| Oxygen lance is one of the indispensable key equipment during converter steelmaking.Traditional structure oxygen lance nozzle having problem with high oxygen consumption,low oxygen supply intensity,long smelting cycle,short service life of the oxygen lance,unsatisfactory slagging effect and splashing from time to time due to the size and layout of each nozzle hole are exactly the same.In order to solve the disadvantages of traditional structure oxygen lance nozzle,in this paper,creatively put forward the design structure of nonconforming of hole size,and adopt the layout mode of double angle and double distance,that is,the center line of large hole and the center axis of nozzle are arranged at a small angle on the inside,and the center line of small hole and the center axis of nozzle are arranged at a large angle on the outside,named staggered double structure six-hole oxygen lance nozzle,which can be applied on large and medium-sized converters,based on delaying jetting attenuation and enlarging reaction area between gas and fluid.The flow field distribution of the jet is detected by experiments,and the distribution characteristics of the key dynamic parameters of the staggered double structure oxygen lance jet are mastered,which lays a foundation for the research of numerical simulation.Through numerical simulation,the influence mechanism of design structure variables and operation process on jet characteristics is clarified,the causes and action mechanism of step-by-step fusion characteristics of staggered dual structure oxygen lance are analyzed,the impact area is defined and divided by S10,S30,S50 and S75,and the mathematical model of jet impact area on molten pool is established.Through hydraulic simulation experiments,the reasons for the decrease of the maximum splash amount and mixing time at the furnace mouth are clarified,and the synergy between the fusion distance of jet,the maximum radial distance,the width of impact pit and the impact area is proved.Industrial test to evaluate the smelting effect of staggered dual structure oxygen lance is the most convincing practical verification means.The results show that the jetting flow exhibit the character of fusing with step by step due to the staggered double structure oxygen lance nozzle with nonconforming structure on design.Each jetting flow reach the maximum splatter point asynchronously by increasing the fusing distance from 1.34 m to 2.25 m.Moreover,the maximum splatter with the novel structure oxygen lance is 39% of maximum by traditional structure oxygen lance,which the problem of splattering is under the control.The method of jetting flow is changed by redesigning the structure which impinging shape transformed from circular to triangle.The nozzle angle of the oxygen lance nozzle dominate the fusing distance,with the bigger nozzle angle,the radial distance of flow and the fusing distance of jetting flow are bigger,the impinging in molten pool is wider,the contacting area between the liquid steel and slag is bigger.The increment of dephosphorization rate is 0.65-2% on average.Relationship between the effective impinging area and the stirring effect in molten pool is positive correlation.Compared to the traditional structural oxygen lance,the staggered double structure oxygen lance nozzle which maximum effective impinging area is twice,its effect on molten pool is enhanced,the corresponding shortest mixing time is shortened by 17 s,and the pure oxygen supply time in the smelting process can be shortened by25-40 s per furnace on average. |
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