Granular filtration in a fluidized bed
A novel filtration concept for particulate cleanup has been developed at the US Department of Energy's Federal Energy Technology Center (FETC). The filtration system consists of a fine, metal-screen filter that is immersed in a fluidized bed of granular material. As a gas stream passes through the fluidized bed, a layer of granular bed material is entrained and deposited on the screen surface. This material provides a natural granular filter that separates fine particles from the gas stream passing through the bed. Because only the in-flowing gas maintains the granular layer at the screen surface, once the thickness and permeability of the granular layer are stabilized, the layer remains unchanged as long as the in-flowing gas flow rate remains constant. The weight of the particles and the turbulent nature of the fluidized bed limit the thickness of the granular layer on the filter, leading to self-cleaning of the filter. The original granular filtration testing system consisted of a set of filter elements; a two-dimensional fluidized-bed; a continuous powder feeder, a laser-based in-line particle counting, sizing, and velocimeter (PCSV) and/or a classical scattering aerosol spectrometer (CSAS); and a continuous solid feeding/bed material withdrawal system. The two-dimensional, transparent fluidized-bed allowed clear observation of the general fluidized state of the granular material and the conditions under which fines are captured by the granular layer. Two different filter element configurations were tested. The original filter showed high filtration performance when low density acrylic powder was used as bed material, but low filtration performance with heavy bed material (sand). The low filtration performance with this material was attributed to the failure to maintain a sufficiently thick granular layer at the screen filter surface. However, experimental data show that filtration performance for heavy bed material can be drastically improved by modifying the filter element. Collection efficiencies of over 99.95% were consistently obtained in a series of experiments under similar operating conditions.
- Research Organization:
- Dept. of Energy, Morgantown, WV (US)
- OSTI ID:
- 20006803
- Report Number(s):
- CONF-990534-; TRN: IM200008%%410
- Resource Relation:
- Conference: 15th International Conference on Fluidized Bed Combustion, Savannah, GA (US), 05/16/1999--05/19/1999; Other Information: 1 CD-ROM. Operating system required: Windows 3.x; Windows 95/98/NT; Macintosh, Power Macintosh; UNIX. All systems need 2X CD-ROM drive.; PBD: 1999; Related Information: In: Proceedings of the 15th national conference on fluidized bed combustion, by Reuther, R.B. [ed.], [1800] pages.
- Country of Publication:
- United States
- Language:
- English
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Granular filtration in a fluidized bed
Granular filtration in a fluidized bed