A Brief Overview of Pneumatic Conveying
Pneumatic conveying and mechanical conveying differ in the materials they transfer, conveyance distances, and system design. Pneumatic conveying, using a gas stream, is enclosed and flexible for moving dry bulk materials, while mechanical conveying is open and optimized for transferring heavier or moist materials.
Pneumatic conveying involves using a suspended gas stream, such as air or an inert gas, to transfer dry bulk materials through an enclosed pipeline. The materials are fed from a hopper and controlled by feeders, while air velocity at the pick-up point carries them through the system. A pressure difference between the start and end of the pipeline is necessary, requiring the use of conveying blowers or compressors.
Critical components of these systems include material introduction points, feed devices, air sources, conveying lines, air-material separators, elbows, pipelines, gaskets, and airflow movement devices. Positive pressure systems and vacuum systems are the most common types, while dilute phase and dense phase systems are used for different materials. Positive pressure systems use blowers or fans to suspend materials, while vacuum systems use a vacuum at the end of the line. Dilute phase systems are ideal for lighter materials like talcum powder, while dense phase systems are better suited for heavier, abrasive materials like plastic pellets.
What is Mechanical Conveying?
Mechanical conveying is the method of transporting heavy bulk materials using traditional machinery. These systems contain numerous moving parts, including Belts, Buckets, Chains, Driver motors, and Rollers or sprockets. An energy source, typically a motor, powers the conveyor to efficiently transport materials. Generally, mechanical conveying systems are open, such as production lines in a factory. However, they can be closed if handling air-sensitive materials.
Mechanical conveying is most suitable for heavy, non-free-flowing materials, such as crushed rock or gravel. It is also the preferred method for materials with high moisture, fat, or oil content, like cake mix, titanium dioxide, and brown sugar. There are various types of mechanical conveying systems, including Screw conveyors, Drag chain conveyors, Bucket elevators, Vibrating feeders, and Belt conveyors. Each type is optimized for specific purposes depending on the product and distance to be transported.
5 Differences Between Pneumatic Conveying vs. Mechanical Conveying
Pneumatic conveying and mechanical conveying differ in their materials transported, industries used in, conveying distance, material routing, and installation. Pneumatic systems use gas or vacuum while mechanical systems use machinery like belts, rollers, and motors. Pneumatic conveying is best for free-flowing dry materials while mechanical conveying is better for heavy, friable or wet materials.
Pneumatic systems aerate dry powders and are suitable for transporting hazardous materials, while mechanical systems are better for air-sensitive products. Pneumatic conveying is ideal for long distances, while mechanical conveying is better for shorter distances. Pneumatic systems can accommodate tight bends and be installed indoors or outdoors, while mechanical systems require more floor space and may need existing machinery to be relocated.
Pros and Cons of Pneumatic vs. Mechanical Conveying
Both pneumatic and mechanical conveying have their own unique pros and cons that highlight their benefits and challenges. Pneumatic conveying offers simplified material routing and flexibility, with enclosed lines reducing material loss and spills. Maintenance is also minimized due to fewer moving parts, resulting in higher productivity and efficiency levels. On the other hand, mechanical conveying is more cost-effective for shorter distances and can position lines at any angle.
It can also handle heavy, fragile, and wet materials without clogging, making it a reliable choice for various types of products. However, it requires more maintenance and takes up more floor space compared to pneumatic conveying systems. Ultimately, the choice between the two will depend on the specific needs of the process.