Solid Liquid Separation Characteristics Of High Speed Horizontal Screw Centrifuge And Analysis Of Its Influencing Factors

The rotating speed of the high-speed decanter centrifuge varies from several thousand to tens of thousands of revolutions,so the screw pusher will cause a large disturbance to the fluid and make the flow have strong swirling property,which causes the complicated fluid flow inside the drum.The data measured in the experiment is very limited and the dynamic real-time transmission of data cannot be achieved.The simulation model of the decanter centrifuge is also calculated based on the steady state.In this paper,based on the transient calculation method,a simulation model of the internal flow field of the decanter centrifuge is established.At the same time,the reliability of the simulation model is verified by the existing experimental results.The two factors of the speed difference and the pitch of the spiral blade are mainly studied.The effect of separation efficiency of decanter centrifuge.In this paper,after reasonable simplification and assumption,the establishment of the threedimensional model of the fluid domain of the decanter centrifuge and the division of the grid are completed by SolidWorks and icem.In the fluent calculation,the Eulerian multiphase flow model was selected.The RNG K-ε turbulence model and the MRF model were combined to calculate the transient flow field of the decanter centrifuge.The reliability of the simulation model is verified by normalizing the simulation and experiment results.When studying the effect of the speed difference on the separation efficiency,the method of comparative test and simulation is used.The test results and simulation results show that: 1.Although the centrifugal force of the particles in the centrifugal field is much greater than gravity,the influence of gravity cannot be neglected.2.The thickness of the solid phase deposition changes periodically with time;3.At the same time along the drum axis The thickness of the solid-phase deposition thickness is gradually increased and accompanied by a local decrease;4.The thickness of the drum cone section is much larger than that of the drum column section.The larger the thickness of the solid phase deposition,the comparison between the experimental and simulation results shows that the optimal speed difference under the working conditions in this paper is 10r/min.At the same time,the functional relationship between the speed difference and the delivery amount is obtained,from which we can get that the delivery amount increases first and then decreases as the speed difference increases,and then gradually tends to a certain value.In the simulation results,the concept of transport volume was proposed to reflect the separation efficiency.The larger the speed difference,the smaller the solid deposition thickness,the smaller the transport volume,and the lower the separation efficiency.However,the larger the speed difference,the greater the transport speed and the greater the separation efficiency.The optimal speed difference is at the balance point of the two contradictory factors of deposition thickness and conveying speed.When studying the influence of the pitch of the screw pusher on the separation efficiency,it was found that: 1.The reflux speed of the drum column section is greater than that of the drum cone section;2.The particle moving speed of the drum column section is greater than that of the drum cone section Conveying speed;the larger the pitch,the greater the return flow speed,and the greater the particle moving speed;3.Excessive pitch will cause the resistance of the transport sediment to increase,and the degree of reflux will become larger;too small pitch will form a stable swirl flow state,but The slag velocity is slow,which will cause the solid phase to be dispersed in the drum column to a large extent.Therefore,the study of the effect of the pitch on the separation efficiency is also to find the balance point of these two factors.