Flash dryers are equipments used for drying wet solids in a vertical column through which a high-speed hot-air current passes.
The feed processed in a flash dryer must be easily disaggregated by friction to ensure a large air-particle contact area that can allow drying with very short residence times. The gaseous current and the solids then pass through cyclones, obtaining a dry product at the discharge while fines-free air is released to the atmosphere.
Due to the drying column geometric design, the air speed inside a flash dryer is pulsating, and thanks to the inertia of the particles, variable relative speeds between them are obtained, resulting in high convective coefficients.
In the case of solids with a higher than recommendable inlet water content, it is possible to use a flash dryer adding a recirculation system of dry product that is mixed with the feed, reducing and homogenizing the water content of the product entering the dryer body. Determining the recirculation flow rate is a key factor for the correct design of the equipment for each process.
The air in flash dryers is usually heated using a direct type hot air generator, in which combustion gasses are mixed with drying air, giving as a result a mix with the correct temperature and flow rate for drying.
In a flash dryer the feed can be disaggregated in different types of equipments. A paddle mixer or double paddle mixer can be used depending on the product and previous processes.
The product enters the drying body feeded by a kicker mounted at the base of the drying column, which spins a high speed and thrusts the product in a vertical and upwards direction, facilitating it to be carried up by the drying air current and avoiding its accumulation on the horizontal parts of the flash dryer. Other way to feed the equipment is with a cascade feeder.
Our standard configuration includes a series of models that cover air flow rates ranging from 0,15 m3/s up to 70 m3/s. We offer different configurations according to more demanding drying processes or products.
Advantages of Flash Dryers
- Optimal heat transfer coefficients allow very short residence times (a few seconds), and combined with cocurrent flow it allows drying heat sensitive products.
- Low operation costs due to high termal efficiency
- Flash dryers convey the product, which avoid installation of additional transport systems
- Outodoor installation, reducing civil work costs
- Large feed flow rates in continuous drying operation
- Fully automizable, reducing operation costs