Compressed air solutions for pneumatic conveying

Once you have assessed what equipment is necessary to convey materials safely and effectively, you can begin looking for a suitable compressed air solution. Understanding how the right installation size can enhance speed and efficiency is crucial, as is identifying the technology that best aligns with your processing requirements and business goals.

If you seek further details about the pneumatic conveying system for sand, do not hesitate to reach out to us.

This section provides a comprehensive overview of dense-phase pneumatic conveying, outlining how these systems operate, their advantages and disadvantages, as well as important factors to consider when designing your own conveyor. With this knowledge, you can make informed decisions about whether a dense-phase pneumatic conveying system meets your material handling needs and operational objectives.

What is Dense Phase Pneumatic Conveying?

Dense phase pneumatic conveying is a method for transferring dry bulk materials through sealed, airtight pipes from one location to another using gas. The hallmark of a dense-phase system is its use of a minimal amount of air to gently push materials along the pipe's bottom, significantly reducing the risk of damage to both materials and equipment.

In contrast to dilute phase conveying, which continuously feeds material into a high-speed gas stream, dense phase conveyors transport materials in slugs. Therefore, the bulk density during transport is similar to that of the materials when at rest. Within the conveying pipes, gas pockets exist between the material slugs, creating a series of individual flows rather than a continuous stream.

Types of Dense Phase Pneumatic Conveying

Dense Phase Pressure Conveying

In dense phase pressure conveying systems, the dry bulk material is first loaded into a pressure vessel. Once this vessel is full, compressed air is employed to transport the materials into the conveying line. After the vessel and line have been emptied, the air supply is halted, and the vessel is reloaded to initiate the process again.

This method is particularly effective for transporting fragile or abrasive materials with particle sizes of ¼ inch or smaller.

Dense Phase Vacuum Conveying

This method is predominantly used by manufacturers for transferring granules and powders during truck or railcar unloading. It features a pressure vessel equipped with a fluidizing bottom, suitable for semi-abrasive and fluidizable powders requiring aeration for discharge into the conveying line.

Although this type is effective for semi-abrasive materials, it is not advisable for fragile materials with variable or larger particle sizes; it is best used for particles that measure ¼ inch or smaller.

What Materials Can a Dense Phase System Convey?

Dense-phase pneumatic conveying is utilized across a range of industries, both light and heavy, and is particularly favored for transporting abrasive materials. This system efficiently handles agglomerated, friable, and blended bulk materials of various types.

Typical materials processed through dense-phase systems include:

• Alumina
• Candies
• Carbon black
• Cocoa beans
• Dextrose
• Feldspar
• Fly ash
• Glass batch mix
• Glass cullet
• Hazelnuts
• Puffed rice cereal
• Resins
• Silica sand
• Sorbitol

Benefits of Dense Phase Pneumatic Conveying

• Minimal material degradation: The airvelocity in dense phase systems usually ranges from 3-8 m/s at the start of the line, ensuring delicate material transfer. This reduces wear, impact, breakage, and waste, thus enhancing product quality and marketability.
• Lower component wear: Reduced material velocity results in less wear on pneumatic components, even under abrasive conditions. This leads to lower maintenance costs and reduced system downtime, ultimately boosting productivity and saving costs.
• Prevention of material segregation: Conveying mixed materials at high density with low airspeed mitigates segregation risks and downstream processing complications, making dense-phase systems ideal for transporting powders post-mixing.
• Energy efficiency: Achieving a high solids load ratio means that dense phase conveying requires less gas, making it an energy-efficient option and keeping operational expenses to a minimum.

Drawbacks of Dense Phase Pneumatic Conveying

• Higher capital costs: Dense-phase pneumatic systems impose a greater initial investment compared to dilute-phase alternatives.
• Larger system dimensions: These systems typically occupy more space than dilute phase systems, which could pose a challenge for facilities with limited floor space.
• Shorter conveying distance: The higher pressure loss associated with dense phase systems generally results in shorter conveyance distances, although this may be addressed by increasing system pressure, which could elevate costs.

Three Considerations for Your Dense Phase Pneumatic Conveying System

If you work with fragile, abrasive, or friable materials that tolerate low gas velocities, then a dense-phase pneumatic conveying system may be the right choice. Before designing your system, consider these three critical factors.

System Design and Calibration

Designing and operating dense-phase systems akin to dilute-phase systems can compromise efficiency and productivity.

Low-pressure dilute phase systems utilize entry air pressures below 15 psig to transport materials rapidly through the conveying line while suspended in the air stream. On the other hand, high-pressure dense phase systems operate with smaller volumes of air at pressures ranging from 15-50 psig, moving materials slowly as slugs. The lower air-to-material ratio generally allows for narrower pipe diameters than in dilute phase systems.

Misaligning air pressure with your system type may lead to increased product damage and heightened component wear.

Fluidization

Fluidization involves using motive gas to enable materials to flow like liquids. Dense-phase systems typically depend on fluidization for effective bulk material movement.

Some materials, like fine granules, may compact under pressure instead of fluidizing, potentially leading to line obstructions and unforeseen maintenance expenses. Similarly, mixtures of unevenly sized powders can segregate, resulting in line blockages.

Conversely, medium-sized particles can operate efficiently without requiring fluidization, provided system length and pressure are aptly calibrated.

Air Injection

Your dense-phase system might enhance efficiency with additional air injectors, which can help sustain conveyance speeds over extended distances while preventing line blockages. These supplemental air bursts can also lessen the risk of bridging fine powders in the transporter.

While you may question whether these additional costs will outweigh the energy savings provided by a dense phase system, their role in ensuring smooth operation can lead to lower maintenance expenses and savings over time.

Achieving Peak Efficiency, Productivity, and Reliability with Industry-Leading Parts

If you handle fragile, abrasive, or friable dry bulk materials, then employing dense phase pressure or vacuum conveying systems may be well-suited for your facility. These dense phase systems excel in energy-efficient transportation with minimal wear on both materials and components, thereby maintaining product quality while minimizing costs.

However, simply designing and installing a dense phase pneumatic conveying system does not optimize performance and profitability. You must also ensure your system employs durable, cost-effective, abrasion-resistant components that offer a competitive advantage.

With over 40 years in the pneumatic conveying industry, we have diligently refined our collection of high-performance components. Every elbow, fitting, and coupling we provide is constructed to endure long-lasting wear, allowing you to depend on our industry-leading parts to maintain peak productivity for your system.

If you are eager to explore more about the sand moving equipment, reach out to us for an expert consultation today!