| Improving the utilization rate of scrap steel resources in the converter smelting process is a necessary path for the steel industry to achieve carbon peak and carbon neutrality,and the key is to solve the heat balance problem inside the furnace.However,the existing thermal compensation technology provides limited heat to the furnace,making it difficult to significantly increase the scrap ratio of the converter.Based on this issue,this article develops a multifunctional oxygen lance for the converter that combines oxygen blowing function and burner function.It adds a layer of casing as the gas channel between the oxygen channel and the cooling water channel of the five hole converter oxygen lance.The gas is mixed with oxygen through an internal mixing gas hole on the Laval nozzle and burned,providing a large amount of heat source for the furnace,preheating and remelting scrap steel,thereby improving the scrap steel ratio of the converter.This article is based on the design principles of oxygen lance and gas combustion theory,and uses FLUENT software to simulate and analyze the flow,mixing,and combustion behavior of multi-functional oxygen lance.It explores the influence of the diameter,angle,and position of gas holes on the mixing effect and combustion characteristics of oxygen and gas,and reveals the influence of gas hole structure on the mixing effect of oxygen and gas;Next,explore the influence of oxygen fuel ratio on the combustion characteristics of coke oven gas and the generation of nitrogen oxides,as well as the influence of lance position on the preheating and remelting process of scrap steel;Finally,the impact of opening holes in the expansion section of the Laval nozzle on the prevalence of ultrasonic rapid injection when only blowing oxygen was analyzed.The conclusions drawn from the study are as follows:(1)As the diameter of the gas hole increases,the mixing effect of gas and oxygen shows a trend of first increasing and then decreasing.The mixing effect is best when the diameter of the gas hole is 10 mm;The influence of the opening position on the mixing effect of gas and oxygen is as follows:as the distance L_t from the opening position to the outlet of the Laval nozzle increases,the mixing effect first increases sharply and then slowly decreases.The mixing effect is best when L_t=0.6 L_e;Gas hole angleθThe influence law on the mixing effect of gas and oxygen is:the mixing effect is different fromθThe sine value of is proportional to the combustion efficiency and NOx emissions,which can be obtained by analyzing the combustion efficiency and NOx emissionsθA temperature of 60°is more suitable.(2)After determining the structure of the gas hole,the influence of oxygen fuel ratio on the combustion performance of the multifunctional oxygen lance was explored.The conclusion was drawn that the higher the oxygen fuel ratio,the lower the CO concentration at the furnace outlet,which means the combustion is more complete;When the oxygen fuel ratio is 1.00,the fuel consumption rate is the fastest;When the oxygen fuel ratio is greater than 1.05,the NOx concentration increases sharply;Increasing the oxygen fuel ratio will increase the ignition delay distance,thereby increasing the risk of misfire;Overall,the oxygen fuel ratio is optimal in the range of1.00 to 1.05.Under the condition of an oxygen fuel ratio of 1.00,the effect of lance position on the preheating and remelting of scrap steel by a multifunctional oxygen lance was investigated.The results showed that the higher the lance position,the more uniform the temperature of the scrap steel,and the higher the melting ratio.(3)Under the design pressure,through the analysis of the velocity and pressure fields inside the Laval nozzle,it can be found that when the multifunctional oxygen lance is used as a regular oxygen lance,opening a gas hole in the expansion section of the Laval nozzle will have a slight impact on the velocity and pressure near the expansion section wall,resulting in an increase of 17 decibels in the noise level inside the nozzle;But the gas hole hardly affects the supersonic flow behavior of oxygen outside the nozzle,that is,the multifunctional oxygen lance with combustion function will not affect the original oxygen blowing function.When the oxygen blowing pressure increases or decreases by 0.05MPa compared to the design pressure,there is no significant change in jet velocity,and the effective impact surface correspondingly increases by 0.01m~2 or decreases by 0.02m~2 at the 45de lance position. |
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