Experimental study of the parametric impact on size growth of maltodextrin particles in counter-current spray dryer

Spray drying is closely related to the final product quality as it is mostly the last unit operation in the processing line. Counter-current spray drying experiments are relatively difficult to perform and due to this reason limited data is available. In this study, extensive experimental data is analyzed and results are presented. To better understand and optimize the performance of the spray dryer, an analysis of the final product received from 45 experimental runs of counter-current drying of maltodextrin solution was performed to check for the dependency of product properties on operating conditions. Effects of varying degrees of drying air swirl, atomizing nozzle gas-to-liquid ratios (GLR), the position of the nozzle with respect to drying air inlet, and power input for drying were analyzed. An optical measurement technique was used to measure the particle size distribution, velocity, and direction of motion. Samples were collected and scanning electron microscope (SEM) images were taken to analyze the particle morphology. Hollow spherical particles with thin crust were generated. Puffing and agglomeration were observed to be the phenomena that contributed to the increase in particle size, however the impact of puffing was found to be marginal. The results proved a strong dependency of the counter-current spray drying process on nozzle spray parameters and its position in the tower. The moisture content of the product showed a strong negative correlation with the temperature of the drying medium.

Automated summary

This study analyzed extensive experimental data to understand the dependency of product properties on operating conditions in counter-current spray drying. The results showed a strong correlation between the nozzle spray parameters, nozzle position, and the performance of the spray dryer. The moisture content of the product was found to have a strong negative correlation with the temperature of the drying medium.