Further development of the cleanable steel HEPA filter, cost/benefit analysis, and comparison with competing technologies
We have made further progress in developing a cleanable steel fiber HEPA filter. We fabricated a pleated cylindrical cartridge using commercially available steel fiber media that is made with 1 {mu}m stainless steel fibers and sintered into a sheet form. Test results at the Department of Energy (DOE) Filter Test Station at Oak Ridge show the prototype filter cartridge has 99.99% efficiency for 0.3 {mu}m dioctyl phthalate (DOP) aerosols and a pressure drop of 1.5 inches. Filter loading and cleaning tests using AC Fine dust showed the filter could be repeatedly cleaned using reverse air pulses. Our analysis of commercially optimized filters suggest that cleanable steel HEPA filters need to be made from steel fibers less than 1 {mu}m, and preferably 0.5 {mu}m, to meet the standard HEPA filter requirements in production units. We have demonstrated that 0.5 {mu}m steel fibers can be produced using the fiber bundling and drawing process. The 0.5 {mu}m steel fibers are then sintered into small filter samples and tested for efficiency and pressure drop. Test results on the sample showed a penetration of 0.0015% at 0.3 {mu}m and a pressure drop of 1.15 inches at 6.9 ft/min (3.5 cm/s) velocity. Based on these results, steel fiber media can easily meet the requirements of 0.03% penetration and 1.0 inch of pressure drop by using less fibers in the media. A cost analysis of the cleanable steel HEPA filter shows that, although the steel HEPA filter costs much more than the standard glass fiber HEPA filter, it has the potential to be very cost effective because of the high disposal costs of contaminated HEPA filters. We estimate that the steel HEPA filter will save an average of $16,000 over its 30 year life. The additional savings from the clean-up costs resulting from ruptured glass HEPA filters during accidents was not included but makes the steel HEPA filter even more cost effective. We also present the results of our evaluation of competing technologies with metallic and ceramic powder filters, ceramic fiber falters, and reinforced glass fiber filters. In general, the metallic and ceramic powder filters have pressure drops in excess of 25 inches of water for HEPA grade efficiencies and are therefore not viable candidates. The ceramic fiber filters cannot meet the HEPA efficiency because the fiber diameters are too large. The reinforced glass fiber filter is a promising candidate for the cleanable HEPA filter but requires additional development and testing to confirm its potential to be repeatedly cleaned. This report is based upon material extracted from a DOE technical review of the Mixed Waste Integrated Program and from the final report of a systems analysis of cleanable steel HEPA filters.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 325071
- Report Number(s):
- UCRL-JC-127233; CONF-960715-; ON: DE98050941; TRN: 99:003635
- Resource Relation:
- Conference: 24. nuclear air cleaning and treatment conference, Portland, OR (United States), 15-18 Jul 1996; Other Information: PBD: 1 Jan 1997
- Country of Publication:
- United States
- Language:
- English
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Development and evaluation of a cleanable high efficiency steel filter
Development and evaluation of a cleanable high efficiency steel filter