Basic Study On Multiphase Jet Behavior Of Spoiler Lance In Blast Furnace

There are two critical and valuable areas in the blast furnace ironmaking process.The first is the soft melting zone,which is located in the furnace body,and the second is the tuyere raceway area,which is located in the boiler and hearth sections.The racetrack provides blast furnace gas and heat.Large blast furnaces will use the process of injecting pulverized coal to replace the role of heating agent and reducing agent of metallurgical coke in the ironmaking process of the blast furnace to reduce the cost of iron per ton,in addition to the combustion reaction of coke in the raceway.To a certain extent,the pulverized coal injection process reduces the coke ratio and maintains the theoretical combustion temperature,but when the amount of pulverized coal injection is too large,it causes abnormal furnace conditions,such as a cooler hearth.As a result,it is critical to investigate the maximum value of pulverized coal injection.A small set of raceway models of the tuyere was established using the method of coupling DEM and CFD based on the actual production data of a 3200m~3 blast furnace in a large ironmaking plant.The injection characteristics of new coal injections were evaluated using the characteristics of pulverized coal injection by traditional coal injection.Finally,the goal of reducing burnout will be met.This thesis is concerned with the following work:(1)Using CFD and DEM simulation software,the gas-solid two-phase unidirectional coupling model is used to describe the movement of coal powder particles and gas phase in traditional coal injection.The maximum velocity and residence time of pulverized coal are most affected by the velocity of hot air.Carrier gas velocity has little effect on residence time.The drag force on pulverized coal in traditional coal injection process depends on the difference between the two velocities.The larger the inclination Angle of tuyere,the shorter the residence time of pulverized coal.The convergence and linear motion of pulverized coal particles cannot be changed by changing the air blast velocity,carrier gas velocity and tuyere inclination Angle.(2)Aiming at the limitation of the traditional coal injection,a new structure of the spoiler gun is proposed,and the optimal injection condition is obtained by changing the bending Angle and velocity of the accompanying gun.The larger the bending Angle is,the larger the accompanying gas velocity is,the larger the dispersion rate of pulverized coal particles is,the greater the pressure on the tuyere small sleeve wall is,and the more obvious the dilution effect on carrier gas is.The velocity distribution of pulverized coal particles in the new coal injection is almost consistent with that in the traditional coal injection.(3)Compared with the traditional coal injection,the new type of spooling coal injection is more discrete and uniform in terms of injection effect.From the perspective of dispersion,the dispersion of the traditional coal injection is only 17%,while the new type of coal injection has a dispersion rate of 72%under the condition that the bending Angle of 45°-45°and the flow rate of the injection is 700m/s.The greater the dispersion rate,the more obvious the injection effect will be improved.With a bend Angle of 45°-45°,the impact pressure on tuyere sleeve reached 1648.2k Pa when the flow rate of the injection was 700m/s.In order to reduce the erosion of coal powder on the tuyere small sleeve wall,the flow rate was set at 600m/s and the bending Angle was 45°-45°.