How To Decide To Choose Direct or Indirect Heat?

Writer： admin Time：2019-06-24 15:03 Browse：℃

There are two main designs for rotary dryers when it comes to the application of heat. Direct heat rotary dryers pass a stream of drying air through the drum. The drying air is directed in either a co-current flow (flowing the same direction as the material), or counter-current flow (moving in the opposite direction of the material).

Direct dryers are the most common choice for drying bulk solids, because they are so efficient. However, there may be cases where direct heat is not an option. If the material to be processed is eventually going to be used in creating consumer products, it may not be appropriate for those materials to come into contact with the combustion gases of a directly heated rotary dryer. There may also be cases where the material to be processed cannot come into contact with oxygen, or needs a completely inert environment. In cases such as these, an indirectly heated rotary dryer is the answer. This configuration transfers heat into the chamber via the shell of the rotary dryer itself. This method also avoids the risk of material becoming entrained in the drying air, which can be a challenge when working with fine materials.