选粉机内颗粒的重力分级对后续离心分级有重要影响。为研究颗粒在选粉机重力分级区内的运动特性，在对颗粒进行受力分析的基础上，分别建立y向和x 向颗粒运动方程，通过理论分析探索了颗粒在y 向和x 向的运动特性。运用计算流体力学理论，考察重力分级区内气流速度在y 向和x 向的变化规律，研究不同粒径颗粒的运动轨迹。结果表明，重力分级区内气流速度在y向上递增，颗粒在y 向做速度不断增大的变加速运动；气流速度在x 向上由返料锥近壁端向远壁端递减，颗粒在x 向做速度不断减小的变减速运动。研究结果可为选粉机的设计提供理论参考和数据基础。
The particle gravitational classification process is one of the important factors affecting the centrifugal classification performance of a classifier. To understand the particle motion characters in the gravitational classification zone of the classifier, an SLK5500 classifier is chosen as the object, and particle motion equations are built in the y direction and x direction by analyzing the action forces on the particle. And theoretical analysis is made to explore particle characters in the y and x directions on the basis of the particle motion equations. According to the computational fluid dynamics theory, the changing rules of gas velocities in the y and x directions of the gravitational classification zone are investigated, and particle trajectories of different diameters are studied. The theoretical analysis and simulation result show that in the gravitational classification zone, the gas velocity increases progressively in the y direction, where particle motion is a variable acceleration motion with an increasing acceleration; the gas velocity decreases from the return cone near wall terminal to the far wall, and the particle motion in the x direction is a variable acceleration motion with a decreasing acceleration. This research has provided a reference and data for the classifier structure design.
[1] 刁雄, 李双跃, 黄鹏. 进料方式对超细分级机分级性能的影响[J]. 化工 学报, 2012, 63(12): 3818-3825. Diao Xiong, Li Shuangyue, Huang Peng. Effect of feeding type on classification performance of superfine classifier[J]. Journal of Chemical Industry and Engineering, 2012, 63(12): 3818-3825.
[2] 张廷龙, 杨福新, 韩春阳, 等. 立磨笼式选粉机切割粒径的计算[J]. 矿 山机械, 2011, 39(7): 12-14. Zhang Tinglong, Yang Fuxin, Han Chunyang, et al. Computation of separation grain size of rotating cage separator for vertical roller mills[J]. Mining & Processing Equipment, 2011, 39(7): 12-14.
[3] 伍勇, 施光明, 方善如. 离心涡轮式气流分级机分级区域研究[J]. 四川 大学学报: 工程科学版, 2001, 33(3): 38-40. Wu Yong, Shi Guangming, Fang Shanru. Investigation for effective separation area of a turbo air classifier[J]. Journal of Sichuan University: Engineering Science Edition, 2001, 33(3): 38-40.
[4] 刘家祥, 何廷树, 夏靖波. 涡流分级机流场特性分析及分级过程[J]. 硅 酸盐学报, 2003, 31(5): 485-489. Liu Jiaxiang, He Tingshu, Xia Jingbo. Air flow field characteristics ana-lyzing and classification process of the turbo classifier[J]. Journal of the Chinese Ceramic Society, 2003, 31(5): 485-489.
[5] Toneva P, Epple P, Breuer M, et al. Grinding in an air classifier mill— Part I: Characterisation of the one-phase flow[J]. Powder Technology, 2011, 211(1): 19-27.
[6] Toneva P, Wirth K, Peukert W. Grinding in an air classifier mill— Part II: Characterisation of the two-phase flow[J]. Powder Technology, 2011, 211(1): 28-37.
[7] 刘圣照, 刘家祥, 冯永国, 等. 涡流空气分级机转笼结构对其分级性能 的影响[J]. 化工学报, 2007, 58(7): 1751-1756. Liu Shengzhao, Liu Jiaxiang, Feng Yongguo, et al. Effect of rotor structure on classification characteristics of turbo air classifier[J]. Journal of Chemical Industry and Engineering, 2007, 58(7): 1751-1756.
[8] 黄强, 于源, 刘家祥. 涡流分级机转笼结构改进及内部流场数值模拟[J]. 化工学报, 2011, 62(5): 1264-1268. Huang Qiang, Yu Yuan, Liu Jiaxiang. Improvement on rotor cage structure of turbo air classifier and numerical simulation of inner flow field[J]. Journal of Chemical Industry and Engineering, 2011, 62(5): 1264-1268.
[9] Finch J A. Modeling a fish-hook in hydro cyclone selectivity curves[J]. Powder Technology, 1983, 36(1): 127-129.
[10] Nageswararao K A. critical analysis of the fish hook effect in hydro cyclone classifiers[J]. Chemical Engineering Journal, 2000, 80(1/2/3): 251-256.
[11] 刘家祥, 徐德龙, 赵江平, 等. 涡流分级机内惯性反旋涡对颗粒分选 的影响[J]. 西安建筑科技大学学报, 1998, 30(1): 63-66. Liu Jiaxiang, Xu Delong, Zhao Jiangping, et al. The effects of inertia counter-roting vortices in vortex classifier on particle classification[J]. Journal of Xi'an University of Architecture & Technology, 1998, 30(1): 63-66.
[12] 刘家祥, 何廷树, 夏靖波, 等. 涡流空气分级机内湍流涡频谱对其性 能的影响[J]. 北京化工大学学报, 2003, 30(5): 48~51. Liu Jiaxiang, He Tingshu, Xia Jingbo, et al. The effect of frequency spectrum of the eddies of turbulent flow in a turbo classifier on its classification characteristics[J]. Journal of Beijing University of Chemical Technology, 2003, 30(5): 48~51.
[13] 杜妍辰, 王树林. 颗粒在涡轮式分级机分级轮中的运动轨迹[J]. 化工 学报, 2005, 56(5): 823-828. Du Yanchen, Wang Shulin. Particle trajectory in vortex classifier rotor[J]. Journal of Chemical Industry and Engineering, 2005, 56(5): 823-828.
[14] Xu N, Li G H, Huang Z C. Numerical simulation of particle motion in turbo classifier[J]. China Particuology, 2005, 3(5): 275-278.
[15] 黄卫星, 诸海碧, 黎梅, 等. 气固循环床上行两相流颗粒曳力系数研 究[J]. 四川大学学报: 工程科学版, 2008, 40(2): 53-57. Huang Weixing, Zhu Haibi, Li Mei, et al. Drag coefficient in gas-solid two phase flow of CFB riser[J]. Journal of Sichuan University: Engineering Science Edition, 2008, 40(2): 53-57.
