Computational fluid dynamics simulation and experimental analysis of ultrafine powder suspension

The suspension characteristics of ultrafine powder slurry in the stirred vessel were simulated by using computational fluid dynamics. The results show that the Rushton disk turbine impeller is more conducive to maintaining suspended homogeneity and circulation of slurry compared with the pitch blade turbine pumping up impeller and the pitch blade turbine pumping down impeller. And the increase in stirring speed enhances turbulent fluctuation and anisotropic velocity of the fluid at the cost of more power consumption, which improves dispersibility and suspensibility of the particles. Meanwhile, the change of impeller clearance has a weak influence on the flow pattern, and the impeller clearance of 0.32T (T is the diameter of the bottom of the reactor) can achieve better dispersivity and suspensibility of the particles with lower power consumption and larger axial velocity. The experiments of surface coating modification of ultrafine titanium dioxide (TiO₂) were carried out under the same conditions for those of the simulation system. The surface film morphology and photocatalytic properties of the modified TiO₂ were analyzed, and the obtained data are well consistent with the simulation results.