Research On Vibration Fluidized Phenomenon For Lignite Based On CFD-DEM Coupling Analysis Method

Lignite vibration fluidized dewatering technology is an effective way to use low calorific value lignite resources. The application of traditional experimental methods for studying the performance of vibration fluidized bed (VFB) is restricted by the difficulties of measuring the data from VBF. Based on the combination of Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD), the vibration fluidized behavior of mixing size lignite in both vertical and horizontal VFB is analyzed in this paper, in order to achieve the vibration fluidized process visualization.The main contents are as follows:(1) The CFD-DEM direct coupling method is used for studying the vibration fluidization phenomena through the comparison of the main gas-solid fluidization research methods and research on the fundamental of DEM. Both the vertical and horizontal VFB coupled simulation model is built. Simplify the distribution plate based on the CFD-DEM coupling and the vibration effect simplifies to a sinusoidal motion of bed. The lignite particle model is established by using the Spherical filling technique.(2) Coupled simulation of the 3D VFB fluidized phenomenon is set basing on the FLUENT12.0 and EDEM2.2 software platform. The interaction and movement of particles in fluid and the process of fluid flow between the particles are coupled in a unified time step. The phenomenon of particles segregation in vibration fluidization process which small particles located at the top large particles at the bottom is founded. In the horizontal vibration fluidized bed, particles in different size have different operating speeds. Because of the effect of walls in the bed, the speed of particles continuously decreases from the center to the wall.(3) Based on the comparison the fluidization phenomenon in different vibration parameters and different wind conditions, the results show that as the wind speed increases, the material layer will have a corresponding rise. The particle segregation can be promoted by increasing wind velocity and vibration intensity. The vibration intensity decays with the thickness of material increases.The research in this paper lays a foundation for further study on numerical simulation of the heat transmission and combustion in the VFB. Research on the lignite vibration fluidized behavior is instructive for the design of process parameters in lignite vibration fluidized dewatering technology.