Authors

Abstract

In order to explore the temporal and spatial distribution and motion state of the grains of wheatgrass (Agropyron) seeds and powder in pelleting process, and to find the optimal inlet air speed of pelleting premixer, the pelleting forming mechanism was revealed. Based on Herz-Mindlin contact theory, the contact mechanics model of seed and powder was established. Besides, CPFD software was used to model and simulate the pelleting premixer, and the contact, collision and friction rules among particles were analysed. The simulation and experimental results show that with the increase of inlet wind speed, the bed expansion increases and the unit volume particle concentration decreases, while the air pressure difference only slightly increases. When the inlet wind speed is set at 3.5 m/s, the atomizing nozzle velocity is set at 4.1 m/s, and the seed coating agent flow rate is 0.36 L/min, the particles are suspended due to air isolation, forming a spouted fluidized bed. It is good for seed and powder contact and rapid prototyping. In this time, the pelleting qualified rate was 95.8%. The results provide theoretical basis and technical support for the research of small irregular seeds pelletizing technology.

Abstract in Chinese

为了探究冰草种子与丸化粉料在丸化过程中的颗粒时空分布、运动状态以及寻找丸化预混合装置最优的进气速度，揭示丸化成型机理。基于Herz-Mindlin接触理论，建立了种粉丸化接触力学模型；采用CPFD软件对丸化预混合装置进行建模与仿真分析，分析颗粒间的接触、碰撞、摩擦规律。仿真与试验结果表明：随着风速增加床体膨胀升高，床体内单位体积颗粒浓度下降，而气压差仅略微增加，当入口风速设为3.5 m/s、雾化喷头速度设为4.1 m/s、种衣剂流量0.36 L/min时，颗粒间因被空气隔离而悬浮，形成喷动式流化床，有利于种粉接触、快速成型，该风速下丸化合格率为95.8%。研究结果为小粒不规则种子丸化技术的研究提供理论基础和技术保障。