning molten metal.
Based on models for coalescence and break-up, a transport equation
for the mean bubble size in turbulent flow has been developed
within FLUENT. Bubble sizes in stirred flows have been measured
in the department’s water model laboratory, and are now used
for CFD model validation. Simulation of bubbly flows and free
surfaces guided SINTEF during analysis of operational problems
that occurred in the fermenter loop at Norferm’s bioprotein plant.
Using FLUENT, SINTEF and Norferm developed a new separator
vessel, allowing the gas produced by the bacteria to escape before
the flow entered the pump.
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