摘要
基于锤片式饲料粉碎机工作状况,研究物料颗粒在气固两相流中运动轨迹的数学模型,得到物料颗粒沿坐标轴方向上的运动微分方程和位移方程;并使用MATLAB对该数学模型进行了数值模拟,得到了物料颗粒理论运动轨迹,对模拟结果按入口固相颗粒速度大于、等于、小于气相速度3种情况进行研究;使用高速摄像机对分离流道内部分颗粒进行跟踪拍摄,并取粒径2mm目标颗粒和粒径8mm完整颗粒,对2种物料颗粒理论模型运动轨迹与真实运动轨迹进行了比较,验证了数学模型的合理性。对进一步研究宏观物料运动、颗粒分布及分离装置结构等提供了参考。
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.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2013年第9期18-23,共6页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金资助项目(81105189)
内蒙古科技大学创新基金资助项目(2010NC045)
