Research Of Experiment About Flow And Mixing Characteristic In An Eccentric Stirred Tank

Stirred reactor is the most widely used chemical reacton equipment in modern chemical industry,universally used in chemical engineering,pharmaceutical engineering,and the like.And especially solid-liquid mixing is one of the most importment part in the reaction process,such as solid-liquid catalysis process,crystallization and so on.But the major of the solid-liquid mixing search is about the drawn-up process of falling particles,and there are a few essays about the flow characteristic of liquid with floating particles.And relevant studies started relatively late,the first article at the end of the 1970’s.This article research the flow characristics in the stirred tank about the solid-liquid mixing with PBT impeller,whose diameter is 0.158m.And run the simulation with different calculation method.The variable facters of flow Characteristics with floating Particles include the flow patterns of the continuous phase fluid,the eccentricity of the blades and the operation mode of the propeller blades(PBTD&PBTU)and solid-liquid density ratio.At the beginning of the research,do the irrelevant verification with the PMMA and sugar-salt solution with the same refractive index.And use the CFD to simulate the flow field at e＝0%and e=12%with k-ε method.And get the conclusion:1.The presence of particles hardly affects the flow of the flow field with low solids ratio.2.Whatever the blade operation mode is PBTU or PBTD,the particles with the center stirring are drawn down along the axis and the direction of the particles is the same with the direction of rotation of the blade.3.Whatever the blade operation mode is PBTU or PBTD,Under the critical drawn-down and dispersion condition of particles,the required agitation speed decreases as the eccentricity increases.4.The eccentric stirring will destroy the symmetry of the flow field in the center stirring.Thus the axial flow and radial flow of the whole flow field are both strengthened,but the radial strengthening is more obvious than the axial flow.5.Under the critical drawn-down and dispersion condition of particles,he required agitation speed with PBTD is small than with the PBTU.