Water Modeling Study of Fluid Flow and Mixing in an AOD Bath With Rotating Gas Jets

摘要

Water modeling was used to investigate fluid flow and mixing characteristics in the bath of an 18-ton AOD vessel with rotating gas jets through two annular spiral-flat tube tuyeres. This work was conducted on the basis of a water modeling study of the characteristics in an 18-ton AOD vessel with non-rotating gas jets through two annular straight-tube tuyeres at a sufficiently full kinematics similarity. The geometric similarity ratio between the model and its prototype (including the straight tube tuyeres) was 1-to-3. A spiral flat brass sheet 0.2 mm thick with a pitch of 46.57 mm was installed in the central tube (the main tuyere) of the tuyere used to obtain a rotating gas jet. Its annular slit (the subtuyere) was the same as the original straight-tube tuyere. The influences of the gas flow rate and the angle included between the two tuyeres on the characteristics, and the suitability of the spiral tuyere as a practical application, were examined. It has been concluded from the results that, at the same gas flow rate, the rotating jet provides a stronger agitation and causes a more vigorous swirling and circulatory motion of the fluids. This results in a better mixing efficiency than the non-rotating jet The gas flow rate of the spiral main tuyere has the larger influence on the fluid flow and mixing in the bath than that of the straight main tuyere. The non-rotating gas jet of the subtuyere also has a physical shielding effect on the rotating gas jet of the main tuyere, but the action is obviously weakened because of the rotating motion of the main tuyere jet. The included angle between the two annular-spiral tube tuyeres has a stronger effect on the fluid flow and the stability of the blowing process, and its optimal range is narrower than when utilizing the annular straight-tube tuyeres. The optimum angle between the two tuyeres for rotating jets is 80 degrees under the conditions of the present work Use of a gas jet with a suitable rotating intensity is feasible, and an annular-spiral tube tuyere with a reasonable structure is well-suited for improving the AOD refining. The relationships between the mixing time and the gas flow rates, the densities of stirring energy, the modified Froude numbers for the main tuyere and subtuyere jets, and the tuyere arrangement have been determined.