Foundries rely on the uninterrupted operation of their dust collection systems to assure a safe and productive work environment and proper operation of equipment. When dust collection systems present maintenance issues, foundries can realize tens of thousands of dollars in inefficiencies. If the issues are unrecognized or ignored, the costs will multiply very quickly and can result in lengthy shutdowns.
This was the scenario that a large Midwestern foundry sought to avoid after enduring multiple shutdowns in a year’s time to perform filter maintenance on their Carborundum baghouse.
The foundry was having significant problems with their filters being blinded by the fine particles in the gas stream. They were operating a pulse jet baghouse with seven compartments, at 250,000 ACFM. The filters that they had in operation used conventional polyester felt technology. The system had been designed at a 4.1/1 air-to-cloth ratio.
The fine particles in the dust stream were of a volume that simply overcame the filter media. This pushed the differential pressure across the baghouse to over 8 inches. The system was rendered unrecoverable and inoperable.
Maintenance was conducted using the same filtration technology, and the blinding effect repeated itself. The filters were only able to stay in operation for six months before the end of their useful life. As a result, the filters and labor cost the foundry in excess of two hundred thousand dollars over a year’s time.
In the search for a solution, the foundry turned to Parker Hannifin. Parker recommended implementing spun-bound polyester BHAPulsePleat filter elements (PFE) in place of the polyester felt bag and cage design that had been in use. These filter elements feature a combination of pleated high-efficiency filtration media and an inner support core that forms a one-piece element that fits directly into an existing baghouse tubesheet. The BHAPulsePleat filter media would offer a much better air-to-cloth ratio of 2.1/1. In addition, the pleated design of the media would not be as susceptible to the blinding effect caused by the fine particles in the gas stream.
The foundry implemented the PFEs in two phases, addressing the most problematic compartments first. After seeing positive results, it moved forward and converted the rest of the collector to pleated filters. The return on the total conversion expense of $285K was realized after sixteen months of efficient operation with no maintenance required.
After twenty-one months of operation, the differential pressure was operating in the 3-5 inch range. The filters had proved capable of handling the fine particle load without blinding. Even after a weeklong accidental shutdown of the cleaning system, the filters were able to have the particle loading and maintain a low differential and efficient operation. At this point, the foundry had realized a filter life three times greater with the pleated filtration in comparison to the polyester felt.
Under the current operating conditions, the foundry is not planning to perform filter replacement maintenance for another twelve months. In this case, they will have seen a five times improvement in filter life by employing the BHAPulsePleat technology.
By employing the technology, this foundry eliminated frequent unplanned shutdowns, increased ROI and extended the life of the filters in its pulse jet baghouse.
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This article was contributed by the Filtration technology team.