旋流式流化床丸化装置数值模拟及试验

Numerical Simulation and Experiment of Swirling Fluidized Bed Pelleting Device

为了提高冰草种子机械播种效率、优化冰草种子丸化机的丸粒工艺,设计了旋流式流化床冰草种子丸化装置。应用计算流体力学(CFD)方法对旋流式流化床中冰草种子和丸化粉料间的时空分布情况进行仿真分析,采用Realizable-K-ε湍流模型模拟气相,利用离散相模型追踪固相冰草种子和粉料的运动轨迹。通过对旋流式流化床的仿真模拟,确定了进风风速、种衣剂喷射量、喷射时间等参数。模拟与试验结果表明:当入口风速为3.5 m/s、喷射量为6mL/s、药液喷射时间为1.1s时,冰草种子与丸化粉料之间因被空气分离而悬浮,形成旋流式流化床,此时的种粉间形成液力桥,有效地提高了种粉间的粘结效果及丸粒强度,单籽率及丸化合格率可达到82%及95%。

In order to improve the seeding efficiency and optimize the pelleting process of agropyron seeds pelleting machine,a swirling fluidized bed pelleting device was designed.Computational fluid dynamics(CFD)was used to simulate the mixing of Agropyron seeds and powders in a swirling fluidized bed.The realizable-k-εturbulence model was used to simulate the gas phase,and the discrete phase model was used to track the trajectory of the solid-state Agropyron seeds and powders.Through the simulation of the swirling fluidized bed,the size of the container(including the cavity and the air guide plate),the inlet air velocity and the injection quantity are determined.The simulation and experimental results show that when the inlet wind speed is 3.5m/s,the injection volume is 6mL/s,and the injection time is 1.1s,the agropyron seeds and pelletized powder are suspended by air separation,forming a swirling fluidized bed.At this time,a hydraulic bridge is formed between seed and powder,which effectively improves the bonding effect and shot strength between seeds and powders.The single seed rate and pelleting qualification rate can reach 82%and 95%.