茶叶圆筛条件分析与过程数值模拟

摘要

Tea plane circular sieve is one of the most important machines in tea sieving, it sieves the tea according to the size. The effect of sieving showed a great impact on the quality of the tea and the efficiency of tea processing. Based on the analysis on the motion path and sieve condition and sieving process of tea particles on the sieve surface was simulated by using discrete element analysis software PFC3D. Theoretical analysis and simulation results showed that: (1) the sieve permeation rate is related to tea motion path, relative radius vector of the sieve and the relative velocity, (2) there are different optimal circular speeds for different sieve mesh, (3) the sieve permeation rate can be improved and the motion path length of tea particles could be prolonged by increasing the radius of circle. The theory based on a single grain of tea is consistent with numerical simulation results of tea partic les. It illustrated this theoretical analysis was suitable for tea particles sieving. The presented results provide the reference basis for the design and exploitation of tea plane circular sieve.%平面圆筛机是茶叶筛分中应用最为广泛的机械之一，其筛分效果影响着茶叶生产的质量与效率。在分析茶叶颗粒群在筛面上的运动条件、运动路径、透筛条件等基础上，运用离散元分析软件 PFC3D对其筛分过程进行了数值模拟。理论分析及模拟试验结果表明，平面圆筛机的透筛率与茶叶的运动路径、透筛的相对矢径和相对速度相关；对于不同目数的筛网，存在不同最佳回转速度；增加回转半径，可以大幅增加茶叶颗粒在筛床上的运动路径长度，提高透筛率。理论分析与模拟试验结果相符，为平面圆筛机的设计与操作提供了参考依据。