关键词: 静态混合器, 液液分散, 响应面分析, 数值模拟, 分布混合, 分散混合

Abstract: Distributive mixing and dispersive mixing for the dispersion of toluene in water in a Kenics static mixer were investigated by means of numerical modelling tools and experimental study. Dispersive mixing performance was described as Sauter mean diameter (SMD), which was measured by photographic technique(direct shooting method on a cross-section).Polynomial expression of SMD was built by three factor Box-Behnken design and response surface analysis, which was based on Design Expert 7.0 code. A physical model of the static mixer was built, which was the same as the experimental apparatus. Mixture multiphase model and standard k-εturbulence model were chosen for CFD modeling. The contours of concentration field and non-uniform coefficient were obtained. Distributive mixing performance was described as non-uniform coefficient, which was calculated by contours of concentration field. The total deviation between simulated and experimental pressure drops was less than 15% in this way. Thus, the simulated results showed good agreement with the experimental results. The results showed that liquid-liquid dispersion in static mixer could be attributed to the combination of distributive mixing and dispersive mixing. A fully developed state for both mixing processes could be achieved through 6—8 mixing units. The influences of superficial velocity, volume fraction of dispersed phase and pipe diameter on fully developed SMD were obvious, but the influence of superficial velocity was most significant. The non-uniform coefficient in fully developed section decreased to below 0.05, so that the static mixer had excellent performance on distributive mixing under wider experimental conditions.

Key words: static mixer, liquid-liquid dispersion, response surface methodology, numerical simulation, distributive mixing, dispersive mixing