The Benefits of Using Spray Nozzles Instead of Rotary Atomisers for Spray Drying Applications
6
Feb 25
Many different industries use rotary atomisers for their spray drying applications. The discs rotate at high speeds, typically between 10,000 to 30,000 rpm, to atomise liquid into small droplets. However, rotary atomisers present several challenges when used for spray drying. These include inconsistent droplet size distribution and increased susceptibility to damage, leading to higher maintenance costs and prolonged downtime for component replacements.
Spray nozzles provide a more practical approach to spray drying as they provide an increased evaporative capacity and keep maintenance costs low. Replacing the use of rotary atomisers with SprayDry® nozzles can be very beneficial to your spray drying applications.
The table below outlines the differences between rotary atomisers and spray drying nozzles.
| Rotary Atomisers | SprayDry Nozzles | |
| Basic Differences |
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| Chamber Size Differences |
As the drying air enters the chamber in a spiral (vortex) motion, the powder residence time is reached at a lower height. Atomisation occurs from the side of the disc, causing the spray to disperse at a tangent, projecting drops onto the walls. Therefore, the chamber must be wide enough to prevent the spray from reaching the chamber wall. | As the drying air enters the chamber in a straight and downward direction, the powder residence time is reached when the drop falls, requiring greater height. As the droplets generated are projected downwards, there is no need for the chamber to be wide, as the spray formed does not typically reach the chamber wall. |
Advantages of Replacing Rotary Atomisers with Spray Drying Nozzles
- Allows for an increase in the evaporative capacity of the dryer (kg of water evap./hour)
- Greater control in the atomisation process
- Delivers results that can only be achieved with spray drying nozzles, including:
- Drying slurries with a solid content above 50%
- Wider range of product types for drying in the same dryer
- New powder density parameters (outside the disc adjustment range)
- Elimination of atomising head maintenance to the following:
- Electric motor
- Hydraulic unit
- Cooling unit
- Pressure switches
- Flow switches
- Bearings, pulleys, gearbox belts, etc.
- Eliminates the need for the rotary atomiser and its entire electrical, mechanical and automation components
- Non-vortex air flow results in decreased formation of agglomerated residue on the dryer walls
- Wide variety of powder density adjustment options available
- Simple and cost-effective maintenance - there is no need to replace the entire nozzle, only its internal components when wear occurs
- Increased evaporative capacity
- Capable of drying solutions with a solid content exceeding 50%
- Enhanced drying capacity for products with high hygroscopic properties, such as sugar and fats For more information about our spray drying nozzles, click here to download the SprayDry® Nozzles bulletin.