| In the process of converter iron and steel smelting,it is an effective way to improve the scrap ratio by means of secondary combustion oxygen lance to achieve high efficiency secondary combustion.The structure of nozzle directly affects the jet flow and secondary combustion behavior,and then affects the scrap ratio of converter.In this thesis,the 260t converter is taken as the research object,and the three-dimensional model is established by Solid Works to explore the oxygen lance jet and combustion behavior of the converter.The effects of the angle,position and flow ratio of the secondary oxygen nozzle on the jet and combustion behavior of the secondary oxygen nozzle are studied,which provides theoretical support for the optimal design of the secondary oxygen nozzle.The research contents and conclusions are as follows:(1)Under the condition that the main oxygen nozzle is fixed,the influence of different secondary oxygen nozzle structures on the suction and deviation of the jet is analyzed.The suction coefficient A is defined to characterize the influence of secondary oxygen nozzle structure on jet deviation and suction.It is concluded that the jet deviation is obviously weakened when the angle of secondary oxygen nozzle increases,the position of secondary oxygen nozzle increases and the jet is weakened by suction.The parameters of secondary oxygen nozzle suitable for converter secondary combustion are explored:the secondary oxygen nozzle flow accounts for 18%,the number of nozzles N=6,the aperture is 28 mm,and the included angle of nozzles is 40,which is 1 m above the main oxygen nozzle.(2)Based on the nozzle structure of the secondary combustion oxygen lance,the VOF method is used to simulate the interaction between the oxygen jet and the molten pool,and the size of the impact crater formed by the jet impacting the molten pool is obtained,which is used as the inlet boundary condition of the converter secondary combustion model CO.It is concluded that the depth and diameter of the impact crater formed under the 35de blowing lance of the secondary combustion oxygen lance are 170mm and 2.42m respectively.The impact characteristics of the secondary combustion oxygen lance under different operating lance positions are also explored.It is concluded that the depth of the impact crater is reduced by 70mm and the impact area is increased by 1.57m~2when the lance position is increased from 30de to 40 de.(3)The finite rate combustion model was used to explore the influence of different secondary oxygen nozzle structures on the secondary combustion rate.The conclusion is that the flow rate of the secondary oxygen nozzle increases from 16%to18%and 20%,and the secondary combustion rate increases by 4.97%and 6.38%respectively.When the secondary oxygen hole position is 1.2 m,1.0 m and 0.8 m,the PCR of secondary combustion rate is 63.73%,63.27%and 59.57%respectively.It can be seen that the increase of secondary combustion rate is also limited with the increase of flow ratio and position.When the angle increases,the secondary combustion rate first increases and then decreases,and the highest secondary combustion rate by PCR is 63.27%at 40.Therefore,considering comprehensively,the secondary combustion rate is the highest when the flow rate of secondary oxygen holes suitable for secondary combustion is 18%,the angle is 40,and the position of secondary oxygen holes is 1 m above the main oxygen nozzle,which is consistent with the results of jet behavior research.By changing the operating lance position,it is concluded that the lance position is increased from 30de to 40de,and the secondary combustion rate is reduced by 8.39%. |
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