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Your Success is Our Goal
Understanding the steel solidification in tundish nozzles X International PHOENICS Users ConferenceX International PHOENICS Users Conference
Melbourne, May 2004Melbourne, May 2004
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Steel Solidification
Chemtech - A Siemens Company, Rio de Janeiro / RJ – BrazilChemtech - A Siemens Company, Rio de Janeiro / RJ – Brazil
Carlos Eduardo FontesCarlos Eduardo Fontes
Flávio Martins de Queiroz GuimarãesFlávio Martins de Queiroz Guimarães
CST - Companhia Siderúrgica de Tubarão, Serra / ES – BrazilCST - Companhia Siderúrgica de Tubarão, Serra / ES – Brazil
Henrique S. FurtadoHenrique S. Furtado
Sandro de Souza SantosSandro de Souza Santos
AUTHORS
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Steel SolidificationProjeto de EquipamentosSistema de Inertização
TUNDISH
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Steel Solidification
Objective and Motivation
To model the steel solidification phenomena that is occurring in the tundish outlet valves in the continuous casting process, in order to identify and mitigate its causes.
To use the CFD technique to simulate this process, since it has already been used by Chemtech to the optimal design of the tundish inertization system.
To analyze the flow of two different steels (Family 10 and 40) and three different valves (MLC1, MLC2 Single and MLC2 Twin).
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Steel Solidification
The Tundish
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Steel Solidification
The Problem
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Steel Solidification
Solidification Model
Entalphy
Velocity
Porosity associated to the lost latent heat fraction
HhH
)TT(c)T(h m
1
S1s
1
TT0
TTT),F1(L
TTL
H
phase solid0
zonemushy ,
phase liquid
1
1
uu
u
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Steel Solidification
Model Validation
Data from Voller & Prakash
Validação de Resultados
0
0,2
0,4
0,6
0,8
1
0 0,2 0,4 0,6 0,8 1
Largura (m)A
ltu
ra (
m)
PHOENICS VOLLER & PRAKASH
Solid fraction in 250 s:
PHOENICS: 34,8% Voller & Prakash: 35%
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Steel SolidificationCST ModelPhysical Properties of Solid Blocks
M a t e r i a l E s p e s s u r a
( m m ) k
( W / m . º C ) C p
( J / k g . ° C )
( k g / m 3 )
I n t o v a l P - 3 8 3 2 , 0 M L C 1 3 6 , 0 M L C 2
3256.0T0002.0k 8 4 0 0 . 6 3 2 1 0 0
F l o w k a s t -7 0 - F M
1 3 0 , 0 M L C 1 1 6 4 , 0 M L C 2 4871.7T0218.0
T102T103k 2539
8 4 0
0 . 6 3 2 1 0 0
J e t m a g - B S -S M
3 1 , 0 9092.6T0138.0
T101T103k 2539
8 4 0 0 . 6 3 2 1 0 0
C e k a s t 8 5 -L C
4 0 , 0 8 4 0 0 . 6 3 2 1 0 0
S e d e k o r 8 5 -B C
8 6 , 5 4575.4T0076.0
T107T102k 2639
8 4 0 0 . 6 3 2 1 0 0
M u l k o r - 8 5 5 2 , 5 2 . 9 0 3 8 4 0 0 . 6 3 2 1 0 0
A l u m a g 8 0 -B R X
4 . 1 8 4 0 0 . 6 3 2 1 0 0
B a s i m a g A P I
1 7 1 , 3 e 7 1 , 3
871.16
T00158.0T105k 26
8 4 0 0 . 6 3 2 1 0 0
R e s i k o r - 8 5 4 8 , 5 4 . 6 5 8 4 0 0 . 6 3 2 1 0 0
A l u m i n a g r a fi t e
3 0 , 0 519.23
T0151.0T107k 26
8 4 0 0 . 6 3 2 1 0 0
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Steel SolidificationCST ModelPhysical properties of Steel
Material T Solidus
(°C) T Liquidus
(°C) Cp
(J / kg.°C) L
(J / kg) k
(W/ m.K)
(kg/ m³)
Aço 10 1525 1533 195000 665 32.7 7145
Aço 20 1512 1530 195000 665 32.7 7145
Aço 40 1465 1520 280000 675 32.7 7145
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Steel SolidificationModel Validation:Use of Field Data
Valve MLC1: start-up programmation given by CST;
Steel heights during the process: 0.5, 0.8 e 1.2 m
Inlet Temperature:1565ºC
Initial Temperature of solid blocks: 1000ºC
Steel Family: 20
External Temperature: 40ºC
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Steel SolidificationComparison with Field data:Mass Flow x Valve aperture
Qmass x Abertura
0,00
0,50
1,00
1,50
2,00
2,50
0,00 10,00 20,00 30,00
Abertura (mm)
Qm
ass
(to
n/m
in)
Experimental
Simulação
Abertura Qmass10,99 0,4510,67 0,5012,14 0,6013,26 0,6814,47 0,7715,52 0,8516,66 0,9417,77 1,0318,73 1,1119,79 1,2020,83 1,2927,37 2,2013,00 0,4915,00 0,8819,00 1,0923,00 1,5425,00 1,7327,00 1,7428,00 1,94
Exp
erim
enta
lB
MK
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Steel SolidificationComparison with Field data: Valve Temperature
Tempo (s)
Temperatura da Válvula Submersa
150 650390 740510 830570 826690 830810 850930 850150 650390 725510 810570 810690 810810 810900 810
posição em metros: (0.795,0.414)
BM
KE
xper
imen
tal
Temperatura da Válvula Submersa
500
550
600
650
700
750
800
850
900
0 200 400 600 800 1000
Tempo (s)
°C
Experimental
Simulação
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Steel SolidificationTesting the Solidification Model:Base Case
Steel flow is function of the steel height inside the tundish
Steel height: 0,5 m
Steel Family: 10
Inlet Temperature: 1535°C (2°C Super-heat)
Valve: MLC1
External Temperature: 40°C
Initial Temperature of solid blocks: 1000°C
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Steel SolidificationBase case results:Solidification after 30 seconds
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Steel SolidificationChoosing the geometry for the analysis:Comparison 2D x 3D
MLC1 Valve with defined steel flow;
Same grid and domain; time: 100 seconds.
2D 3D
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Steel SolidificationComparison 2D x 3D:Velocity Profiles
2D
3D
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Steel SolidificationComparison 2D x 3D:Temperature Profiles
2D
3D
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Steel Solidification
Simulated Cases
MLC1 Valve with Family 10
MLC1 Valve with Family 40
MLC2 Single Valve with Family 10
MLC2 Single Valve with Family 40
MLC2 Twin Valve with Family 10
MLC2 Twin Valve with Family 40
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Steel Solidification
Valve: MLC1
Steel: FAM 10
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Steel SolidificationMLC1 – Family 10Solid Fraction
t = 160 s
t = 150 s
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Steel SolidificationMLC1 – Family 10Temperature
t = 150 s
t = 160 s
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Steel SolidificationMLC1 – Family 10Pressure and Velocity
Pressão
Velocidade
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Steel Solidification
Results Analysis
Tendency of steel solidification in the sliding plate region [begin of the process];
Tendency of steel solidification in the end of the valve [begin of the process] – However it is not real, since the valve is ducked in liquid steel.
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Steel Solidification
Remarks of this Group of Simulations
Tendency of steel solidification in the sliding plate region – This
behavior is commented in many papers;
Tendency of steel solidification in the end of the valve [begin of the
process] – However it is not real, since the valve is ducked in liquid
steel.;
Results show that solidifation problem only occurs before the first
200 seconds.
Process fluid dynamics is not conclusive about the causes of the
solidification problem.
Sensibility analysis (SH, Tini)
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Steel SolidificationSensibility AnalysisSimulation Conditions
MLC1 Valve 12mm opened.
Boundary condition for Inlet is a constant pressure of 60000 Pa
(equivalent to a 0.8 m steel height in tundish).
Simulation Time: 200 s.
Super-Heats (°C) Família
do Aço
Temperatura Inicial (°C) 05 10 20 30
600 X X
800 X X X X 10
1000 X X
600 X X
800 X X X X 40
1000 X X
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Steel SolidificationWorst caseFamily 10 – SH 05 – Tini 800°C
Temperature Solid fraction
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Steel Solidification
A zoom in the problem
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Steel Solidification
Suggestions and Next steps:
Super-heat temperature is more sensible than blocks initial
temperature, although is more difficult to control.
The possible solutions for the problem are:
Increase pre-heating temperature;
Increase super-heat;
Increase the steel flow, respecting process constrains.
Model improvements [next steps]:
To include the valves cooling system;
To use the 3D model of the whole tundish to get more information of the phenomena.
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Steel Solidification
Kontaktadresse:
Peter MusterI&S GCSchuhstraße 6091052 ErlangenTel: 09131-7-24607
Mail: peter.muster@siemens.com
Your Success is Our Goal
www.siemens.com/itps1 www.chemtech.com.br
Contact:
Flávio GuimarãesSenior Manager
Tel: +55 (21) 3233-5100
Mail: flavio.guimaraes@chemtech.com.br
THANK YOU
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