The Experimental And Numerical Study Of The Effect Of Cross-shaped Vortex Finder On The Performance Of Cyclone Separator

Owing to the advantages of its simple construction,low maintenance costs,relatively stable operation and high separation efficiency,cyclone separators are widely used to collect particles and liquid in gas-solid phase and multi-phase flow.The gas to be cleaned swirls downward near the wall and forms the outer vortex zone(quasi-free vortex)where the particles are separated by centrifugal force.When the gas touches the bottom of cyclone,it reverses the axial flow direction and exits through the vortex finder,forming the inner vortex(the quasi-forced vortex).Although the rotating flow can collect the particles effectively,the friction between the flow and wall,the turbulence kinetic energy of the flow in the vortex finder as well as the loss of kinetic energy of the inlet make up the total pressure drop of cyclone separator which cannot be ignored.Especially,owing to the significant flow in the inner vortex convergence under the vortex finder and escape from it,the flow represents extremely disorder and flow turbulence energy wastes in the vortex finder,thereby causes a main pressure loss of cyclone separator.At present,the researches on the influence of vortex finder on the performance of cyclone separator mainly focuses on its geometries such as diameter,length and shape.The results show that these parameters increase the separation efficiency and the pressure drop simultaneously.It seems that increase of the separation efficiency and decrease of pressure drop are unable to come true.However,it is noteworthy that these traditional vortex finder parameter studies have not modified the vortex finder construction and the flow field by adding some complementary equipment to study the effect of vortex finder on the cyclone performance.In this study,a series of new-type of metal part,cross-shaped blades,which can change the flow field of the vortex finder,are added into the vortex finder to form a cross-shaped vortex finder.By changing the blade length and width,changing the flow field construction of the vortex finder and cyclone body in the axial and radial directions,thus achieve the purpose of reducing the pressure drop while increasing the separation efficiency.Firstly,the physical model is established,such as,the geometry and mesh of the cyclone separator.Secondly,10 sets of different lengths and 6 sets of different widths blades are added to the traditional Lapple cyclone.The separation efficiency and pressure drop of each blade corresponding to the cyclone were measured,which provided the basis for the analysis of the flow field.Finally,based on the experimental results,the numerical simulation of the corresponding models of different leaves is carried out.The Reynolds stress model(RSM)was used to simulate the characteristics of gas-phase flow field,such as flow velocity field,pressure and turbulence intensity.The mechanism of the influence of the blade lengths and widths on the performance of cyclone separator was analyzed.Combined with the three-dimensional flow velocity and pressure in the flow field,the Barth model and the MM pressure model are used to calculate the proportion of the pressure drop of each part,so as to provide the basis for the follow design of the separator.Based on the gas-phase flow field,the motion and distribution of particles with different particle sizes in the separator are simulated by the Euler-Lagrangian method(LPT)and the separation efficiency curve is obtained.The results show that the cross-shaped vortex finder can change performance of cyclone separator and achieve the purpose of reducing the pressure drop while increasing the separation efficiency.When the blade width is 10 mm,the maximum pressure drop is 16.41% and the separation efficiency is increased by 0.74%.The cross-shaped blades reduce the tangential velocity in the vortex finder and increase the tangential velocity in the separation space,which has a positive effect on the separation efficiency.The cross-shaped blades expand the internal pressure of the vortex finder,and then cause the pressure of the whole cyclone separator changes;cross-shaped blades turn the air flow in center of the vortex finder upward and reduce the flow resistance;the increase of turbulence intensity in the vortex finder and the inner vortex will not have a negative effect on the separation efficiency of the cyclone separator,while its increase in the outer vortex will result in a decrease in the separation efficiency of the separator.