CFD Study Of The Parameters Affecting The Performance Of A Cyclone Separator

As an efficient dust separating equipment, cyclone separator has the advantages of simple structure, lower cost, convenient maintenance, and is wildly used in metallurgy, oil, coal, environmental protection areas. In spite of simple structure, gas-solid two-phase flow inside cyclone muff is very complicated during the process of dust separation. By now there is still no theory that could perfectly explain the mechanism of inner fluid flowing state and particle separation. The cyclone separator commonly used now is efficient to particles with a diameter more than 10 μm, but it doesn’t work so well to those diameters less than 5 μm.So people are still trying to find the proper parameter to improve the separation. Because of experiments requiring large amount of time and long-term investment, more and more people chose numerical simulations to simulate and optimize.In this paper, some software, such as ANSYS ICEM—CFD、Fluent, is used to compute the inner gas-phase flow field and gas-solid two-phase flow field. The gas flow and the process of dust separation are intuitively observed. Its specific contents:First, build the 3D model of cyclone separator by analyzing its construction features, and then mesh and set boundary conditions. Thorough the comparison between different models, it shows that when Reynolds stress model is selected for turbulence model and the second order discrete mode for discrete mode and non-balance wall function make simulations match the data best.Secondly, simulate the gas flow field to get the inner flow regime: the velocity shows double spiral flow structure in cyclone separator. The outer flow is downward eddy current and the inner is upward eddy current. The maximum velocity is showed in the junction area. To the pressure field, the lowest pressure located in the center of the operator, the outer part higher pressure which causes the short –circuit current on the exhaust pipe. The internal turbulence of cyclone separator shows strong anisotropy according to its strong turbulence pulsation, so the process should be simulated using the Reynolds stress model.Thirdly, simulate the gas-particles two-phase flow; observe the path of particles with different diameter: particles with larger diameter are easier separated out and the different incident position has a great influence on the particle movement.Fourthly, simulate and analyze the pressure loss and separation efficiency under different parameters, such as inlet velocity, pipe diameter, the exhaust pipe insert depth and the length of cylindrical section. ①the pressure loss of cyclone separator increases as inlet velocity and the exhaust pipe insert depth increases, decreases as the diameter of outlet and the length of cylindrical section grows. ② the particle separation efficiency increases as inlet velocity and the exhaust pipe insert depth increases, but with the diameter of outlet and the length of cylindrical section growing,the trend increases firstly and then decreases.Through the research on the above problems, this thesis offers some theoretical frames for the further research of the internal flow state and improvement of performance.