Development Of Mini Pellet Experiment Platform And Research On Pellet Feed Strength Distribution Characteristic

With the further development of the feed industry, more and more strict demands are proposed in the quality consistency of pellet feed. However, the test platform and methods of determining the quality of pellet feed need to be improved. In view of this situation, the forming process of pellet feed was analyzed and a small pellet mill which meets the processing test was designed. Based on the fact that pellet feed is a kind of isotropic brittle material, the method that using the dispersal strength data of pellet feed to describe quality consistency of pellet feed was put forward. The results are as follow:1. Based on the pellet feed forming conditions and combining with the characteristies of pellet feed forming process, the main structure characteristics of mini pellet mill was put forward:axial multi-points steam adding conditioner+double roller ring die pellet mill. When the mini pellet mill was completed, the performance of the mini pellet mill was tested,2.2t test feed was produced, platform run stable, and the PDI and moisture of the pellet feed were meet the requirements of pellet feed quality.2. The core structure parameters of the mini pellet mill:the diameter of conditioner is100mm, the length of conditioner is600mm, the inner diameter of the ring die is180mm, the width of the ring die is15mm, and the diameter of the roller is70mm. The working parameters of the mini pellet platform: the range of conditioning temperature is48℃～90℃, the maximum productivity (taking the big pig feed for example) is42kg/h.3.Based on the pellet feed is a kind of isotropic brittle material, the strength was chosen as evaluating indicator of pellet feed quality.6kinds of feed were selected in this study, with the compression test by universal material testing machine,55specimens of pellet feed was measured. After analyzing the strength of sample, the results showed:the strength data of pellet feed were discrete, and it was unimodal distribution. The strength data were fitted by unimodal distribution and the distribution function were fitted by K-S function. It was found that the strength obeyed Weibull distribution.4.The study is conducted to evaluate the effect of processing technique on pellet feed quality consistency. When the conditioning temperature was75℃,t he PDI increased from95.6to97.3, and the shape parameter m value of Weibull distribution decreased from3.727to2.094with the increase of raw material particle size; when the conditioning temperature is85℃, the PDI decreased from96.8to95.8and then increased to97and the shape parameter m value of Weibull distribution decreased from3.808to1.863with the increase of raw material particle size; scale parameter σ0values fluctuated around a horizontal line; when the conditioning temperature was75℃and the grinding screen was2.0mm, there was an obvious fluctuation. Maybe this is because that the material surface area increases with the decrease of the particle size, heat transfer speeded up in the conditioning process, the material is more homogeneous, the differences between products are reduced, and the quality consistency is improved.The results are as follow: the shape parameter m value of Weibull distribution could reflect the negative influence on the pellet quality consistency, but the conventional evaluation index PDI could not reflect the change of quality consistency very well. The scale parameter σ0of the weibull distribution parameter could be used as index to evaluate the strength of the pellet feed; the shape parameter of Weibull distribution is an effective and feasible method to evaluate the quality consistency of pellet feed.