Because the Gold Series unit packs so much filtering capacity into a small footprint, sizing calculations determined that ten filter elements would do the job of the existing 64. Sized for 5,000 cfm and 9 in. of static pressure w.g., the unit (Figure 1) was designed for use with the existing fan and ductwork, reducing capital expenditures while also simplifying permitting requirements.
Amway's engineers already had noticed that spun-bond polyester filtration media are effective in capturing the detergent dust, which is moisture-laden and so fine it sometimes almost looks like smoke. So, a 100% spun-bond medium was selected for the HemiPleat filter cartridges. Use of this oleophobic medium prevents dust from clogging the filters and also allows cartridges to be washed and re-used.
The project team wanted to ensure the collector would meet stringent new combustible-dust safety requirements of the National Fire Protection Association (NFPA) and the U.S. Occupational Safety and Health Administration. These require dust collectors to have an explosion venting or suppression device unless the dust being handled is known to be inert. Camfil Farr commissioned explosibility testing of a dust sample; it showed the dust was slightly combustible, probably due to the surfactant loading characteristic of the powdered detergent. So, the company equipped the dust collector with an explosion vent manufactured in accordance with the latest NFPA standards.
After eight months of operation, the HemiPleat filters show no sign of increased pressure differential. This has allowed manufacturing engineer Karle Iberle to extend the maintenance cycle. And when a filter change-out is needed the whole process will be complete within an hour, he believes. "The filters slide in and out of the collector, so our workers can quickly and safely perform this task from outside the unit — which also eliminates the need for confined-space-entry paperwork. It's a big improvement from a maintenance standpoint, with projected labor savings of $1,500 per filter change."
The other main area of improvement is in compressed air usage, thanks to a Farr Dust Collector controller that reliably and efficiently handles the pulse-cleaning cycle. "This controller allows true 'on-demand' cleaning: the compressed air cleaning system is activated only when needed to pulse dust off the filter surfaces — about 30 minutes per eight-hour shift, instead of firing constantly as it did before," states Iberle. "We are saving an estimated 90% in compressed air costs, amounting to nearly $600 per year."
Further improvements in TCO are in the works, says Dauber: "… We are working on new filtration media that will raise the bar in terms of longevity, cleanability and sustainability. These are still in the testing and development phase."
A NEW ALTERNATIVE
Reducing TCO also was a key driver in the development of Tri-Flow Compact filters by Tri-Mer Corp., Owosso, Mich. The new filters, which deliver high-efficiency particulate air (HEPA)-level performance with a minimum efficiency reporting value (MERV)-16 rating, are designed to be a higher-performing alternative to bag, cartridge and pocket filters. They provide plants with the ability to improve air emissions and enhance workplace safety and productivity, using a cleanable filter system. "In the past, common air filtration systems used a non-cleanable HEPA system, which was very costly to maintain. In addition, the space-saving housing configurations have been helpful to facility engineers who are dealing with space limitations," says Ron Doneff, director of sales, dry dust collection.