Rotary drum granulator
A rotary drum granulator is a powder granulation device with a rotating, inclined cylinder as its core working component. Through the rotation of the cylinder, the material rolls and rubs within the cylinder, agglomerating into pellets under specific humidity and temperature conditions, thus completing the granulation process. The equipment boasts significant advantages such as high output, high pellet strength, low power consumption, and low maintenance costs. The rotary drum granulator can operate continuously for 24 hours, making it suitable for large-scale industrial production needs.

Structural Disassembly and Component Description

From an operation and maintenance perspective, the structure of a rotary drum granulator can be divided into the following modules:

(I) Drum Module: This is the working space for granulation. The outer wall of the drum is equipped with a front rolling ring, a rear rolling ring, and a gear ring. The drum is welded from high-quality medium carbon steel plates and lined with rubber or stainless steel plates.

(II) Support Module: This includes a front support roller device and a rear support roller device, corresponding to the front and rear rolling rings respectively. The support roller device bears the entire weight of the drum.

(III) Transmission Module: This includes a reducer transmission device, which drives the drum to rotate through gear meshing with the gear ring on the drum.

(IV) Spraying Module: This includes hot water pipes, steam pipes, and spray nozzles. The steam pipes are supported by a steam pipe rack and communicate with the inner cavity of the drum.

(V) Discharge Module: A discharge box is located at the other end of the drum.

Application scenarios and applicable industries
Rotary drum granulators are widely used for: granulation of organic fertilizers (livestock and poultry manure, straw, etc.); granulation of compound fertilizers and blended fertilizers; and granulation of powder materials in the chemical, pharmaceutical, and feed industries. The equipment is highly adaptable to materials with medium moisture content (25%-60%), and the particle size can be controlled within the range of 2-8mm.

Common material types

The rotary drum granulator has a wide range of raw material adaptability.

Organic materials: Well-rotted livestock and poultry manure (chicken manure, pig manure, cow manure, sheep manure), straw waste, edible mushroom residue, distiller's grains, medicinal residue, humic acid, municipal sludge.

Inorganic materials: Urea, ammonium chloride, ammonium sulfate, ammonium bicarbonate, superphosphate, superphosphate, monoammonium phosphate, diammonium phosphate, calcium magnesium phosphate fertilizer, potassium chloride. Industrial materials: Slag, pulverized coal, iron concentrate, etc.

Working mechanism and operating logic
The main motor drives the belt and pulley, which transmits power to the drive shaft via a reducer. A split gear mounted on the drive shaft meshes with a large gear ring fixed to the machine body, driving the cylinder to rotate. The cylinder rotates at a low speed supported by rollers. Material is fed in from the inlet end and repeatedly lifted and thrown by the lifting and guiding plates with a special internal structure. Under the action of water or steam sprayed by the spray device, it agglomerates into balls and is finally discharged from the outlet end.

Production capacity and equipment selection
Rotary drum granulators offer a wide range of production capacities. Small models have a capacity of 5-10 tons per hour and a power of approximately 22kW; medium models have a capacity of 10-30 tons per hour and a power of approximately 37kW; and large models have a capacity of 30-50 tons per hour and a power of approximately 75kW. Customers can choose different specifications based on factors such as raw material moisture content, target output, and site conditions.

Maintenance tips and schedule

Maintenance of the rotary drum granulator should be carried out at three levels: daily, periodic, and long-term.

Lubrication Management: Bearings bear the entire load of the machine, and good lubrication is crucial to bearing life. The lubricating oil used must be clean, and seals must be in good condition. Main lubrication points include rotating bearings, roller bearings, all gears, moving bearings, and sliding surfaces.

Daily Inspection: Observe whether all parts of the machine are working properly; check the wear degree of easily worn parts and replace worn parts promptly; check if the wheel rims are loose.

Periodic Maintenance: Regularly check the wear of gears, wheel rims, and easily worn parts, and replace abnormal parts promptly; regularly clean the inner wall of the drum to prevent material accumulation; regularly check the contact between the support rollers and the roller rings.

Shutdown Maintenance: Before shutting down, stop feeding and let the drum idle for a short time to expel internal material before disconnecting power. Before restarting after a long period of inactivity, a comprehensive inspection and no-load test run should be performed.

Summary of common faults

Based on extensive user feedback, rotary drum granulators are prone to the following problems:

(I) Uneven particle size: The finished product contains an excessive amount of large particles and fine powder. Main causes include improper raw material moisture content, excessively fast feeding speed leading to insufficient residence time, unsuitable drum rotation speed, and blockage of the screening device.

(II) Excessive equipment vibration and noise: Severe vibration accompanied by abnormal noise during operation. Causes include loose anchor bolts, poor contact between the support rollers and the drum ring, misalignment of the drum axis, and uneven distribution of raw materials within the drum, resulting in uneven weight distribution.

(III) Frequent material adhesion to the inner wall of the drum: A large amount of material adheres to the inner wall and the lifting plates. Causes include excessively high raw material moisture content, excessively low drum temperature, and an unreasonable lifting plate structure.

(IV) Sudden drop in equipment output: A significant decrease in granulation efficiency. Causes include insufficient motor power or reducer failure, blockage of the feeding system, and severe wear of the lifting plates.

(V) Insufficient particle strength: Finished particles are easily broken. Causes include insufficient binder addition, unreasonable raw material ratio, and insufficient drying. (vi) Abnormal noise from transmission gears: Periodic impact sounds or sharp friction sounds are emitted when the large and small gears mesh. Causes include improper gear clearance, tooth surface wear, insufficient lubrication, and foundation settlement.

Troubleshooting and Repair Solutions

The solutions to the above-mentioned problems are as follows:
Uneven particle size:Control the raw material moisture content to 12%-18% (adjust slightly according to raw material characteristics); appropriately reduce the feed rate to ensure sufficient tumbling and forming time; adjust the drum speed to a suitable range (generally 20-40 r/min); clean the screening screen promptly.

Vibration and noise:Check and tighten all anchor bolts; measure the contact between the support rollers and the rolling ring, and adjust the adjusting bolts on the support roller seats to ensure even load distribution on all four support rollers; use a level and theodolite to correct the drum axis, ensuring the front and rear support roller groups are on the same horizontal plane; adjust the feed uniformity to avoid uneven distribution.

Material adhesion to the inner wall:Control the raw material moisture content to avoid excessive moisture; appropriately increase the drum temperature and add an insulation layer; optimize the lifting plate structure and add self-cleaning lifting plates; perform regular shutdown cleaning, using a high-pressure water gun for wall cleaning assistance.

Reduced output:Check the motor operating status and reducer lubrication level; shut down and clean any blockages in the feed inlet and conveying pipes; replace worn lifting plates. Insufficient particle strength: Appropriately increase the amount of binder; optimize the raw material ratio, increasing the proportion of highly viscous raw materials; adjust the drying temperature and time to ensure uniform particle drying.

Gear noise: Check the tooth tip clearance and tooth flank clearance, and adjust the pinion position; check the gear lubrication oil sump to ensure sufficient oil level and clean oil; if the foundation has settled, the cylinder height needs to be readjusted; if the gear surface is severely worn, the gear pair needs to be replaced.

Regular inspection, standardized operation, and timely maintenance are key to ensuring the long-term stable operation of the drum granulator.