| Green development has become the overall tone of China’s new era of ecological civilization construction.Against this backdrop,sewage treatment,as an important link,has seen a continuous increase in the number of treatment plants.However,many sewage treatment plants have poor operating conditions,with high operating costs,poor sewage treatment effects,and failure to meet discharge standards.As a type of grading equipment,the hydrocyclone has the advantages of high processing capacity,high separation efficiency,simple structure,and low cost,and has been applied in multiple industries.Applying hydrocyclones to sewage treatment can effectively remove fine inorganic impurities in sludge and improve the efficiency of sewage treatment.Although the structure of hydrocyclones is simple,the internal flow field movement is very complex,and there are still shortcomings such as insufficient separation accuracy and high energy consumption.Therefore,the exploration of its operating mechanism and the optimization of separation performance remain a hot topic.In this work,a combination of computational fluid dynamics and physical experiments was used to optimize the thickness of the vortex finder wall,inlet form,and cone structure of the hydrocyclone.Furthermore,the changes in the angle of the underflow discharge,an online performance monitoring indicator,were studied through physical experiments.The influence of the overall structure size and the contact material of the internal surface of the hydrocyclone were also considered.The research contents of the paper are as follows:Study on the influence of vortex finder wall thickness.First,the accuracy of the hydrocyclone simulation model was verified through the implementation of physical experiments.Subsequently,a study was conducted on the controversy surrounding the effect of vertex finder wall thickness,using the relative outer diameter of the vertex finder as an indicator.The results indicate that,for a classification-type hydrocyclone,the vertex finder wall should be as thin as possible,which aligns with the majority of research findings.However,for a concentration-type hydrocyclone,a different approach is required,necessitating an appropriate adjustment of the vertex finder wall thickness.In this study,the optimal relative outer diameter of the vortex finder for the concentrating hydrocyclone FX25 was 0.72,which resulted in the highest recovery efficiency and a 20% reduction in pressure drop compared to the thin wall,with the lowest split ratio.Study based on structural optimization for sewage treatment.The inlet form and cone structure of the hydrocyclone were optimized and designed,and the excellent performance of the new structural design was demonstrated through Experiments.The mechanism of the new structure was analyzed through numerical simulation.The results showed that the new design improved the steepness coefficient of the separation curve to 0.47,while reducing the pressure drop by 7 k Pa.In addition,a smooth coating on the internal surface of the hydrocyclone could reduce the pressure drop and split ratio,but the larger sliding friction coefficient reduced the separation efficiency of particles larger than 18 μm.Experimental study on the state of underflow discharge.The influence of the optimization of the inlet form and cone structure and inlet conditions on the change in the angle of the underflow discharge and the specific impact of rope-like discharge on the separation performance of the hydrocyclone were studied.The results showed that the improvement in separation efficiency and reduction in split ratio brought about by structural optimization made the hydrocyclone more prone to rope-like discharge as the inlet conditions increased.When rope-like discharge occurred,the separation efficiency curve deteriorated,the separation size increased to 79 μm,the split ratio sharply decreased,with a maximum reduction of 89%,and the pressure drop decreased by 50 k Pa at different inlet flow rates compared to pure water conditions. |
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