Study On Gas-solid Flow Model Of Fluidized Bed Based On Fluent Software

Gas-solid fluidized bed is an important equipment in energy sources,chemical engineering,metallurgy,petroleum industries. This fluidized equipment is more easier for controlling and large-scale, more higher efficiency on heat and mass transfer process, better bed temperature distribution than traditional reaction and combustion devices. Although people had pay more attentions on it for decades years because of its broad application prospects of it, there are lots of difficult for designing,optimizing and magnifying fluidized bed equipments because of an unclear understanding of gas-solid flow law in which is with complexity and non-linear in bed.A 2D single jet bubbling fluidized bed and air distributor fluidized bed which both are filled with Geldart B particles are targeted as study objects, base on Two Fluids Model and Fluent CFD software to do cold numerical simulations. Application of multiphase flow in Fluent software and the method of drawing meshes are studied, discrete equations are achieved by Finite Volume Method. Time-step,under relax factors and effect of solver choice are studied. Effect of control equations,close relation,boundary condition of wall,the model of gas-solid drag force and the model of particle-phase viscosity are analyzed. Another more, two types of gas-solid drag fore models which are written by author and based on different theory are inserted in Fluent software by UDF function.Via comparing gas solid no slip,gas no slip solid slip,gas slip solid no slip,gas solid slip four schemes of wall boundary condition it's found that Gas no slip, solid phase slip can be better used for simulation; The gas-solid drag force is more important than inter-particles force in Two Fluids Model.Via comparing to k-ε,RNG k-ε,Realizable k-εthree types of turbulent model it's found that Standard k-εturbulent model has the best impact on simulation than RNG k-εand Realizable k-εturbulent models; Via comparing to Gidaspow,Koch-Hill,Di-Felice three types of drag force model it's found that the Gidaspow model performed a better predictable ability than Koch-Hill's in 0s-0.14s period, but a little worse than Koch-Hill's in 0.14s-0.20s period. Di-Felice drag force model can simulate the bubble formation process but can not simulate the process of bubble ascend exactly; The gas surface tension exist in gas-solid bubbling fluidized bed.Two fluids model can be used for simulating the bubbling process in bubbling fluidized bed. The results agree well with the fluidization principles and results reported in literatures, and this model can be used by designing and optimizing bubbling fluidized bed equipments.