Numerical Analysis On Hydrocyclone Structure And Flow Field Performance

Hydrocyclone,as one of separation equipments,has the advantages of simple structure,none moving components,easy installation and easy maintenance,etc.It has been widely used in various industries.Although the hydrocyclone is simple in structure,the internal flow field is very complex.A little change of dimension will affect the performance of hydrocyclone.In the process of sewage treatment,hydrocyclone is not widely used in the separation of solid sludge in small particle size currently.First,here we make numerical simulation for the internal flow field of solid-liquid hydrocyclone separation by using computational fluid dynamics(CFD)method.The classical 75mm type hydrocyclone is chosen as its foundation model in the numerical simulation,and proves the rationality of selected turbulence model and its numerical calculation method,by verifying this paper's numerical simulation results referenced to experimental data from other famous scholars.Second,the paper takes 17 kinds of solid-liquid hydrocyclone commonly used in industry as the research objects.Based on the CFD method,the effects from diameter of overflow tube and insertion depth of overflow tube towards air column,split ratio,pressure drop and the separation efficiency inside the hydrocyclone are disscused.Based on the numerical simulation,the optimum size range of the diameter of overflow tube and the insertion depth of overflow tube are obtained for these 17 kinds of solid-liquid hydrocyclone.Third,the numerical simulation is carried out for five kinds of hydrocyclone with different inlet styles,while comparing the performances of the five kinds of hydrocyclone.The numerical simulation results show that the internal flow field of the double inlet rectangular tangential feed tube hydrocyclone has better symmetries;the hydrocyclone with contractive rectangular tangential feed tube has better separation efficiency;three-dimensional spiral feed tube hydrocyclone can greatly improve the processing capacity of hydrocyclone and have the best combination property;The optimal inlet angle of 75mm type single inlet rectangular tangential feed tube hydrocyclone is 5 degrees.Fourth,this paper analyzes the high speed spiral flow in the hydrocyclone,by which the spiral pressure restoring blades what can make the high speed rotating flow in the overflow tube into direct current is designed.The numerical simulation results show that blades installation at the bottom of the overflow pipe is the best;four-blade has better effect compared to three-blade and two-blade,and it can reduce the inlet total pressure for about 9%?16%,and 50%?70%to the overflow outlet total pressure;further more installation of the spiral pressure restoring blades can hardly affect the separation efficiency of the hydrocyclone.At last,according to the problem of low efficiency of the filter press or the hydroextractor in the sewage treatment plant,a set of combined hydrocyclone is designed.The optimum structure style of combined hydrocyclone through numerical simulation is determined.Cooperated with relevant groups,a set of combined hydrocyclone and a set of 350mm type hydrocyclone were designed.By experimental verification,it is found out that the set of combined hydrocyclone can increase the solid content ratio from 2.7%to 7.1%within sewage,and 350mm type hydrocyclone can increased the solid content ratio from 2.7%to 4.3%within sewage.The experimental results fully verify the rationality of the related structure designs,and successfully solve the practical problems of low efficiency of the filter press and hydroextractor.