Bag Leak Detection Blog

Particle Speed, not Air Speed!

Pneumatic conveying plays a large role in many industrial processes across many industries. From batch mixing and manufacturing, to fuel feed rates for boilers and furnaces, pneumatic conveying controls must be set correctly or else serious complications can arise leading to loss of product, damage to equipment or even potential safety or emissions violations.

Recently, Auburn Systems has had great success integrating their triboelectric particulate monitoring solutions directly with pneumatic conveying system controls to dynamically adjust fan settings to increase/decrease air flow and velocity through the processes. This can be done by measuring actual particle speed with the TRIBO.hs 5000 particle velocity monitoring series. Let’s examine a few of these advantages.

Advantage #1 - Automate Control Settings to Respond to Process Changes

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

Real World Complications

When unloading bulk material, sudden changes in air flow can create complications for material conveying systems. Rapid increases in material flows, or high volume air flow as material flow suddenly slows, can damage filters within the system filter receiver. Often this change occurs quickly, and even if operators are diligently observing, they may not react quickly enough to prevent damage.

How can plants avoid these issues and prevent damaging their filters?   

Common Causes of Sudden Increases in Flow Rates

In most cases, there are several causes of sudden increased material flow. 

Pneumatic Conveying Convenience and Flaws

Many industries use pneumatic conveying as part of their manufacturing process. This includes many food processing and manufacturing plants as well. It's often used for the conveying of certain "dusty" food ingredients such as grains and sugar which pose certain well documented challenges including combustible dust hazards, sanitary or flow rate control. 

Does Damage You Don't See Matter?

Plastic resin often passes through extensive pneumatic conveying systems during it's manufacturing and use. While those pneumatic systems are efficient and appropriate, they're not without complications to quality and throughput.

Is the "Status Quo" Good Enough?

For many plants that make use of pneumatic conveying systems, maintaining the status quo seems sufficient. Many manufacturing plants have many years of service in them and many believe fully in the adage “if it aint broke, don’t fix it”. While it makes for a catchy slogan, when misapplied it can lead to stagnation and a gradual decline in quality and competitiveness over time. Because in many cases it actually is broken...but nobody has bothered to fret too much because there's been no good solution.

It's common to hear stories about blockages that cause unplanned downtime, quality problems with blending applications and wasted product during line restarts. Maintenance issues and product damage/loss are also common pain points.

The problem is that there's really never been an accurate way to measure actual particle speed. Calculations were made based on system parameters, and in some cases air/gas speed was measured. Those are substantially different than actual particle speed itself which will often determine which baked goods will crumble, which resin will smear and which products will create blockages.

To this end, many have seen the benefits of incorporating triboelectric monitoring systems into their dust collection and associated pneumatic conveying systems to improve operational efficiency, reduce costs and increase reliability. Let’s consider 2 areas that are commonly overlooked where a triboelectric system can provide real benefits. 

1. Flow/No Flow and More Flow/Less Flow Monitoring Prevents Blockages in Pneumatic Conveying Lines

Stop guessing & start controlling

Controlling bulk material feed rates is essential for a wide range of industrial processes. Traditionally though process engineers have had to calculate, or frankly, guess. Industry has lacked an effective instrumentation for monitoring actual particle velocity often using gas/air velocity as a very approximate proxy.. Auburn Systems has solved this with an adaption of their patented triboelectric technology for use in bulk flow monitoring.

Positive Physical Control vs. Indirect Control

The two primary means of conveying bulk products are by pneumatic and mechanical conveying with the most common type of mechanical conveyor being the screw conveyor. Both methods have benefits in certain applications over others. In general, finer, more consistently sized materials as well as some granular and pelletized materials work well with pneumatic conveyors whereas larger, irregularly sized materials, as well as moist, doughy, and packable materials work better with screw conveyors. However, in the middle reside the majority of materials for which both systems could be appropriate. 

In cases where either system could be used, sometimes previous hassles or perceptions of pneumatic conveying problems may lead engineers to use a screw type system. Let’s review three of these and consider why engineers should not be hasty to rule out pneumatic conveying - in fact how to overcome these problems to make pneumatic conveying more reliable. 

3 Pneumatic Conveying Challenges:

1. Justifying Investment in “Complex” Pneumatic Systems

Understanding What's Happening Inside Your Cyclone Dust Collector

Cyclone dust collectors find use in many industrial applications with high volumes of product flow. Unlike other types of dust collectors, such as fabric filter collectors, cyclones can handle very high dust levels without sacrificing efficiency or sustaining damage. This is precisely why cyclones are often used as prefilters, removing the majority of the material from the airstream before it enters into a final “polishing” unit, such as a baghouse or cartridge collector. In other applications, cyclones are used for particle sorting or bulk material transport. 

Even though cyclones do not have a high enough collection efficiency to be used by themselves, they do play a large role in many applications, for emissions as well as process applications. In process applications, many have asked if triboelectric monitoring can control product flows through the cyclone. The answer is yes!

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.