Numerical Simulation Of Sintering Process With Different Carbon Carbon And Distribution Modes

In recent years,with the rapid development of China’s iron and steel industry,in order to meet the normal production demand of blast furnace,there is also a greater demand for sinter output.Under the existing production equipment capacity,it is difficult to improve the sinter output by increasing the thickness of material bed.Therefore,the double-layer sintering technology is put forward.This topic uses the method of establishing mathematical model,according to the actual production situation,carries on the numerical simulation of double-layer carbon distribution sintering and double-layer ignition sintering process,analyzes the change of temperature field and concentration of material layer,and establishes the quality evaluation system of sinter,so as to provide the theoretical guidance and feasibility analysis of doublelayer sintering process.The main results are as follows:(1)For 600mm single-layer sintering,the heat of upper material layer is insufficient,the melting rate is low,and the sinter strength is low,which leads to the increase of sinter return;However,the heat of the lower layer is excessive,the melting rate is high,the material over melting is serious,and the reducibility of sinter is poor;The quality of sinter in the upper and lower layers is not uniform,the sinter yield is low,and the finished sinter is mainly concentrated in the middle and lower parts of the layer.The effect of automatic heat storage is mainly reflected in the middle and lower parts of the material layer;After ignition,the melting rate of 10 mm thick sinter is lower than 0.15,the quality of sinter is poor,and it is easy to produce return ore.when sintering to the bottom of the bed,the melting rate is higher than 0.4,resulting in more liquid phase,and the reducibility of sinter is poor;The higher CR value and MQI of the upper layer,the faster cooling rate and the less melt amount lead to the better reducibility but the lower sinter strength of the upper layer.The lower CR value and MQI of the lower layer,the slower cooling rate and the more melt amount lead to the worse reducibility but the higher sinter strength.(2)The results show that the MQI increases with the increase of temperature in the upper layer and decreases with the decrease of temperature in the lower layer;The temperature difference between the upper and lower material layers decreases,the temperature is more uniform,and the melting degree of the upper and lower material layers is more uniform;The results show that the melting residence time of the material in the upper layer is longer,the difference between the melting residence time of the material in the upper layer and that in the lower layer is shorter,the thermal efficiency and the yield are improved.The maximum melting rate of the bed appears at the bottom of the upper high carbon distribution zone,and the thickness of the upper high carbon distribution zone has a great influence on the sinter quality.Under the condition that the average carbon content of the bed is the same as the uniform carbon content of the single layer,and the total thickness of the bed is the same,when the thickness ratio of the upper high carbon zone and the lower low carbon zone is 1:1,the yield of the sinter is 4.85%higher than that of the single layer;When the ratio of the upper layer height and the lower layer height is 5:7,the yield can be increased by 21.66%compared with the uniform carbon distribution;When the ratio of the thickness of the carbon distribution zone to the height of the low carbon zone is 7:5,the over melting rate of the upper layer is 41.67%,which leads to a 3.34%lower sinter yield than that of the single layer uniform carbon distribution.(3)In the double ignition sintering process,without oxygen supplement operation after the second ignition,the oxygen volume fraction in the lower material layer will be reduced to 6%,which will reduce the coke combustion rate.At y=0.2m,the maximum temperature of the material layer is 1345k,which can not-provide enough heat to melt the material,and can not achieve the effect of increasing the sinter output.In the Case of oxygen supplement,oxygen supplement should be carried out after secondary ignition.The concentration of oxygen supplement is 25%and the duration of oxygen supplement is 10min,which can ensure the lower layer temperature above 1400k and ensure the normal sintering process.To sum up,the mathematical model of exhaust sintering process is established in this paper.On this basis,the numerical calculation of double-layer carbon distribution sintering process and double-layer ignition sintering process is carried out.The research results can provide some theoretical guidance for double-layer sintering.