Research of materials motion law in separation flow of new type hammer feed grinder

In order to fundamentally solve the existing problem of high temperatures of material, excessive crushing, and low separation efficiency in traditional pulverizers, a new type of hammer crusher to be used for conventional crushing, separation mode, and annular tooth plate were installed in the grinding chamber, while the sieve was not installed. Its' ability to crush materials rely's on striking and friction, and used the separation means to separate the materials. The materials that met the size requirements were immediately pushed through a sieve, and particle materials which failed to meet the size requirements went back to the crushing chamber for circulation crushing under the double action of the crushing chambers central negative pressure and high material weight. Basing on the working condition of the feed hammer crusher, we studied the mathematical mode of material particles in gas-solid, two-phase flow trajectory, and determined the material motion differential equation and displacement equation of x axis and y axis direction. According to the actual prototype separation flow parameters, we used MATLAB to analyze the numerical simulation. We set the material grain equivalent diameter to 2 mm, where the collision between material and the channel wall is a perfectly elastic collision. We also used the intersection between separation channel entrance and wall surface on the outer as the X axis / Y axis coordinate plane (0, 0) point position, where the granular material entrance initial position are respectively (0, 25 mm), (0, 50 mm), (0, 100 mm), and (0, 150 mm). We determined the material motion track by utilizing different angles, initial velocity, and inlet position in the runner trajectory. The results show that entrance velocity at the angle of 45° is very proper, without collisions between particles and the separation channel, while at the same time it can easily reach the screen surface through the screen. Due to the separation channel being relatively short and the high velocity of the materials, the particle trajectory is minimally affected by gas phase and gravity. Through tracking the shooting of the particles with a high speed camera in the separation channel, we verified the rationality of the mathematical model. We also made comparisons of material simulation positions and real positions. The studies show that: the movement track of theorized material particles and practice material particles is basically the same, the target particle error is 0-3.5 mm; and the intact granules error is 0-3.3 mm. From the plan, it also can be seen that wind effects are larger for the 2 mm target particles and the actual trajectory is located above the trajectory of theoretical model; however, the energy change of 8mm intact grains is greater because of gravity, and particle collisions, and other factors, while the actual motion trajectories float in the vicinity of theoretical trajectories. The main reasons for this difference occurring: (1) The theoretical mathematical model did not consider the material motion effects between the material interaction; (2) Particle size influences the selection of particle motion parameters, particularly the effect of particle velocity in separation flow. We hope that the study of hammer fodder grinder movement law in separation flow can provide a reference for further study of macro material movement, particle size distribution, and structure of the separating device.