Actions for MECHANISMS IN ELECTROSTATIC FILTRATION OF AEROSOLS WITH FIXED AND FLUIDIZED GRANULES
MECHANISMS IN ELECTROSTATIC FILTRATION OF AEROSOLS WITH FIXED AND FLUIDIZED GRANULES
- Author
- Anderson, D. M.
- Published
- United States : [publisher not identified], 1958.
[Oak Ridge, Tennessee] : [U.S. Atomic Energy Commission], 1958. - Physical Description
- microopaque : positive ; 8 x 13 cm
- Additional Creators
- Silverman, L.
- Summary
- With fibrous media, success has been limited because of the difficulty of frictioncharging fibers deep within the filter mass. It is shown that granular media are more easily handled and triboelectrified. Furthermore, these medin can also be fluidized, i.e., the filter beds can be expanded by the aerosol stream to be filtered, such that flow resistance remains constant after initial expansion, thus bringing filtration power requirements in to a region competitive with fiber filters and other cleaning devices. Electroetatic collection forces besides those due to charged collector surfaces also operate in any filter and are due to electric image effects produced by charged aerosols. A convenient grouping of all electrostatic filtration forces is as follows: (1) those arising from the charges residing on the aerosol particles; (2) those arising from the charge residing on the filter element; and (3) those arining from interaction of aerosol and filter surface charge. The effects of these forces were studied using conducting and dielectric granular beds in both the fiked and fluidized stntes. The dielectric media tester (polystyrene) had surface charge generated by in situ charging using especially designed network system, contact-separation chaging occurring between fluidized granules and interspersed conducting wires, and by remote charging using a vibrating cylindrical lucite trough. The test aerosol (gentian violet microspheres) was charged to a low level by the generation of droplets containing the dye from a spinning disk. Filtration effects were tested in an exploratory way at the start of the study using polystyrene granules with atmospheric dust as the test aerosol. The results indicated tht a surface charge density of 0.09 esu/cm/sup 2/ on these granules raised the filtration efficiency (strain method) from a fixed bed unchanged (net) level of 64% to 96% for fluidized beds expanded to 120% of the original bed depth, thus obtaining better performance in conjunction with greater air handling capacity at no increase in flow resistance. An economic evaluation of the performance data was made which indicated that chrged fluldized miktures of polystyrene with opposite charging characteristics will filter five times as efficiently as grounded conductor media and at the same time handle over twice as much as volume at equivalent resistance. Comparison of the performance of such beds with available commercial air cleaning devices indicated that a competitive system is now available at a possibly reduced cost. (A C.)
- Report Numbers
- NYO-4615
- Other Subject(s)
- Aerosols
- Atmosphere
- Cleaning
- Cylinders
- Density
- Dielectrics
- Droplets
- Dusts
- Economics
- Efficiency
- Electric charges
- Electric conductivity
- Electrostatics
- Expansion
- Fibers
- Filters
- Friction
- Gas flow
- Images
- Interactions
- Lucite
- Mass
- Matrices
- Mixing
- Particles
- Pellets
- Performance
- Physics
- Planning
- Polymers
- Polystyrene
- Surfaces
- Testing
- Vibrations
- Volume
- Wires
- Collection
- U.S. Atomic Energy Commission depository collection.
- Note
- DOE contract number: AT(30-1)-841
NSA number: NSA-12-015626
OSTI Identifier 4302518
Research organization: Harvard Univ., Boston. Air Cleaning Lab.
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