The Simulation Study Of Internal Flow Field And Particle Movement In Three Cone Hydrocyclone

With the constant improvement of the coal mining mechanization, the yield of coarse coal slime in coal preparation plant increases gradually, how to realize the efficient separation become a focus of coal preparation industry. Practice shows that the three cone cyclone, a new separation equipment of coarse coal slime, has an good separation effect that far better than the single cone cyclone. So far, there is no clear mechanism of three cone cyclone to improve the separation effect of coarse coal slime and separation principle of three cone cyclone. Therefore, this research takes three cone cyclone as the main object and single cone cyclone as the contrast object, and studies the multiphase flow field and particle motion in these two cyclones contrastively with the method of CFD numerical simulation. Besides,the research also studies the influence of structural parameters and operating parameters on water-gas flow field in three cone cyclone.The appropriate CFD models of three cone cyclone and single cone cyclone were built after exploring the types of mesh, turbulence model and multiphase flow model, boundary conditions,and then compared the simulation results and laboratory determination results of feed rate and overflow traffic under different feeding pressure. The comparison result showed that the CFD models were accurate and reliable. The research result indicated that the feed rate and overflow traffic of these two cyclone had same change trend as the change of feeding pressure, and the feed rate of three cone cyclone was larger, the overflow traffic of three cone cyclone was lower than single cone cyclone under the same feeding pressure.The multiphase flow field of these two cyclone were simulated and studied with Fluent after injecting the water, air, and a single fine particle phase to the CFD models of cyclone. The results showed that the distribution regularity of pressure, velocity and air column in the two cyclones were almost same, but the distribution regularity of turbulence intensity and density in the two cyclones had a large difference. In the same condition, a stronger turbulence existed in the cone of three cone cyclone, so the materials could be fully loosed. Compared with single cone cyclone,the density layer in the cone of three cone cyclone was distributed not only along the vertical direction of cone, but also along the axial direction of cyclone. The density of three cone stage increased gradually from the top down, and the high density layer hidden in the bottom of low density layer was exposed after the change of cone angle. Therefore, the materials in three cone cyclone could be better separated.The influence of parameters to waters-gas two phase flow field in three cone cyclone was simulated and studied. The results showed that the influence of overflow pipe diameter and feeding pressure was greater than overflow tube insertion depth.As the rise of feeding pressure,the tangential velocity and axial velocity increased, the turbulence intensity increased, the formation time of the air column decreased; As the increase of overflow pipe diameter, the pressure decreased, tangential velocity decreased,axial velocity increased,the air column diameter increased; As the increase of overflow tube insertion depth, the tangential and axial velocity increased, pressure rised and reduced again, the formation time of the air column increased.On the basis of the study of flow field, particle movement inside the cyclone was simulated to reveal the principle of three cone cyclone further. Firstly, studied the single particle with different properties in three cone cyclone, the simulation result showed that the particles were separated mainly in the cone of cyclone, and the separation location was in the density layer closed to particle density.Three cone cyclone had a good separation effect for 1 mm particle size,low density particles came into overflow after separation, and high density particles came into underflow; The separation effect of 1450 kg/m3 particles in three cone cyclone were greatly influenced by particle size, the fine particles came into overflow after separation, and coarse particles came into underflow. Then, the simulation experiment of particle group in three cone cyclone and single cone cyclone were carried out, and compared with lab experiment. These two kinds of test results all showed that three cone cyclone had a better separating effect compared with single cone cyclone, the overflow ash content was lower and sorting accuracy was higher.Through the study of this thesis, the mechanism of three cone cyclone to improve the separation effect of coarse coal slime could be revealed, the separation principle of three cone cyclone could be perfected, and the theoretical basis for optimization and choice of parameters could be provided, also the foundation for subsequent more in-depth research could be laid.