Rotary dryer parts

rotary dryer parts

The rotary dryer is composed of a rotating drum and a series of mechanical parts. In most cases, rotary dryers are direct-fired type, which means that the drying air comes into direct contact with the material. However, some dryers are indirect, meaning that the dryer is externally heated,it effectively avoids the contact between raw materials and drying air.

Rotary dryer structure

Qingdao Palet Machinery rotary dryers are customized around the material to be processed, and the customization includes items such as rotary drum size, shell material, dryer parts, mechanical components, and additional devices.


Rotary dryer shell is the main part of the dryer. Most often ,it can be made from carbon steels or stainless steel. Some dryers,however, are made from hastelloy, Inconeland or other alloys. The shell can also be customized in different ways, depending on the material and process required. For example, the thickness of the shell can be adjusted to meet the strength and insulation requirements for the interior of the dryer. The shell can also be made into an insulated structure to help retain heat. The manufacturing technology of the shell is critical; in order to work properly, the shell needs to run concentrically with the mechanical components of the dryer, and the shell also needs to ensure roundness and coaxiality requirements. A poorly manufactured drum will promote wear and tear on all components, reducing equipment efficiency and life.

Raw material feed chute

The feed chute is usually use a feed screw or chute. The feed chute is specially designed to be strong, resistant to wear and tear, and to reduce material accumulation.


In the combustion chamber duct and drum, where the discharge port meets the drum, there needs to be a sealing ring. Its purpose is to prevent air and material from leaving the drum prematurely. There are many different sealing options , which also depend on the needs of the rotary drum structure.

Drive Components

The drive assembly is composed of a motor, a drive mechanism, a reducer, and a coupling. The motor provides the power for the drum rotation. There are several types of drives here: gear and pinion, chain and sprocket, friction drive and direct drive. Gear and pinion drives are suitable for large weight drives with a power of 75 hp or 55kw or more. Chains and sprockets are suitable for, operating at up to 75 hp or 55 kw. In both drive component types, additional reducers are required for higher torque applications. Friction drives are used for very small size drums with low power, who do not require high speed and torque. Direct drive is used for special structured drums, where there is an output shaft at the front and rear of the drum, and the motor and reducer are connected directly to this shaft using a coupling. Special structures are set up inside the drum of this structure to handle some special raw materials.

rotary dryer transmission
rotary dryer reducer
gears process

Rolling circle

The roller ring increases strength and structural support to the drum shell and serves as a part to absorb stress. The roller ring is on the supporting wheel. In most cases, the material of the roller ring is cast steel, grade ZG35-45. The drum has 2 roller rings, the size and structure of which depends on the size of the drum.

Rolling circle

Support roller

The support roller pushes the roller ring around so that the contact surface of the rolling circle is completely on the drag wheel, ensuring a smooth and concentric rotation during operation. The wheels are mounted on a steel support base with sealed roller bearings, and the support rollers carry the weight of the drum. The width of the roller will be somewhat larger than the width of the roller ring. In most cases, the material of the roller is cast steel, grade ZG35-45, and the drum has 4 drag wheels. The size and structure of the roller depends on the size of the roller ring and the drum.

Retaining Wheel

The retaining wheel is mounted on either side of the rear rollers to stop the drum from drifting, or moving horizontally. It is the same as a support roller, They are also a wear part, and they are cheaper and easier to replace than the roller rings themselves.

rotary dryer pinion
support rollers and retaining wheel

Discharge area

The product discharge area is where the product leaves the dryer. At the discharge port, the product leaves the dryer and goes to screening, cooling, storage or transport, where it can go to the next step of the process. In most cases, the dried material enters the rotary cooler, is conveyed, and finally finishes with packaging and storage through the packaging machine.

Exhaust treatment

The exhaust gas system removes the exhaust gas from the system. Firstly, the dryer exhaust gas enters the cyclone separator to remove small particles, then it passes through the scrubber or settling chamber, and finally passes through the baghouse or dust room to discharge clean air into the atmosphere.