Classification Of Multi Particle Size Powder Products Research

Most centrifugal classifiers can only obtain two particles products,namely coarse products and fine products.With the development of modern industry,particles with better monodispersity and different average particle sizes are required.To obtain the particles products within the certain diameter range,multiple classification process have bo be perform when using the centrifugal classifier,which increases the production cost.Gravitational-crossflow classifier can usually obtain various particles products,but because the particles collectors are set in the bottom of the classifier.Which causes that the larger velocity of crossflow flow field,the larger space of the classifier,And when the velocity of the crossflow field is smaller,the yield of particles products is unsatisfactory.Gravitational-counterflow classifer has small transverse size,but can not obtain a variety of powder particle products.A novel multi-product particle classifier is designed in this paper by constructing the classification flow field superimposed by Gravitational-crossflow zone and Gravitational-counterflow zone.The following research has been carried out:(1)According to the current development and research status of particle classifier,To learn the classification principle of classifier and summary characteristics of classifier.It is planned to design a classifier that can obtain a variety of particle products by constructing the classification flow field superimposed gravitationalcrossflow and gravitational-counterflow zone.(2)Through analysis and modeling theoretically,the dynamic equation of particles in fluid is solved;The movement of particles in the fluid are explored,and the conditions for the separation of coarse and fine particles are found;The possibility of to classify particles by using the classification flow field superimposed gravitationalcrossflow and gravitational-counterflow zone is expounded theoretically.(3)The classification domain of the classifier is set obliquely upward and the initial velocity direction of particles is vertical downward,and the classification flow field superimposed by gravitational-crossflow zone and gravitational-counterflow zone is constructed;CFD simulation shows that a stable classification flow field with roughly constant velocity direction and small difference in velocity value can be formed in the classification zone,which provides flow field conditions for particle classification.(4)DPM model is used to simulate the movement and classification of particles.Results show that as the accelerating flow filed velocity increases,the particles change from the state of large spacing between coarse particles to that of fine particles.In the process of change,there is an accelerating air velocity,which makes the particles distribution law is the particles approximately have a relatively uniform distribution of spacing between coarse and fine particles.According to the simulation results of particle classification,different powder particle products with increasing average particle size can be obtained at the outlet 1-10.(5)Under the guide of the simulation results,the particle classification experiment is carried out.The results show that the CSR values of outlet 1,outlet 3 and outlet 6relative to outlet 10 are 3.99,0.96 and 0.47 respectively.A variety of particle products with large difference in particle size distribution are obtained at the outlet of the classifier;The Dv90 of particles products at outlet 1 is 27.6 μm.This value is about0.09 times of the maximum particle size,and the classifier obtains particle products with small average particle size;Numerical simulation and experimental results show that: The novel multi-product classifer designed in this work,whose most noteworthy feature is that it can obtain a variety of particle products with different average particle sizes.Compared with other multi-product classifer,the wider diameter range of the raw materials can be accepted.Compared with gravitational classifier,the classifier can obtain particle products with smaller average particle size.And the yield of particles product is higher due to the large the classification flow field velocity.The classification space is also smaller because the outlet is set in side direction of the classifer.