AIR CLEANING STUDIES. Progress Report for July 1, 1957 to June 30, 1958
F 5 9 5 9 A * r Performance. The collector resistance of the Mikro-Pulsaire at 500 cfm was measured for fly ash and vaporized silica aerosols at various dust loadings, cleaning pressures, and pulse rates. The results indicate that relatively large loading variations do not cause extreme deviations in operating resistance, doubling the jet pressure gives a nearly fourfold reduction in the resistance, and doubling the pulse rate (except for vaporized silica) reduced the resistance by a factor of 1.5. For vaporized silica, the primary mechanism for duct dislodgement appears to be associnted with the initial pressure impulse. Aerosol Filtration by Fixed and Fluidized Beds. The merits of charged granule beds are compared with those of non-charged beds. It was found that bipolar effects are an adjunct of collection efficiency only when the granule diameters exceed 0.4 mm and that the actual interstitial or jet velocity in granular media is several (up to 40) times greater than the face velocity. The impaction effect in granular fixed beds was determined and found to agree well with other work, and the effect of fluidizing velocity on the collection efficiency was studied for an uncharged poly-styrene bed (50%--50% mixture of heated and unheated granules). An evaluation of charged polystyrene granule bed performance indicates that, relative to grounded media, net target efficiencies were increased fivefold and the air handling capacity was more than doubled for the same resistance to air flow. Incinerator Gas Cleaning Studies. A filter unit containing slag wool fiber in a 55-gallon drum was substituted for the glass filter bags in an incinerator and tested with burning sawdust charges. The results indicate that (1) lining of combustion chamber walls with fire brick gives improved combustion, (2) ratios of overfire to underfire air in the range of 1.5/1 to 1/1.5 do not affect the combustion products, (3) incinerators should be operated continuously, (4) slag wool fiber is satisfactory for particulate filtration at gas temperatures of 300 to 800 deg F, and (5) wet charges should be pre-dried or diluted with dry combustibles. NaK Fume Filtration. A filter unit composed of 3 and 6 denier bonded Dynel fiber was tested in the field. Other devices for NaK fume filtration are discussed. Blast Effects on Filter S stems. Damage to AEC absolute type filters was studied at the Nevada Test Site; field pressure measurements were made on both sides of each collecting device. No observable physical damsge occurred in AEC high-efficiency,filters exposed to shock pressures of 1.6 psig or lower, whereas glass fiber roughing filters located normal to the direction of the approaching shock wave were completely destroyed at overpressures)1.5 psi. The results show that roughing or precleaning filters retain 20 to 60a of the dust blown off the high-efficiency collectors and that wire screen viscous filters may be a practical means of restricting dust re-entrainment. Filtration Studies. Preliminary test results on several types of synthetic fibrous media with aerosols are presented. Iodine Collection Studies. Several coated forms of 4- mu slag wool fibers were tested with respect to their collection efficiency for I/sup 1//sup 2//sup 7/; Ag coatings were found to give the highest efficiency (99.9%) and lowest resistance. Tests with Sn and Cu ribbons and Zn granules indicate for Cu a high efficiency (99.99%) and a low resistance for iodine concentrations of 50 to 500 mg/m/sup 3/. The tests made with Cu ribbons indicate that (1) iodine collection increases significantly at higher gas temperatures (300 to 350 deg C), (2) water vapor increases iodine collection efficiency, (3) Cu collectors once used at high temperatures are no longer functional at room temperature, and (4) service life at high temperatures is approximately 25 hr. Agplated Cu mesh was also studied; the efficiency at room temperature is slightly lower than for Cu alone but increases at 300 deg C. Over a test period of 100 hr at 300 deg C, collection efficiency remained above 99.6% with no apparent
- Research Organization:
- Harvard Univ., Boston. Air Cleaning Lab.
- DOE Contract Number:
- AT(30-1)-841
- NSA Number:
- NSA-15-018369
- OSTI ID:
- 4013736
- Report Number(s):
- NYO-4812
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- United States
- Language:
- English
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