Your Success is Our Goal Understanding the steel solidification in tundish nozzles X International PHOENICS Users Conference Melbourne, May 2004

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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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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The Tundish


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The Problem


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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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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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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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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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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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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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A zoom in the problem


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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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Kontaktadresse:

Peter MusterI&S GCSchuhstraße 6091052 ErlangenTel: 09131-7-24607

Mail: [email protected]


www.siemens.com/itps1 www.chemtech.com.br

Contact:

Flávio GuimarãesSenior Manager

Tel: +55 (21) 3233-5100

Mail: [email protected]

THANK YOU

Documents

Your Success is Our Goal Understanding the steel solidification in tundish nozzles X International PHOENICS Users Conference Melbourne, May 2004