Production of highly soluble foliar fertilizer in a spouted bed dryer

ABSTRACT The drying process can be useful to change the particulate structure, improving the powder solubility. In this study, we investigated the drying of foliar fertilizer in a spouted bed using polyethylene pellets as inert particles to improve its solubility. A 23 factorial experimental design was used to evaluate how the powder yield and moisture were affected by the feeding time, intermittency time, and feed atomizer position. The spouting instability caused powder retention on the bed wall, which decreased the powder recovery efficiency by 2.3-26.6%. Although the powder recovery efficiency was low, the solubility time was reduced by 5.9 times, probably due to particle agglomeration, which increased the amorphous phase of the fertilizer. Design alterations, suggested by the CFD data, can increase spouted bed stability and facilitate centralized spouting. Based on this, the spouted bed drying technique was applied, and it effectively increased the solubility of commercial fertilizer, thus, incorporating more desirable characteristics for field applications.

摘要：干燥工艺可用于调控颗粒结构，提升粉体溶解性。本研究以聚乙烯颗粒作为惰性粒子，在喷动床（spouted bed）中对叶面肥开展干燥处理，以改善其溶解性。采用2³析因实验设计，考察进料时间、间歇时间与进料雾化器位置对粉体收率与含水率的影响。喷动不稳定会导致粉体附着于床壁，使粉体回收效率降低2.3%~26.6%。尽管粉体回收效率偏低，但粉体溶解时间缩短至原时长的1/5.9，该现象或源于颗粒团聚提升了肥料的非晶相占比。计算流体动力学（Computational Fluid Dynamics，CFD）数据提示的工艺调整方案可提升喷动床稳定性，促进集中喷动。基于上述结果，本研究将喷动床干燥技术应用于商业化肥料，有效提升了其溶解性，赋予该肥料更适配田间应用的优良特性。