The Separating Characteristics Of Liquid-liquid Hydrocyclone With The Interaction Of The Dispersion Phase

In the hydrocyclone, the dispersed phase is separated from the multiphase flow by the centrifugal force that is caused by the difference of density between the phases. In the numerical simulation of the hydrocyclone, the diameter of the dispersed droplet is often set as a constant value, thus the flow field’s influence on the dispersed droplet is ignored. In this article the separating characteristics of the hydrocyclone was studied, based on the breakup and coalescence of the dispersed phase. The main contents and conclusions are listed as follows.The flow field of hydrocyclone, the stress of the dispersed droplet and the mechanisms of the breakup and coalescence were analyzed in theory. It is concluded that the flow field of the hydrocyclone is composed of the free vortex and the forced vortex. The droplets are prone to breakup, when the Weber number greater than 12. The coalescence only happened when the contact time of the two colliding droplet is long enough.The kernel functions which were used in the liquid-liquid systems were compiled in this article. By comparing the numerical simulation with the experimental date, for the hydrocyclone with the low concentration of the dispersion phase, the optimizing kernel functions were chosen. At the same time the flow filed, the velocity distribution, the concentration of the dispersion phase and the distribution of the coalescence and breakage were analyzed. The results show that the Lerh’s breakup kernel function and coalescence kernel function are more suitable than others for the hydrocyclone with the low concentration of dispersion phase. Comparing with the experimental date, the error is chose to 12%. Consistent with the theoretical analysis, the velocity and turbulence intensity distributions are in the form of combination of vortex.The volume fraction of the dispersed phase and the source terms were analyzed. And the flow field and the distribution of the dispersion phase in hydrocyclone with different inlet flow were studied. The results show that with the concentration of the dispersed phase increasing, the coalescence rate increased. The breakup rate increased along with the turbulence intensity and velocity gradient enhancing. With the inlet flow enlarging, the velocity and the turbulence intensity in the hydrocyclone is increased, the concentration of the dispersed phase in the cylindrical section, large conical section and the lower part of the small conical section is enhanced. By increasing the inlet flow, the breakup are more likely to occurred,and the amplitude decreased.A new method for calculating the separation efficiency of the hydrocyclone with lightweight dispersed phase was deduced. By comparing the experimental date with different inlet flow and structures, it shows that the value of the deviation is under the 0.01. Because the interactions of the dispersed phase are not considered in the method, the accuracy of the method is low when the breakup obvious.