Continuous Opacity Monitoring vs Triboelectric detection - What's best?

Posted by Justin Dechene on Oct 28, 2015 10:30:00 AM

The good news is that you've got options for particulate matter monitoring.  The choice of a monitoring system is an important one with capital acquisition cost, operational cost and compliance implications. It directly affects the bottom line at your facility. In short, facilities have to chose from two types of detection technology, optical (typically COM / continuous opacity monitoring) or triboelectric. Rather than selecting one by "its always been done this way", we recommend you carefully consider these four questions to determine which will prove the best fit. 

What Is Required By Your Air Permit?

Depending the application, different State and Federal (EPA) sets of rules may cover your operation. For general industry, optical methods such as visual testing and opacity meters may be acceptable. In other cases, industry-specific MACT standards (Maximum Achievable Control Technology) apply. For example, the MACT standard for Secondary Lead Smelters in 1995 specifically required triboelectric detection systems for dust collectors stating that optical methods were not sensitive enough to detect such small amounts of particulate matter emissions.  After that Triboelectric Bag Leak Detection Systems were included in all subsequent MACT standards involving fabric filters.

A triboelectric dust emissions monitoring device from Auburn Systems is often a superior alternative to continuous opacity monitoringDoes your facility fall under a MACT standard?

If so, does it require the use of triboelectric monitoring devices for your dust collectors?

What's your budget?  Today & tomorrow

Continuous opacity monitoring equipment is typically expensive to install....and often requires frequent adjustment, calibration and maintenance.

Not only is it more expensive (often in the range of $25K/installation) it's typically limited in application to the main stack.

In contrast tribo typically runs around 10% of that per monitoring point - a huge upfront savings which just gets bigger when you consider long-term maintenance implications.

Do You Want Just a Red/Green Alarm or Something More?  Do you run day and night?

Many operators think of their PM monitoring as simply a red light that alerts them when something has gone wrong with the dust collector. Until recently this was all the majority of monitoring systems were capable of providing.

In contrast to optical methods like continuous opacity monitoring, triboelectric-based systems can make use of multiple preset alarm levels, including at levels far lower than the maximum limit set by regulatory bodies. Combining these data points with specific maintenance plans for each level can prevent minor issues from escalating. Earlier detection means less abatement, less damage to bags/unit and less downtime. 

Triboelectric works day and night, just like you.  Where as COM by definition needs light to measure particulate, tribo uses triboelectric signasl.  So it's a 24X365 solution.

And an array of triboelectric detectors are often networked throughout a system from the main stack, down to baghouse, and even compartment level.  That aids in rapid troubleshooting and leak location - it's a radically different approach to the single continuous opacity monitoring point in the main stack which can only alert you when the whole system is out of compliance.

Which Will Bring The Most Maintenance and Operational Benefits?

Having access to real-time emissions data improves maintenance planning. For example, comparing emissions data with dust collector differential pressure readings can be used to establish the actual condition of the dust collector filters. When operators see the emissions levels rise over time, they can interpret this data to estimate when the filters will no longer meet required emissions limits and plan a change out. 

Another added benefit of detectors with greater sensitivity is the ability to pinpoint leaking filters in the dust collector. With these systems you can locate leaking filters down to the specific unit, compartment, and even row of bags. 

And then there's adjustments and calibration.  You'll never send someone scaling the main stack to clean or adjust a retro-reflective device.  Modern tribo detectors don't require periodic calibration, and aside from occasional probe fouling in certain applications (which can be detected with self diagnostics) there's essentially no maintenance.

Conclusion - Don’t Settle for Bare Minimum Required

Clearly, the choice of which monitoring system to use is important. 

Your choice should comply with any applicable air standards (i.e. MACT), offer more than just a Red/Green alarm  function, and contribute to improving overall operation and maintenance at your facility. 

These are just four basic considerations when choosing a particulate matter monitoring system. For a detailed guide to selecting the best solution for your plant, we invite you to download our free guide 15 Tips to Selecting The Best Bag Leak Detection System or contact Auburn Systems and one of our engineers will assist you today! 


Topics: Air Quality, Particulate Monitoring, Dust Detection, Environmental Monitoring