venkatersan_foseco
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venkatersan_foseco


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steel of wide 
chemistry variations were casted in the 
same tundish (Paul Rasmussen5 for Dofasco 
Inc., Canada). Studies done in steel plants 
like AK Middletown, OHIO USA, Sollac, 
France, Nucor Hickman, USA. US Steel 
Gary, USA, Algoma, Canada has also 
revealed similar trends.
Recent trends, as discussed above, do 
make it imperative to study in details the 
fluid flow pattern for every plant\u2019s tundish 
in order to design a custom made flow 
modifier system. This will enable the steel 
makers to optimise steel flow pattern in 
the tundish in order to derive maximum 
benefit.
2.3 Physical (Water) and Mathematical 
Modelling
Fluid flow in steelmaking system has been 
the subject of extensive study in recent 
years. The approaches used included both 
physical and mathematical modeling.
Mathematical predictions of flow pattern6-9 
has gained wider popularity in recent years 
with the advent of improved numerical 
procedures and refined turbulence models. 
When augmented by experimental work, 
mathematical modelling can be useful in 
explaining or verifying the observed results, 
and for providing guidelines for experi-
mental design.
The flow of liquid steel in a continuous 
casting system cannot be observed directly. 
The application of the technique of 
mathematical modelling is complicated by 
the occurrence of intense turbulence and 
biphasic flow in certain regions of the 
system. Thus, physical modeling using 
water at room temperature (due to 
kinematic viscocity similarity with liquid 
steel at 1600°C) as a medium is finding 
widespread application for the study of 
fluid flow in the tundish, especially in 
designing tundish flow modifiers.
To attain similarity between two flowing 
systems the flowing four conditions must 
be met10-13
1. Geometric Similarity \u2013 the ratio of length 
in one with the corresponding one of 
the another is constant. This ratio is 
termed as scale factor
2. Kinematic Similarity \u2013 the streamlines in 
one system are geometrically similar to 
the streamlines in the other system.
3. Dynamic Similarity \u2013 the magnitude of 
forces at corresponding locations in 
each system are in a fixed ratio.
4. Thermal Similarity \u2013 the dimensionless 
numbers involving heat transfers are 
equal in both systems. Thermal 
similarity is not important when 
considering flow within a tundish since 
forced convection in these regions is 
likely to be predominant.
2
Fig 3. Schematic diagram of various flow modifier position for Plant - B
Steady State Liquid Metal Level
1200 mm
Dam - 2 Dam - 1
Striker Pad
Steady State Liquid Metal Level
320 mm
Baffle Dam - 1
Striker Pad
Steady State Liquid Metal Level
320 mm 1000 mm
Dam - 1 Baffle
Striker Pad
1000 
mm
Steady State Liquid Metal Level
TURBOSTOP at 40 mm from end wall
TURBOSTOP at 40 mm from end wall
TURBOSTOP at 40 mm from end wall
TURBOSTOP at 40 mm from end wall
TURBOSTOP at 40 mm from end wall
Steady State Liquid Metal Level
Short Dam with drain holes
Steady State Liquid Metal Level
320 mm
180 mm
High Dam (1&2)
Steady State Liquid Metal Level Steady State Liquid Metal Level
Configuration - A Configuration - B
Configuration - C Configuration - D
Configuration - E Configuration - F&G
Configuration - H Configuration - I
320 mm
Baffle Dam - 1 Baffle
320 mm
Flow modifiers set-up studied for both type 
of tundish is given in Table 2 and 
schematic drawing showing positioning of 
the flow modifiers is given in Fig 3 & 4.
4.2 C-Curve - RTD Curve Study (Steady 
State)
C-Curve Study helps assess the flow 
characteristics of steel in the tundish at 
steady state casting condition with 
different sets of flow modifiers. During the 
experiment water is filled up to the 
working level and then held at that level 
with inlet and outlet flow remaining same 
for a duration of 3theta (1 theta=one 
tundish emptying time at existing flow 
rate) to allow the bath to stabilise. 
Subsequently a pulse of dye is injected as 
tracer. The dye concentration is monitored 
at the outlet at every 5sec time intervals. 
Computer directly acquires the data and 
concentration curve (C-Curve) is generated 
online.
3. Reduction of Slag Emulsification during 
ladle change over
4. Reduction of turbulence near the pouring 
area \u2013 Minimise Red-Eye formation
Two type of slab caster tundish was 
studied with the above primarily objective 
which are
.Flat Bottom Tundish \u2013 Plant A
.Well Shaped tundish \u2013 Plant B
Table 1. shows the values of different 
parameters used for water modelling (all 
conversions are done using Froude number 
similarity & Liquid Steel: Water density ratio 
of 7:1)
4. Water Modelling Experiments 
Done
4.1 Set-up
A 1/3rd & 1\u20442 scale tundish model for Plant 
A & Plant B respectively was taken up for 
Water Modelling Studies. Red colour liquid 
food dye having similar density as that of 
water was used as a tracer for both C-
Curve and F-Curve studies. The outlet dye 
concentration was measured with the help 
of an optical probe at an interval of 5 secs. 
The concentration data is acquired online 
by a computer through an data acquisition 
set up while the experiment is going on. A 
special software simultaneously plots the 
respective curves (C-Curve & F-Curve) using 
the online concentration values. At the end 
of each experiment the computer 
computes the values of key parameters 
(e.g. Plug Volume %, Dead Volume % etc) 
from C-Curve.
Table 1. Values of different parameters used for Water 
Modelling Study
Table 2. Flow Modifier Set-up details
3
Fig 4. Schematic diagram of various flow modifier position 
for Plant - A
Steady State Liquid Metal Level
626 mm
Brick Dam 250 mm Dam
Configuration - A & B
Steady State Liquid Metal Level
Weir
1650 mm
Configuration - C & D
Steady State Liquid Metal Level
Configuration - E & F
Steady State Liquid Metal Level
TURBOSTOP - 40 mm from end wall
Configuration - G
Steady State Liquid Metal Level
TURBOSTOP - 40 mm from end wall
TURBOSTOP - 40 mm from end wall
Configuration - H & I
Steady State Liquid Metal Level
Configuration - J
626 mm
Brick Dam 250 mm Dam
626 mm
Brick Dam 250 mm Dam
300 mm
Brick Dam / Medium Dam
High Dam - 
75% of Liquid Metal Ht
300 mm
Weir
1900 mm
Theta (time taken to empty 1
tundish volume at above 
mentioned casting rate) 
Casting Rate 2.64 tons/min 2 tons/min24.19 lt/min of
water
50.51 lt/min of
water
Scale Factor (f) 1 11/3rd 0.5
Tundish Weight at steady state 24 tons 29 tons126.98 lt of
water
517.86 lt of
water
9.09 min 14.5 min314 secs 615 secs
Water Model
Study Value
Plant ValueWater Model
Study Value
Plant Value
Plant - BPlant \u2013 A
Parameter
A
B
C
D
E
F
G
H
I
J
A
B
C
D
E
F
G
H
I
SymbolDescriptionConfigurations
Plant - A
Plant - B
Brick Dam (Existing System)
250 mm Dam
Weir (1650 mm from shroud end wall) & Brick Dam
Weir (1650 mm from shroud end wall) & 250 mm Dam
Weir (1900 mm from shroud end wall) & Brick Dam
Weir (1900 mm from shroud end wall) & 250 mm Dam
TURBOSTOP Only
TURBOSTOP & Brick Dam
TURBOSTOP & Short Dam with holes
TURBOSTOP & High Dam, Dam ht - 75% steady state metal level
BD
D1
W(1650)+BD
W(1650)+D1
W(1900)+BD
W(1900)+D1
TS
TS+BD
TS+SD1/holes
TS+HD1
Striker Pad & Dams (1&2) (Existing System)
Striker Pad, Dam (1) & Baffle
Striker Pad, Baffle & Dam (2)
TURBOSTOP Only
TURBOSTOP & Short Dam with drain holes
TURBOSTOP & High Dam (1), Dam ht - 75% of steady state metal level
TURBOSTOP & High Dam (2), Dam ht equal to steady state metal level
TURBOSTOP & Baffle at 320 mm from the slope
TURBOSTOP & Baffle & Dam (1)
SP+D1+D2
SP+D1+B1
SP+B1+D2
TS
TS+SD1/holes
TS+HD1
TS+HD2
TS+B1/320
TS+B1+D1
Each test was also visually observed using a 
video recorded and event recorded. Table 3 
gives the parameters for which a com-
parative analysis is done for different sets 
of flow modifiers.
The characterization of the flow for the 
experimental RTD curves is carried out 
using the methods of Sahai and Emi1 as 
well as the principles presented by