Abstract: In order to solve the problems of low efficiency and high energy consumption of cyclone separator in the actual separation process,a slit at the overflow pipe of cyclone separator and couple with a screen was proposed,according to which the structural models of single-layer,double-layer and triple-layer slits of the overflow pipe were designed,and 2 types of screens of 150 mesh and 200 mesh were coupled with the slit respectively,and 6 kinds of improvement schemes were obtained. The pressure drop error between the actual model and the porous step model was compared,and the effects of the number of layers of the overflow tube and the number of meshes on the separation efficiency under different velocities were analysed. The results showed that when the flow rate was greater than 10 m/s,the relative error in pressure drop between the actual model and the porous step model for the 2 types of 150 mesh and 200 mesh meshes was 0.70 % and 0.40 %,respectively,and this validation demonstrated the reliability of the porous step model. At the same inlet flow rate,the greater the number of layers of the overflow tube,the lower the tangential velocity of the cyclone. At the same inlet velocity,the more slotted layers,the lower the tangential velocity,the lower the pressure drop,and the slightly lower the cyclone separation efficiency. At the same number of slotted layers,the tangential and radial velocities under the 150 mesh screen coupling were lower than those under the 200 mesh screen coupling,and the maximum reduction in pressure drop of the improved cyclone could reach 18.76 %. The separation efficiency of the 6 improved cyclones under a 20 m/s inlet velocity is 97.25 % to 97.59 %, which is very close to the originel cyclone′s sepration efficiency of 97.63 %. The design of the cyclone separator overflow tube with open slot and coupling screen can effectively reduce the energy consumption under the premise of maintaining the efficiency.

Key words: hydrocyclone, overflow pipe, screen, porous jump boundary model