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????