CFD Modeling and Simulation of Maltodextrin Solutions Spray Drying to Control Stickiness

Abstract

Particle stickiness during spray drying can lead to operational problems or be used to perform agglomeration inside the chamber. A simplified computational fluid dynamics approach is proposed to simulate the spray drying of 40% w/w aqueous solutions of maltodextrin DE12 and DE21 in a pilot cocurrent spray dryer equipped with rotary atomizer. Drying was simulated at steady state considering the geometry of the equipment (drying chamber, air inlet, atomizer) and the close relation between drying air and product properties. To take into account the lower drying rate of liquid solutions compared to pure water, the water vapor pressure of the drying particles was decreased with a coefficient determined from experimental data on air temperatures and humidities measured in the chamber. The evolution of particle temperature and water content was simulated. From these values and glass transition temperatures of the considered materials, it was possible to determine zones and operating conditions for which particles could be sticky inside the chamber. Maltodextrin DE12 was quickly dried close to the atomizer reaching a stable nonsticky state below glass transition temperatures Tg, while maltodextrin DE21 with lower Tg could exhibit a sticky behavior in a wider part of the chamber, depending on the liquid flow rate. This approach provides a methodology to evaluate possible stickiness to avoid fouling of the plant or to optimize powder insertion position for agglomeration.

Microencapsulation Quality and Efficiency of Lactobacillus casei by Spray Drying Using Maltodextrin and Vegetable Extracts

“…The final moisture content and water activity (a w ) are also defined by the spray drying process (Huntington, 2004;Gianfrancesco et al, 2010) and are important parameters to maintain good quality of the powders obtained; Ananta et al (2005) suggest moisture values lower than 5% and a range of 0.15 to 0.3 of a w , to avoid agglomeration problems during transportation and storage. The moisture content and a w values of the powders obtained in this study, are within the suggested ranges.…”

“…Some fruits and vegetables rich in these kind of compounds are tubers, quince, celery, arthichoke, broccoli, carrots, banana, plum, oranges, and apples, among others (Chau & Huang, 2003;Altieri, Bevilacqua, & Sinigaglia, 2011). However, special attention must be given in choosing the mixture suspension to be used for microencapsulation by spray drying due to some stickiness problems in the drying chamber (Palzer, 2005;Gianfrancesco, Turchiuli, Flick, & Dumoulin, 2010) or during storage (Langrish & Chiou, 2008) which may affect the final product quality or spray drying efficiency.…”

Modeling and Scaling Up of Industrial Spray Dryers: A Review

“…Figure 5 shows that droplets mainly stick to the walls in the upper main chamber, the lower main chamber and at the base of the bustle as in these regions the flow field streamlines are tightly curved and the particles traversing the streamlines impact with the walls. Gianfrancesco et al (2010) elaborated CFD model to simulate the spray drying of maltodextrin DE12 and DE21 in a pilot co-current spray dryer to control material sickness. They estimated zones and operating conditions for which particles could be sticky inside the chamber on the basis of the evolution of particle temperature, water content and glass transition temperatures.…”

Spray Drying for the Production of Nutraceutical Ingredients—A Review

“…Due to their low glass transition temperature and hygroscopic nature, the dried products become sticky (Jaya and Das 2009). The stickiness of particles during the spray drying can lead to many operational problems as well as be responsible for the formation of agglomerations inside the chamber which may reduce product recovery (Gianfrancesco et al 2010).…”