Experiments And Numerical Simulation On Vertical Double Vortex Classifier

The vertical double vortex air classifier is a centrifugal static air classification device formed based on the structural improvement of the cyclone classifier.It has the advantages of simple structure,low cost,easy installation and maintenance,high classification accuracy,etc.Therefore,it has a wide application prospect.However,currently,the understanding of vertical double vortex classifiers is not in-depth,and there is a lack of systematic research on the classification flow field from the perspective of overall unit.It is not clear what kind of flow field shape forming at each air inlet is facilitating the clear classification of particles.In this paper,the numerical simulation method was used to investigating the flow field characteristics of the vertical double vortex classifier,which provided basic support for the design optimization of this type of cyclone classifier;at the same time,taking the FCC catalyst as the test material,the effect of the classifier on the particle separation performance was investigated through experiments,in the industrial background of FCC catalyst production and application.The main contents include:firstly,the effect of the diameter of the exhaust pipe on the flow field performance of the classifier was investigated through numerical simulation,and then the bottom secondary air structure was added based on fixed diameter of the exhaust pipe to reveal the adjustment mechanism of secondary air volume and secondary air velocity on the elutriation flow field.The simulation results show that the exhaust pipe diameter,secondary air volume,and secondary air velocity can change the flow field inside the classifier,but the adjustment mechanisms are different.The diameter of the exhaust pipe has a greater influence on the main field area of the classifier,and the particle size distribution of the classifier product can be controlled in a larger range.The secondary air volume adjusts the control area of the elutriation flow field and the airflow axis of the central area The change of the direction velocity and the secondary air velocity regulate the swirling intensity of the elutriation flow field.The combination of the three can form an appropriate flow field strength,and simultaneously create favorable conditions for the secondary classification and timely discharge of fine particles,Improved classification accuracy.The classification performance test results show that in the classification of the FCC catalyst particles,by adjusting the structural parameters and operating parameters,the content of fine powder under 20?m in the coarse product can be controlled at 1.38%,and the coarse powder yield can reach 96.5%while the classification accuracy K remains below 1.55.The optimum condition is the diameter of the exhaust pipe in 160 mm,the inlet air velocity at 14 m/s,and the secondary air volume in 20%of the inlet air volume,maintaining the secondary air velocity of 15 m/s,feeding at the maximum tangential velocity meet the particle size requirements of industrial production for catalyst products.