Controlling Particle Velocity to Reduce Blockages in Pneumatic Conveying Systems

Posted by Earl Parker on Apr 27, 2017 2:00:00 PM

Common systems and common frustrations

Dilute phase and dense (bulk) phase pneumatic conveying systems are widely used in industrial facilities for moving materials throughout a facility and as part of larger dust collection systems. They are efficient and effective - but they're also the cause of many frustrations. Frequent blockages, unplanned downtime, material attrition, energy cost and maintenance are all common complaints. In all cases, keeping the system free of blockages is crucial for proper operation. Blockages can lead to process disruption and lost production. They can also cause damage to the conveying system or other connected equipment. In other situations they create severe fire or explosion hazards when handling combustible dusts. 

Traditionally maintenance and engineering teams only had calculations and gas/air speed measurements as tools to use to help optimize conveying - minimizing blockages, energy cost and product attrition while maximizing throughput.

New advances in triboelectric detection, however, enable direct observation of particle speed in pneumatic conveying systems which puts operators in charge of the process!

The applications vary a bit between dense and dilute phase conveying.

Dense Phase Blockage Prevention

For dense phase systems Auburn has developed a range of monitoring technologies, including Flow/No Flow detectors to alert when flow stops, and More Flow/Less Flow detectors that allow operators to see when there are changes in the flow rates that could indicate a problem such as a blockage is developing. 

Prevent Dilute Phase Blockages with Particle Velocity Monitoring

Particle Velocity Monitor

Dilute phase pneumatic conveying systems face different challenges due to blockages. In order to stay suspended in the airstream the material needs to stay at or above a certain speed. This speed is called the minimum conveying velocity of the material. Density, weight and particle size all affect the velocity required to keep the material entrained in the airstream. 

You can prevent blockages by carefully monitoring particle velocity in the ductwork at various points throughout the system. An Auburn Systems particle velocity monitoring system makes use of the same patented Auburn Systems detection technology to accurately measure particle velocity regardless of dust load or temperature fluctuations (within acceptable range). The Auburn Systems TRIBO.hs 5000 measures velocity by measuring the time it takes for the particles to pass by two inline tribo instruments.

Because so many pneumatic conveying systems are used in the food industry, Auburn's particle velocity measuring systems use in-line non intrusive rings  to avoid any concerns of interfering with the flow or product damage. 

Equipped with a TRIBO.hs 5000 a facility can keep careful watch for any drops in particle velocity. Once a drop is detected maintenance personnel can investigate the cause and take corrective action to remedy the situation. Alternatively control signaling can tie directly into fan controls to reduce/increase gas velocity as required.

Conclusion

Preventing conveying system blockages can prevent a host of operational and production issues. The incurred tangible and intangible costs from these blockages can come from the effects of system downtime, increases in rejected product, wear on system parts, increased hazard of combustible dust explosions/fires, or increased energy costs from inefficient air usage.

If you would like more information on how to prevent these and other major issues involving pneumatic conveying system feel free to contact Auburn Systems!

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Topics: Process Control, Flow Control