Dense phase vs dilute phase :

Dense phase and dilute phase are two types of pneumatic conveying systems used to transfer bulk solids (powders, granules, etc.) from one place to another.

Dilute phase conveying is a pneumatic conveying system in which the material being transported is suspended in the air and conveyed at high velocity through a pipeline with a low solids-to-air ratio. This results in a lower pressure drop and higher air velocities, which makes it suitable for conveying materials over longer distances. Dilute phase conveying is typically used for free-flowing materials, such as sugar, flour, and plastic pellets.

Dense phase conveying is a pneumatic conveying system in which the material being transported is pushed through a pipeline as a plug or slug, rather than being suspended in the air. This results in a higher solids-to-air ratio and lower air velocities, which reduces the risk of material degradation and makes it suitable for conveying fragile materials, such as pharmaceuticals, ceramics, and catalysts. Dense phase conveying is typically used for materials that are cohesive, abrasive, or friable.

In summary, dilute phase conveying is suitable for free-flowing materials and longer distances, while dense phase conveying is suitable for fragile materials and shorter distances.

 

Dense phase vs dilute phase calculation

Dense phase and dilute phase are two different modes of conveying materials in pneumatic conveying systems. The primary difference between the two modes is the concentration of the material being conveyed.

Dense phase conveying is characterized by a high concentration of material in the conveying line, typically in the range of 15-40 kg/m3. The material is conveyed at low velocities, usually below 6 m/s, which minimizes the amount of air required for conveying. This mode of conveying is often used for fragile or abrasive materials that are sensitive to breakage or degradation.

Dilute phase conveying, on the other hand, is characterized by a low concentration of material in the conveying line, typically in the range of 1-10 kg/m3. The material is conveyed at high velocities, usually above 15 m/s, which requires a significant amount of air to be used for conveying. This mode of conveying is often used for materials that are less sensitive to breakage or degradation, such as powders or granular materials.

The calculations for designing a dense phase or dilute phase conveying system are different due to the differences in the mode of conveying. Some of the factors that need to be considered in the design calculations for each mode of conveying are:

Dense phase conveying:

  • Material density
  • Pipeline diameter
  • Conveying pressure
  • Air pressure
  • Air volume flow rate
  • Conveying distance
  • Pipeline bends and fittings
  • Material degradation and attrition

The design calculations for dense phase conveying are typically more complex due to the higher material concentrations and slower conveying velocities. The pressure drop calculations are more critical, and the risk of material degradation and attrition is higher.

Dilute phase conveying:

  • Material flow rate
  • Pipeline diameter
  • Air velocity
  • Air volume flow rate
  • Conveying pressure
  • Conveying distance
  • Pipeline bends and fittings
  • Material degradation and attrition

The design calculations for dilute phase conveying are simpler than those for dense phase conveying, but the conveying velocities are higher, which can increase the risk of material degradation and attrition.

In both modes of conveying, it is essential to ensure that the conveying system is properly designed and operated to avoid material buildup, blockages, and other operational issues.

Dense phase vs dilute phase working principle

Dense phase and dilute phase are two types of pneumatic conveying systems used to move bulk solids such as powders, pellets, and granules.

Dilute phase conveying involves moving the material in suspension in a gas stream at a velocity higher than its terminal settling velocity. In other words, the material is carried along in a relatively low-pressure, high-velocity air stream. The air-to-material ratio is typically high, ranging from 20:1 to 50:1. This type of conveying is suitable for materials that are free-flowing and non-abrasive, such as cereal grains, plastic pellets, and cement.

Dense phase conveying, on the other hand, involves moving the material at a much slower velocity than in dilute phase, typically less than the material’s minimum conveying velocity. The material is conveyed in a slug-like manner, with the particles forming a solid plug that is pushed through the pipeline by a low-pressure, high-volume gas stream. The air-to-material ratio is low, typically less than 15:1. This type of conveying is suitable for materials that are abrasive, fragile, or cohesive, such as coal, sand, and sugar.

In summary, the main difference between dense phase and dilute phase conveying is the velocity at which the material is transported. Dilute phase conveying moves the material in suspension at high velocity, while dense phase conveying moves the material in a solid plug at low velocity. The choice between these two types of conveying systems depends on the properties of the material being conveyed and the specific requirements of the application.

Dense phase vs dilute phase advantages and disadvantages

Dense phase and dilute phase are two types of pneumatic conveying systems used to move bulk solids, such as powders or granules, through pipelines or tubes. Here are some advantages and disadvantages of each system:

Dilute Phase: Advantages:

  • Lower material velocities reduce the likelihood of material degradation, particularly for fragile or abrasive materials.
  • Lower capital and operating costs due to the reduced pressure requirements and simpler control systems.
  • High conveying capacity, particularly for lighter materials.
  • Greater flexibility in terms of conveying distance and direction.

Disadvantages:

  • Greater power consumption due to the need to maintain a high air-to-solids ratio.
  • Greater air volume requirements, which can lead to increased system noise and potential safety concerns.
  • Limited conveying distance, particularly for heavier materials.
  • Increased wear and tear on the system due to higher material velocities.

Dense Phase: Advantages:

  • Reduced power consumption due to lower air-to-solids ratios and lower material velocities.
  • Reduced material degradation, particularly for heavier or more abrasive materials.
  • Greater conveying distance, particularly for heavier materials.
  • Lower noise levels and potential safety concerns due to lower air volumes.

Disadvantages:

  • Higher capital and operating costs due to the need for larger compressors and more complex control systems.
  • Lower conveying capacity, particularly for lighter materials.
  • Limited flexibility in terms of conveying direction.
  • Increased risk of blockages due to the higher material concentrations.

In summary, dilute phase conveying is generally preferred for its lower capital and operating costs, higher conveying capacity, and greater flexibility, while dense phase conveying is preferred for its reduced material degradation, greater conveying distance, and lower power consumption. The choice between the two systems ultimately depends on the specific material being conveyed, the conveying distance and capacity required, and the budget and operational requirements of the system.

 

 

 

By RKP