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The spray cooler is ideal for:
• Encapsulated materials
• Fats
• Glycerides
• Hydrates
• Inorganic/organic melts
• Quaternary ammonium compounds
• Stearic acid/stearates
• Waxes |
What is spray cooling/congealing?
The transition of a melt from a soft or fluid state to a rigid or solid state by cooling is called congealing. The various droplet formation techniques and the efficient droplet / air contact make the spray drying concept ideal for making spherical particle powder by congealing of melts. During the spray cooling / spray congealing process a melt is formed into particles of spherical shape by spraying the melt into a cooling chamber.
The spray cooling process
Cooling is performed by air introduced at sufficient low temperature. The melt can be atomized or prilled by a rotary atomizer equipped with a special designed wheel. Another option is to atomize the melt by pressure nozzles or 2-fluid nozzles.
Spray cooling is utilized in the chemical, food, and pharmaceutical industries. It is a convenient method of transforming melted feed stocks into free-flowing particulates of controlled particle size.
Niro’s spray cooling plants
The selection of a spray cooling plant design depends upon the particle size specified as well as the need for post-cooling/crystallization for the cooled product:
• Process plants can be designed with co-current-, mix-current- or counter-current air flow in the chamber. The bottom of the chamber is either conical or flat and can be equipped with or without internal fluid beds
• Fine particle products with mean particle size 50-150 micron are often congealed in co-current conical based cooling chamber with high-speed rotary atomization
• Coarse particle products with mean particle size 150-300 micron - conical based cooling chamber with fountain nozzle
• Extra coarse particle products with mean particle size 300-1000 micron, also called prills. Atomization is made by low-speed rotary atomizer in cooling chambers of large diameters and often additional cooling is needed to ease full congealing
• Slowly solidifying products: In cases where melts are slow to solidify, the cooling time available in the spray chamber may be insufficient and particles can leave the chamber without being completely solid, stable and cool, which leads to product caking and lumping during storage. A second stage is then required to complete the operation, either by fluid-bed cooling or pneumatic conveying
Recent developments in spray cooling include the use of congealing chambers with integrated bag filters for congealing and separation of product in one unit. This design is very compact and thus space-saving.
SIMPLIFIED FLOW SHEET: