Pneumatic conveying

Systems for pneumatic conveying of powder and granules.

Choose the right solution for pneumatic conveying:

WHAT IS A PNEUMATIC CONVEYING SYSTEM? 

Pneumatic conveying systems / pneumatic transport  is done by using either vacuum or pressure. When using pressure, a distinction is made between “dilute phase” and “dense phase” transport. Oftentimes we supply the pneumatic conveying as part of a complete transport system, including rotary valves, screw conveyors, cyclones, automatic debagging, fans/compressors and silos. 

Essentially, pneumatic means that something is being transported using air. This is exactly what a pneumatic conveying system does, it moves product using air in a closed system. This is done creating pressure differentials to move product seamlessly and utilizing airflow generated by a device such as a fan or compressor. Usually, product is transported through pipes that are pressurized to create an internal airflow that transport the material in question between different sections of your production line.   

The advantages of using pneumatic conveying systems in your production lines are many. Among other things they allow for long distance transport of goods. They can also be fitted to work around machinery currently in use in your production facility as they require very little floor space and can be fitted around existing production infrastructure. Furthermore, pneumatic conveying operates in a closed system which limits dust and other particles spilling into your production area, and similarly it reduces the risk of your product being contaminated   

There are many varieties of pneumatic transportation and each of them depends on a variety of factors to determine which is the most optimal to use. Circumstances such as pipe length, material density, product fragility etc. all determine which solution is more suitable to your specific product and system. The relevant phases and methods are covered in the section below.  

Typically, pneumatic transport is categorized into four phases that each refer to different operating conditions based on the concentration of material being conveyed. The four phases are:  

Dilute Phase Pneumatic conveying

In the “dilute phase”, the concentration of material is relatively low. The material is mixed with a large amount of air, resulting in a dilute mixture. This phase is characterized by high air velocity and low material-to-air ratio. The material is typically suspended in the air stream and conveyed as a turbulent flow. Dilute phase conveying is suitable for light, non-abrasive materials over long distances.  

At dilute phase, the medium is sent through a pipeline at a relatively high speed, as the particles must be airborne. Dilute phase transport can be performed with either vacuum or pressure. When vacuum is used, it requires that the pressure drop in the piping does not exceed 400-500 mBar, while a pressure system can work with a pressure loss of up to 900-1000 mBar.

Dilute phase conveying is characterized by the following:

• Used for the transport of materials that can withstand transport at high speeds
• Used for short pipe strings of up to 50 m
• Handles mass flow of bulk material from 0.5 t/h to 50 t/h
• Air/Material speed of approx. 20-32 m/s

Dilute phase is an energy efficient form of transport under the above conditions. Furthermore, the costs for blower, piping and filters for a dilute system are relatively low as long as the distances are kept short.

If the transport distance is increased, this form of conveying becomes more energy demanding as the pressure drop in the piping increases.

Dense Phase Pneumatic conveying

In “dense phase”, the material is conveyed at a lower speed using compressed air. The dense phase system is suitable for longer pipelines, and the transport speed is only 3-8 m/s. This means significantly less wear and tear on pipes and pipe bends, which results in savings for the customer, due to less downtime and reduced costs for replacing pipes and pipe bends.

Dense phase transport is also more energy efficient for transport over long distances. The high energy efficiency arises because large quantities of material are conveyed using a relatively small amount of air.

Compared to the cost of the blower and pipes that must be used for Dilute phase transport, the costs of a Dense phase system become relatively low when the transport distance is increased.

Dense phase systems can be used for the conveying of many different products, from wood chips to flyash.

Dense phase conveying is characterized by the following:

• Very gentle on the material being transported
• Transport over long distances, up to 1500 m
• Mass flow of bulk goods from 0.5 to 150 tons/h
• The air and material speed is approx. 3-8 m/s, depending on the particle size
• Is suitable for conveying of abrasive materials

Pneumatic transport since 1935

At PAM we have extensive experience customizing pneumatic transport system designs to our customers needs and specifications. We have been developing solutions for pneumatic transport since 1935, and over the years we have continued to modernize and develop our approach. Thus, we can surely develop one that fits perfectly in your production line.   

Call us to find out which system best suits your needs.

Check a couple of cases here:

• Pneumatic conveying of fishmeal
• Mechanical and pneumatic conveying at a powerplant
• Handling of powders in chemical industry