what is a Rotary Cooler?

A Rotary Cooler is an industrial machine specifically designed to cool the material seems like a necessary final step.

A high-efficiency rotary cooler does much more than just lower temperature. It’s crucial for recovering valuable heat (saving fuel!), stabilizing product quality, minimizing dust emissions, and enabling safe downstream handling and storage.

The basic structure of the drum cooler

• Rotating Shell: A long steel cylinder, often lined with refractory materials at the hot end or equipped with internal lifters.
• Support System: Riding rings (tires) mounted on the shell rotate on support rollers (trunnions), bearing the main weight. Thrust rollers manage axial movement.
• Drive System: A girth gear around the shell is driven by a pinion connected to a motor and gearbox, providing slow, controlled rotation.
• Seals: Positioned at both the feed (hot) end and discharge (cool) end to control airflow and prevent dust leakage.
• Incline: The drum is set at a slight slope (typically 1-4 degrees) to help material flow from the feed end to the discharge end via gravity as it rotates.

It directly mirrors the robust construction of rotary kilns and dryers, designed for continuous, demanding industrial environments.

How Does a Rotary Cooler Work?

Hot material enters the elevated end and tumbles through the rotating drum. Simultaneously, cool ambient air flows through the drum (usually counter-current to material flow), making direct contact with the hot material, absorbing its heat before exiting.

ZONEDING can propose four different kinds of rotary coolers in function of inlet temperature of product, desired outlet temperature and of type of product as well as:

• Air Rotary Coolers
• Water Rotary Coolers
• Direct Rotary Coolers
• Indirect Rotary Coolers

Air Rotary Coolers

Construction of Air Rotary Coolers is similar to Direct Rotary Dryers.

The product is fed inside a cylinder internally provided with spiral and lifting flights in order to achieve the contact between fresh air and the hot product to be cooled.

The heat of product is dissipated by convection by a stream of fresh air which flows in counter current configuration.

Air Rotary Coolers are mostly applied to cool down product at exit of Direct Rotary Dryers (temperature approx 100 °C).

Water Rotary Coolers

In Water Rotary Coolers heat transfer occurs by radiation since water is sprayed against the wall of a rotating cylinder.

Sprayed water that did not evaporate is collected in the bottom of a hood and then recycled to the spraying device.

Cylinder can also consist of a various number of tubes connected each other in order to increase the cooling efficiency.

Water Rotary Coolers find application to cool down products at higher temperatures than the ones operated with Air Rotary Coolers (up to 900 °C and more) and for dusty products and products that cannot go in contact with air.

Direct vs. Indirect Cooling Comparison

Which Industries Use Rotary Coolers and for What Materials?

Rotary coolers are workhorses in industries like cement (cooling clinker), lime (cooling calcined lime), mining/metallurgy (cooling sintered ores, pellets), chemicals (cooling various calcined products, fertilizers), and sometimes aggregates (cooling dried sand/gravel).

They are essential wherever bulk solids need their temperature drastically reduced after a high-temperature thermal process.

Common Applications Across Industries:

• Cement and Lime: This is perhaps the most prominent use. Rotary coolers receive cement clinker directly from the rotary kiln at temperatures often exceeding 1300°C, cooling it rapidly to below 100°C for grinding. Similarly, they cool calcined lime from lime kilns. Sticking and ringing can be challenges here.
• Mining and Metallurgy: Used to cool sintered iron ore, pellets from pelletizing plants, roasted ores (e.g., zinc, copper concentrates after roasting), or slag from smelting operations before further handling or processing.
• Chemical and Fertilizer: Cooling various calcined products like petroleum coke, catalysts, pigments (e.g., titanium dioxide), phosphates, potash, or granular fertilizers after drying or granulation steps where elevated temperatures are involved. Indirect cooling might be used here for sensitive products.
• Waste Processing & Recycling: Sometimes used to cool incinerator ash or other thermally treated waste products.
• Aggregates: Less common, but can be used to cool sand or gravel after high-temperature drying if immediate handling is required.

Essentially, any industry performing high-temperature calcination, sintering, roasting, or drying of bulk solids is a potential user of rotary coolers.

What Key Parameters and Selection Points Matter When Choosing a Rotary Cooler?

Key selection factors include detailed material properties (flow, temperature, stickiness), required throughput, target temperature drop, cooling type (direct/indirect), internal design (lifters), construction materials for heat/abrasion resistance, and robust drive/support systems. Considering the entire system, including airflow and heat recovery, is crucial.

Critical Selection Criteria:

• Material Characteristics:
  • Feed Temperature & Target Outlet Temperature: Defines the cooling duty.
  • Throughput Rate (e.g., tons per hour): Dictates the required size (diameter and length).
  • Particle Size Distribution (PSD): Affects airflow resistance and lifter design.
  • Bulk Density, Specific Heat, Thermal Conductivity: Needed for heat transfer calculations.
  • Flowability & Angle of Repose: Influences lifter design and drum slope.
  • Abrasiveness: Impacts choice of shell liners and lifter materials.
  • Stickiness/Plasticity Range : Critical for assessing risk of build-up and informing design choices (e.g., internal knockers, special liners).
  • Sensitivity to Air/Contamination: Determines if direct or indirect cooling is needed.
• Process Requirements:
  • Cooling Medium: Usually ambient air, but temperature and humidity matter. Sometimes chilled air or inert gas (in indirect) is used.
  • Heat Recovery Needs: If heat recovery is desired, the design must accommodate hot air offtakes and proper sealing.
• Cooler Design Features:
  • Diameter & Length: Determines residence time and heat transfer area. L/D ratio is important.
  • Rotational Speed & Slope: Adjustable parameters affecting residence time and material bed depth.
  • Lifter Design : Customization is key for efficiency.
  • Sealing System : Quality and type impact efficiency and fugitive emissions.
  • Construction Materials : Appropriate steel grades (carbon steel, stainless, heat-resistant alloys) for temperature and abrasion.
• Drive and Support Systems: Robustness and reliability are paramount for continuous operation. Sizing must handle the full load.

What are Advantages of ZONEDINGMACHINE?

ZONEDINGMACHINE has proven experience on cooling your specific material, strong engineering capabilities for customization, high manufacturing quality standards, comprehensive installation and commissioning support, and responsive after-sales service including readily available spare parts.

ZONEDINGMACHINE Strengths:

1. Proven Application Experience: ZONEDINGMACHINE has specific references and detailed case studies where they have successfully supplied coolers for materials and processes similar to yours.
2. Engineering & Design Expertise: ZONEDINGMACHINE engineers team understand the thermodynamics, airflow dynamics, material science, and mechanical stresses involved.ZONEDINGMACHINE can offer customized designs based on your needs (e.g., specific lifters, alloys, seal types). And can grasp the importance of heat recovery if applicable.
3. Manufacturing Quality Control: With high manufacturing standards, ZONEDINGMACHINE can inspect their facilities or previously built machines. Look for quality welding, precise machining of components like riding rings and seal surfaces, and robust construction. As a direct manufacturer, ZONEDING controls quality throughout the process.
4. Installation & Commissioning Support: ZONEDINGMACHINE can offer experienced supervisors or teams to oversee proper installation (especially critical alignment) and commissioning, and operator training.
5. Spare Parts Availability: ZONEDINGMACHINE can supply critical wear parts like seals, liners, rollers, or drive componentsquickly. Long lead times mean extended downtime. Direct-manufacturers like ZONEDINGMACHINE often have better control over spares inventory.
6. After-Sales Technical Support: ZONEDINGMACHINE provides technical support after installation, experienced engineers accessible for troubleshooting and operational advice and quickly typical response time.
7. Warranty and Guarantees: ZONEDINGMACHINE provides one-year warranty.

ZONEDINGMACHINE with demonstrated expertise in handling challenging materials like cassava residue and a strong commitment to after-sales support provides peace of mind and ensures better long-term operational success.

General Specification

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