LBM-DEM Coupled Numerical Simulation Of Flow Characteristics In A Spouted Bed

The spouted bed has characteristics of high gas solid contact and heat transfer efficiency,simple manifolds,low operating voltage,and easy to deal with the heat sensitive materials.The research on gas solid two phase flow in the spouted bed is of great significance for the design and research of the spouted bed.The numerical simulation can overcome the experimental methods' disadvantages of high cost and not reveal the inherent mechanism of particles movement from the micro perspective effectively,and theoretical analysis methods' disadvantages of complex model.It has become an important research method for the flow characteristics of particles in the spouted bed.In this paper,the lattice Boltzmann method is combined with the discrete element method.The gas phase is solved by modified lattice Boltzmann method which considers the porosity and relative slip velocity of gas and solid.The particle phase is solved by discrete element method.The coupling between gas and solid is based on the Newton's third law,and the program is compiled by Fortran language.The evolution of bubble formation in a bubbling bed with a jet of 0.006 s is simulated by the compiled program.Results successfully show the single bubble formation,growth,rising and rupture process,and compared with the related literature,which verify the correctness of the program and numerical method.Then simulate the flow process of particles in the spouted bed.The fluidization process sequence diagram,the distribution of gas and particle velocity in the bed,the distribution of particle volume fraction along the bed height and bed width and the velocity vector of the particles in the bed are obtained.The results show that there is a strong particle internal circulation in the bed,and with the increase of the velocity of the jet,the movement of the particles is more severe and the bed height increases.The middle spouted area is the dilute phase region,and the two sides of the annulus area are dense phase region,and the volume fraction of the particles along the bed height is gradually decreased.There is no vector information,almost no movement in the stagnation region.In the end,the mixing and separation process of particles in the spouted bed is simulated.The sequence diagram of particle mixing and separation,axial and radial mixing,the influence of wind velocity and particle density on mixing and separation process are obtained.The results show that the axial mixing is mainly due to the upper and lower transposition of the particles,and the radial mixing is mainly due to the left and right transposition of the particles.The axial mixing effect is better than that of the radial mixing.The increase of the jet velocity or the decrease of the particle density is helpful to the mixing process of the particles.The increase of the velocity of the jet or the difference of the density of the particles all contribute to the separation of the particles.But the separation of same diameter particles is not very obvious.