Enhanced fabric filtration through controlled electrostatically augmented dust deposition

• US 4,904,283 A
• Filed: 10/11/1988
• Issued: 02/27/1990
• Est. Priority Date: 11/24/1987
• Status: Expired due to Term

• Current Assignee: Government of The United States As Represented By Administrator Environmental Protection Agency
• Original Assignee: Government of The United States As Represented By Administrator Environmental Protection Agency
• Inventors: Daniel, Bobby E., Hovis, Louis S., Plaks, Norman
• Primary Examiner(s): Nozick, Bernard
• Application Number:
  US07/257,119
• Time in Patent Office: 504 Days
• Field of Search: 55/2, 55/131, 55/139, 55/151, 55/152
• US Class Current: 96/66
• CPC Class Codes: B03C 3/155 Filtration

Abstract

A simple electrostatically enhanced fabric filtration system for removing fine particulate matter or dust entrained in a gas flow, has a single, elongate, central, corona-generating electrode positioned within a cylindrical fabric filter, closed at one end, into which the particulate bearing gas flow is directed. In one embodiment, a grid-like cylindrical grounded electrode is disposed proximately outside the filter element and establishes a radially directed electrostatic field with the corona electrode. Particles passing through the corona acquire charges of like polarity and are subjected immediately to Coulombic forces driving them radially outward toward the filter fabric where they collect prominently near the filter element inlet, thus allowing easier passage to the gas further downstream. Other embodiments have a plurality of grounded electrodes attached to the inside of the filter element or as wires woven therethrough. Corona concentration near the filter element entrance by known techniques, e.g., roughening, addition of points to, or by changes in cross-section of the corona electrode, can also be utilized to further enhance all embodiments.

Claims

1. An electrostatically enhanced fabric filtration system utilizing a high voltage source for separating particulate matter from a gas stream, comprising:

a substantially cylindrical fabric filter element having a first end and a second end and comprised at least in part of a grounded electrically conductive material;

a substantially rigid and substantially cylindrical open-ended metal sleeve member so attached to the first end of said filter element as to maintain said first end in open condition for communication therewith, said sleeve having a gas inlet aperture open to the interior of said sleeve and said filter element such that a particulate laden gas stream may flow through said aperture and said sleeve to the interior of the filter element;

a closure means at the second end of said filter element maintaining said second end in closed condition;

a linear corona electrode connected to said high voltage source to receive a high voltage therefrom relative to ground, coaxially disposed within said filter element and having one end attached to the closure means at the second end of the filter element and having its other end extended through said gas inlet aperture, said sleeve and said first end of said filter element;

an electrical insulating means interposed between said corona electrode and said closure means, whereby said electrode is electrically insulated from said filter element at said second end thereof;

an electrical insulating means surrounding said corona electrode for insulating said corona electrode from said sleeve at the region where the electrode extends through the gas inlet aperture and the sleeve;

whereby a corona discharge is generated along said corona electrode when a high voltage is applied to said corona electrode, said corona discharge providing an electrical charge to the particulate matter entering the filter element and simultaneously generating an electrostatic field between the corona electrode and said grounded electrically conductive material that is a part of said fabric filter element, whereby the charged particles are attracted toward an inside surface of the filter element under the influence of the electrostatic field.

2. An electrostatically-enhanced fabric filtration system according to claim 1, wherein:

said fabric filter element comprises fiber-glass fabric and said grounded conductive material comprises conductive wire filaments woven therein.

3. An electrostatically enhanced fabric filtration system according to claim 1, further comprising:

corona-intensification means on said corona electrode, at a predetermined location within said filter element coaxial therewith, for intensifying electrical corona thereat.

4. An electrostatically-enhanced fabric filtration system according to claim 3, wherein:

said corona-intensification means is provided close to said first end of said filter element.

5. An electrostatically-enhanced fabric filtration system according to claim 4, wherein:

said corona-intensification means comprises a deliberately roughened portion on the exterior surface of said corona electrode.