your success is our goal inertization system of steel casting with phoenics ix international...

Your Success is Our Goalwww.siemens.com/itps1 www.chemtech.com.br

INERTIZATION SYSTEM OF STEEL CASTING WITH PHOENICS

IX International PHOENICS Users ConferenceIX International PHOENICS Users Conference

Moscow, 26Moscow, 26thth September 2002 September 2002

Your Success is Our Goal

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Steel Casting

IX International PHOENICS Users Conference

Chemtech - A Siemens Company, Rio de Janeiro / RJ – BrazilChemtech - A Siemens Company, Rio de Janeiro / RJ – Brazil

Flávio Martins de Queiroz GuimarãesFlávio Martins de Queiroz Guimarães

Bruno de Almeida BarbabelaBruno de Almeida Barbabela

Luiz Eduardo Ganem Rubião Luiz Eduardo Ganem Rubião

CST - Companhia Siderúrgica de Tubarão, Serra / ES – BrazilCST - Companhia Siderúrgica de Tubarão, Serra / ES – Brazil

Henrique S. FurtadoHenrique S. Furtado

Sergio Lopes MattediSergio Lopes Mattedi

AUTHORS


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Longitudinal SectionLongitudinal Section Aluminum Oxide CrystalsAluminum Oxide Crystals

INTRODUCTION – THE PROBLEM

Oxidation of the steel surface during casting Oxidation of the steel surface during casting producing metallic oxidesproducing metallic oxides

Obstruction of all discharge pipesObstruction of all discharge pipes

Addition of impurities and reduces process yieldAddition of impurities and reduces process yield


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INTRODUCTION – THE SOLUTION

ARGONIN

OXYGENOUT

Introduction of inert gases in the casting system to expel the existing atmosphere

This process usually makes use of noble gases as argon, which is very expensive to purchase

Simulations have been executed to predict the optimal argon inflow, time of inertization and process yield with minimum operational costs of impurities and reduces process yield


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TUNDISH

INTRODUCTION – THE SYSTEM


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Upper ViewUpper View

OUTLETS & INLETS (IN BLUE)

THE TUNDISH – GEOMETRY STRUCTURE

Frontal ViewFrontal View

BAFFLES


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All simulations were run on PHOENICS v3.4.All simulations were run on PHOENICS v3.4.

The follow configurations were setting:The follow configurations were setting:

Total Geometry: Total Geometry: 9494 mm x 1543 mm x 1790 mm9494 mm x 1543 mm x 1790 mm

Grid: Grid: 270 000 volume elements (cartesian grid) 270 000 volume elements (cartesian grid)

PARSOL: PARSOL: activeactive

Energy Equation: Energy Equation: activeactive

Turbulence Model: Turbulence Model: k-k- Chen-Kim model (KECHEN) Chen-Kim model (KECHEN)

Transient Solution: Transient Solution: activeactive

Total Number of Outlets: Total Number of Outlets: 3 (three) outlets3 (three) outlets

Total Number of Injectors: Total Number of Injectors: 3 (three) to 8 (eight) injectors3 (three) to 8 (eight) injectors

Argon Inlet Rate: Argon Inlet Rate: 250 to 380 Nm250 to 380 Nm33/h/h

Property models computed by INFORM.Property models computed by INFORM.

GENERAL SETTINGS


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PROPERTIES SETTINGS – SPECIFIC HEAT

The following formulae for the pure components were used:The following formulae for the pure components were used:

Based on the above pure component specific heats, a Based on the above pure component specific heats, a formula for the mixture specific heat was developed. It was formula for the mixture specific heat was developed. It was considered in this formulation that the mixture is ideal and considered in this formulation that the mixture is ideal and that the air has a constant composition (21% Othat the air has a constant composition (21% O22).).


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PROPERTIES SETTINGS – DENSITY

The following formula describe the evaluation of the mixture The following formula describe the evaluation of the mixture density. It was considered in this formulation that the mixture density. It was considered in this formulation that the mixture is ideal and binary (argon and air only).is ideal and binary (argon and air only).


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PROPERTIES SETTINGS – VISCOSITY

The following formula describe the evaluation of the mixture The following formula describe the evaluation of the mixture viscosity. It was considered in this formulation that the viscosity. It was considered in this formulation that the viscosity is independent of the mixture composition. The viscosity is independent of the mixture composition. The temperature was computed, despite of the great difference of temperature was computed, despite of the great difference of temperature among the air inside the tundish and argon inlet temperature among the air inside the tundish and argon inlet by nozzles.by nozzles.


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PROPERTIES SETTINGS – DIFFUSIVITY

The following formula describe the The following formula describe the evaluationevaluation of the mixture of the mixture diffusivity. It was considered in this formulation that the diffusivity. It was considered in this formulation that the mixture is ideal and binary (argon and air only). mixture is ideal and binary (argon and air only).


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OUTPUT – OXYGEN CONCENTRATION


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FIELD TEST VALIDATION

1 2 3 4 5ARGONNOZZLES

BAFFLES

OUTLETS OUTLETSOUTLETS

5 (five) sample points have been measured to 5 (five) sample points have been measured to analyze the dynamic behavior of the processanalyze the dynamic behavior of the process


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FIELD TEST VALIDATION – TURBULENCE

Although both models fitted well this data, Although both models fitted well this data, the k-the k- Chen-Kim Chen-Kim

(KECHEN) was chosen(KECHEN) was chosen because the simulations results have because the simulations results have

shown that it had a little better mean correlation value andshown that it had a little better mean correlation value and

first step result fitted closer to the experimental curve. first step result fitted closer to the experimental curve.


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Point 1

0.00

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0 50 100 150 200 250 300

Time (s)

%O

2 (v

/v)

Low High CFD

FIELD TEST VALIDATION – KECHEN MODEL


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Point 2

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Time (s)

%O

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Low High CFD



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Point 3

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Time (s)

%O

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Low High CFD



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Point 4

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Time (s)

%O

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Low High CFD



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Point 5

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%O

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Low High CFD



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Time = 2 minutes

Time = 3 minutes

Time = 1 minute

OXYGEN CONCENTRATION


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Time = 4 minutes

Time = 5 minutes

OXYGEN CONCENTRATION


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FINAL CASE

Several simulations have been performedSeveral simulations have been performed

The injections were relocated in order to avoid The injections were relocated in order to avoid stagnation zonesstagnation zones

The following figures show the results for the The following figures show the results for the final optimum injection pattern, as currently final optimum injection pattern, as currently implemented for daily operation (maximum residual implemented for daily operation (maximum residual oxygen concentration after 5 minutes of 2.08 %v/v):oxygen concentration after 5 minutes of 2.08 %v/v):


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FINAL CASE – OXYGEN DYNAMIC PROFILE


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FINAL CASE – OXYGEN PROFILE

OXYGEN CONCENTRATIONAFTER 5 MINUTES


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OXYGEN CONCENTRATIONAFTER 5 MINUTES

FINAL CASE – OXYGEN ISOPLETH


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CONCLUSION

The results showed:The results showed:

Excellent quantitative agreement with field data Excellent quantitative agreement with field data and good qualitative behaviorand good qualitative behavior

How CFD simulations are becoming even more a How CFD simulations are becoming even more a very important tool for equipment optimization in very important tool for equipment optimization in the process industriesthe process industries


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FINAL

THANK YOUTHANK YOU

&&

QUESTIONSQUESTIONS

your success is our goal inertization system of steel casting with phoenics ix international...

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