Analysis Of Global Composite Desulfurization Flow Field Characteristics And Optimization Of Process Parameters

Automobile manufacturing,energy and chemical industry,shipbuilding and Marine engineering and other industries,the quality and performance of steel requirements are particularly outstanding.However,the output of high quality steel in China can not fully meet the increasing material demand,so it is urgent to improve the level of smelting technology.Desulphurization is a necessary process for the production of high-quality steel,especially special purpose steel and high value-added steel.Although the research on the specific implementation process of desulphurization is relatively perfect,the research on the relationship between its mechanism and parameter model is not deep enough,leading to many empirical decision-making problems.In order to solve the above research deficiency,improve the desulfurization efficiency of molten iron pretreatment.In this paper,three kinds of molten iron pretreatment process methods were extracted in more than 10 steel mills,and characterized by three different types,respectively,and the mixing effect was evaluated from the aspects of mixing flow field speed,turbulent kinetic energy distribution,agitator wear and so on.Under the same parameter conditions,the optimal desulfurization process is optimized,and the vibration in the desulfurization process is analyzed.The main research contents are described as follows:(1)Based on the basic theoretical knowledge of computational fluid mechanics,the desulfurization process is analyzed,and the multi-phase flow model suitable for the desulfurization process is clearly defined.Numerical simulation analysis using CFD software,observe and measure the change of the free liquid level,and compare the numerical results with the water mode experiment,to verify the feasibility and accuracy of the numerical simulation method.(2)The traditional KR desulfurization process,four-leaf mixing and blowing desulfurization process and whole-region composite desulfurization process of water iron were compared and studied.The results of the speed of mixing flow,turbulent kinetic energy,and wear.The results showed the global composite desulfurization process>four-leaf mixing and blowing desulfurization process>traditional KR desulfurization process.(3)The flow field speed is optimized by adjusting the process parameters such as the mixing speed,the diving depth and the nozzle ventilation flow rate.Using response surface test,it is found that the depth has the most influence on the field velocity,followed by mixing speed and nozzle ventilation flow.The optimal numerical simulation process parameters are:stirring speed 170 r/min,diving depth 400 mm,and nozzle ventilation flow 4.408 m~3/h;the optimal process conditions for actual production are stirring speed 102 r/min and diving depth 2400 mm.(4)By constructing the flow-solid-thermal transient coupling model and analyzing the flow field,temperature field and deformation transfer relationship,the maximum thermal deformation of the mixer is 8.2011 mm(located near the lower blade),the minimum thermal deformation is at the top connection end,the maximum equivalent thermal stress is 113.29 MPa(appearing at the lower blade),and the minimum equivalent thermal stress is 0.2887 MPa(occurring at the top connection end).(5)For the multi-field coupling action mixer vibration problem,the unidirectional flow-solid-thermal coupling mode analysis is used to study the harmonic response in the flow field and the temperature field.When the frequency is 260 Hz and 1800 Hz,the maximum displacement in Y and Z direction is 0.0016 mm,0.0003 mm(260 Hz);0.0063 mm and 0.0022 mm(1800 Hz).