Experimental Study On Performance Of Solid-liquid Separation In Small Diameter Hydrocyclone

Hydrocyclone is a device that could separate and classify two-phase or multi-phase mixtures with a certain density difference or particle size difference by using the principle of centrifugal sedimentation.It has been widely used in various industrial fields because of its simple structure,no moving parts,and many other advantages.The traditional solid-liquid separation hydrocyclone has a good separation performance when separating large particles,but the research topic on the separation of fine materials with a small hydrocyclone is still in the exploration stage.Therefore,there is an urgent need to strengthen the separation performance of fine particles in a small diameter hydrocyclone.In addition,the improvement of the separation efficiency in the hydrocyclone is often accompanied by an increase of energy loss,and too low separation efficiency or excessive energy consumption will give rise to lose the industrial application value.Therefore,researching and designing a more optimized structure to improve the separation performance of small-diameter hydrocyclones for fine solid particles have become an urgent problem,which should be solved in the research field of hydrocyclones.In this work,a small diameter hydrocyclone with a diameter of 50 mm is applied as the research object to separate the mixture of brown corundum from water,and experimental research was carried out on the influence of the inlet gas entrainment,cone structure and vortex finder structure of the hydrocyclone on the solid-liquid separation performance.The research content includes:?1?Experimentally studied the effect of gas entrainment on the solid-liquid separation performance of the hydrocyclone,and the influence of inlet aeration on the split ratio,separation efficiency and pressure drop of the hydrocyclone was investigated.The results show that the split ratio of the hydrocyclone gradually decreases with the increase of the inlet fluid velocity at the situation of without controlling the split ratio;and the split ratio tends to increase slightly as the gas flow rate increases.After injecting gas into the inlet line of the hydrocyclone,the aeration rate increases from 3 L·min^-1 to 15 L·min^-1,the separation efficiency of the hydrocyclone decreases slightly.When the inlet ventilation keeps constant,the pressure drop of the hydrocyclone increases with the increase of the inlet fluid velocity.However,when the inlet fluid velocity is fixed,the amount of ventilation does not affect the pressure drop of the hydrocyclone significantly.?2?The separation performance in the double cone structure and the traditional single cone structure hydrocyclones was studied experimentally.Based on these investigations,the experimental study on the influence of the insertion depth and diameter of the vortex finder on the hydrocyclone separation performance was carried out.The results show that the traditional single-cone structure hydrocyclone has a better separation performance than that in the double-cone hydrocyclones.The diameter of the vortex finder has a greater influence on the separation performance of the hydrocyclone than that of the insertion depth.It can be inferred from these experimental data that the small hydrocyclone has the best separation performance when the ratio of the depth of the vortex finder to the diameter of the column?h/D?is0.86 and the ratio of the diameter of the vortex finder to the diameter of the column?d_o/D?is 0.30.?3?The influences of length,position,number and style of the tangential slits on the separation performance of the hydrocyclone are investigated experimentally.It is shown that compared with the traditional hydrocyclone,the pressure drop of the slit-cone hydrocyclone is significantly reduced.The separation efficiency of the hydrocyclone tends to increase at first and then decrease when the length of the slit increases from 10 mm to 50 mm,and an optimal slit length of 20 mm is observed.In the process of moving the 20 mm slit upward from the first 6 mm slit at the bottom of the cone,the influence of the second slit position on the separation efficiency of the hydrocyclone is similar to that of the slit length.That is to say,it tends to increase at first and then decrease,and there is an optimal distance of 80 mm between the first slit and the second ones.When keeps the cross-section area of the slits equaling to that of the underflow in the traditional hydrocyclone under the conditions of optimized slit length and position,it is found that the separation efficiency of one slit in the cone is better than that of two,and the style of two-slits located at opposite direction is the best among all the cases investigated here.Compared with the classical hydrocyclone,the separation efficiency in the optimal slit-cone hydrocyclone can decrease only 1.48%,while the absolute pressure drop can reduce as high as36.84%at a high flow rate.Therefore,it is a promising hydrocyclone for industrial applications to save energy consumption.