Experimental and numerical analysis of soybean meal drying in fluidized bed

Soybean meal is the main source of protein used in animal feed worldwide. This highly competitive market leads to the continuous search for improvements in product quality and reduction of process costs. Drying is one of the key steps in the production of soybean meal, contributing significantly to the final quality of the product. In this context, the main objective of this work was to study experimentally and computationally the soybean meal drying in a fluidized bed dryer. In order to determine the kinetics of soybean meal drying and the influence of temperature, speed of drying agent, and bed height on the fluidized bed drying process, experimental runs were performed, varying each of these parameters. The experimental results show that the drying rate of soybean meal has only the decreasing period, so the factor that controls this process is the diffusion inside the material. Temperature had a significant influence on the process, while the height of the bed of particles and the speed of the drying agent did not have significant influence in the range of experimental conditions investigated. An Eulerian-Eulerian model was used to simulate fluid dynamics and fluidized bed drying, and the numerical simulations were performed with the CFD (computational fluid dynamics) code MFIX. A mass transfer model was incorporated into the available fluid dynamics model in order to study the soybean meal drying in the fluidized bed. The comparison of the numerical results obtained through computer simulations with experimental results showed good agreement. The mathematical model is thus suitable to describe both fluid dynamics and drying of soybean meal in the fluidized bed, indicating potential use of CFD in fluidized bed drying problems. (C) 2012 Elsevier B.V. All rights reserved.