When it comes to buying an industrial dryer, people are often faced with the decision to choose between a rotary dryer, and a fluid bed dryer. Though the choice between the two can be material specific, ultimately, each dryer has its advantages and disadvantages, and the decision often comes down to customer preference.
Historically, rotary dryers have been used for more industrial applications, such as minerals, fertilizers, sand, etc., while fluid bed dryers have been used in the pharmaceutical and food industries, although, there can be a lot of overlap in applications for the two dryers.
Rotary dryers have been called the “workhorse” of the industry, due to their heavy-duty construction, their high capacity capabilities, and their ability to accept a wide variability in feedstock. Because of this, rotary dryers are better suited for heavy duty materials where a lot of variety in feedstock is a given, such as in the case of various minerals. Rotary dryers are known for their ability to take what is given, big or small, wet or dry, and churn out a quality product.
Conversely, fluid bed dryers have a very tight window when it comes to variability in feedstock. Whereas a rotary dryer will just keep running, variability in feedstock with a fluid bed dryer can cause process problems and the potential to leave an operation at a standstill.
Fluid bed dryers have the advantage of being modular. Though they are smaller in size than a rotary dryer, fluid bed dryers can be added on to, making them ideal for operation growth. Though not always an issue, rotary dryers require more space than a fluid bed dryer. Rotary dryers are often reliant on the ability of a material to tumble through the first few feet of the drum, where fluid bed dryers have no such need.
While a rotary dryer is robust, it does require more maintenance, because it is made up of so many moving parts. Although, rotary dryers do live a long productive life, when maintained well. Additionally, though it is material-specific, rotary dryers typically have slightly more attrition than fluid bed dryers, because they are picking up and showering the material. However, the rotational movement of a rotary dryer is an advantage in many cases, because it is ideal for rounding and polishing the product, something the fluid bed dryer does not accomplish.
The choice between a rotary dryer or fluid bed dryer is also a matter of energy. Fluid bed dryers work by fluidizing the material, which requires a high magnitude of air. Fluid bed dryers can be slightly more thermally efficient, but subsequently, can require much more electricity to run because of the need to “fluidize” and lift the material with air. Because the material is fluidized, it is not always practical to run high volume, heavy materials through a fluid bed dryer, because of the extra energy required to fluidize the material.
While the choice between a rotary dryer and a fluid bed dryer may seem complex, ultimately, it comes down to material characteristics, capitol costs, energy costs, and space.
FEECO custom engineers robust rotary dryers to handle the specific needs of your material. For more information on rotary dryers, contact us today!