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X International PHOENICS Users Conference
Understanding the
steel solidification
in tundish nozzles
Melbourne, May 2004
Your Success is Our Goal
Steel Solidification
Chemtech - A Siemens Company, Rio de Janeiro / RJ – Brazil
© IT PS 2003
AUTHORS
Carlos Eduardo Fontes
Flávio Martins de Queiroz Guimarães
CST - Companhia Siderúrgica de Tubarão, Serra / ES – Brazil
Henrique S. Furtado
CST
20-08-03
Slide 2
Sandro de Souza Santos
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Steel Solidification
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Projeto de Equipamentos
Sistema de Inertização
CST
20-08-03
Slide 3
TUNDISH
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Steel Solidification
 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.
© IT PS 2003
Objective and Motivation
 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.
CST
20-08-03
Slide 4
 To analyze the flow of two different steels (Family 10 and 40)
and three different valves (MLC1, MLC2 Single and MLC2
Twin).
Your Success is Our Goal
Steel Solidification
CST
20-08-03
Slide 5
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The Tundish
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Steel Solidification
CST
20-08-03
Slide 6
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The Problem
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Steel Solidification
H  h  H
h(T)  c  (T T m )
 Velocity
L
T  T1


H  L(1  Fs ), T1  T  TS

0
T  T1

 u1 liquid phase

u  u1  , mushy zone
 0
solid phase

Slide 7
 Entalphy
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Solidification Model
CST
20-08-03
 Porosity associated to the lost latent heat fraction
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Steel Solidification
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Model Validation
 Data from Voller & Prakash
Solid fraction in 250 s:
Voller & Prakash: 35%
Validação de Resultados
PHOENICS
VOLLER & PRAKASH
1
0,8
0,6
0,2
0
0
0,2
0,4
0,6
0,8
1
Largura (m )
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20-08-03
Slide 8
0,4
CST
Altura (m)
PHOENICS: 34,8%
Steel Solidification
Material
Espessura
(mm)
k
(W/m.ºC)
Cp
(J/kg.°C)


(kg/m3)
Intoval P-38
32,0MLC1
36,0MLC2
k  0.0002 T  0.3256
840
0.63
2100
Flowkast70-FM
130,0 MLC1
164,0 MLC2
8
40
0.63
2100
 0.0138 T  6.9092
840
0.63
2100
k  2 10 9 T 3  7 10 6 T 2
840
0.63
2100
840
0.63
2100
2.903
840
0.63
2100
4.1
840
0.63
2100
840
0.63
2100
840
0.63
2100
840
0.63
2100
Jetmag-BSSM
31,0
Cekast 85LC
40,0
 0.0218 T  7.4871
k  3 10 9 T 3  1 10 5 T 2
52,5
171,3 e 71,3
Basimag API
k  5 10 6 T 2  0.00158 T
 16.871
Resikor-85
48,5
Alumina
grafite
30,0
4.65
k  7 10 6 T 2  0.0151 T
 23.519
20-08-03
Mulkor-85
CST
86,5
Slide 9
 0.0076 T  4.4575
Sedekor 85BC
Alumag 80BRX
k  3 10 9 T 3  2 10 5 T 2
© IT PS 2003
CST Model
Physical Properties of Solid Blocks
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Steel Solidification
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CST Model
Physical properties of Steel
Material
T Solidus T Liquidus
Cp
L
k

(°C)
(°C)
(J/kg.°C) (J/kg) (W/m.K) (kg/m³)
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
CST
20-08-03
Slide 10
Aço 10
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Steel Solidification
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Model 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
CST
20-08-03
Slide 11
 External Temperature: 40ºC
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Steel Solidification
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Qmass x Abertura
2,50
2,00
1,50
Experimental
1,00
Simulação
0,50
10,00
20,00
30,00
Abertura (mm)
Slide 12
0,00
0,00
20-08-03
Qmass
0,45
0,50
0,60
0,68
0,77
0,85
0,94
1,03
1,11
1,20
1,29
2,20
0,49
0,88
1,09
1,54
1,73
1,74
1,94
Qmass (ton/min)
Abertura
10,99
10,67
12,14
13,26
14,47
15,52
16,66
17,77
18,73
19,79
20,83
27,37
13,00
15,00
19,00
23,00
25,00
27,00
28,00
CST
BMK
Experimental
Comparison with Field data:
Mass Flow x Valve aperture
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Steel Solidification
Temperatura da Válvula Submersa
900
850
800
750
°C
150
390
510
570
690
810
930
150
390
510
570
690
810
900
Temperatura
da Válvula
Submersa
650
740
830
826
830
850
850
650
725
810
810
810
810
810
Experimental
700
Simulação
650
600
550
500
0
200
400
600
800
1000
Tempo (s)
Slide 13
BMK
Experimental
Tempo
(s)
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Comparison with Field data:
Valve Temperature
CST
20-08-03
posição em metros: (0.795,0.414)
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Steel Solidification
 Steel flow is function of the steel height inside the tundish
 Steel height: 0,5 m
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Testing the Solidification Model:
Base Case
 Steel Family: 10
 Inlet Temperature: 1535°C (2°C Super-heat)
 Valve: MLC1
 External Temperature: 40°C
CST
20-08-03
Slide 14
 Initial Temperature of solid blocks: 1000°C
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Steel Solidification
CST
20-08-03
Slide 15
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Base case results:
Solidification after 30 seconds
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Steel Solidification
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Choosing the geometry for the analysis:
Comparison 2D x 3D
 MLC1 Valve with defined steel flow;
 Same grid and domain; time: 100 seconds.
20-08-03
Slide 16
3D
CST
2D
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Steel Solidification
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Comparison 2D x 3D:
Velocity Profiles
Slide 17
3D
CST
20-08-03
2D
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Steel Solidification
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Comparison 2D x 3D:
Temperature Profiles
Slide 18
3D
CST
20-08-03
2D
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Steel Solidification
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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
CST
20-08-03
Slide 19
 MLC2 Twin Valve with Family 40
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Steel Solidification
Valve: MLC1
CST
20-08-03
Slide 20
Steel: FAM 10
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Steel Solidification
MLC1 – Family 10
Solid Fraction
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t = 150 s
CST
20-08-03
Slide 21
t = 160 s
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Steel Solidification
MLC1 – Family 10
Temperature
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t = 150 s
CST
20-08-03
Slide 22
t = 160 s
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Steel Solidification
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MLC1 – Family 10
Pressure and Velocity
Slide 23
Velocidade
CST
20-08-03
Pressão
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Steel Solidification
 Tendency of steel solidification in the sliding plate region
[begin of the process];
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Results Analysis
CST
20-08-03
Slide 24
 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
 Tendency of steel solidification in the sliding plate region – This
behavior is commented in many papers;
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Remarks of this Group of Simulations
 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.;
CST
Sensibility analysis (SH, Tini)
20-08-03
 Process fluid dynamics is not conclusive about the causes of the
solidification problem.
Slide 25
 Results show that solidifation problem only occurs before the first
200 seconds.
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Steel Solidification
 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).
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Sensibility Analysis
Simulation Conditions
 Simulation Time: 200 s.
Super-Heats
(°C)
600
10
40
800
10
20
X
X
X
30
X
X
X
1000
X
X
600
X
X
800
1000
X
X
X
X
Slide 26
05
20-08-03
Temperatura
Inicial
(°C)
X
CST
Família
do Aço
X
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Steel Solidification
20-08-03
Slide 27
 Solid fraction
CST
 Temperature
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Worst case
Family 10 – SH 05 – Tini 800°C
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Steel Solidification
CST
20-08-03
Slide 28
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A zoom in the problem
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Steel Solidification
 Super-heat temperature is more sensible than blocks initial
temperature, although is more difficult to control.
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Suggestions and Next steps:
 The possible solutions for the problem are:
 Increase pre-heating temperature;
 Increase super-heat;
 Increase the steel flow, respecting process constrains.
 To use the 3D model of the whole tundish to get more information
of the phenomena.
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CST
 To include the valves cooling system;
20-08-03
Slide 29
 Model improvements [next steps]:
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Steel Solidification
THANK YOU
www.siemens.com/itps1
www.chemtech.com.br
Mail:
[email protected]
09131-7-24607
[email protected]
Your Success is Our Goal
Your Success is Our Goal
20-08-03
Tel:Mail:
CST
Flávio
Guimarães
Peter
Muster
Senior
I&S
GC Manager
Schuhstraße 60
Tel: Erlangen
+55 (21) 3233-5100
91052
Slide 30
Contact:
Kontaktadresse: