Pneumatic vs. Mechanical Conveying Systems: Which Is Better?

Many businesses use conveying systems to transport products, raw materials, and goods easier within a small area. They are used in manufacturing, packing, and material handling because they allow quick and effective transportation for companies that deal with heavy, sharp, and mass-produced goods. 

In order to transport large quantities of items, mechanical conveying systems employ belts, buckets, chains, and trays, while pneumatic conveying systems utilise sealed pipelines to transfer dry powders, and granular materials in bulk. The purpose of this blog is to examine the advantages and disadvantages of pneumatic and mechanical conveying systems, and determine the most suitable system for fulfilling specific business needs.

A] Understanding Pneumatic Conveying Systems

A pneumatic conveying system is used for transferring bulk granular and powdered materials with minimal loss. It employs a pipeline chain that pumps air to transport items comprising granules or powders. These systems work by pushing materials using sealed, enclosed pipelines while applying pressure, airflow, or another form of gas.

There are various types of pneumatic conveying systems, such as dilute phase pneumatic conveying, dense phase pneumatic conveying, vacuum pneumatic conveying, pressure pneumatic conveying, and hybrid pneumatic conveying.

Advantages of pneumatic conveying: 

• Pneumatic conveyors can be operated horizontally or vertically over long distances.
• These systems are easy to find since they occupy less floor area.
• These systems are more versatile due to the small layout of pipe transfer lines.
• The covered design keeps impurities out of the pipeline while preventing dust from entering nearby areas.
• Operators are capable of constantly maintaining a regulated environment.
• Multiple points for picking up and discharging materials are available.
• These systems require less maintenance since they have fewer moving components.

Limitations and challenges of pneumatic conveying:

• These systems can be difficult to use with higher production volumes.
• Fans and blowers can generate a lot of noise.
• There is a risk of product damage and pipeline blockage when handling wet or fragile products.
• Open-circuit systems with dust collectors may release dust into the atmosphere, which might require authorization.
• The size of the blower is restricted, limiting the system’s scalability.

Interested in learning more about the pneumatic conveying system? Refer to our guide, ‘Pneumatic Conveying – Different Types, Design, and Uses.’

B] Exploring Mechanical Conveying Systems

Mechanical conveying effectively transports large volumes of product from one location to another, frequently across long distances. These products are transferred horizontally, vertically, or in a titled way through a powder processing machine.

In a mechanical conveying system, several moving components often transfer items quickly, including belts, buckets, chains, and trays. There are various types of mechanical systems, such as belt conveyors, screw conveyors, and bucket elevators.

Wide belts are placed over rollers in belt conveyors to transport material. It’s ideal for transporting many bulk materials or travelling over long distances. Screw conveyors transport goods in an auger-like motion, usually horizontally or slightly inclined. The bucket elevators are designed to transport materials upward and facilitate significant elevation changes.

Advantages of mechanical conveying:

• When compared between pneumatic vs. mechanical conveying systems, mechanical conveying exhibits higher energy efficiency.
• These systems eliminate the need for larger dust collection systems as it doesn’t involve material separation from an air stream.
• These systems offer enhanced safety against fire and explosions when handling combustible bulk solids.
• They are ideal for transporting dense, heavy, granular, and adhesive materials that are prone to causing blockages in pipelines.
• These systems are cost-effective, offering a more affordable option for design and installation.

Limitations and challenges of mechanical conveying:

• There are limitations to material selection. Ensure suitable durability by avoiding inadequate or unsuitable construction materials.
• Avoid under-sizing conveyors to maintain long-term reliability, safety, and efficient operation within defined limits.
• There are no proper safety systems. A single system breakdown can impact the entire upstream workflow.
• These systems can be damaged easily and quickly as they run faster for longer.
• There is no proper ventilation which accumulates dust within industrial and agricultural products.

C] Difference Between Pneumatic Conveying Vs. Mechanical Conveying

The main difference between pneumatic and mechanical conveying systems is the design. Mechanical systems move products utilising equipment such as belts, rollers, and motors, as opposed to pneumatic systems, which employ a gas stream or a vacuum. In addition to design, there are several other differences as well:

1. Efficiency

One of the key differences between pneumatic and mechanical conveying is the system’s efficiency. Pneumatic conveying uses an air stream for long distances requiring more energy to get proper air pressure making the system less energy efficient. While mechanical conveying is appropriate for shorter distances relying on mechanical power, resulting in higher energy efficiency.

2. Cost

Pneumatic conveying has a higher upfront cost due to the installation of pipelines and specialised equipment such as fans and blowers. Mechanical conveying involves simpler equipment, such as belts and gears, which have a lower upfront cost. Mechanical conveying systems typically have a lower operating cost when compared to pneumatic conveying systems. 

3. Flexibility:

The key difference between pneumatic conveying vs. mechanical conveying is flexibility. Pneumatic conveying is a flexible, covered system that employs a flow of gases to transport dry bulk items with the ability to fluidize. In contrast, mechanical conveying uses an open system that is ideal for moving heavy or wet materials.

4. Maintenance

The major difference between pneumatic conveying vs. mechanical conveying is the number of moving components present. Pneumatic systems don’t involve any moving components. In contrast, mechanical systems depend on moving components such as belts and rollers to complete tasks. These components require thorough maintenance to remain a reliable tool for the workplace.

6. Space and Layout

The mechanical conveying systems are large and occupy a lot of floor space. Compared to pneumatic conveying systems, even if they have pipes, they do not require as much floor space as mechanical conveying. Installing a pneumatic conveyor system is simpler and smoother than setting up a mechanical conveyor.

7. Material Handling Characteristics

The most noticeable difference is the materials transferred by the two systems. A pneumatic conveying system is suitable for transferring fluidizable, fine, and dry powders along with pelletized and granular materials. Meanwhile, mechanical conveying is well-suited for granular materials that are heavy, wet, packable, and doughy.

8. Environmental Impact

The pneumatic conveying system is enclosed, which minimises the risk of material spillage and is preferable for transferring hazardous products. Contrarily, mechanical conveying is an open system giving access to material spillage resulting in loss of materials. It has a risk of potential tripping and hazards in the workplace.

9. Safety

Safety is one of the major differences between Pneumatic Conveying vs. Mechanical Conveying. Since pneumatic conveying does not involve moving parts, it reduces the risk of injury and minimises noise. Meanwhile, mechanical conveying with belts, gears, and other moving parts contributes to the chance of injury while naturally developing a noisier environment.

So, take these factors into consideration before selecting a conveying system for your business.

D] Applications and Industries

1. Industries where pneumatic conveying systems are commonly used

The food sector prefers pneumatic conveying systems because they can handle dry materials and foodstuffs quickly and securely. These systems accommodate shifting consumption habits while providing improved cleanliness and flexibility. Closed-loop pneumatic conveying systems are becoming more and more popular in the pharmaceutical business, especially for employing inert gas to transport dangerous or explosive materials. 

The petrochemical sector needs pneumatic conveying systems, filtering options, and bagging equipment to handle bulk materials and guarantee safety precautions. Breweries and distilleries use pneumatic conveying systems to manage wasted grain with varying moisture levels and to handle dry commodities.

2. Industries where mechanical conveying systems are commonly used

Mechanical conveying is crucial in various industries such as mining, mineral processing, iron making, hydrometallurgy, energy, ports, and supply chain. It can be divided into two primary applications: process or in-plant applications and transport (overland) applications. In-plant applications involve material transfer, stacking, reclaiming, and feeding functions within the plant. 

They also serve as interfaces between the plant and external facilities for unloading and loading materials. On the other hand, transport applications are longer, often connecting geographically distant locations, and require more complex conveying geometry. They can handle higher capacities and serve as trucking and rail transport alternatives. Dynamic analysis is typically necessary for evaluating transport conveyors.

Conclusion

Selecting the right conveying system is crucial for material handling in various industries. When selecting the most suitable conveying system, evaluate the pros and cons of a pneumatic vs. mechanical conveying system to make the right choice. Pneumatic conveying systems are flexible, closed, and can handle fine, fluidized, and dry materials, but they are less energy efficient and have higher upfront costs. Mechanical conveying uses belts, motors, and other equipment with lower upfront costs, but they are highly energy efficient and require more maintenance. 

Both systems have their strengths and weaknesses. If you are looking for advanced pneumatic conveying processes, contact Macawber Engineering Systems, a leading pneumatic conveyor manufacturer specialising in innovative material handling solutions for various industries.