Types of dryer’s heat transfer 1-2 / Convective heat transfer / Box shape dryer

One of convective heat transfer typed dryers is box shape dryer.The important points of this type are how to blow the blast and how to put the materials, in other words how to contact the hot blast with the materials most efficiently and keep the hot blast as higher temperature as possible.
A box shaped dryer needs blower.When materials are heated to be dry, water and liquid come out because of the heat energy of the blast, however, the water and liquid stay around the material if there is no blow.In case that temperature gets higher and humidity is also high, material cannot be dried since air itself is not dried, so it is the situation like a steam bath in common parlance.
One of the main roles of blower are to prevent the situation described in the above by blowing water out, and also there is another role which is to blow blast for materials.If the capacity and static pressure of blower is too high, it just blows off the water before heat of blast is conducted to material and before the material are dried.
There are several types of dryer using convective heat transfer other than box shaped and they are rotary dryer, flush dryer, and so on.
These dryers are not suitable for drying sticky an adhesive materials such as sludge, slurry, ingredient of pet foods and feedstuffs. These materials adhere to inside of dryer and the dryer is clogged, or only the surface of the material is dried and inside is not.