Coupled Analysis Of Gas-solid Two-phase Flow In Jet Fluidized Bed Air Flow Pulverize

Ultra micro powder nanotechnology is widely used in various industries.It has the characteristics of large crushing strength,fine particle size,narrow particle size distribution,and change of surface activity.It plays an important role in the research and development of new materials and the preparation of traditional Chinese medicine.In the modern industrial products,the requirements of material particle size are getting smaller and smaller,the distribution of particle size is also becoming narrower and narrower,and the requirements of classification equipment are getting higher and higher.In this paper,the grinding chamber with a blade attached grading wheel is taken as the research object.When the grading wheel is used for particle grinding,its structure can effectively generate vortex phenomenon.The coarser particles will flow to the top of the grading wheel along with the air flow,and they will be thrown down when they meet the attached blades at the top of the grading wheel,effectively preventing the coarser particles from entering the inner part of the grading wheel and being separated.The structure of the grading wheel in the grading equipment has a very important influence on the grading efficiency and quality,so it is of great significance to study the influence of the grading wheel on the particle crushing effect.Most of the grading wheel structure is based on experience design,and there is less in-depth research on the grading wheel,which lacks a strong theoretical basis.In this paper,numerical simulation method is used by computer software,and fluent software is used to simulate and analyze the grinding chamber of the attached blade grading wheel.By using CFD method,the flow field of gas-solid two-phase flow in the grinding chamber of the classifier with attached blades is simulated,which provides certain theoretical basis for the further optimization design of the structure of the classifier and the improvement of the classification function and performance.The main research work and results are as follows:(1)The three-dimensional model of the pulverizing chamber of the jet fluidized bed air flow pulverizer is established by using ANSYS The software workbench simulates and calculates the flow field distribution of the crushing area,fluidization area and classification area in the air flow pulverizer's crushing chamber,and gives the velocity distribution nephogram,particle distribution track nephogram and velocity distribution nephogram above the crushing chamber under the lithium carbonate and silicon carbide materials,and gives the corresponding explanation and analysis.Three velocity distributions at different positions of the lower grading wheel with different materials are given and the corresponding analysis and explanation are made.Set up the experimental device in the practice place,and carry out the actual grinding experiment of two kinds of materials,lithium carbonate and silicon carbide.(2)From the simulation results of gas-solid coupling,it is feasible to use the gas phase and solid phase coupling in the grinding chamber.Particles in the grinding chamber will collide and break with each other as the air flow drives,and the gassolid coupling in the grinding chamber is verified.(3)In this paper,the numerical simulation of the grading wheel with attached blades is studied.The particle velocity and particle distribution nephogram of two different materials show that the flow field around the grading wheel is generally better.However,from the nephogram,it can be seen that there are still slight eddy phenomena at the bottom and side of the grading wheel,indicating that the grading wheel with attached blades can prevent eddy phenomena to a certain extent The simulation results show that there are still a few coarse particles separated from the grinding chamber.(4)In order to observe and analyze the velocity distribution of the grading wheel in the process of particle separation,the velocity distribution of three axial directions from the bottom to the top of the grading wheel in different materials is analyzed.The results show that the velocity distribution in the z-axis direction of particle air flow fluctuates greatly,and the larger and reverse velocity fluctuation is in the higher position of the grading wheel,or the coarser particle diameter will follow the blade of the grading wheel It is thrown down;there is a part of air flow overflow phenomenon,and the speed distribution on both sides is different;the more the x-axis direction goes to the outside of the grading wheel,the greater the maximum speed,the more obvious the fluctuation,and the more likely to cause the uneven distribution of particle concentration;the more the y-axis direction goes to the upper part of the grading wheel,the greater the speed,the air flow overflow will occur.The above conclusions can be used to optimize some important parameters(such as the number of blades,the ratio of height to diameter,etc.)of the classifier with attached blades.(5)Based on the analysis of the experimental and simulation data,several abnormal phenomena are found.The abnormal phenomena are explained.In view of the simulation results,large particles are still separated from the grinding chamber,which affects the particle size distribution range of the product.This paper proposes to optimize the bottom structure of the grading wheel,install the rectifying plate,improve the structural parameters of the equipment,and design the industrial design of the jet air flow pulverizer It provides some technical guidance and theoretical basis for the popularization and application.