Spray Drying Tower Experiments

Zbiciński, Ireneusz; Piątkowski, Marcin

doi:10.1081/drt-120038732

Cited by 24 publications

(12 citation statements)

References 6 publications

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“…[1,2] As follows from the observations made during research carried out earlier at Lodz Technical University, an improper definition of some initial parameters, particularly atomization parameters, e.g., each fraction should be characterized by the distribution of both velocity and spraying angle and not assumed as equal for all fractions, can be also of vital importance. [3] Due to the flexibility and effectiveness, computational fluid dynamics (CFD) technique has been widely applied in designing and scaling-up of spray-drying process since the 80-ties. Most of CFD models of spray-drying process [1,2] enable correct determination of the continuous-phase parameters (e.g., distributions of drying air temperature and humidity) regardless a number of simplified assumption in initial and boundary conditions but taking into account heat losses to the environment, the effect of atomizing air, and selecting proper model of flow turbulence.…”

Section: Introductionmentioning

confidence: 99%

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Conditions for Accurate CFD Modeling of Spray-Drying Process

Zbiciński

2006

Drying Technology

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The paper presents concluding results of extensive experimental and theoretical research on confident CFD modeling of spray drying. An earlier developed experimental method to determine spray-drying kinetics in a lab scale allowed us to find a critical material moisture content and to determine generalized spray-drying curves. The generalized drying curves, identical in shape in the laboratory and pilot plant units, were used in the CFD model of spray drying process. Extensive simulations for spray drying of 10, 30, and 50% of initial solid content of maltodextrin proved high accuracy of the predictions of discrete (particle size distribution, particle moisture content, particle velocity, spray temperature) and continuous-phase parameters (gas temperature and humidity). Maximum error of the predictions of discrete-phase parameters was on the level of 20%, which is probably close to the current capacity of the CFD technique for modeling of spray-drying process. Comparison of experimental measurements and theoretical results shows that incorporation of realistic spray-drying kinetics into the CFD model and correct definition of initial drying and atomization parameters enable reliable simulations of spray-drying process.

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Section: Introductionmentioning

confidence: 99%

“…Appropriate data to evaluate particles were taken from PDA measurements. [3] In Fig. 1, the triangles represent selected measurements in the pilot-scale spray dryer.…”

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confidence: 99%

Conditions for Accurate CFD Modeling of Spray-Drying Process

Zbiciński

2006

Drying Technology

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“…As it is difficult to follow the changes in the drop surface properties during spray drying, we assumed that the flows of air and particles are associated and that evolution of drying air properties is representative of drop drying, especially in a co-current single-step spray dryer. Air properties can be measured inside the chamber to estimate the particle drying rate, the amount of water evaporated and the maximal product temperature at different levels in the chamber [17].…”

Section: Introductionmentioning

confidence: 99%

Powder agglomeration during the spray-drying process: measurements of air properties

Gianfrancesco

Turchiuli

Dumoulin

2008

Dairy Sci. Technol.

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-Instant food powders are usually produced by spray drying of formulated liquid and powder agglomeration, either into the drying chamber or in an external fluid bed. During spray drying, according to the liquid composition, the viscosity of the initial liquid drops increases more or less rapidly, until the drop surface reaches a rubbery state considered as sticky, before further drying. This sticky property may be used to produce agglomerates inside the chamber by adding dry solid particles, as fines. The present study deals with a methodology to identify regions where the drying drops are sticky in relation to drying conditions (inlet air temperature 144-159-174 • C, liquid flow rate 15 to 75 mL·min −1 ), using a co-current pilot spray dryer with rotary atomizer. Assuming that drying air properties' (temperature and humidity) evolution is representative of drop drying (drying rate, amount of evaporated water), we realized a map of temperatures and relative humidity for drying air inside the drying chamber. Trials were performed with water (feasibility) and a maltodextrin aqueous solution (40% w/w, DE12) as a model product with sticky properties during drying. The results showed that drying behavior was different for water and aqueous maltodextrin solution. For both, in the tested conditions, the percentage of evaporated water was found to vary from 57 to 89% in the top part of the chamber, close to the atomizer. That represents a possible region where dry fines could be introduced for agglomeration. Résumé -Agglomération de poudres au cours du processus de séchage par pulvérisation : mesure des propriétés de l'air. Les poudres alimentaires instantanées sont habituellement produites par séchage par pulvérisation d'une solution formulée, suivi d'une étape d'agglomération, soit dans la chambre de séchage soit dans un lit fluidisé externe. Au cours du séchage, selon la composition du liquide, la viscosité des gouttes liquides augmente plus ou moins rapidement jusqu'à ce que la surface de la goutte devienne collante, avant séchage ultérieur. Cette propriété collante peut être exploitée pour produire des agglomérats dans la chambre par introduction de particules solides sèches, les fines. Cette étude cherche à établir une méthodologie pour identifier des zones où les gouttes qui sèchent deviennent collantes en fonction des paramètres de séchage (température d'entrée d'air 144-159-174 • C, débit liquide de 15 à 75 mL·min −1 ), en utilisant un séchoir pilote co-courant équipé avec une turbine de pulvérisation. En supposant que l'évolution des propriétés de l'air (température et humidité) au cours du séchage soit représentative du séchage des gouttes (vitesse de séchage, quantité d'eau évaporée), des cartographies des températures et des humidités relatives de l'air dans la chambre de séchage ont été réalisées. Des essais ont été effectués avec pulvérisation d'eau (faisabilité), puis d'une solution de maltodextrine (40 % w/w, DE12) comme produit modèle pouvant avoir un comportement collant au cours du séchage. ...

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“…The temperature of continuous and disperse phase and air humidity in the dryer were tested on-line. Commercial Dantec systems (Particle Dynamics Analyzer (PDA) and Laser Doppler Anemometry (LDA)), were used to determine the distribution of particle diameters and velocities (Zbicinski and Piatkowski 2004). Samples of material were taken to determine changes in moisture content along the drying path (Delag 2002).…”

Section: Experimental Set-upmentioning

confidence: 99%

“…These systems permit complex studies on momentum, heat and mass transfer during concurrent and counter-current spray drying (Zbicinski and Piatkowski 2004).…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Mechanism of Counter-current Spray Drying

Piątkowski

Zbiciński

2006

Transp Porous Med

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Results of experimental investigations of the effect of drying and atomization parameters on counter-current spray drying are discussed. Based on 96 experimental tests, the local and global distributions of velocity, temperature, drying air humidity and moisture content of material dried in the drying tower were determined. Analysis of the results showed that the process of agglomeration during counter-current spray drying depended mainly on air temperature in the atomization zone.

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Spray Drying Tower Experiments

Cited by 24 publications

References 6 publications

Conditions for Accurate CFD Modeling of Spray-Drying Process

Conditions for Accurate CFD Modeling of Spray-Drying Process

Powder agglomeration during the spray-drying process: measurements of air properties

Analysis of the Mechanism of Counter-current Spray Drying

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