Spray drying scale-up: an overview of process, atomization, and scale-up critical parameters

Sexta-feira, Janeiro 28, 2022 - 14:15

Universidade Católica

Rua Diogo Botelho, 1327
4169-005 PORTO
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Rui C. Silva will talk about his research on the 28th of January 2022 starting at 14:15. No need to register

Spray drying technology was first patented in the 1870s, with initial development of equipment and techniques occurring over the subsequent three decades. However, it was only in the early 1900s that spray drying was used commercially for production of powdered milk products by the dairy industry. In general terms, spray drying is the continuous evaporation of a fluid feed into dried particulate form by atomization into a hot drying medium. The feed may be a solution, slurry, emulsion, gel or paste, as long as its rheological behavior allows it to be pumpable and, thus, capable of being atomized.

The process consists in supplying a heated gas medium into a chamber to which a highly dispersed liquid is introduced to produce evaporation and drying of liquid droplets. The droplets while losing their liquid to the hot gas remain at temperatures much below the hot gas temperature for a very short time, which is why spray drying is known as "Low Temperature Drying", and form particles which are then collected into a collector, typically, a cyclone. The gas medium is then exhausted with liquid vapor.

Rapid drying kinetics from liquid droplet to solid particle, which can take on the form of powders, granules, or agglomerates, the mild temperature exposure of the drying droplet owing to evaporative cooling, and the short residence time of particles in the drying chamber, allied to the physical and chemical properties of the feed, the dryer design and final powder properties desired provide spray drying a notable capability in manipulating powder/particle characteristics such as size, morphology, density and level of residual solvents. Owing to these properties spray drying has become one of the most sought-after unit operations for the manufacturing.

Spray drying has become a standard technology in several industries such as chemical, food, biotechnology and pharmaceutical. It is applied in amorphous solids dispersions, microencapsulation, granulation and complex formation, as well as the modification of biopharmaceutical properties and the formulation of dry powder aerosols and heat sensitive materials in scales ranging from lab units where milligrams of material can be produced to very large commercial units capable of handling several tons per day. 

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