Evaporation is a type of vaporization of a liquid that occurs from the
surface of a liquid into a gaseous phase that is not saturated with the
evaporating substance.
In the flash dryer, particles are dispersed by different means depending on the product into a hot air stream at high velocity conveying and drying the product to a free flowing powder in a very short time.
Hot air is passed through the moving porous bed of the wet material. The moisture is transferred from the wet particles to the hot air. The material becomes progressively dry as it traverses along the length of the belt dryer.