Steel Refinement by Gas Injection
Gene BaumpME447Term Project Presentation
Argon gas Injection Diagram
What’s the Point?
• Increase reaction rates• Reduce concentration of dissolved gases, Carbon, and Oxides• Homogenous mixture in less time
Benefit of using gas Injection1. Reduction of scrapped castings2. Less time spent on clean up
1. Better surface finish 3. Uniform material properties4. SAVING MONEY $$
Phenomena Occurring in the Steel Bath• Convective fluid flow• Gas-liquid mass transfer • Liquid-gas mass transfer• Reactions
Turbulent Fluid Flow with Bubble Dispersion Assumptions made in deriving the governing equations;1. Steady state
2. Constant density at the liquid-gas interface
3. Constant liquid density
4. Incompressible flow
5. Axial symmetry
6. Effective Diffusivity is equal to Effective Kinematic
Viscosity
Flow pattern developed using CO2 injection into water contained in a uniform cylindrical vessel.
(qg=83.3 × 10-6 m3/s)
Governing Equations
Turbulent Fluid Flow with Bubble Dispersion
Boundary Conditions
Turbulent Fluid Flow with Bubble Dispersion
Standard k – ɛ Turbulence Model Governing Equations
Turbulent Fluid Flow with Bubble Dispersion
Boundary Conditions for k – ɛ Turbulence Model
Turbulent Fluid Flow with Bubble Dispersion
Plug into CFD program and hit solve →
Results…
Turbulent Fluid Flow with Bubble Dispersion
Calculated and Observed results for velocities are compared at a volumetric flow rate of
) where for (a) , (b)
Turbulent Fluid Flow with Bubble Dispersion
Calculated and Observed results for the bubble dispersion zone.
Gas-Liquid Mass Transfer Model
Equation used was derived by Kataoka and Miyuchi “Eddy-cell Model”
Assumptions;1. Surface renewal is made by the smallest eddy with highest frequency
Governing Equation
Gas-Liquid Mass Transfer Model
Calculated and observed results for the volumetric Mass-transfer coefficient at the free surface.
Where the open circles represent the observed values.
Determination of the overall volumetricMass transfer coefficient for the liquid .
Assuming change in surface area due to surface agitation as negligible .The mass transfer coefficient at the surface can be determined.
Gas-Liquid Mass Transfer Model
Finally, the mass transfer coefficient at the bubble dispersion may be determined by equation 20.
Gas-Liquid Mass Transfer Model
The calculated and observed values for volumetricmass-transfer coefficient in the bubble dispersion zone.
The open circles represent the observed values.
Conclusion
• Successful in determining flow pattern, velocities, and gas hold-up distribution at the plume, surface, and throughout the vessel. • Returned reasonable results for the volumetric mass-transfer
coefficient at the surface and in the bubble dispersion zone. • The overall mass transfer model returned larger values than those
observed.• This is a result of assuming an axisymmetric surface agitation.
• In fact it fluctuates and causes more energy dispersion than accounted for.
Questions????
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