超细粉体的涡轮分级研究

发布时间：2018-06-27 01:27

本文选题：超细粉体分级 + 涡轮分级机　；参考：《北京化工大学》2015年硕士论文

【摘要】：随着超细粉体的广泛应用,对超细粉体的粒度和纯度等方面都有了更高要求,也对超细粉体的粉碎和分级设备有了更高的要求。本文设计了—台高速机械冲击粉碎机对实验物料进行粉碎,采用计算流体力学软件(Fluent)模拟分级流场来研究涡轮分级机的操作参数和涡流空气分级机的转笼叶片数量对分级机流场的影响。开展粉碎粉体的分级实验,研究了操作参数对分级性能的影响。本论文主要研究及结果如下：1、利用冲击粉碎原理设计了高速机械冲击粉碎机,通过两个粉碎盘相向旋转提高冲击速度来改善粉碎效果,粉碎机内部结构都采用耐磨陶瓷内衬来保证产物的纯度。该粉碎机适用的粉碎物料粒度为2～3mm,粉碎后粒径大约为50～150μm。2、对FTW-350型涡轮分级机的内部气流和物料的流动状态采用气固两相数值模拟进行分析。涡轮分级机的操作参数分别以分级轮转速、加料速度和出口压力为变量,其余两操作参数保持不变,对比分析流场的动态压力、湍动能、切向速度、径向速度和轴向速度的分布情况。结果表明：转速在6000-7000r/min范围内,分级轮转速越大,流场中的动态压力、湍动能和速度分布更加均匀,说明流场比较稳定：加料速度越大,分级区域和细粉出口的压差越大、湍动能和各个分速度也越小；出口压力在较低范围内增加,动态压力、湍动能和速度的增量较小,但出口压力增加到-3500Pa后,流场的压力和各个分速度都随之急剧增加且分布不均匀,不利于流场的稳定。3、将新粉碎机制备的高岭土粉体在FTW-350型涡轮分级机上进行分级实验,通过激光粒度测试仪对分级产物进行粒度测试分析,得到体积累积和频度分布曲线。结果表明：增加分级轮转速有利于提高细粉含量并减小粒度分布范围,但转动频率增加到75Hz后对分级粒度影响较小；加料速度在一定范围内增加可以提高细粉含量,在高转速下的影响较小。4、针对涡流空气分级机内的单相气流流场状态,对12、24、36、48、60和72六组转笼叶片数量下流场的动态压力、切向速度和径向速度进行对比分析表明：叶片数量由12增加至48,分级流场的压力和速度分布的均匀性不断提高,且气流涡旋不断减小；叶片数量继续增加,流场的均匀性降低：叶片数量为48时,叶片间的气流涡旋相对较小,流场的动态压力和速度分布都比其他叶片数量时均匀,即流场相对稳定,达到最优分级效果。
[Abstract]:With the wide application of ultrafine powder, there are higher requirements for particle size and purity of ultrafine powder, as well as higher requirements for crushing and classifying equipment of ultrafine powder. In this paper, a high-speed mechanical impact pulverizer is designed to crush the experimental materials. The influence of operating parameters of turbine classifier and the number of rotor blades of swirl air classifier on the flow field of turbine classifier was studied by using fluent software. The influence of operating parameters on the classification performance was studied. The main research and results of this paper are as follows: 1. Using the principle of impact comminution, a high-speed mechanical impact crusher is designed. The impact speed is improved by rotating two comminuted disks in opposite direction to improve the comminution effect. The internal structure of the mill is made of wear-resistant ceramic lining to ensure the purity of the product. The particle size of the comminuted material is 2 ~ 3 mm and the particle size is about 50 ~ 150 渭 m 路m ~ (-2). The gas flow and material flow state in FTW-350 turbine classifier are analyzed by gas-solid two-phase numerical simulation. The operating parameters of the turbine classifier are as follows: the speed of the stage wheel, the feeding speed and the outlet pressure, respectively, while the other two operating parameters remain unchanged. The dynamic pressure, turbulent kinetic energy and tangential velocity of the flow field are compared and analyzed. Distribution of radial velocity and axial velocity. The results show that in the range of 6000-7000r/min, the larger the speed of the classifier wheel, the more uniform the dynamic pressure, turbulent kinetic energy and velocity distribution in the flow field, which indicates that the flow field is more stable: the greater the feeding speed, the greater the pressure difference between the classifying region and the exit of fine powder. The smaller the turbulent kinetic energy and velocity, the lower the outlet pressure, the smaller the increment of dynamic pressure, turbulent kinetic energy and velocity, but when the outlet pressure increased to -3500Pa, the increase of dynamic pressure, turbulent kinetic energy and velocity was smaller, but when the outlet pressure increased to -3500Pa, The pressure and velocity of the flow field increase rapidly and the distribution is uneven, which is not conducive to the stability of the flow field. The kaolin powder prepared by the new pulverizer is tested on the FTW-350 turbine classifier. The volume accumulation and frequency distribution curves were obtained by analyzing the granularity of the classification products by laser particle size tester. The results show that increasing the rotating speed of the classifier wheel can increase the content of fine powder and decrease the particle size distribution, but the increase of rotation frequency to 75 Hz has little effect on the particle size, and the increase of feeding speed can increase the content of fine powder in a certain range. Under the condition of high rotating speed, the influence is small. 4. In view of the single phase flow field state in the eddy current air classifier, the dynamic pressure of the flow field under the number of 12 ~ (24) ~ (36) ~ (6) ~ (6) rotating cage vane and 72 groups of rotating cage blades is studied. The comparison and analysis of tangential velocity and radial velocity show that when the number of blades increases from 12 to 48, the uniformity of pressure and velocity distribution of the flow field increases continuously, and the vortex of air flow decreases, and the number of blades continues to increase. The uniformity of flow field is reduced: when the number of blades is 48, the vortex between blades is relatively small, and the dynamic pressure and velocity distribution of the flow field is more uniform than that of other blades, that is, the flow field is relatively stable, and the optimal classification effect is achieved.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.8

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