Spray Dryers

Information on spray dryers, the different drying modes and their advantages.

The main advantage to powder producers is the ability to control powder form. Niro spray dryers are designed to produce the desired properties: particle size, bulk density, moisture content, solubility, dispensability etc.

The versatile size range for development and small scale production. For a given capacity, the properties of liquids to be dried, particle size distribution and powder quality to be produced are most important, and these must be carefully considered when selecting design of spray dryer and type of atomizer.

For development and small scale production the versatile range of Niro spray dryers – size 6.3 make an excellent choice. Three dryers make up the series, each with the same air flow rate and evaporative capacity ranging from 20 to 60 kg/h depending on drying temperatures.

For a given dryer capacity, the properties of the liquid to be dried, the particle size distribution, and the quality of the powder to be produced are most important, and these must be carefully considered when selecting the design of spray dryer and the type of atomizer.

For development and small scale production the versatile range of Niro spray dryers make an excellent choice. Three dryers make up the series, each with the same air flow rate and an evaporative capacity ranging from 20 to 60 kg/h, dependant upon drying temperatures. They have proven to be ideal for continuous small scale production of specialist powders and/or products where plant is required validated.

Custom-Designed Versions In-house expertise also covers engineering of custom-designed plants to meet special specifications:

Validation documentation
Aseptic execution
CIP systems (Cleaning-in-Place)
Spray Cooling
Fire and/or explosion protection
Emission-free operation
- Active carbon bed for solvent adsorption
- Closed cycle layout
- Vapor condensation for solvent recovery
- HEPA filtration

Different drying modes

Co-current Mode: Rotary Atomizer
Atomization is achieved by feeding liquid onto a high speed wheel. The rotary atomizer is placed in the ceiling air disperser and operates with a vaned atomizer wheel for non-abrasive feeds, or with a carbide bushing wheel for abrasive feeds. Other wheel designs are available for special applications. The particle size of the powder produced is controlled through change of wheel speed.

Co-current Mode: Two-fluid Nozzle
Atomization is achieved by using compressed air to atomize the liquid feed. The nozzle is placed close to the outlet of the ceiling air disperser. This arrangement is ideal for heat sensitive feeds and has the added advantage of being able to handle both low and high viscosity liquids. The particle size is controlled by varying the nozzle flow ratio between compressed air and feed.

Fountain Mode: Two-fluid
Nozzle or Pressure Nozzle. The nozzle is placed in the conical section of the drying chamber, spraying upwards into hot air entering the drying chamber through the ceiling air disperser. The fountain mode has the advantage of spray drying higher solid feeds and producing coarser powders. Selection of nozzle type depends on the feed properties and powder specification.

Read more about spray dryers.

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