Study On Amplification Effect And Structure Optimization Of α-Type Cyclone Sepearator

With the enlargement of industrial equipment,the handling capacity of dust-containing gas is also increasing day by day,which puts forward higher requirements for the handling capacity of cyclone separators.However,the cyclone separator has obvious amplification effect due to the obvious mutual disturbance of internal and external vortices.In this paper,numerical simulation was used to study the variation of internal flow field,local vortex and particle trajectory with the increase of diameter inα-type cyclone separator,and structural improvement measures are proposed.The research work provides theoretical basis for industrial scale-up and optimal design of cyclone separators.The main research conclusions are as follows:(1)Numerical simulation ofα-type cyclone separators with cylinder diameters of 80mm,240mm,320mm,450mm and 1000mm respectively shows that under the same inlet gas velocity,the cyclone separators show the following variation rules with the increase of diameter:tangential velocity gradually decreases,and axial velocity distribution changes from inverted"V"to inverted"W";The local vortex in the cone section increases obviously,and the maximum local vortex increases from15mm to 136mm;The maximum deviation distance of the vortex core in the cyclone separator increases from 4.27mm to 48.55mm and tends to approach the dust outlet.The"short circuit flow"at the bottom of the exhaust pipe and the phenomenon of tail swinging near the dust outlet are intensified,which make the flow field stability of cyclone separator worse and reduce the separation efficiency of particles.(2)The pressure drop increases with the increase of the cylinder diameter.The numerical simulation results of classification efficiency show that the separation efficiency of particles with the same particle size decreases with the increase of cyclone diameter.The amplification effect of cyclone separator reduces the separation efficiency of fine particles below 10μm more obviously,but has no significant effect on the separation efficiency of particles above 20μm.(3)Based on the concept of flow field diversion,it is proposed to set a diversion layer in the cylindrical section of theα-type cyclone separator to reduce the amplification effect of the equipment.The results show that after adding the diversion layer,the velocity contour line in the diversion channel becomes sparse,the fluid flow is relatively regular,and the secondary vortex scale is reduced from 0.25 to 0.13;The radial distance between the particles and the wall surface is shortened to 1/2 of the original,which makes it easier to be thrown towards the wall surface.The proportion of downstream area near the dust outlet increases to 0.28;Both static pressure and turbulent kinetic energy are reduced,and the separation efficiency for particles with a particle size of more than 5μm is improved.(4)The structure of the equipment is further optimized by opening slots in the diversion layer.The simulation results show that the gas flow in the diversion channel still makes regular rotation after opening slots,but in the slotted part,the gas in the inner diversion channel has a tendency to move towards the outer layer;Near the lower end of the exhaust pipe,the radial position r/R of the maximum tangential velocity after the diversion layer is slit is reduced from 0.46 to 0.37,the proportion of the downstream area is increased from 0.54 to 0.57,and the maximum turbulent kinetic energy is reduced from 12.5 m~2/s~2 to 10.4 m~2/s~2;The tangential velocity near the inner wall surface of the ash hopper is reduced from 8.85 m/s to 5.74 m/s,and the maximum turbulent kinetic energy is reduced from 11.0 m~2/s~2 to 3.0 m~2/s~2.The amplification effect of cyclone separator is effectively improved,which is conducive to particle separation.