Taking the Good with the Bad

Pneumatic conveying systems are the best solution for many bulk product handling requirements. They have a number of advantages, but also some associated drawbacks. Product damage, blockages and maintenance are widely recognized challenges. Less frequently discussed, but perhaps just as costly is the energy requirement to push or draw the volume of air/gas through the system to move product.

Direct costs from fans, blowers and compressors for pneumatic conveying systems can be substantial. However, new technologies allow companies to precisely measure particle velocity, and to dynamically adjust fan/air speed accordingly. This reduces energy wasted on excessive conveying speed (which is dissipated as heat and results in damage) and eliminates the need for manual adjustments.

Pneumatic Conveying - Flying Blind in Strong Headwinds

Both dense phase and dilute phase conveying systems require careful management of blower power in order to achieve the best results. Too high a setting can easily damage the conveyed materials through greater friction as the material makes its way through at higher speed. This increased friction in many cases also damages the material by creating excess heat. (Plastic resin in particular is known for its tendency to degrade quickly when subjected to higher than recommended conveying velocities.)

Similarly, too low a blower setting creates problems with blockages that can damage equipment or create unsafe conditions. Lower settings can also counter intuitively increase cost as they reduce output and negatively impact productivity across multiple departments. 

Central to the challenge are inherent efficiencies of pneumatic solutions for conveying bulk products. Pushing materials through a long run of piping requires enormous power to keep particles suspended and overcome friction. As such, the longer the runs the more pneumatic conveying velocity is lost. This means that you need to balance the speed and pressure at the beginning of the run with the requirements at the end of the run (not too high to damage the materials or system at the beginning but sufficient pressure to maintain the flow at the far end). What makes this more difficult is the fact that most conveying systems are subject to constant changes that affect these figures. Trying to account for the effect of these, such as increased or decrease load, changes in materials, environmental changes, equipment performance, etc., can prove exceedingly difficult. 

Particle Velocity Monitoring to the Rescue

With the development of Auburn Systems’ TRIBO.hs model 5000 particle velocity monitor plants have a new way to address these challenges. Using two non-intrusive probes placed in sequence on the conveying duct, the model 5000 determines the speed of the particles in the duct by calculating how long it takes the particle to travel  past both detectors. This results in an accurate and reliable measurement of actual particle velocity, not just air velocity. With this data, operators can then adjust blower or compressor systems as required to operate the system at peak efficiency. 

Additionally, Auburn has developed the capability for the monitor to directly interface with the variable speed controls on system fans/blowers to automatically adjust the settings in real time, changing the conditions in the conveying line. This automated process greatly improves efficiency on these systems and results in both direct and indirect savings for plants. 

Conclusion

Pneumatic conveying will always provide a challenge to system designers, operators and maintenance personnel. But it's a great option for many applications and rather than replace it, companies want to improve it. Triboelectric particle velocity monitoring with integrated compressor and blower control capabilities has proven to be one of the most significant and economical improvements to pneumatic conveying controls in recent years. And the energy cost savings are proving significant! Learn more about how your plant can benefit by speaking with an Auburn representative today!