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.

SPRAY COOLING PLANT DESIGN

The selection of a spray cooling plant design depends upon the particle size specified as well as the need for post-cooling/crystalization for the cooled product:

  • Fine particle products with mean particle size 50-150 micron - 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. Atomization by low-speed rotary atomizer in cooling chambers of large diameters with flat-base or a 2-stage fluidized bed base design. In the flat bottom execution, the product particles fall onto the floor of the chamber and leave with the exhaust air through the slowly-rotating broom-like exhaust air duct. In the 2-stage fluidized bed design a rotary cup- or bucket-type atomizing
  • 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.

PRODUCTS

  • Encapsulated materials
  • Fats
  • Glycerides
  • Hydrates
  • Inorganic/organic melts
  • Quaternary ammonium compounds
  • Stearic acid/stearates
  • Waxes