Study On Optimized Shape Of Oxygen Blast Furnace

Oxygen blast furnace is an ironmaking process,where oxygen is used substitute for hot blast in traditional blast furnace.Compared to the traditional blast furnace,oxygen blast furnace has many advantages,such as high PCI rate,high top gas calorific value,low coke rate and reducing environment pollution.Oxygen blast furnace can obtain good economic benefits and environmental benefits,but it also faces many problems.It use oxygen blast,which will inevitably lead to blast volume reduction,so it will cause the unreasonable of gas flow distribution and solid flow,which is disadvantageous to the blast furnace production.Reasonable furnace inner profile is the basis of blast furnace process.In addition,it is the basis of reasonable gas flow distribution and solid flow.So it is necessary to study the reasonable furnace inner profile of oxygen blast furnace.The main works are as follows:(1)Physical simulation of oxygen blast furnacesThe physical models are set up with three different 2100 m3 oxygen blast furnaces,which are designed by Central Iron and Steel Research Institute.Based on the theory of similarity,the similarity was derived.Three physical models were scaled down 20 through considering the similarity dimensionless.In the simulation experiments,the solid flow pattern under different gas flow rates when only used polyethylene particles in the model,the solid flow under different gas flow rates and different oxygen blast furnaces when used polyethylene particles and medicinal stone grain for distributed layer after layer were investigated.The calculation results show that the solid flow changes with linear-inverted trapezoidal-W type in the model.The gas flow rates have an effect on the solid flow pattern,the larger is gas flow rate,the slower is solid flow near the wall and the larger is dead zone.Under the same gas flow rate,each of models appears dead zone in the bottom and the No.3 furnace has the largest dead zone.(2)Mathematical simulation of oxygen blast furnacesConsidering the distribution of voidage in the burden bed,the model is developed to calculate the gas flow in the blast furnace.The gas velocity field and blast furnace permeability index are calculated with the models.Besides,the residence time distribution(RTD)of gas is also obtained by a tracer gas under different gas velocities and different furnaces.The calculation results show that when gas velocity reachs 245 m/s the gas flow for three blast furnaces are close to piston flow.The permeability index of the No.1 furnace is 18.04 m3/(min kPa)which is the maximum,so its permeability is the best.The permeability index of the No.3 furnace is 17.28 m3/(min kPa)and it is the minimum,so its permeability is the worst.As the gas velocity is increasing the gas residence time will be shorter,the dead zone proportion also will be increasing.As the blast velocity increases from 184 m/s to 306 m/s,the average residence time of gas in the furnace decreases from 3.091 s to 2.326 s.The gas residence time of the No.1 furnace is 2.711 s and it is the longest,the No.2 fumace is taking second place,but the No.3 furnace having the shortest gas residence time is 2.281 s.