Differential Pressure - Not necessarily the best parameter for dust collector/baghouse monitoring
DP is the king of dust collector monitoring metrics. However, some users have come to think that it is the ONLY metric to monitor on an industrial dust collector. This certainly is not the case…especially as the size and complexity of the system increases. Here are 4 important areas for which differential pressure cannot provide adequate insight.
Total Emissions Levels
A common misconception is that differential pressure measures the collection efficiency of the dust collector. This is not true. DP measures the resistance to flow the filters generate, usually as a result of dust buildup on the surface or within the depth of the fabric.
For example, the differential can be reading in the optimal range of 3” - 6” w.g. and still have visible emissions.
The confusion stems from years of air permits which only required plants to monitor the differential pressure and maintain it within a certain range. This is a reasonable indicator because baghouses generally are at their peak efficiency within this range. Further, if the unit were to have high DP this most likely would indicate the filters were worn out and in need of replacement. And for years no reliable technology existed to actually measure particle emissions - so DP was a measurable, approximate surrogate for direct emissions monitoring.
So, while useful to an extent, DP cannot provide accurate measurement of emissions, especially in light of today’s stricter emissions standards.
Presence of Leaking Filters
Related to the above point, differential pressure is not able to indicate with any certainty the presence of a leak in the system. For this reason, a number of industries are required under MACT standards or other state regulatory requirements to include bag leak detection systems, such asTRIBO.dsp series, in order to monitor for leaks that may develop. Nor can DP help to quickly locate a leak within a baghouse or compartment.
On high temperature units, such as those treating flue gas from industrial boilers, incinerators, certain process gases, etc. controlling the flue gas within the acceptable temperature range requires careful monitoring of the temperature at the inlets and outlets of the unit. In these systems, this data metric must be closely watched. This may be the most critical metric to ensure the integrity of the filters and overall pollution control system.
Providing sufficient suction to maintain the required minimum conveying velocity is a key aspect of dust collection system operation. Any loss in vacuum will result in a loss of air velocity that can lead to product dropout, causes blockages in the ductwork among other issues.
Operators should keep careful eye on overall DP in the dust collector as an early warning sign, but for better results they can utilize the far more accurate triboelectric particle velocity monitors for real time measurement of velocity at multiple points throughout the duct work system.
While DP has and should remain the first and foremost monitoring metric for operating dust collection systems, as we have seen it cannot provide adequate insight into every needed area of the system operation.
Do you want to know more about how you can improve your dust collector monitoring? Let Auburn Systems use their 40+ years of experience to help you get more from your dust collector. Contact us today to discuss your application.