Effect Of Inlet Structure And Breaking Wing Of Vortex Core On Flow Field And Performance Of Dense Medium Cyclone

As one of the world's major energy sources,green coal production can play a vital role.In the past 20 years,Dense Medium Cyclone(DMC)has been widely used in coal mine sorting process due to its small footprint,no moving parts,high sorting efficiency and large processing capacity.It can improve the sorting efficiency of coal and remove impurities,improve the quality of coal products,reduce SOx,NOx and other pollutants generated in coal combustion,and reduce pollution to the atmospheric environment.The large-diameter dense medium cyclone has a wide industrial application prospect,and its geometric structure optimization can be of great significance for both research and application.This paper intends to optimize the large diameter DMC structure from volute inlet and breaking wing of vortex core.The methods used to study DMC include experimental and numerical simulations.Considering the high cost of experimental research,this paper intends to use computational fluid dynamics(CFD)to study the DMC with the volute inlet and breaking wing of vortex core.The Mixture model was used to simulate dense media and air columns,the Reynolds stress model(RSM)was used to simulate turbulence in the flow field,and the Lagrangian particle tracking model(LPT)was used to track particles in the flow field.The particle force data is output through secondary development of CFD software,and a viscosity model is used to correct the viscosity of the dense medium suspension.These models were verified by comparison between experimental data and simulation results.Moreover,the effects of the nose angle of volute inlet,the inlet head and the breaking wing of vortex core on the performance and flow field of the DMC was studied.The results show that:(1)the increase of the nose angle of volute inlet can significantly improve the stability of the flow field and reduce the short-circuit flow.Increasing the nose angle also increases the absolute value of the difference between the centrifugal force and the radial pressure gradient force of the coal dust,which improves the separation performance.When the nose angle is 180°,the feed head,media split ratio and density difference have larger values,the separation performance is better.Secondly,the DMC with nose angle 180° is used to study the effect of the inlet head.Increase the inlet head without considering the energy consumption,the stability of the flow field is enhanced and the processing capacity is increased,also the separation performance is improved.(2)The breaking wing of vortex core can restrain the air entering into the flow field from outside.It can significantly reduce the tangential velocity of the overflow outlet fluid and the overall pressure of the system,so that the energy consumption of the dense medium cyclone system is significantly reduced(decrease by 12.2%).The breaking wing of vortex core also can block the rotary motion of the fluid within the diameter of the fin,destroys the internal swirl not the outer swirl.It increases the separation space of the DMC main body while the tangential velocity of the fluid in the separation space does not decrease,and the separation performance of the dense medium cyclone is improved.In summary,the DMC with 180°nose angle and breaking wing of vortex core(rod diameter 200 mm,wing length between LMTV and LZVV)has a superior structural design.It can improve the separation performance of DMC while reducing system energy consumption.This research results in this paper provide reference for structural optimization of dense medium cyclone.