巴旦木物料壳仁风选装置试验及参数优化

Experiments and parameter optimization of almond shell and kernel air separation device

为了研究巴旦木壳仁物料的空气动力学特性,确定较优的壳仁风选参数,提高清选率,该研究采用理论计算与试验相结合的方式对巴旦木物料的空气动力学特性进行研究,根据悬浮速度研究结果设计巴旦木壳仁风选装置并对破壳后的巴旦木壳仁混合物料进行风选试验,基于响应面法优化求解得出风选装置较优参数组合。巴旦木壳仁混合物料的空气动力学特性试验结果表明,大壳、中壳、小壳和仁的悬浮速度变化范围分别为:9.92~11.03、8.86~9.66、8.27~8.85、13.10~13.96 m/s,控制气流速度在8.27~11.03 m/s范围内可较好地分离壳和仁。风选装置流场仿真分析结果表明,风选装置筛面风速分布呈中心高、四周低的特点。巴旦木壳仁风选试验结果表明,风选装置工作参数对清选率的影响从大到小排序为:筛体振动频率、清选风机转速、波纹筛倾角、风选装置喂入量、离心风机转速,结合壳仁风选试验与软件优化求解得出清选率较高的较优参数组合为:风选装置喂入量6 kg/min、清选风机转速1160 r/min、筛体振动频率为47 Hz、波纹筛倾角3°、离心风机转速1275 r/min,采用优化参数组合进行验证试验,清选率达99.144%。研究结果可为巴旦木壳仁风选设备研发与优化提供理论依据。

This study aims to explore the aerodynamic characteristics of almond shells,thereby optimizing the structure parameters in an air separation device.The finite element(FE)simulation was also performed on ANSYS 16.0-fluent flow field platform.A single-factor orthogonal test was selected to determine the optimal parameters for better performance of air separation and higher index of cleaning rate.Taking the Shache No.18 as the research object,the density and moisture content of almond shells and kernels were measured in a field test.A suspension speed test bed was used to optimize the aerodynamic characteristics of almond shells and kernels at the Agricultural Mechanization Research Institute of Xinjiang Academy of Agricultural Sciences,China.A field test was also performed on the mixture of cracked shell kernels in an air separation device with an optimized structure.A Design Expert 10.0 software was used to calculate for a better parameter combination of the air separation device.The results showed that there was a great variation in the suspension velocities of a large shell,medium shell,small shell and kernel of Shache 18 almond,ranging from 9.92 to 11.03,8.86 to 9.66,8.27 to 8.85,and 13.10 to 13.96 m/s,respectively.The flow field simulation showed that the distribution of air velocity was higher on the vibrating screen surface of the air separation device,particularly in the center and low around.Subsequently,a systematic optimization was made on the feeding and discharging ports of the air separation device after the simulation.The single factor test showed that there was a great influence of feed rate and cleaning fan speed on the loss rate of the material.Additionally,since the loss rate of the material under each factor was within the acceptable range during the test,the orthogonal test did not consider the loss rate so far.Correspondingly,the orthogonal test demonstrated that the influence of working parameters on the cleaning rate was ranked in order from large to small:screen vibration frequency,cleaning fan speed,corrugated screen inclination angle,and feeding amount in the air separation device.Consequently,an optimal parameter combination of high cleaning rate was also calculated as follows:the feeding amount of 6 kg/min,cleaning fan speed of 1160 r/min,screen vibration frequency of 47 Hz,inclination angle of 3°for the vibrating screen,and the speed of centrifugal fan was 1275 r/min,particularly combining with the orthogonal test and optimization function of shell kernels in an air separation device.A verification test was then conducted to calculate the average of parameters in the optimal combination under the same test environment and conditions.It was found that the cleaning rate reached 99.144%.The findings can provide sound theoretical support to the development and optimization of air separation equipment for the shell and kernel of almond.