Performance of spouted bed on drying of foliar fertilizer: analysis of yield and powder retention

Abstract

Foliar fertilization is one of the most important management techniques used to improve crop productivity and quality.  To increase the efficiency of fertilization, the fertilizer must be highly soluble. The drying of paste and solutions in spouted bed can change the powder structure, making it more soluble. However, depending on the operational conditions, the powder yield produced in this operation may be low. As such, the goal of this research was to investigate the impact of operational conditions on powder yield and powder losses caused by adhesion on the walls of the bed and cyclone, on the particle surface, on the exhaust tube, filter, and filter overflow. To accomplish this, a 23 factorial design was used. The results of powder yield (between 2.3 and 26.6%.) were like those obtained in other spouted bed applications, but lower when compared to spray-dryer. The higher powder retention occurred on the surface of the inert particles and at the bed wall. A high level of instability was observed during spouting, which may have increased the powder adherence at the equipment\u27s walls. The powder obtained after drying was solubilized about 5.9 times fast than the original fertilizer, demonstrating that the technique is promising if the bed stability is maintained.La fertilización foliar es una de las principales técnicas de manejo utilizadas para mejorar la productividad y calidad de los cultivos. Para que la fertilización sea más eficiente, el fertilizante debe ser altamente soluble. El secado de pastas y soluciones en un lecho de chorro es capaz de cambiar la estructura del polvo para hacerlo más soluble. Sin embargo, el rendimiento de polvo producido en esta operación puede ser bajo, dependiendo de las condiciones de operación. Así, este trabajo tuvo como objetivo estudiar la influencia de las condiciones de operación en el rendimiento de polvo y las pérdidas de polvo que ocurren por adherencia en las paredes de lo lecho, ciclón, tubo de escape, filtro y salida del filtro. Para ello se utilizó un diseño factorial 23. Los resultados del rendimiento del polvo (entre 2,3 y 26,6%). La mayor retención de polvo se produjo debido a la adhesión en las paredes del lecho y en la superficie de las partículas. Se observó alta inestabilidad del chorro, lo que pudo haber aumentado la fracción de polvo retenido en las paredes del equipo. El polvo obtenido presentó un tiempo de solubilidad 5,9 veces menor que el material in natura, demostrando que la técnica es promisoria, siempre y cuando se mantenga la estabilidad en el lecho.Foliar fertilization is one of the most important management techniques used to improve crop productivity and quality. To increase the efficiency of fertilization, the fertilizer must be highly soluble. The drying of paste and solutions in spouted bed can change the powder structure, making it more soluble. However, depending on the operational conditions, the powder yield produced in this operation may be low. As such, the goal of this research was to investigate the impact of operational conditions on powder yield and powder losses caused by adhesion on the walls of the bed and cyclone, on particle surface, on the exhaust tube, filter, and filter overflow. To accomplish this, a 23factorial design was used. The results of powder yield (between 2.3 and 26.6%.) were like those obtained in other spouted bed applications, but lower when compared to spray-dryer. The higher powder retention occurred on the surface of inert particle and at the bed wall. A high level of instability was observed during spouting, which may have increased the powder adherence at the equipment\u27s walls. The powder obtained after drying was solubilized about 5.9 times fast than the original fertilizer, demonstrating that the technique is promising if the bed stability is maintained