Just because...it's time
Many plants change their baghouse filters based on a firm schedule. Others prefer to wait until the filters begin to show signs of leaking and then they replace them. Others use differential pressure as a guide, replacing the filters once the DP begins to trend above a certain level. And others simply wait until a reportable event, citation from an air quality inspector or massive loss in system suction (process flow) before taking action. What is the best method for scheduling filter replacement?
Balancing Performance with Cost
Deciding when to replace filter bags requires balancing two objectives: Maintaining operations at peak capacity and reducing operating costs wherever possible.
Stretching filter life as long as possible reduces direct costs for new filter media, but can create indirect costs, such as compromised worker health and safety conditions, increased emissions, and lost productivity/production due to the poor performance of a baghouse with old, worn out filters. Often these indirect costs exceed any slight savings gained from stretching filter service life longer than recommended. But companies may be inclined to try because the recommended filter bag rotation schedule often seems to favor the media supplier.
Instrumentation can inform the effort of management, maintenance and engineering to strike an effective balance. This starts with a realistic understanding of how dust collector downtime affects plant operations, including a financial analysis which accurately reflects an average cost per hour, shift, or day lost due to baghouse downtime. Since this figure will likely differ between systems even within the same plant, its best to conduct the same evaluation for each significant dust collection system in the plant.
Combine Multiple Monitoring Sources to Decide When to Change Filters
How can plants evaluate and monitor the state of their filters in order to inform this balancing act? Combining differential pressure monitoring together with a triboelectric baghouse monitoring system is key. A triboelectric dust detection system, such as the Auburn TRIBO.dsp 3400, can accurately monitor emissions from a dust collector down to 0.000002 g/dscf. This accuracy means that these systems can detect minute emissions levels coming from a dust collector - typically long before a reportable event, and often well in advance of a filter media failure.
While many associate triboelectric monitoring systems with broken filter detection, their detection sensitivity also allows for predictive maintenance capabilities regarding filter life. As they collect emissions data over the life of a set of filters, operators can track rising emissions levels through the trending data. This means they can accurately forecast when the filters will start emitting above acceptable limits. In many cases, this provides them with some months of advanced warning of when their filters will need replacement.
This early notice allows for advanced planning which provides procurement efficiency of replacement bags and reduces labor and production disruption costs associated with last minute changeouts. It accommodates scheduling of changeouts at the most opportune time (such as annual outage or before permit testing). Finally, it enables plants to comfortably predict how long they can use their filters before emissions rise too high. This helps maintenance planners get the maximum life out of their filters without risking production downtime due to high differential pressure or emissions.
Balancing performance of your baghouse dust collection system vs lowering maintenance costs can pose a challenge for even experienced personnel. The key is to not leave it to chance. Plants need to inform this process with accurate estimates of both direct and indirect costs associated with system downtime which can be confidently weighed against extending filter life.
Guessing when filters need replacement is an inexact process without a triboelectric dust monitoring system - with it, however, it can become an informed business decision.
Want to learn more about the predictive power of triboelectric dust collector monitoring? Watch our webinar on demand.