Optimizing The Structure Of In-line High Shear Mixer By CFD Simulation

High shear mixers,as a new process intensification equipment,have a great potential role of intensifying the process for mixing,emulsification,dispersed and reaction with high turbulence and shear.In this paper,the effect of the key structural parameter,such as the tip-to-base clearance and shear gap width,on the character of hydrodynamics and power consumption in pilot-scale in-line HSMs were investigated by CFD and experiment.Meanwhile,combined with the residence time distribution,the structure of in-line blade-screen HSM were optimized by CFD.Firstly,with viscous Newtonian and Non-Newtonian fluid,the effect on flow pattern and power consumption of standard in-line HSM with ultrafined teeth resulted from the change of tip-to-base and shear gap width were explored by CFD.The power predicted by CFD was validated by experimental torque with torque sensor.For other in-line HSMs,the flow pattern and power consumption were predicted by CFD with laminar model and LES model for laminar and turbulent regime,respectively.With the increasing of tip-to-base clearance and shear gap width,the shear strain rate and turbulent strength were greatly reduced,and the area of dead zone was increased.The value of Kp and Ks of in-line HSM is higher than that of stirred tank in laminar regime.The correlations of the predicted Kp and Ks of all designs which show their linear relationship with the tip-to-base clearance in axial direction f/(f+h)and exponential variation with shear gap width in radial direction g/D.Furthermore,the structure of in-line blade screen HSM was optimized by CFD according to the RTDs which were predicted by LES model and species transport method.The predicted RTDs of HSMs with different hole of stator agree well with the experimental data with acceptable error,and the hole of stator was optimized.Then,this method was applied to predict the RTD of other HSM by CFD.The results indicate that the imperfect flow appear in the in-line HSM because of the inefficient chamber design of in-line HSM.In this paper,shorten distance in axial direction of chamber,the volute,and tangential outlet were great helpful for improvement of imperfect flow.