Numerical Experiment And Optimization Study Of A Cyclone Separator With Swirling Blades

With the wide application of cyclone separator in various industries,the research work on improving the separation performance was also being carried out.Due to particles were ultimately escaped from the exhaust pipe,so one of the most effective measures to improve the efficiency of the cyclone separator was to reduce the number of particles escaped from the vortex finder.In the two-phase flow of cyclone separator,the tangential velocity decreased with the decrease of the cylinder diameter in the inner vortex,the centrifugal force of particles also decreased continuously.Once the particles were involved in the inner vortex,there was little chance that the particles would be separated.This paper proposed a new efficient cyclone separator to improve the efficiency of cyclone.The new cyclone could be obtained by setting a group of swirling blades in the adjacent area of the interface of inner vortex and outer vortex below the vortex of the traditional cyclone separator.This paper simulated the gas-solid two-phase flow of the cyclone through the Reynolds stress model and the Discrete Random Walk model of the discrete phase.Further,the performance of the new cyclone and the traditional cyclone were compared and analyzed.From the aspect of the direction,relative height,radial position and swirling angle of the swirl blades,the relationship between the structure parameters of the swirl blades and the flow field and the performance of cyclone were studied.The optimal combination of the structure parameters of the swirl blade was obtained by orthogonal numerical test when the cut-off size was as the test evaluation index.The influence of inlet velocity and incident particle density on the performance of the cyclone with swirling blades was analyzed and calculated,the results showed that:(1)The swirling blades which were set in the adjacent area of the interface of inner vortex and outer vortex below the vortex of the traditional cyclone separator,could make the particles collision with blades.Moreover,the direction of movement would be changed and the momentum would be lost,which could effectively block the particles into the vortex and achieved the goal of the efficiency improvement.(2)Compared with the traditional cyclone without swirling blades,the addition of swirling blades enhanced the distribution symmetry of the tangential velocity and the axial velocity,weakened the phenomenon of“eccentricity”,“local secondary vortex flow”and the“secondary entrainment”near the bottom of cyclone,increased the tangential velocity overall and significantly improved the separation efficiency.(3)The influence of the structure parameters of the swirl blade on the separation performance is from large to small in order of:blade direction,radial position,relative height,swirling angle.(4)The cyclone performance was better when the direction of swirling blade was same as the rotation of airflow,the swirling angle was 45°,the relative height of blade was 0.56 and the radial position of blade was in(0.55-0.65)D_e.Compared with the basic cyclone,the cut-off size of the optimized new cyclone was decreased by 70%and the pressure drop was increased by 19.3%.(5)When the inlet velocity was changed between 10 to 20 m/s,the ascension of swirling blade on separation performance rate was stable in the range of 60%~70%,and the separation performance was best when inlet velocity was 15 m/s.Moreover,the improvement of separation efficiency of small particle size and low density particle was more significant.