Narrowing down your choice by product first, then distance and energy, will get you to the right system faster.
Choosing the wrong mode of conveying can cause serious problems – such as broken products, blocked-up pipes and low efficiency. By choosing the right mode of conveying on the basis of five different criteria, you can avoid these problems.
Check Your Material’s Fragility
Dilute phase conveying suspends the material in the air stream. In order to achieve this, fast flow velocities are required, typically over 15 m/s. Granular materials are typical for dilute phase conveying. However, also pellets and powders that are not too friable can be conveyed in this manner. However, also fine powdery products can be fluidized by the high speed air stream and damaged in the process. Dense phase on the other hand conveys the material at low velocities, typically below 5 m/s. Thus, also very fragile or abrasive products can be conveyed safely in this manner.
Consider Particle Size and Bulk Density
Fine, low density powders, that easily fluidize, are best conveyed using dilute phase systems. Coarser, denser products such as sugar, plastic pellets or sand are better suited to being conveyed using dense phase, where the material is conveyed in a solid slug or plug and particles are kept together and do not scatter.
Factor In Pipe Distance
Dense phase is well suited for longer distance conveying, particularly cross-site transfer over distances greater than 100m.
Weigh Up Energy Costs
Dilute phase systems can move high volumes of product quickly but use more air than a Dense phase system to achieve the same result. However, when looking at the amount of air used to move a tonne of product, Dense phase actually works out to be less in most continuous production scenarios. For a good reference on system selection criteria, bulk solids handling guidance from chemical engineers is a very good technical reference.
Know When a Hybrid Helps
A Hybrid system allows operation in either Dense or Dilute phase and can be advantageous where a single line needs to run a variety of products. More on Pneumatic Conveying Systems can be found at www.aptech.uk.com/pneumatic-conveying-systems.
By looking at your product first, then distance between locations and finally energy costs, you can find the correct material handling system more quickly.
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