| The oxygen lance is a critical piece of equipment in the steelmaking process.The structural features of the oxygen lance nozzle have a direct impact on smelting efficiency,steel quality,production safety,and other essential converter steelmaking indicators.A new type of oxygen lance is the staggered oxygen lance.A unique single-channel staggered oxygen lance nozzle is constructed by altering the typical nozzle structure of equal flow rate and equal Angle.Although this construction has apparent advantages in big converters,the jet properties for 120 t converters remain unknown.As a result,the 120 ton converter of a steel plant was chosen as the research object in this thesis,and the outlet Mach number was 2.08.The influence of nozzle arrangement,flow ratio of internal and external holes,and internal hole inclination Angle on interleaved jet behavior was studied using eight groups of interleaved six-hole oxygen lance effluents.At room temperature(300K)and steelmaking temperature(1873K),the jet properties of a staggered six-hole oxygen lance and a typical five-hole oxygen lance were compared and examined,and the following conclusions were reached:(1)Because jet convergence is severe when the big hole is inside the staggered six-hole oxygen lance used in the 120 t converter,the arrangement of sprinkler heads should choose the big hole outside.On the basis of the large hole layout,increasing the flow ratio of the outer holes and the dip Angle of the inner holes increases the independence of each flow strand of staggered jets,weakens mutual pumping between the flow strands,delays jet convergence and fusion,increases the length of the core segment of the jet,and slows jet velocity attenuation.A larger effective impact area can be generated with more swirling kinetic energy.As a result,the best flow ratio of inner and outer holes in all staggered six-hole oxygen lance schemes is 40%/60%,and the larger the inclination Angle of inner holes is within a particular range,the better.(2)The internal hole jet independence of the staggered six-hole oxygen lance is poor compared to the traditional five-hole oxygen lance,but the external hole jet independence is better,and the pumping effect between the flowing streams is stronger;the core length of the interleaving oxygen lance is shorter than that of the five-hole oxygen lance,and the efflux velocity attenuates faster,but the effective impact area is larger.The reason for this is because the jet independence of the porous oxygen lance reduces as the number of jet holes increases(that is,the flow ratio of a single hole lowers)and the inclination Angle decreases.Because the staggered six-hole oxygen lance has more jet holes than the five-hole oxygen lance and the flow ratio and inclination Angle of the internal hole are smaller than those of the five-hole oxygen lance,the internal hole’s jet independence is weak.The dip Angle of the external hole jet is considerable,and the flow ratio is not significantly different from that of the five-hole oxygen lance,indicating that the exterior hole jet is independent.The velocity attenuation of a porous jet slows down as the flow ratio and inclination Angle rise.The flow rate of the interlocking oxygen lance is relatively low in the inner hole,while the inclination Angle of the outer hole is greater,resulting in faster velocity attenuation of the inner and outer holes.The internal hole jets of the staggered oxygen lance converged and fused earlier,resulting in a higher velocity on the oxygen lance’s central axis,which delayed the velocity attenuation of the oxygen lance.Furthermore,because the radial enciphering capacity of the exterior hole jets was greater and the flow strand was thicker,the staggered six-hole oxygen lance had a bigger slag melting area and effective impact area.(3)The radial entrainment of the jet intensifies,and the mixing of the flow strand boundary advances and deepens,and the flow strand becomes coarser,resulting in a larger impact area as the ambient temperature rises.The effective impact area of a staggered oxygen lance is 12% greater than that of a five-hole oxygen lance at room temperature,the slag area is 39% greater,and the fusion distance between the inner and outer holes is 0.15 m.At high temperatures,the staggered oxygen lance has an11.1% larger effective impact area than the five-hole oxygen lance,a 59.3% larger slag area,and a 0.3m fusion distance between the inner and outer holes.The characteristics of non-synchronous fusion between the inner and outer holes are more visible,resulting in a significant reduction in the liquid steel spray rate. |
PDF Full Text Request