Key points
TL;DR Summary: Understanding Aeromechanical Conveyors (AMCs) and Drag Conveyors
Aeromechanical Conveyors (AMCs) use a high-speed wire rope with discs inside a fully enclosed tube to create a fluidised airstream for fast, efficient powder transfer. They prevent contamination but require controlled feeding and are unsuitable for oily or sticky materials. Drag Conveyors use a chain or cable with discs to mechanically drag materials through an enclosed tube.
They offer flexibility with multiple loading points and handle abrasive, wet or sticky materials but need more maintenance. Cable-based drag conveyors have lower wear and are easier to clean than chain versions, making them preferred for food and pharma sectors. Selecting the right conveyor depends on material properties, flowability, maintenance needs, and application requirements.
Given my extensive background transitioning from a scientific researcher role at a university to a test manager in a full-scale testing facility, I have observed firsthand the significant disparity between laboratory-scale research and industrial-scale production.
This experience has underscored the critical importance of addressing the challenges associated with scaling research. Often, scaling considerations are underestimated during initial study phases, yet they are crucial for enhancing the commercial viability and industrial impact of research findings.
One of the key challenges in this transition involves the handling and transfer of materials. While material handling may appear less complex compared to the advanced scientific techniques employed in the laboratory, it presents unique challenges, particularly in the selection of appropriate conveyor systems tailored to specific material properties.
Conveyors are vital components in numerous industrial processes, enabling the efficient transport of materials between different stages of production. In this context, this article delves into the detailed operational mechanisms and applications of two primary conveyor types: Aeromechanical Conveyors (AMCs) and Drag Conveyors. Understanding these systems is essential for effectively navigating the complexities of scaling research to industrial applications.
Aeromechanical Conveyors
Principle of Operation:
Aeromechanical conveyors operate on the principle of creating a fluidized airstream. This is achieved by attaching a series of discs to a wire rope, which moves at high speed within a fully enclosed tube. The high-velocity airstream generated mimics the effect of pneumatic conveyors, drawing material into and through the conveyor efficiently.
Design and Functionality:
- Structure: AMCs consist of a fully enclosed tube housing a continuous wire rope with attached discs.
- Performance: AMC is known for its high-speed and efficient conveying. They operate at speeds up to 10 times faster than tubular cable drag conveyors. This high speed is essential for fluidising materials such as powders, ensuring efficient transfer through the system.
- Material Handling: They are suitable for transferring powders and other particulate materials but are not ideal for materials that need to maintain their shape and size.
Applications:
AMCs can be connected to various sources, including bins, hoppers, silos, mixers, and bulk bag dischargers. They require controlled feeding and are efficient in preventing product contamination and dust containment.
Pros and Cons:
| Pros | Cons |
| Fully enclosed to prevent contamination | Higher maintenance costs |
| Capable of conveying at any angle | Inability to start/stop under full load |
| Low energy requirements | Requires a controlled feed |
| Not applicable for fatty or oily materials |
Drag Conveyors
Principle of Operation:
Drag conveyors use a tubular housing that encloses a continuous chain or wire rope with attached discs. A motor-driven sprocket engages with this assembly, pulling material through the conveyor.
Design and Functionality:
- Structure: These conveyors can be installed across multiple planes as a single continuous system, typically utilizing a stranded steel cable or chain equipped with polyethylene or metal discs.
- Performance: Drag conveyors offers flexibility which can accommodate multiple loading and discharge points and are capable of conveying materials at different angles.
- Material Handling: They handle diverse materials, including powders and granules, even if these are abrasive or dense.
Applications:
Drag conveyors are versatile, suitable for handling both wet and dry materials, and are often used in environments requiring minimal contamination, such as food processing.
Pros and Cons:
| Pros | Cons |
| Self-loading | Wear and tear from abrasive materials |
| Multiple loading and discharge points | Potential for product buildup on tube walls |
| Enclosed tube to contain dust | May degrade fragile materials |
| Suitable for complex routes with various angles | Higher energy costs |
| Ideal for materials with bulk density of < 32 g/cm3 |
Comparing Cable and Chain Benefits
When choosing between cable and chain systems within conveyors, it's essential to consider several factors:
- System Uptime: Cables lack the moving components found in chains, such as links, plates, pins, and bushings, which reduces friction and wear. This leads to increased system uptime, as localised strain breaks in cables allow for load redistribution without a complete system shutdown.
- Food Safety and Sanitation: Nylon-coated cables prevent direct contact between the stainless steel cable and food, minimising contamination. Cables are easier to clean and sanitise compared to chains, which can trap water and food particles in their components.
- Maintenance and Durability: Chains require more frequent maintenance due to their moving parts, while cables offer improved durability and reduced maintenance needs, especially in applications involving food safety and sanitation.
Conclusion
Choosing the right type of conveyor depends on the specific requirements of the operation, including material characteristics, speed, contamination prevention, and maintenance considerations.
Aeromechanical conveyors are ideal for high-speed, enclosed transfer of powders, while drag conveyors offer versatility in handling a variety of materials with multiple loading and discharge points.
Understanding these differences ensures the selection of the most efficient and cost-effective conveyor system for any industrial application.
| Feature / Conveyor Type | Aeromechanical Conveyor | Tubular Drag Chain Conveyor | Tubular Drag Cable Conveyor |
| Principle of Operation | Fluidized airstream created by high-speed discs on a wire rope | Mechanical movement using chains with discs to drag material | Mechanical movement using cables with discs to drag material |
| Material Handling | Suspends and moves material in an airstream | Drags material through a fully enclosed tube using a chain | Drags material through a fully enclosed tube using a cable |
| Energy Consumption | Moderate to high due to high-speed operation | Moderate | Low to moderate |
| Dust and Contamination Control | Fully enclosed, minimizes dust and contamination | Fully enclosed, good control | Fully enclosed, good control |
| Flowability (Hausner Ratio) | Best for free-flowing materials (Hausner Ratio < 1.25) | Can handle poor flow materials (Hausner Ratio 1.25-1.4) | Best for free-flowing materials (Hausner Ratio < 1.25) |
| Flowability (Angle of Repose) | Best for angles 25°-30° | Can handle angles up to 45° | Best for angles 25°-30° |
| Flowability (Carr's Index) | Best for Carr's Index < 15% | Can handle Carr's Index 15%-25% | Best for Carr's Index < 15% |
| Stickiness | Not suitable for sticky materials (adhesive strength < 1 N/m²) | Can handle sticky materials (adhesive strength 1-5 N/m²) | Not suitable for sticky materials (adhesive strength < 1 N/m²) |
| Abrasiveness | Low to moderate (abrasion index < 1.5) | High, suitable for abrasive materials (abrasion index 1.5-5) | Low (abrasion index < 1.5) |
| Fragility | Not suitable for very fragile materials (breakage < 5%) | Can handle moderately fragile materials (breakage 5-15%) | Suitable for very fragile materials (breakage < 5%) |
| Hardness | Handles soft to moderately hard materials (Mohs hardness 1-5) | Can handle hard materials (Mohs hardness 1-7) | Handles soft to moderately hard materials (Mohs hardness 1-5) |
| Particle Size Distribution | Effective for particle sizes up to 10 mm | Can handle larger particle sizes, up to 50 mm | Effective for particle sizes up to 10 mm |
| Density Requirements | Typically handles low to medium bulk density materials (0.1 to 1.5 g/cm³) | Can handle a wide range of bulk densities, including high-density materials (0.1 to 2.5 g/cm³) | Typically handles low to medium bulk density materials (0.1 to 1.5 g/cm³) |
| Moisture Content | Best for dry, free-flowing materials with low moisture content (up to 5%) | Can handle materials with higher moisture content (up to 20%) | Best for dry, free-flowing materials with low moisture content (up to 5%) |
| Fattiness or Oil Content | Not suitable for high oil content materials (up to 3%) | Can handle materials with higher oil content (up to 15%) | Not suitable for high oil content materials (up to 3%) |
| Handling of Liquids | Not suitable for liquid handling; primarily for dry materials | Limited liquid handling capabilities; may require additional components for liquids | Not suitable for liquid handling; primarily for dry materials |
| Speed and Throughput | High speed, high throughput (up to 100 m³/h) | Lower speed compared to aeromechanical, moderate to high throughput (up to 80 m³/h) | Lower speed compared to aeromechanical, moderate throughput (up to 60 m³/h) |
| Heat and Static Generation | Generates less heat and static than pneumatic conveyors | Generates minimal heat and static | Generates minimal heat and static |
| Maintenance Requirements | Moderate, requires periodic maintenance of wire rope and discs | Higher, chain and discs require regular inspection and maintenance | Moderate, cable and discs require regular inspection and maintenance |
| Flexibility in Installation | Limited flexibility, best for straightforward paths | High flexibility, can navigate complex paths and multiple planes | High flexibility, can navigate complex paths and multiple planes |
| Cost of Operation | Moderate to high due to energy use and maintenance | Moderate to high due to maintenance | Low to moderate due to lower energy consumption and maintenance |
| Application Industries | Pharmaceuticals, food processing, chemicals, agriculture | Food, pharmaceuticals, chemicals, mining, bulk solids | Food, pharmaceuticals, chemicals, fragile materials |
| ATEX Requirements | Generally requires explosion-proof design for hazardous areas (ATEX Zone 1/21) | Can be designed for ATEX compliance (ATEX Zone 1/21) | Can be designed for ATEX compliance (ATEX Zone 1/21) |
| Examples of Suitable Materials | Granulated sugar, powdered milk, flour, fine chemicals, coffee grounds, baby powder | Cereal grains, pellets, minerals, coarse powders, animal feed, coffee beans | Pharmaceutical powders, fine chemicals, granulated sugar, spices |
FAQs: Aeromechanical and Drag Conveyors
What is the main difference between aeromechanical and drag conveyors?
AMCs use a high-speed wire rope creating a fluidised air stream while drag conveyors mechanically pull material using chains or cables with discs.
Which materials are best suited for aeromechanical conveyors?
Dry, free-flowing powders and particulates with low moisture and oil content, not sticky or fragile materials.
Can drag conveyors handle sticky or abrasive materials?
Yes, especially chain-based drag conveyors can handle sticky, abrasive and wet materials.
What advantages do cable drag conveyors have over chain drag conveyors?
Cables have fewer moving parts, lower maintenance, better uptime and are easier to clean, ideal for food and pharmaceutical uses.
Are aeromechanical conveyors suitable for materials needing shape retention?
No, they are not ideal for materials that must maintain particle integrity or are fragile.
How does flowability affect conveyor choice?
Materials with poor flowability or high stickiness usually require drag conveyors; AMCs are best for free-flowing powders.
What industries typically use these conveyors?
Pharmaceuticals, food processing, chemicals, agriculture, mining, and bulk solids handling.
How flexible are drag conveyors in system layout?
Highly flexible, they can navigate complex routes and multiple planes with multiple loading and discharge points.
What maintenance is required for these conveyors?
AMCs require periodic wire rope and disc maintenance; drag conveyors, especially chains, need more frequent inspections and upkeep.
Are these conveyors suitable for ATEX hazardous zones?
Yes, both can be designed for explosion-proof ATEX compliance in Zone 1/21 environments.
What throughput speeds can be expected?
AMCs offer high speed and throughput (up to 100 m³/h), drag conveyors moderate speeds depending on chain or cable type.
