Physical Modeling of Slag ‘Eye’ in an Inert Gas-Shrouded Tundish Using Dimensional Analysis
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Abstract
The formation of an exposed eye in the gas-stirred metallurgical vessels such as ladle or tundish is a common observation. Although gas stirring results in proper homogenization of melt composition and temperature, the resulting exposed eye leads to higher heat losses, re-oxidation of liquid steel, and formation of inclusions. Most of the previous research related to slag eye were carried out explicitly for ladles. In the present work, a large number of experiments were performed to measure the slag eye area in full scale and one-third scale water models of an inert gas-shrouded tundish under various operating conditions. Based on the polynomial regression of experimental data, and the method of dimensional analysis, correlations for diameter of gas bubbles and plume velocity were developed. Subsequently, these results were used to obtain correlations for the slag eye area, and critical gas flow rate in an inert gas-shrouded tundish in terms of the operational parameters viz., gas flow rate, thickness of the slag and melt baths, along with the physical properties of the liquids viz., kinematic viscosity and density. It was observed that the dimensionless slag eye area can be expressed in terms of dimensionless numbers such as the density ratio, Froude number, and Reynolds number.
Keywords
LLDPE Nozzle Diameter Bubble Diameter Slag Layer Bubble PlumeNomenclature
- Q
Gas flow rate (m3 s−1)
- H
Depth of bulk fluid phase (m)
- h
Depth of upper fluid phase (m)
- Ae
Area of the slag eye (m2)
- ρl
Density of bulk fluid phase (kg m−3)
- Δρ
Density difference between lower and upper fluid phases (kg m−3)
- vs
Kinematic viscosity of upper fluid phase (m2 s−1)
- Up
Plume velocity (average rise velocity of the gas-liquid mixture) (m s−1)
- g
Acceleration due to gravity (m s−2)
- db
Diameter of the gas bubbles (m)
- ρb
Density of the gas bubbles (kg m−3)
- µl
Viscosity of the lower fluid phase (kg m−1 s−1)
- db*
Non-dimensional gas bubble diameter
- Q*
Non-dimensional gas flow rate
- Up*
Non-dimensional plume velocity
- Ae*
Non-dimensional plume velocity
- Qc
Critical gas flow rate
- Qc*
Non-dimensional critical gas flow rate
- LLDPE
Linear low-density polyethylene
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