While rotary kilns are often engineered around the characteristics of the material to be processed, the base of a rotary kiln can be somewhat standard. This presentation looks at the construction and components of both indirect-fired and direct-fired rotary kilns.

1. Construction
Experts in process design and material
processing for over 65 years.
Rotary Kiln

2. Rotary kilns are an advanced thermal
processing tool used to cause a chemical
reaction or physical change in a solid
material through the application of
high temperatures.

3. While rotary kilns are engineered around the
material to be processed in order to yield
optimal processing conditions, the basis of a
rotary kiln can be somewhat standard.

4. While rotary kilns are engineered around the
material to be processed in order to yield
optimal processing conditions, the basis of a
rotary kiln can be somewhat standard.
The following information offers an explanation
on some of the standard components of a
rotary kiln, as well as available customizations.
Some information may be specific to FEECO
rotary kilns.

5. Standard
Components

6. Construction of a
DIRECT-FIRED KILN

7. Construction of an
INDIRECT-FIRED KILN

8. Drum Shell
Direct-fired kiln shells are typically made
from carbon steel.

9. Drum Shell
Direct-fired kiln shells are typically made
from carbon steel.
Indirect-fired kilns, however, must be more
resistant to high temperatures, and
therefore, are made from a more
heat-resistant alloy.

10. A properly constructed shell is of the utmost
importance. The shell must run true and
concentric in order to maintain process
efficiency and be reliable for years to come.

11. A properly constructed shell is of the utmost
importance. The shell must run true and
concentric in order to maintain process
efficiency and be reliable for years to come.
A poorly manufactured shell will promote wear
on all components, reducing efficiency, and
often resulting in premature failure.

12. Burner
The burner supplies the energy to the
process and is typically mounted on the
discharge end housing.

13. Burner
The burner supplies the energy to the
process and is typically mounted on the
discharge end housing.
Burners can be designed to
accommodate a variety of fuel sources,
such as:

14. Burner
The burner supplies the energy to the
process and is typically mounted on the
discharge end housing.
Burners can be designed to
accommodate a variety of fuel sources,
such as:
• Natural Gas

15. Burner
The burner supplies the energy to the
process and is typically mounted on the
discharge end housing.
Burners can be designed to
accommodate a variety of fuel sources,
such as:
• Natural Gas
• Propane

16. Burner
The burner supplies the energy to the
process and is typically mounted on the
discharge end housing.
Burners can be designed to
accommodate a variety of fuel sources,
such as:
• Natural Gas
• Propane
• Diesel

17. Burner
The burner supplies the energy to the
process and is typically mounted on the
discharge end housing.
Burners can be designed to
accommodate a variety of fuel sources,
such as:
• Natural Gas
• Propane
• Diesel
• And more…

18. Raw Material Feed
Also called the feed chute, this is where
raw material feedstock is fed into the kiln.
This is typically carried out using a feed
chute or screw.

19. Raw Material Feed
Also called the feed chute, this is where
raw material feedstock is fed into the kiln.
This is typically carried out using a feed
chute or screw.
This area must be designed to be robust
and to lessen the opportunity for build-up
to occur. It is often made of a heat-
resistant alloy.

20. Air Seal
The seal connects the discharge
breeching to the rotating drum in order to
keep air and material from prematurely
exiting the drum.

21. Air Seal
The seal connects the discharge
breeching to the rotating drum in order to
keep air and material from prematurely
exiting the drum.
It also prevents outside air from leaking
into the system, allowing the proper
temperature to be maintained within.

22. Air Seal
The seal connects the discharge
breeching to the rotating drum in order to
keep air and material from prematurely
exiting the drum.
It also prevents outside air from leaking
into the system, allowing the proper
temperature to be maintained within.
Various seal options exist.

23. Drive Assembly
The drive assembly is what causes the
drum to rotate. Various options are
available depending on the horsepower
and size of the drum. Options include:

24. Drive Assembly
The drive assembly is what causes the
drum to rotate. Various options are
available depending on the horsepower
and size of the drum. Options include:
- Chain and Sprocket

25. Drive Assembly
The drive assembly is what causes the
drum to rotate. Various options are
available depending on the horsepower
and size of the drum. Options include:
- Chain and Sprocket
- Gear and Pinion

26. Drive Assembly
The drive assembly is what causes the
drum to rotate. Various options are
available depending on the horsepower
and size of the drum. Options include:
- Chain and Sprocket
- Gear and Pinion
- Friction Drive

27. Drive Assembly
The drive assembly is what causes the
drum to rotate. Various options are
available depending on the horsepower
and size of the drum. Options include:
- Chain and Sprocket
- Gear and Pinion
- Friction Drive
- Direct Drive

28. Riding Ring
The riding ring is part of the support
structure for the drum and provides a
place for pressure to be absorbed.

29. Thrust Rollers
Thrust rollers push against the riding ring to
prevent the drum from moving
horizontally, or “drifting.”

30. Trunnion Wheels
The trunnion wheels serve as the cradle for
the rotating drum, helping to ensure
smooth and concentric rotation.

31. Trunnion Wheels
The trunnion wheels serve as the cradle for
the rotating drum, helping to ensure
smooth and concentric rotation.
Trunnion wheels also serve as a wear
piece, since they are more cost-effective
to replace than the riding ring itself.

32. Discharge Breeching
The discharge breeching is where product
exits the kiln and the exhaust gas system
removes off-gases and small particulates.

33. Refractory
Refractory insulates and protects the shell
of the drum from the high temperatures
within. Refractory is available in brick or
castable material, and is very
customizable. Refractory is specific to
direct-fired kilns.

34. Furnace
The furnace, sometimes called a heat
shroud is specific to indirect-fired kilns. This
is essentially a shell that encloses the
rotating drum, creating a space for the
drum to be externally heated.

35. Conclusion
Rotary kilns are a critical component in many
industrial processes and should be designed
around the material to be handled. While the
base of a kiln can be somewhat standard,
many options and customizations are available
to maximize efficiency and prolong the life of
the equipment.

36. 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 kilns.

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