Study On Nozzle-twisted Lance Applied To BOF Steelmaking Converter

In recent years,with the development of steel industry in China,the demand for high quality steel products and low cost production requirement is greatly increasing.BOF converter steelmaking is one of the key processes for controlling molten steel cleanliness.Oxygen lance is one of the main equipment of oxygen converter steelmaking,and thus its performance characteristics directly affect the effect of smelting,refining efficiency,and the quality and quantity of steel.In this work,a new type lance,named as the nozzle-twisted lance,is proposed and the jets characteristics from this lance as well as the application of the lance in steelmaking converter are studied.Firstly,a non-isothermal,compressible and three-dimensional mathematical model for a swirling jets is established.The jets vortex characteristics,coalescence behavior,kinetic parameters distribution,such as axial velocity and dynamic pressure distribution,and the flow field distribution are analyzed systematically.The effect of the nozzle twist angle is discussed.Then,water model experiments are carried out to study the bath feature of a steelmaking converter with nozzle-twisted lance,such as the bath mixing,splashing rate and splashing distribution in space,and cavity characteristics and so on.The following conclusions can be arrived from this study.(1)The nozzle twist angle of nozzle-twisted lance is the key parameter compared with the traditional oxygen lance.The jet from the nozzle-twisted lance produces swirling flows around the axis of the lance.The swirling extent depends on the nozzle twist angle and the jets travelling distance,and the increase of the nozzle twist angle can strengthen the swirling flow.Furthermore,the jets coalescence extent decrease and the decay rate of the jets velocity increase for the nozzle-twisted lance.(2)The nozzle-twisted lance can produce a tangential velocity component in the circumferential direction,which increases with the nozzle twist angle.When the nozzle twist angle increases to 20 degrees,an obvious rotational flow will be produced in the reactor.The nozzle-twisted lance increases the circumferential movement of the fluid in the reactor,and strengthens the stirring efficiency of the reactor effectively.(3)When the nozzle twisted lance is used,the cavity depth decreases,and the impacting position of the jets becomes scatter and move towards furnace wall with the increase of the nozzle twist angle.In the considered range of the nozzle twist angle,the shortest mixing time is arrived.(4)When the nozzle twisted lance is used,the gradient of splashing amount along the radial direction become smaller as the twist angle increased from 0 degree(corresponding to the traditional oxygen lance)to 30 degrees.The intensity of the bath oscillation decreases,and the amplitude of liquid surface oscillation gradually decreases with the increase of nozzle twist angle.It is beneficial to the smooth smelting of the converter and reduce the occurrence of spattering...