Incipient Motion Of Multi Particles In The Stirred Tank—Experiment Analysis

The initial movement of solid particles is common in various chemical processes,such as surface cleaning,solid transportation,filtration and separation.The research on the motion characteristics of single particles on different types of plane and the simplified mechanical model have been mainly studied.The research on the initial motion characteristics of multi particles in the stirred tank is rarely reported.In this paper,the initial motion characteristics of the multi particles on the regular substrate in a solid-liquid mixing tank are studied,and the force analysis of the initial state of the multi particles is carried out by numerical simulation.The experimental stirred tank is a cube mixing tank with a border length of 220 mm,and the regular substrate is made up of 149 glass particles with a diameter of 10 mm,which is located in the center of the bottom of the stirred tank.The experimental blade is a standard Rushton turbine propeller with an off base height of 55 mm.In this paper,the influence of the spacing,density,diameter and circumference position of double particles on the initial motion characteristics of particles is studied by camera and image processing,and the typical working conditions are numerically simulated with the lattice Boltzmann method,and the force state of the initial movement of multiple particles is analyzed.The results of this study show that:(1)the adjacent particles along the x direction obstruct the initial movement of the measured particles;with the increase of particle spacing,the interference of the particles to be measured is reduced.When the particle spacing is delta x?2ds,the interaction between particles can be ignored.(2)the influence of the density of the particles upstream of the measured particles on the initial movement of the measured particles Smaller,and increasing the density of downstream particles will impede the initial motion of the measured particles.(3)with the increase of the upstream or downstream particle diameter,the critical speed of the initial movement of the measured particles increases,and the influence of the upstream is more significant.(4)in the direction range of the moving direction of the measured particles less than 90 degrees,when there is the presence of interfered particles,the number of initial motion Shields of the measured particles increases obviously.If there are other particles outside the direction,the initial motion of the particles is slightly higher than that of the particles.In addition,the initial motion phenomena and trajectories predicted by numerical simulation are in good agreement with the experimental data.Under the state of initial motion,the results of the force analysis of the particles show that the effect of the moment on the particles can not be ignored.