Dust Collection in Plasma and Wire Spray Operations
How one company reduced downtime and disposal costs.
Pamarco Southern, located in Atlanta, was experiencing problems collecting metal dusts from a plasma and wire spray operation that produces metal coatings for rolls used in the printing industry. Microscopic, irregularly shaped dust particles generated during this operation were causing dust collector filter cartridges to load prematurely, resulting in unwanted downtime. Filter disposal also was getting costly, since the cartridges had to be treated as hazardous waste because they contained different metals.
"To get a handle on costs, we needed to find a way to increase cartridge life and reduce high differential pressure across our dust collectors," stated David Drozd, plant manager at the Pamarco facility.
Time for a Change
"Over the years, we tried several types of dust collection equipment in this facility and two others, but we encountered problems with each type," Drozd said. Several years back, Pamarco used baghouse dust collectors. However, baghouses typically required a large footprint and, in this case, the use of exotic media to achieve required filtration efficiencies, so they became too costly for the company.
The company then switched to cartridge-type collectors, which offered more compact designs and enhanced capture of fine dusts. When operating collectors with horizontally mounted cartridges, the company found that dust tended to resettle on the cartridge surfaces after cleaning, necessitating frequent filter change-outs. Vertically mounted cartridge collectors eliminated this dust re-entrainment problem but yielded only modest improvements in filter life, to a maximum of about six months.
Working with his equipment supplier, Drozd set out to identify the reasons for poor collector performance. In analyzing past experiences, he determined thaI several factors were contributing to short filter life:
- Inefficient inlet design
- Incorrect equipment size for the application
- Inadequate cleaning power
- Filtration media
Figure 1 - Each vertically mounted cartridge incorporates an extra inner cone of media for a total of 425 square feet of media.
Eventually, Drozd selected a high-efficiency Gold Series® cartridge collection system manufactured by Farr Air Pollution Control (APC), Jonesboro, Arkansas, because it offered design features that addressed each of these concerns. The system uses a high entry inlet that creates a cross flow through the filters, eliminating problems associated with traditional hopper inlets. The unit contains 48 vertically mounted cartridges that use silicone-impregnated polyester-cellulose media.
The patented design, which incorporates an inner cone of media, provides 425 square feet of media in each cartridge (see Figure 1). This results in high dust-holding capacity with high filtration efficiency. In addition, this design makes it possible to meet airflow requirements with a 25 percent smaller housing.