孜然脱粒机风筛式清选装置的设计与试验

    Design and test of the wind-sieve type cleaning equipment for cumin threshing machine

    • 摘要: 由于孜然籽粒粒径小、脱出物外形尺寸相似,且缺少专用的清选装置,导致孜然籽粒的清选含杂率高、清选效率低。该研究在孜然籽粒特有物理特征分析的基础上,结合现有各类清选装置的工作原理,设计了一种风筛式孜然清选装置,开展了具有针对性的清选装置关键部件的设计,包括复合式双层筛、贯流式风机、风挡拦截装置等。通过气固耦合仿真技术对清选流场压力分布、气流速度及清选物料固相运动规律进行分析,验证装置结构设计合理性,确定影响清选效果的主要因素为风速、振动频率、入风角度;将风速、振动频率、入风角度作为试验因素,以损失率及含杂率为评价指标,通过三因素三水平正交试验,得到自变量与清选效果的二次多项式响应面回归模型,并通过多元回归拟合分析得到清选装置最优工作参数为:风速10.27 m/s,振动频率4.07 Hz,入风角度20.26°。根据最优参数自制试验台架进行验证试验,得到孜然籽粒清选后的平均损失率、含杂率分别为3.40%和5.28%,损失率、含杂率的理论预测值与台架试验结果的相对误差分别为0.94%、1.73%,证明回归模型具有较高的准确性,孜然脱粒机清选装置的设计满足孜然籽粒清选作业标准。

       

      Abstract: Cumin grains face significant challenges during cleaning, due mainly to their small particle size and similar external dimensions. Specialized cleaning devices are necessary to improve a high impurity content rate and low cleaning efficiency. In this study, a wind-screen cumin cleaning device was designed, according to the unique physical characteristics of cumin seeds and the working principles of existing cleaning devices. The key components of the cleaning device encompassed the structural and parameter design of the composite double-deck sieve, the cross-flow fan, and the wind-blocking and intercepting device. Gas-solid coupling simulation was utilized to ensure its effectiveness. The pressure distribution was examined in the scavenging flow field, the airflow velocity, and the solid-phase movement of scavenging materials. The device structure was verified after the simulation. The main influencing factors on the scavenging effect were determined as the wind speed, vibration frequency, and air inlet angle. The three-factor and three-level orthogonal test was conducted as the test factors with the loss rate and the evaluation index as the impurity rate. A quadratic polynomial response surface regression model was obtained to further investigate the relationship between the independent variables and the scavenging effect. The optimal working parameters were identified for the scavenging device, with a wind speed of 10.27 m/s, a vibration frequency of 4.07 Hz, and an inlet angle of 20.26°. A homemade test stand was utilized to validate the optimal parameters. The combination of working parameters was tested as well. The average loss rate and impurity rate after cumin seed cleaning were 3.40% and 5.28%, respectively. The theoretical prediction value was close to the test ones, indicating the high accuracy of a regression model. Furthermore, the composite double-deck sieve was carefully considered to ensure efficient cleaning while minimizing loss. The cross-flow fan and wind-blocking-intercepting device also contributed to the overall effectiveness of the cleaning device. In conclusion, the wind-screen cumin cleaning device can serve as an effective solution to the challenges during cleaning. The optimal working parameters can be expected to minimize the grain loss and impurity rates. The gas-solid coupling simulation was used to further validate the structure design. The findings can provide a strong reference for the practical application and effectiveness of the cleaning device.

       

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