Conveying by pneumatic transport Pneumatic of Bulk Solids

In this brief article, we will touch on the Pneumatic Conveying of Bulk Solids. One of the most important techniques for bulk solids handling in a solids handling plant is solids transport. When solids are suspended in a stream of air, this process is called pneumatic conveying. You can perform pneumatic conveying over horizontal, inclined, or vertical surfaces, with distances ranging from a few to several hundred meters.

This transportation method can handle material sizes from fine powder to millimeter-sized granules, depending on the pipeline diameter. Compared to other conveying methods, pneumatic conveying offers a flexible combination of pipelines.

The range of materials suitable for pneumatic conveying depends on specific physical properties. Key factors include particle size, hardness, resistance to damage, and cohesive properties. Most cohesive and sticky materials are often unsuitable for pneumatic conveying. For example, materials with high oil and fat content can easily cause pipeline blockages.

Pneumatic conveying of bulk solids can be categorized into two main types based on the relative positioning of solids and the velocity system. These types are called diluted phase and dense phase. Dense-phase pneumatic conveying typically transfers particulate solids over short distances.

Diluted-phase pneumatic conveying offers several advantages: (1) it is relatively cheaper, (2) it is easier to maintain, and (3) its pipeline design is more flexible for small spaces. In contrast, dense-phase pneumatic transport provides benefits such as (1) high loading capacity, (2) relatively low attrition levels in the system, and (3) reduced segregation of mixtures by transporting at high density with low air velocity.

In our field testing area, we have several small-scale pneumatic transport setups equipped with radius bends and mitered bends. These setups allow us to study the impact of various variables on conveying through pneumatic transport, including the number of bends, type of bend, air velocity, and the differences between dense phase and dilute phase. This enables us to determine early in the process of design and product development whether the product properties are suitable for pneumatic conveying.

However, several common problems can occur in pneumatic conveying systems: Friable materials, such as protein food, coffee beans, or grains, can impact the bend wall at high speed. This impact causes breakage and the formation of fines, which can decrease product quality, consistency, and saleability while increasing waste.

Abrasive materials, such as sand, glass, alumina, or mineral-filled plastic pellets, can also create issues. When these materials hit the outside radius of conventional impact bends at high speed, they cause continuous wear on the bend wall. This wear can lead to frequent replacements of bends, resulting in additional labor and downtime in the pneumatic conveying system.

Friable materials, such as protein food, coffee beans, or grains, can impact the bend wall at high speed. This impact causes breakage and the formation of fines, which can decrease product quality, consistency, and saleability while increasing waste.

Abrasive materials, such as sand, glass, alumina, or mineral-filled plastic pellets, can also create issues. When these materials hit the outside radius of conventional impact bends at high speed, they cause continuous wear on the bend wall. This wear can lead to frequent replacements of bends, resulting in additional labor and downtime in the pneumatic conveying system.