Rotary dryers are frequently used throughout a variety of industries for processing bulk solids. This presentation gives an overview of rotary dryers and how they work.

1. Rotary Dryers
Experts in process design and material
processing for over 60 years.
An Introduction to

2. The field of industrial drying is centuries old,
beginning with only the sun and wind as
drying tools.
As demand for greater drying capabilities
grew, better drying methods were
developed.

3. Today, advanced drying systems allow us to
churn out products and materials at
unprecedented speeds and capacities,
making the industrial drying industry an
integral part of modern civilization.

4. Rotary dryers are often the industrial drying
equipment of choice when it comes to drying
bulk solids, offering high throughput, heavy-
duty construction, and the ability to handle
variation in feedstock.

5. This flexibility in processing has resulted in
rotary dryers finding their way into a multitude
of industries, from minerals and fertilizers, to
specialty chemicals, and nearly everything in
between.

6. How
Rotary Dryers Work

7. Rotary dryers work by tumbling material in
a rotating drum in the presence of a
drying air. This is referred to as a
direct-fired dryer, because the process
relies on direct contact between the
material and drying air to efficiently
dry the material.

8. In some instances, direct contact
between the drying air and the material is
not an option, so an indirect configuration
would be necessary.

9. In some instances, direct contact
between the drying air and the material is
not an option, so an indirect configuration
would be necessary.
Indirect-fired dryers are externally heated,
and rely on the heat of the dryer shell to
dry the material within. This type of dryer is
used far less than its direct-fired
counterpart, because it is significantly
less efficient.

10. In a direct-fired dryer, material is fed into
the rotating cylinder, where flights, or
lifters, pick up the material and drop it
through the drying air as the drum rotates.
This maximizes heat transfer efficiency.

11. In a direct-fired dryer, material is fed into
the rotating cylinder, where flights, or
lifters, pick up the material and drop it
through the drying air as the drum rotates.
This maximizes heat transfer efficiency.
When used after an agglomeration
process, the tumbling action in the dryer
can further polish the granules or pellets.

12. Direct-fired dryers can be either of the
co-current, or counter current airflow
configuration. This refers to which direction the
drying air flows in relation to the material flow.

13. Co-Current Air-Flow
Counter Current Air-Flow

14. Material is processed for a specified amount of
time in order to bring the moisture content of
the material down to the desired range or
percentage. This set amount of time is referred
to as retention time.

15. Rotary dryers are available in standardized
sizes and configurations. However, most
often, a custom solution designed around the
unique characteristics of the material to be
processed will produce the best results.

16. This is because a variety of material
characteristics will influence how the material
will behave in the drying process. These
characteristics must be prepared for and
designed around in order to reach the
desired end product results.

17. Conclusion
Rotary dryers are a critical component in many
industrial processes, offering high capacities,
heavy-duty construction, and the ability to
accept variance in feedstock. While
standardized options are available, a
custom solution will provide the best results.

18. has been a leader in the thermal processing
industry since the 1950s, providing process &
product development, feasibility testing,
maintenance services, and high-quality,
custom rotary dryers.
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