An overview of the recent advances in spray-drying

Abstract

-A global overview is presented of recent developments in spray drying. Recent advances in computational fluid dynamics modeling have provided new insights into the flow processes occurring within the spray chamber. This is important since detailed experimental measurements within an operating spray dryer are almost impossible due to the hostile environment of hightemperature two-phase flow, which may be unsteady, and the high cost that would have to incur. Some recent predictive studies on predicted effects of innovative chamber geometry, reduced pressure operation, operation in low dew-point air and superheated steam are presented. Also, a comparison is made between steady and unsteady state computations to highlight the critical issues. Predicted results on a horizontal spray chamber configuration are also presented. Finally, a brief survey is made on the recent literature on spray freeze-drying as well as multi-stage drying processes.computational fluid dynamics / modeling / spray drying / CFDRésumé -Récentes avancées dans la conception et l'optimisation des installations de séchage par pulvérisation : une vue d'ensemble. Un inventaire des récents développements dans le domaine du séchage par pulvérisation est dressé. Les dernières avancées de la dynamique des fluides numérique ont permis d'obtenir de nouvelles représentations des processus d'écoulement ayant lieu à l'intérieur de la chambre de séchage. Ces modélisations sont très importantes car des mesures expérimentales détaillées à l'intérieur d'une installation de séchage en fonctionnement sont pratiquement impossibles à réaliser, en raison des conditions hostiles liées au flux à température élevée de deux phases, pouvant être irrégulier, et aux coûts qui seraient engendrés. Des études prédictives récentes sur les effets d'une géométrie innovante de la chambre, de conditions de pression réduite, d'air à bas point de rosée et de vapeur surchauffée, sont notamment présentées. Article published by EDP Sciences Une comparaison des calculs réalisés dans des conditions stables ou instables est également réalisée afin de mettre en lumière les points critiques. Les résultats de la prédiction pour une configuration de chambre horizontale sont présentés. Enfin, les dernières publications sur le couplage séchage par pulvérisation-lyophilisation et les procédés de séchage multi-étage sont présentées rapidement.dynamique des fluides / modélisation / séchage par pulvérisation / CFD

The Maillard Reaction in Powdered Infant Formula

“…Spray drying of the concentrated preparation is characterized by the atomization of the liquid into small droplets whose water molecules are evaporated by a flow of heated air. The hot air stream temperature varies between 140 and 200 °C but, due to the relatively brief exposure time of the particles to heating, their core temperature does not exceed 45 ºC [21,22].…”

Twin-fluid atomization of viscous liquids: The effect of atomizer construction on breakup process, spray stability and droplet size

“…Internal-mixing twin-fluid atomizers have been used in countless commercial applications over the recent decades, such as in gas turbine engines (Lefebvre, 1988), internal combustion engines (Wade et al, 1999), scramjet engines (Gadgil and Raghunandan, 2011), spray drying (Mujumdar et al, 2010), spray coating (Esfarjani and Dolatabadi, 2009;Qian et al, 2011), process industries (Loebker and Empie, 1997) and fire suppression (Huang et al, 2011;Lal et al, 2010). Y-jet nozzles in particular have been widely used in oil boilers, industrial furnaces, agricultural sprays, spray dryers and paint sprays (Zhou et al, 2010).…”

Influence of processing conditions on functional and reconstitution properties of milk powder made from Osmanabadi goat milk by spray drying

“…Spray drying process mainly involves five steps: concentration, atomization, droplet-air contact, droplet drying and separation (Patel et al, 2009) each stage affect of which has associated process variables which affect the efficiency of the process or the quality of the product (Callaghan and Cunningham, 2005). Spray drying technology is suitable to dry many heat-sensitive products, e.g., dairy products, foods and pharmaceuticals, due to the short drying time and ability to obtain a product in the form of powder (Mujumdar et al, 2010). The advantages of spray drying of heat sensitive products include a combination of shorttime processing which leads to a better quality product.…”