Flash airflow dryer
It dewaters through brief contact between high-temperature air and the material. Drying is fast, which suits inorganic salts and chemical powders that need rapid dewatering. Common sizes are Φ220, Φ280, Φ325, Φ400, Φ500 and Φ600.
Rotary dryer
The rotating drum tumbles the material for more even heating. It suits sawdust, plastic pellets and flake materials that do not break up while tumbling.
How to decide
Look at the material form and whether it is sticky. Powders and fast-dewatering duties point to flash airflow; granular or flake materials needing even heating point to rotary. The moisture content and target final moisture still have to be taken into account.
A common misunderstanding
Some assume that because a rotary dryer heats more evenly it suits every material. In practice, tumbling sticky powders causes wall build-up and caking, where a flash airflow dryer performs better.
References and Standards
- JB/T 10176—2012 Rotary flash dryer[S]. Beijing: China Machine Press, 2012. (in Chinese)
- JB/T 10278—2015 Flash dryers[S]. Beijing: China Machine Press, 2015. (in Chinese)
- JB/T 3266—2015 Rotary drum dryer[S]. Beijing: China Machine Press, 2015. (in Chinese)
- Liu G W. Design Handbook of Drying Equipment[M]. Beijing: China Machine Press, 2009. (in Chinese)
- Levy A, Borde I. Pneumatic and flash drying[M]//Mujumdar A S. Handbook of Industrial Drying. 4th ed. Boca Raton: CRC Press, 2014.
- Krokida M, Marinos-Kouris D, Mujumdar A S. Rotary drying[M]//Mujumdar A S. Handbook of Industrial Drying. 4th ed. Boca Raton: CRC Press, 2014.