Experimental Study On Separation Characteristics Of Solid-liquid Hydrocyclone

In recent years,as people's environmental consciousness constantly enhancing,the facilities represented by hydrocyclone are widely used in gas purification,separation and recycling of solid particles,environmental protection and so on.Hydrocyclone,as one of the most efficient separation technologies,which rose in 1980 s,has been studied much by many scholars for years.By setting up the experiment platform and carrying out reasonable experiment design,our research mainly studied the change rules of the Solid-liquid separation performance and inner separation flow of the hydrocyclone with inner diameter of 137.5mm.The total separation efficiency of the hydrocyclone was obviously enhanced with the increase of the particle flow in the entrance has been found by doing the experiment of solid-liquid separation.When the rate increased from 7m3/h to 21m3/h,the average separation efficiency increased from 32.62% to 80.60%.Meantime,the cut diameter also decreased significantly,reduced from 30.41 um to 18.83 um.Namely,the ability of the hydrocyclone to separate particles with smaller size was strengthened.Although the separation efficiency increased when the particle flow in the entrance increased,the excessive flow rate will result in a greater pressure drop.The pressure differential increased from 49 mbar to 183 mbar,leading to greater energy consumption.Thus,we should try to reduce the flow rate on the basis of meeting the separation needs.Capturing the forming process of the air column by using the High-speed photography,it could be concluded that the forming process consisted of three stages: the generation of the initial air column,expansion of the air column and the stability of the column.As the flow increased,the formation time of air column decreased from 3.24 s to 0.73 s.Meantime,the diameter of the air column increased significantly which from 7.55 mm to 19.03 mm.The effect of the split ratio on the air column is also significant.In this experiment,with the increase of the split ratio,the size of the air column was significantly increased.Observing the internal flow conditions basing on the PIV(Particle Image Velocimetry)particles velocity measuring technology,the distribution of separation flow in cone partwhere the suffering force is the strongest was gained.Through changing the particle flow in the entrance and the depth of the overflow pipe,analyzing the change rules of the inner separation flow under different particle flow and in different depth of the overflow pipe.With the increase of the inlet flow rate and the insertion depth of the overflow pipe,the velocity of the flow field which inside the cone of the hydrocyclone rises significantly.The high-speed area mainly distributed in the inner part and eventually extended to the whole cone section.At the same time,the secondary flow in the cone obviously reduced and the whole flow field is more suitable for the separation of the mixture.That provides the basis for the previous conclusion.