糙米的碾白过程模拟及破碎影响分析

Simulation of Blanching Process of Brown Rice and Analysis of Crushing Effect

为减少糙米碾白的碎米率问题,进行了糙米碾白过程的数值模拟及糙米破碎分析研究。基于离散元技术,利用EDEM离散元系统建立了糙米的离散元模型,在不同米筛边数和碾辊结构的情况下,进行了糙米在碾白室内的运动过程模拟,分析了糙米破碎的影响规律。结果表明:正四边形米筛中糙米沿米筛径向方向运动能力差,易位翻滚能力较弱,导致碎米率较低而碾白压力却最高,正八边形米筛中糙米运动能力最弱,糙米磨削大幅度下降,碎米率最低;增加碾筋个数使糙米在碾白室内沿径向方向的运动速度和自转角速度明显增加,糙米产生过碾,碎米率增大,减少碾辊直径后,增大了碾白室的轴筛间隙,糙米碾白均匀而不过碾,碎米率较低。

To reduce the crushing rate of brown rice,the whitening process of brown rice,including numerical simulation and crushing analysis was studied.Based on discrete element technology,EDEM discrete element system was utilized to establish a discrete element model of brown rice.The movement process of brown rice in the milling room was simulated under the conditions of different sieve edge number and roll structure,and the influence law of brown rice breakage was analyzed.The results show that the brown rice in the regular quadrilateral sieve has poor motion along the radial direction of the sieve and weak tumbling ability in translocation,resulting in a low rate of rice breaking and the highest rolling pressure.Due to the weakest movement ability of brown rice in the regular octagon rice sieve,the brown rice grinding drops greatly,resulting the lowest broken rice rate.Additionally,with the increase of the number of grain,the radial velocity and rotational angular velocity of the brown rice in the milling room increase obviously,making a increasing broken rate.After reducing the diameter of the roller,the gap of shaft and screen in the milling chamber is increased.The whitening process of brown rice occurre uniformly,which result a lower crushing rate.