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EPA FABRIC FILTRATION STUDIES: 4. BAG AGING EFFECTS
Citation:
Donovan, R., B. Daniel, AND J. Turner. EPA FABRIC FILTRATION STUDIES: 4. BAG AGING EFFECTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/7-77/095a (NTIS PB271966).
Description:
The report gives results of a study to determine the effects of aging on filter bags made of woven polyester. Fabric filter life can be divided into three periods: break-in, steady-state, and wear-out. During the break-in, both bag collection efficiency and the pressure drop across the bag increase. In the steady-state, performance parameters remain relatively constant until the fabric begins to fail catastrophically (bag efficiency and pressure drop both decrease), signalling the onset of the wear-out. The transition between the break-in and the steady-state can be interpreted in terms of dust buildup in or on the fabric, ending in a steady-state in which the dust arriving during a complete filtration cycle equals that leaving during the same period. Dust permanently added to the fabric filter during the break-in is at 'bulk' sites--sites which are not emptied during the shake-cleaning step of the cycle. Dust can be emitted or lost from these sites, however, as is evident from baghouse operation with clean air only and from performance measurements made after washing the fabric filter with soap and water. The report presents evidence that supports a further subdivision of the dust trapped at bulk sites into: that which is loosely bound and which affects bag pressure drop primarily; and that which is more tightly held and which influences bag collection efficiency primarily.