Study on Gas Phase Flow Characteristics and Particle Separation Efficiency of Three-Stage Internal Cyclone Separator in Fluidized Bed Reactor (FBR) of in Cold Hydrogenation Reaction

In fluidized bed reactor(FBR) of cold hydrogenation reaction of silicon tetrachloride(SiCL4), three-stage internal cyclone separator is an important equipment for separating silicon powder and chlorosilane mixed gas. To optimize the separation efficiency and energy loss of the internal cyclone separator in FBR, the main structural parameters affecting the performances are deeply determined. Based on ansys fluent(CFD) software code, the trace of solid particle size is numerically simulated by the response surface model and Lagrange model. The effect of the feed location, the feed velocity, the pipe diameter of gas outlet and leg height on separation efficiency was well studied. The results show that the diameter of the inlet pipe has little effect on the pressure drop(△p)and the separation efficiency. The diameter and velocity of the exhaust pipe have great effects on the pressure drop and the separation efficiency while the interaction between the diameter of the inlet pipe and the feed velocity is obvious for internal cyclone separator. As for silicon particle size of 0.5~10 μm of the reactant, the optimal parameters are De/D=0.35、Dd/D=0.37、V=12 m/s: the outer diameter(D) the dust outlet diameter (D_d), exhaust port diameter (D_e), and inlet velocity (V).The optimal operation parameters are applied into one certain three-stage internal cyclone separators which diameters are separately 1.2m,0.8m and 0.5m. There is little error of < 5.0% between the industrial data and the simulated data while the separation efficiency of 0.1μm particle size is increased to >99.5% and the pressure drop is decrease to <3.2KPa by half drop. The established response surface model can accurately describe the relationship between design variables and objective functions Therefore the industrial equipment’s efficiency of cold hydrogenation reaction was greatly improved. These studies provide an effective guidance for the separation of 0.5-10 μm particle size in three-stage internal cyclone separation.