The NARA Paddle Dryer once was designed as an indirect dryer. Since that time its application is diversified from basic process applications like drying, heating and cooling to more sophisticated processes like crystallization, coating, sterilization and calcination. Because of its wide range of applications the paddle dryer is used in the food industry as well as in the pharmaceutical and specialty chemical industry.
By far the largest amount of the global SAP (super absorbers, as used in diapers) is produced in this type of machine.
The Paddle Dryer is well known for its compact construction and the consequently small need of installation space. This results from the high heat transfer coefficient and heat efficiency. These features combined with the self-cleaning effect of the paddles assure a homogeneous product for continuous and/or batch unit operations.
But the NARA paddle dryer potential still extends even further: a drying step and a reaction step or a heating process and a cooling process have been already realized in one machine. Such processes are of importance e.g. in the food industry where materials are dried and transformed into a new structure for special applications. Where materials are stored or packed directly after drying they are cooled for operator and material protection.
The advantage is obvious - one machine substitutes two machines to save space energy and investment cost. Both types – the NPD-D and the NPD-C – are successfully operating for various substances at clients worldwide.
- Drying, solvent recovery, heating, sterilization, reaction, cooling, vacuum drying, etc.
- Wide range of particle size and shapes such as fine particles, granules, pellet, flakes. Also available for the material with high moisture content, slurry, and high viscosity.
- Dryer size is minimized due to the large heat transfer area per volume.
- The wedge shaped paddles goes into the powder to enhance contact to the heat transfer area, and the heat transfer coefficient is relatively high due to the good mixing. So, high heating factor can be obtained. Also, the fullness of the materials is high as 80-90%, therefore large heat transfer area can be efficiently used.
- Since two shafts overlap each other, it prevents the adhesion of powder on the paddle wings, therefore keeping a good heat transfer.
- The residence time distribution is sharp and the powder is uniformly dried.
- Since the required carrier gas amount is small, the exhaust gas treatment system can also be minimized. This is a big advantage, especially for the closed system with inert gas circulation for solvent recovery.
- Slurry with high moisture content or materials with high viscosity can be treated.
- Available under the vacuumed condition as well, for materials which are sensitive to high temperatures.
- By using oil for the heat medium, it is possible to use high temperature up to 290°C.
- Drying and cooling can be realized by separation of heat exchange area into segments.
Concept Paddle Dryer
For types others than displayed above, we can design in accordance to your request.