| Multiphase flow phenomenon exists widely in the field of industrial application,which is more common in metallurgical reactors for iron making and steelmaking.Understanding the dynamics of multiphase flows in the reactor is of critical significance to guide optimization,improvement of process operation parameters or reactor design.In this paper,two emerging and worth studying reactors for ironmaking and steelmaking are taken on as the research object,which is the molten bath reactor in the iron bath C-H2 smelting reduction process and the airlift reactor in the RH powder injection refining process.The flow behavior is studied in final reduction furnace of smelting reduction process and RH vacuum chamber of injection powder refining process by using numerical simulation method.The main research contents and results are summarized as follows:I.Simulation study on the iron bath smelting reduction processBased on the previous research work,a three-mathematical model has been developed to study the effect of top jet,bottom jet and side jet combined blowing with thick slag layer and the double tiers side injection.The effect of different upper tier lance flow rate,lower tier lance flow rate and top lance flow rate on the flow and mixing characteristics in the molten bath is studied by using the orthogonal experiment:?1?The simulated results show that the influence of the flow rate of lower lances on mixing time is the most important,followed by the flow rate of upper lances and top lance.The optimum parameters are as follows:the flow rate of lower lances is 14Nm3/h,the upper lance is 15 Nm3/h and the top is 36 Nm3/h.?2?The simulated results based on the orthogonal schemes that the influence of the flow rate of lower lances on splashing in the upper space is primary,while the impact of the upper rate and the top rate is equivalent.For the mixing time and the amount of splash,the optimum parameters are as follows:the lower rate is 14 Nm3/h,the upper rate is 10 Nm3/h and the top rate is 18 Nm3/h.II.Simulation study on RH powder injection refining processA three-dimensional mathematical model is established to study the effect of the double side injection in the lower part on flow behavior,based on a 300 t RH powder injection furnace in a company.?1?With the increase of the gas flow rate,the liquid level of the molten pool in the lower part ascend,the treatment capacity strengthens,and the gas volume fraction in the downleg increases.The influence of injection gas on the flow of molten steel in the lower part and the downleg is greater than that in the upleg,but there is no significant change on the main flow pattern in the furnace.?2?With the increase of the gas flow rate,the stress acting on the lower groove is also increasing,especially near the nozzle.The residence time of tracer is also increasing,while the circulation of molten steel is increasing.In a word,the increase of gas flow rate strengthens the flow in the RH vacuum chamber.?3?When the intersection angle of the two lances in the lower part is small,the stress is less acting on the bottom and the side wall of the lower part,and the average residence time of the tracer is relatively long,which is helpful to the refining process.The residence time of the tracer was the longest when the angle was 60 degrees.?4?The orthogonal experiment shows that the lifting gas flow rate and the powder injection gas flow rate are the main factors affecting the change of the circulation flow rate,while the powder injection gas flow rate and the vacuum chamber pressure are the main factors affecting the residence time of tracer.?5?The changing of injection angle of the lances has no significant effect on the flow pattern of molten steel,and its influence is related to the direction of gas jet and the flow of molten steel.As a whole,the wall stress is the least when the jet direction of the lance and the flow of molten steel are opposite.After the deflection of the lance,the residence time of tracer has increased,and the residence time has reduced while the lances anticlockwise twirl 30 degrees and 15 degrees.The clockwise deflection of the two lances has been helpful to prolong the residence time,which is beneficial to improving the refining effect.In this work,the various mathematical models are used to study the flow characteristics of different metallurgical reactors to further understand the multiple-phase flow behavior in typical metallurgical reactors and to provide help for optimization or improvement of process design parameters. |
PDF Full Text Request