Rotary Cooler

The OFEC Rotary Cooler is the key cooling equipment in organic fertilizer production lines, designed to rapidly cool down organic fertilizer granules after drying to temperatures suitable for packaging and storage. With drum diameters from 0.8 to 4.6 meters and capacities from 1 to 200 TPH.

Product Overview

In organic fertilizer production, granules discharged from the rotary dryer typically have a high outlet temperature. If sent directly to packaging, the residual heat can damage packaging materials and cause moisture regain and caking, compromising product quality and storage stability. Therefore, hot organic fertilizer granules must be cooled before packaging, storage, and transport to minimize attrition and dust generation during subsequent handling and shipping.

The OFEC rotary cooler operates on a counter‑current air cooling principle, using ambient or cooled air in full contact with the hot material to rapidly reduce granule temperature through efficient heat exchange. This cooling process not only prevents caking but also enhances granule strength.

Equipment Components

The rotary cooler consists of the following main components:

A – Cylinder (Drum): The core working part where cooling takes place
B – Feeding Device: Feeds hot material into the drum
C – Discharging Device: Discharges cooled material
D – Support Wheel Assembly: Supports the rotating drum
E – Transmission: Drives the drum rotation
F – Protecting Cover: Safety protection
G – Rolling Ring (Tyre): Works with support wheels
H – Big Gear: Drive component
I – Pinion: Drive component
J – Exhaust Outlet: Discharges hot exhaust air
K – Lifting Plate: Lifts material to increase heat exchange
L – Spiral Blade: Guides material flow

● Cylinder (Drum): The core working part where cooling takes place

● Feeding Device: Feeds hot material into the drum

● Discharging Device: Discharges cooled material

● Support Roller Assembly: Supports the rotating drum

● Transmission: Drives the drum rotation

● Protecting Cover: Safety protection

● Rolling Ring (Tyre): Works with support wheels

● Big Gear: Drive component

● Pinion: Drive component

● Exhaust Outlet: Discharges hot exhaust air

● Lifting Plate: Lifts material to increase heat exchange

● Spiral Blade: Guides material flow

Working Principle

The rotary cooler is a slightly inclined, horizontal rotating cylinder, supported by riding rings and driven by a gear drive system. Its working principle is similar to that of the rotary dryer, but the cooling medium is ambient air rather than hot gas.

Counter-Current Cooling Design: Hot material enters the drum from the feed end, while cooling air is introduced from the discharge end, flowing in the opposite direction. This counter-current configuration provides the largest temperature difference and achieves maximum heat exchange efficiency – the most important feature that distinguishes the cooler from the dryer, resulting in the lowest discharge temperature and highest cooling efficiency.

As the drum rotates, internal lifting flights pick up the material and shower it through the cooling air stream, forming a falling “curtain” that ensures thorough contact between the material and the cooling air. Heat is carried away by the airflow, rapidly reducing the material temperature. The cooled material moves gradually towards the discharge end under gravity and exits the drum, completing the cooling process.

Technical Specifications

Model	Drum Diameter (m)	Drum Length (m)	Capacity (t/h)	Power (kW)
ZLQ-0.8×8	0.8	8.0	1–1.5	4
ZLQ-1.2×12	1.2	12.0	4–7	11
ZLQ-1.8×16	1.8	16.0	10–15	18.5
ZLQ-2.2×20	2.2	20.0	20–25	30
ZLQ-2.6×24	2.6	24.0	30–40	45
ZLQ-3.6×30	3.6	30.0	60–80	75
ZLQ-4.5×35	4.5	35.0	150–200	500

Model

Drum Diameter (m)

Drum Length (m)

Capacity (t/h)

Power (kW)

ZLQ-0.8×8

0.8

8.0

1–1.5

ZLQ-1.2×12

1.2

12.0

4–7

ZLQ-1.8×16

1.8

16.0

10–15

18.5

ZLQ-2.2×20

2.2

20.0

20–25

ZLQ-2.6×24

2.6

24.0

30–40

ZLQ-3.6×30

3.6

30.0

60–80

ZLQ-4.5×35

4.5

35.0

150–200

500

Features and Benefits

High Cooling Efficiency

Counter-current air cooling design maximizes heat exchange, achieving the lowest possible discharge temperature.

Rugged Construction

Heavy-duty design capable of withstanding demanding continuous operation.

Proven Reliability

Rotary drum technology has been validated over decades – one of the most mature and reliable cooling solutions in the organic fertilizer industry.

Easy Maintenance

Simple structure, intuitive operation, few wear parts.

Efficient Sealing

End seals minimize air leakage, ensuring consistent cooling performance.

Strong Adaptability

Insensitive to fluctuations in material characteristics, maintaining stable cooling performance even when feed conditions vary.

Industry Solution for Organic Fertilizer Cooling

Cooling is a critical step bridging upstream and downstream processes in organic fertilizer production, directly affecting final product quality and storage stability.

Typical Process Flow
Organic fertilizer granulation → Drying → Rotary cooling → Screening → Coating (optional) → Packaging

Solution Advantages
● Effectively reduces granule temperature, preventing damage to packaging materials from residual heat
● Rapid cooling reduces crystal bridging between granules, significantly lowering caking risks
● Cooling enhances mechanical strength of granules, reducing attrition and dust during handling and transport
● Prevents moisture regain, keeping the product dry for long-term storage
● Stable discharge temperature creates optimal conditions for subsequent screening, coating, and packaging