The "Alphabet Soup" of Industrial Dust Detection
Continuous Opacity Monitoring Systems (COMS) for dust detection form an integral part of many facilities’ environmental control systems. While we don't sell COMS dust detection systems, we field a lot of questions from engineering and maintenance teams about how they compare to other solutions. This article will answer a few of the common questions.
In many facilities, COMS systems were required by early permits to monitor particulate matter emitted from the facility. They were the "go to" CPMS (Continuous Parameter Monitoring System) for several years until USEPA first amended the MACT standards to incorporate triboelectric instruments.
Most COMS dust detection systems are placed after the emissions control system(s) such as a fabric filter dust collector to monitor its operation and efficiency at all times. They were an early technology, however, and in recent years, the limitations and inherent drawbacks of COMS for dust emissions detection have led some to investigate new technologies. One such technology mentioned is PEMS or Predictive Emissions Monitoring System.
Predictive Emissions Monitoring Systems or PEMS
PEMS are an interesting new player in the emissions monitoring industry. A predictive emission monitoring system (PEMS) basically determines gas concentration or emission rate by using a process or control device for parametric measure of operating conditions. Those measurements are then manipulated through a conversion equation, a graph, or computer program to produce results in units of the applicable emission limitation or standard. At present, the EPA has conducted several rounds of trials with various PEMS OEMs, and even published temporary guidelines for designing of the algorithms as well as accuracy levels.
PEMS strive to overcome some of the key drawbacks of operating a conventional continuous emissions monitoring system (CEMS) for various pollutants regulated by the Clean Air Act and other associated legislation in the US (as well as under similar environmental regulations internationally.) A PEMS attempts to ascertain emissions data by calculating emissions levels based on careful monitoring of source operations rather than directly measuring emissions when generated. For example, a conventional CEMS uses various instruments in the outlet stack on a natural gas boiler to directly measure and record pollutants such as carbon monoxide, nitrogen dioxide or sulfur dioxide among other things. A PEMS would instead monitor operating conditions on the boiler (i.e. source equipment) such as temperature, feed rate, flow rate, etc., and then using that data calculate the emissions that would normally be generated and output them.
PEMS To Replace COMS Dust Detection?
PEMS are being studied by the EPA for use in a possible application in monitoring of NOx emissions. OEMs haven't begun intensive development of PEMS for use in monitoring PM emissions nor has the EPA began studying the proposition. For now, PM emissions for the most part still fall under the requirement for monitoring through stack testing, opacity monitoring or direct measuring with triboelectric detection system. On larger installations, plants may be required to monitor and record PM as part of a Continuous Opacity Monitoring Systems (COMS dust detection) or as part of a larger CEMS (Continuous Emissions Monitoring System.)
Predictive Monitoring Capabilities of PM Emissions with Triboelectric Detectors?
It's worth noting that predictive monitoring capabilities already exist for PM sources making use of triboelectric dust monitoring systems such as the Auburn Systems’ TRIBO series of detectors. Using the highly accurate PM detection capabilities of its dual band AC/DC triboelectric technology, TRIBO units can help plants effectively predict maintenance needs for particulate control systems, such as fabric filter dust collectors.
By recording trending emissions data in realtime down to 0.000002 g/dscf operators can accurately predict (1) when individual bags in the initial stages of failure (e.g. holes, loose connection, etc.) will reach critical levels and (2) when entire sets of filters will reach the end of their useful service life and need to be replaced. The latter alone can save plants significant amounts in replacement bags and production disruption by allowing them to accurately plan filter replacements to avoid common pitfalls including urgent filter procurement, production disruption and even contracted labor. While traditional COMS dust detection may alert operators when control devices no longer are operating at required capture efficiencies, they cannot provide this level of predictive capabilities due to their inherently lower sensitivity.
Would you like to learn more about the benefits of predictive maintenance that are possible with triboelectric dust detection systems from Auburn Systems? Please visit our blog to learn more or contact us today.