Post on 20-Mar-2018
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 1
Modeling of Fluid Flow, Mixing and Inclusion Motion in Bottom Gas-
Stirred Molten Steel Vessel— Development of a Process to Continuously Melt, Refine, and Cast
High-Quality Steel
Lifeng Zhang, Brian G. ThomasUniversity of Illinois
May 10, 2004
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 2
Acknowledgements
- Continuous Casting Consortium at UIUC- UMR (Prof. Kent Peaslee, Prof. David
Robertson, Mr. Jorg Peter)- Department of Energy (DOE)- Fluent Inc.- National Center for Supercomputing
Applications at UIUC
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 3
heated holding ladle (for EAF or tundish),or pig the steel
0
1
2
3
4
5
6
7
8
9
10
11
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16length (meters)
heig
ht o
r wid
th (m
eter
s)
Ar Ar Ar
Ar
Ar
Ar
mold
CO,Ar
0.15%C
2890ºF
measure
measure
measure
measure
heating rods
Ca wire
wire feeding adjustment?
Deo
xidi
zer,
CaO
, MgO
CaO, MgO
alloys
Side view
Top viewlooking at steel surface
Conceptual layout for 110 tph process
27 t20 t20 t30 min 50 t
2910ºF 2880ºF2870ºF
2830ºF
+ 12 min + 12 min + 21 min = 75 min
melt
oxidize
reduce
homogenize & float
?
O2 + Ar
7 t –
23 t
Figure from Jorg Peter, UMR
Vessel II
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 4
Geometry of Vessel II Geometry of Vessel II
Inlet
Vessel II
Outlet SEN
Outlet Launder
Gas Injection inlets:Position: 1/4 and 3/4 diameter of the bottomDin=0.2m
Inlet Launder
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 5
Geometry of Vessel IIGeometry of Vessel II
Inlet(Din=0.14m, Dout=0.2m,Submergence depth:0.15mSimulated inlet SEN length: 0.5mDistance of inlet center line to left wall: 0.2mVin=0.23m/sKin=0.01m2/s2
in=0.06m2/s3)
Vessel II(Din=1.4m,Depth: 2.0m) Outlet SEN
(Din=0.14m, Dout=0.2m,Length: 1.1m, no slide gateDistance of outlet center
line to right wall: 0.2m)
Outlet Launder:Thickness:0.3m
Inlet Launder:Left depth: 0.3mRight depth:0.6mLength: 1mThickness:0.3m
0.3m
0.4m
0.4m
1.1m
0.7m0.9m
0.3m
ε
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 6
Geometry of Vessel IIGeometry of Vessel II
Inner diameter: D=1.4mSteel bath height: Hsteel= 2.0mSlag depth: Hslag=0.2mDiameter of gas porous plug: 0.2m (two plugs)Inlet nozzle inner diameter: Dsteel, in=0.14mInlet nozzle outer diameter: 0.2mInlet submergence depth: 0.15mInlet SEN length: 1.1mModeled inlet length: 0.5mDistance from inlet center line to right side wall: 0.2mMolten Steel temperature: To=1900K Inlet and outlet launders on opposites of vessels and directed radially
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 7
Input Flow ConditionsInput Flow Conditions
Steel flow rate: 99.5 tons/hourSteel density: 7020 kg/m3
Mean inlet velocity: 0.232 m/s
Cold argon gas flow rate: 0.49 m3/minHot argon gas flow rate: 1.314 m3/minMean bubble injection velocity: 0.35 m/sMean bubble size: 48mm
Discrete multiphase transient flow input: 19 bubbles/0.1s at each of the two gas inlets at the bottom
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 8
Fluid Flow and Particle Motion with Argon
Injection
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 9
Fluid Flow with Argon Injection Fluid Flow with Argon Injection
Fluid flow velocity Gas concentration
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 10
Fluid Flow with Argon InjectionFluid Flow with Argon Injection
Turbulent Energy Dissipation RateTurbulent Energy
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 11
Typical Trajectories of Alumina Inclusions Typical Trajectories of Alumina Inclusions (300(300µµm, 3500 kg/mm, 3500 kg/m33) (With Argon Injection)) (With Argon Injection)
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 12
Transient Fluid Flow with Argon Injection Transient Fluid Flow with Argon Injection
500 Bubbles injection per seconds
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 13
Fluid Flow and Particle Motion without Argon
Injection
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 14
Fluid Flow VelocitiesFluid Flow Velocities
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 15
Typical Trajectories of Tracer Particle Typical Trajectories of Tracer Particle (Without Random Motion)(Without Random Motion)
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 16
Typical Trajectories of Particles (With Typical Trajectories of Particles (With Random Motion)Random Motion)
Tracer particles Alumina Inclusions
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 17
Fluid Flow, Particle Motion, and Mixing in a
Argon-Stirred Ladle(300 ton, 4.5m height, 0.5 m3/min argon injection, bubble
size: 33mm)
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 18
Fluid Flow Fluid Flow
(m)
(m)
00.511.52
0
0.5
1
1.5
2
2.5
3
3.5
4
4.50.0 0.3 0.5 0.8 1.0
speed (m/s)
(m)0 0.5 1 1.5 2
1m/s
Velocities
0 0.5 1 1.5 2(m)
(m)
00.511.52
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0.0001 0.0006 0.0040 0.0251 0.1585 1.0000
gas concentraction (kg/m3)
Gas Concentration
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 19
Particle Motion and Mixing Time Particle Motion and Mixing Time
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
1
2
3
4
5
6
7
Calculated gas column shape (0.001 isoline of the gas volume fraction)
50µm 100µm 300µm
(m)Inclusion Trajectories
0.1 1 10 100 100010
100
1000
123456
50t ASEA-SKF 50t Ar-stirred 58.9t Ar-stirred 6t Ar-stirred 200RH 65kg Water model
τ=523ε - 0.4
Current 300tonne Ar-stirred ladle
Mix
ing
time,
τ (s
)Stirring power, ε (Watt/ton)Mixing Time
Average Moving path length before reaching top surface:- 100µm inclusion: 47.0m (285s); - 33mm bubble: 5.0m (3.9s)
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 20
Dissolution of Aluminum Alloy in Ladle Dissolution of Aluminum Alloy in Ladle
0s 3s
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 21
Overall process summary Overall process summary
50s10s
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 22
ConclusionsConclusions
1. The developed Lagrangian-Lagrangian multiphase model can predict the fluid flow, inclusion motion and mixing in vessels of this continuous steelmaking process
2. Without gas injection- Generating short circuiting flow pattern (from the
inlet launder quickly and directly to the outlet launder), very detrimental for the process.
- The inlet jet impinges strongly against the shallow bottom of the inlet launder, so possible splashing and erosion of the refractory bricks
- Possible improvement: making the outlet launder not align directly across the vessel from the inlet.
Univ. of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • L. Zhang, 2004, 23
ConclusionsConclusions
3. With gas injection- Generating a strong recirculation in the whole height of the
vessel.- Particles recirculate a long time,good for reactions.
4. Useful researches for this project (now and future):- Solute mixing (such as alloy dissolution) (done by L. Zhang and
J.Aoki for gas stirred ladles)- Reactions such as deoxidation, impurity element and
inclusion removal, depending on mixing phenomena at the interface of slag / metal and gas/metal.
- Modeling inclusion nucleation, growth, collision (done by Lifeng )and interact with gas bubbles (done by Lifeng and Jun Aoki in gas stirred ladles)
- Investigating the emulsification of the top slag