立式紊流搅拌机多相流场及混合性能

Multiphase flow field and mixing performance of vertical turbulent mixer

为研究液体与固体颗粒在大容积立式搅拌机中的混合特性,建立了转轴与转筒耦合运动形式的双轴立式搅拌机和单轴立式搅拌机模型,利用计算流体动力学仿真软件Fluent中的双欧拉模型和RNG k-ε湍流模型,以污泥和铁尾矿颗粒作为混合介质,分别模拟2种搅拌机内部物料的混合过程,对流体流动特性以及固相颗粒体积分布规律进行分析,并对比分析了双轴搅拌和单轴搅拌对液固两相混合性能的影响.结果表明:相同工况下,2种搅拌机内的流场特性差异较大,双轴搅拌机内流体的紊流效果明显强于单轴搅拌机;固相颗粒在单轴搅拌机内从上到下呈阶梯状分布,而在双轴搅拌机内各处均匀分布;结合示踪剂扩散时间可得出,双轴搅拌机单位体积混合能耗远小于单轴搅拌机,所以双轴搅拌机的搅拌混合效果以及混合效率优于单轴搅拌机.研究结果可为大容积搅拌混合设备的设计与优化提供重要的参考.

In order to research the mixing characteristics of liquid and solid particles in large-volume vertical mixer,the models of dual-axis vertical mixer and single-axis vertical mixer with coupled motion of rotating shaft and rotating drum were established.The mixing process of material inside the two types of vertical mixers was simulated by using the Euler-Euler model and RNG k-εturbulence model in the computational fluid dynamics simulation software Fluent.Sludge and iron tailings particles were used as mixing media respectively.The flow field characteristics of fluids and volume fraction distribution of solid particles were analyzed and the effects of biaxial and uniaxial stirring on liquid-solid mixing were compared.The results show that under the same operating conditions,there is a significant difference in the flow field characteristics between the two types of mixers,and the turbulent flow effect of the fluid in the dual-axis mixer is significantly stronger than that of the single-axis mixer.Solid phase particles are distributed in a stepped pattern from top to bottom in a single axis mixer,while they are uniformly distributed throughout the dual-axis mixer.Based on the diffusion time of the tracer,it can be concluded that the mixing energy consumption per unit volume of the dual-axis mixer is much lower than that of the single-axis mixer.Therefore,the mixing effect and efficiency of the dual-axis mixer are better than those of the single axis mixer.The simulation results can provide important reference for the design and optimization of large volume mixing equipment.