| Summary: | 碩士 === 國立成功大學 === 材料科學(工程)學系 === 86 === In this thesis study, a mathematical model has been developed
tosimulate the flow phenomena for gas stirring in the iron bath
of the smelter for direct iron ore smelting reduction process. A
corresponding water model has also been constructed to observe
the flow pattern in the liquid bath system. The flow phenomena
of concerns includes flow pattern and mixing time at various
rate of gas injection for liquids of different viscosity. To
assure the accuracy of the simulation model, the calculated
results are also compared with the experimental observation from
the water model.To develop the three dimensional fluid flow
analysis system, a computational fluid dynamics technique;
called SOLA-SURF, and the κ-εtwo equation turbulence model are
used to analyze the fluid flow pattern in the smelter. The
simulations are performed for liquids of under various rate of
gas injection. A water model has also been constructed.
Experiments are performed to observe the flow pattern and
measure the mixing time under various conditions. To observe the
flow pattern, a light page is generated from a laser beam to
lighten a certain cross section of the water model. Tracer
particles are added to the system and a camera is used to take
the pictures of fluid pathlines. Mixing time is also measured by
monitoring the change of conductivity with time. The
measurements/observations are also used to verify the accuracy
of the mathematical model. The mathematical model is tested on a
smelter system with four tuyeres blowing gas into the liquid
bath from the bottom with the conditions identical to the water
model. The results reveal that the liquid flows faster with
higher gas flow rate, which results in larger recirculation and
higher surface liquid speed near the surface. This in turn has
shorter mixing time. The flow fields for liquids with two
different viscosities; 1cP and 2 cP respectively, look similar.
However, the flow speed is slower and the dead zone is larger
for liquid of higher viscosity. These in turn result in higher
mixing time and thus less efficient for stirring. The results
of the mathematical simulations are compared with the
measurements and observations from the water model. They show
good consistency. With the developed mathematical model, it can
aid to evaluate the effects of processing conditions and
viscosity of liquid on the flow conditions of the liquid in the
direct iron smelter.
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