Two flexible methods for producing fine powders: Spray drying and spray congealing
Spray processing is a flexible technology that can produce powders with a range of physical properties by either drying or congealing. Once the sole domain of bulk chemical manufacturers, spray processing technology now yields such products as coffee and laundry detergent. Read this article for an introduction to spray processing: Sections cover spray drying and spray congealing, required equipment, and how feed fluid properties and process parameters affect spray processing efficiency.
Spray processing has been used to manufacture products ranging from pharmaceutical granules to encapsulated flavors. The two main spray processes are spray drying and spray congealing [also called spray chilling]. Both use the same basic equipment and operating principles and are typically continuous: A feed fluid [typically containing a suspended material or a melted material] is atomized inside a cylindrical vessel. The droplets are then exposed to either a hot gas, which evaporates the liquid from the droplets, or a cool gas, which congeals the droplets. A cyclone typically separates the resulting particles from the gas.