design and plant experience using an advanced pouring box to receive and distribute the steel in a...
DESCRIPTION
Based on water and math modeling work, a refractory device was designed aiming to improve the liquid steel flow in the tundish of the ACINDAR~2 billet, bloom and minislab caster. The simulation work took into account sequence start, Iadle change and steady state. The device improved flow behavior for the inner strands and helped minimizing slag emulsification and the contact of the steel with the air, especially at ladle change. Better inclusion counts and temperature homogeneity throughout the sequence were obtained when using APB in the tundish.TRANSCRIPT
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Design and Plant Experience Using an
Advanced Pouring Box to Receive and
Distribute the Steel in a Six Strand Tundish
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Steel Plant
DRI Plant 1,000,000 tpy DRI
3 EAF x 110 t 1,500,000 tpy
2 LF x 110 t
2 CC Machines x 6 strands
A: billets, blooms and minislabs, oil or powder
casting, carbon and low alloy steels
B: 120 x 120 mm sq. billets, oil casting, carbon
steels (0,05 to 0,8 % C)
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Tundish with Baffles
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Objetives
Improving flow conditions during start, steady
state and ladle change, aiming at better
ceanliness of the steel, particulary for inner
strands.
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Start of the Sequence
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Ladle Change
Hot
Water
Cold
Water
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Ladle Change - Slag Simulation
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Ladle Change - Slag Simulation
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RTD Curves, Tundish with
Baffles, Steady State
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 0.5 1 1.5 2 2.5
Tiempo adimensional
Co
nc
en
tra
ci
n a
dim
en
sio
na
l
Lnea 1 y 6
Lnea 2 y 5
Lnea 3 y 4
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Residence Time and Volume Type
Tundish with Baffles, Steady State
Strand residence
time mn.
s
residence
time med.
s
%
plug
flow
%
perfect
mix
%
dead
volume
1 & 6 58 190 12 56 32
2 & 5 24 161 5 52 43
3 & 4 10 126 2 43 55
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Results of Tundish with Baffles
better start when using slidegate slag emulsification during ladle changes change in flow pattern during ladle changes short circuit for strands # 3 and # 4 second peak in RTD curves, strands 2 to 5 low plug flow volume, strands 2 to 5
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Tundish with Turbulence Inhibitor
dead volume
short circuit
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Shroud
APB
Advanced Pouring Box
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Optimization of Advanced
Pouring Box
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00,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
Time (adimentional)
Conc
entrat
ion
(adi
men
tiona
l)
Lnea 1
Lnea 2
Lnea 3
0
0,5
1
1,5
2
2,5
3
3,5
4
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
Time (adimentional)
Con
cent
ratio
n (a
dim
entio
nal)
Lnea 1
Lnea 2
Lnea 3
Baffles
APB
RTD Curves
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APB vs. Baffles, Steady State
Baffles
APB
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050
100
150
200
Minimum Residence Time Medium Residence Time
Tim
e [s] Baffles
APB
0
10
20
30
40
50
60
% Plug Volume % Dead Volume
%
Baffles
APB
APB vs. Baffles, Steady State
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Tundish with APB, Ladle Change
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Math Modeling
Speed Fields
Baffles APB
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Math Modeling
Turbulent Kinetic Energy
Baffles APB
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Plant Experience 1
trouble during tundish assembly
crack formation during APB preheating
problems with shroud movement during ladle opening
improved steel flow during start of sequence
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Plant Experience 2
elimination of start up problems
good abrassion resistance in sequences up to 7 heats
better inclusion counts in carbon steel billets for bars
better thermal homogeneity along the sequence
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Baffles
APB
Continuous Temperature Measurement
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Conclusions
APB is a good solution for long, narrow multistrand tundishes still operating in many
billet machines
better flow conditions for inner strands (residence time, plug flow, no second peak)
no slag emulsification during ladle change
lower inclusions counts
temperature uniformity along the sequence