An Introduce to Rotary Dryers

The field of industrial drying has been around for centuries, even if rudimentary at first. Drying began with only the wind and sun as its tools, civilization demanded faster drying methods, people began to use others tools in a more controlled manner to maximize the drying process. Soon, basic ovens were tasked with drying goods and materials, and as industrial needs continued to increased, so too did drying technologies.

Today, advanced drying systems allow us to churn out products at unprecedented speeds. Industrial drying systems continue to become more advanced, further increasing efficiency and effectiveness of the drying process.

When it comes to drying bulk solids, rotary dryer is often the industrial drying equipment of choice. For over a century, their robust build, reliability, and aptitude for handling variation in feedstock has made them an ideal choice for efficiently drying bulk solids of nearly all types.

The flexibility of rotary dryers has allowed them to expand into nearly every industry, from food and specialty chemicals, to minerals, fertilizers, and nearly everything in between.

And while rotary dryer is common place in many industries, they are still surrounded by a multitude of questions and opportunity for confusion.

This guide serves to give a basic overview of rotary dryer and the industrial drying process, as well as answer some of the common questions asked about these robust industrial drying systems.

How Rotary Dryers Work

Rotary dryer use a tumbling action in combination with a drying air in order to efficiently dry materials. Most often, rotary dryer is of the direct-fired type, meaning that the drying air is in direct contact with the material. Some rotary dryers, however, are of the indirect type, whereby the dryer is heated externally, to avoid direct contact between the material and the drying air.

Rotary dryer is comprised of a rotating drum, into which the material is fed, in combination with the drying air. Flights, or lifters, pick up the material from the bed, carrying it over, and dropping it through the air stream to maximize heat transfer between the material and drying air.

Material is processed for a specified amount of time, referred to as the retention time, at the desired temperature, in order to produce a product with the required moisture content.

While rotary dryer is available in standardized models, designing a rotary dryer around the unique characteristics of the material and process needs will produce the best results and offer the most reliability. Various aspects of the dryer are considered during initial design in order to reach the exact desired parameters of the end product.

Rotary Dryer Construction

While great wall rotary dryers are custom designed around the material to be processed, the basis of a rotary dryer is somewhat standard, with customizations coming in terms of sizing, materials, mechanical components, and add-ons, among other items. The diagram on the next page shows some of the basic standard components found on a rotary dryer.