Filtration device using absorption for the removal of gas phase contaminants

• US 5,713,971 A
• Filed: 10/24/1996
• Issued: 02/03/1998
• Est. Priority Date: 12/23/1994
• Status: Expired due to Term

• Current Assignee: FRAM Group IP, LLC
• Original Assignee: Alliedsignal Inc.
• Inventors: Unger, Peter D., Rohrbach, Ronald P., Jones, Gordon W., Kheradi, Bijan, Sturgeon, Richard M.
• Primary Examiner(s): Chiesa, Richard L.
• Application Number:
  US08/736,308
• Time in Patent Office: 467 Days
• Field of Search: 261/104, 261/107, 261/DIG. 17, 261/DIG. 65, 55/233, 55/234, 55/302, 55/303, 95/210-212, 210/634, 428/398
• US Class Current: 96/181
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 47/027 by directing the gas to be cleaned essentially tangential to the liquid surface
• CPC Class Codes: B01D 47/028 by directing the gas through a wetted wire mesh or a perforated plate B01D47/14 takes precedence
• CPC Class Codes: B01D 50/60 Combinations of devices covered by groups B01D46/00 and B01D47/00
• CPC Class Codes: B01D 53/18 Absorbing units; Liquid distributors therefor B01D3/16, B01D3/26, B01D3/30 take precedence; packing elements B01J19/30, B01J19/32
• CPC Class Codes: B01J 20/28014 characterised by their form
• CPC Class Codes: B01J 20/28021 Hollow particles, e.g. hollow spheres, microspheres or cenospheres
• CPC Class Codes: B01J 20/28023 Fibres or filaments fibres or filaments in the form of membranes B01J20/28038; B01J20/28007 takes precedence
• CPC Class Codes: B60H 2003/0691 Adsorption filters, e.g. activated carbon
• CPC Class Codes: B60H 3/06 Filtering B60H3/0078 takes precedence
• CPC Class Codes: B60H 3/0633 with provisions for regenerating or cleaning the filter element
• CPC Class Codes: B60H 3/0658 Filter elements specially adapted for their arrangement in vehicles B60H3/0608 takes precedence

Abstract

A filter device and technique are described which rely on absorption rather than adsorption for the removal of gas phase contaminants. A filter media is composed of a plurality of wicking fibers each of which comprising a strand with a hollow region impregnated with any of a variety of liquid phase absorbing systems made from the combination of a carrier liquid and soluble complexing/degrading agent or agents. Each strand has a slot which connects the interior hollow region with an external surface. Capillary forces act on the carrier liquid such that the external surface is substantially dry and no appreciable adsorption of contaminates occurs on the external surface which would restrict the flow of an air stream through the filter media even after an extended period of use. The wicking fibers may be connected to an external reservoir which can be used to supply fresh absorbing fluid to the filter media giving them a potentially inexhaustible capacity. The filter media may be made from any of a variety of fibers which can rapidly transport a liquid phase by the nature of either their geometry or their chemical composition. Geometries may include multilobal cross-sectional configurations, porous hollow fibers, porous or striated fibers or tightly bundled microfibers, all of which exhibit the property of wicking fluid from an external source.

Claims

1. A cabin air filtration system for removing gas phase contaminants comprising:

a cavity;

an air flow path through the cavity;

a liquid inlet into the cavity;

a liquid outlet from the cavity;

a fibrous wicking material having a plurality of elongated strands which are aligned to define a mesh within the cavity, said strands each having a hollow internal region extending longitudinally along said strand connected to an outer surface through at least one slot extending longitudinally along said strand, said hollow internal region transferring liquid from the inlet to the outlet along a path transverse to the air flow path;

means for supplying a gas absorbing liquid to the inlet;

means for conveying the gas absorbing liquid and any absorbed gases therein from the liquid outlet; and

means for circulating air from a cabin, through said mesh along the air flow path, the cavity and back into the cabin, the gas phase contaminants being communicated to said gas absorbing liquid through said slot in said fiber wicking material whereby the gas phase contaminants are absorbed by said gas absorbing liquid retained in said hollow region without essentially affecting the air flow through said mesh.

2. The cabin air filtration system of claim 1 wherein the liquid inlet is higher than the liquid outlet so that liquid is communicated from the inlet to the outlet of each strand through natural migration.

3. The cabin air filtration system of claim 1 wherein said strands comprises a plurality of generally parallel elongated fibers oriented to extend generally in the direction of the liquid transfer path.

4. The cabin air filtration of claim 1 wherein the liquid transfer path and air flow path are generally orthogonal to one another.

5. The cabin air filtration system of claim 1 further including means for receiving the gas absorbing liquid and any absorbed gases from the means for conveying and for separating the absorbed gases from the liquid whereby the liquid may be returned to the liquid inlet for re-use.

6. The cabin air filtration system of claim 1 wherein capillary forces acting on said gas absorbing liquid retained in said hollow region of each strand prevents the gas absorbing liquid from being communicated from said fibrous wicking material to the outer surface of a strand.

7. The cabin air filtration system of claim 6 wherein the fibrous wicking material is made of at least one material selected from the group consisting of:

nylons, polyesters, and polyolefins.

8. A cabin air filtration system for removing unwanted gases comprising:

a cavity;

a liquid reservoir;

a gas absorbing liquid within the reservoir;

an air flow path through the cavity;

an internally wicking fibrous material having a plurality of elongated strands which are aligned to define a mesh within the cavity, said strands each having a hollow internal region extending longitudinally along said strand connected to an outer surface through at least one radial opening extending longitudinally along said strand, said hollow internal region transferring said gas absorbing liquid along a path transverse to the air flow path within the cavity to move liquid from the reservoir into the air flow path without significantly restricting the air flow path as unwanted gases are absorbed by said gas absorbing liquid after passing through said radial openings; and

means for circulating air from a cabin through the mesh in the cavity along the air flow path and back into the cabin.

9. The cabin air filtration system of claim 8 wherein the internally wicking fibrous material is formed of extruded strands having hollow interior regions which communicate with the outer strand surface.

10. The cabin air filtration system of claim 8 wherein the internally wicking fibrous material is made of at least one material selected from the group consisting of:

nylons, polyesters, and polyolefins.

11. The cabin air filtration system of claim 8 wherein the liquid reservoir comprises a lower liquid-tight portion of the cavity.

12. A cabin air filtration system comprising:

a cavity;

an air flow path through the cavity;

a liquid inlet into the cavity;

a liquid outlet from the cavity;

an internally wicking fibrous material having a plurality of elongated strands which are aligned to define a mesh within the cavity, said strands each having a hollow internal region extending longitudinally along said strand connected to an outer surface through at least one longitudinal slot extending longitudinally along said strand, said hollow internal region transferring liquid from the inlet to the outlet without wetting said outer surface;

means for supplying an air-borne material absorbing liquid to the inlet;

means for conveying the air-borne material absorbing liquid and any absorbed materials therein from the liquid outlet; and

means for freely circulating air from a cabin, through the cavity along the air flow path and back into the cabin without appreciable adsorption of air-borne material on said mesh, said air-borne material absorbing liquid absorbing of air-borne material communicated through said slot such that circulated air returned to said cabin is essentially free of said air-borne material.

13. The cabin air filtration system of claim 12 wherein the liquid comprises an inert carrier with a chemically aggressive agent dissolved therein.

14. The cabin air filtration system of claim 13 wherein the inert carrier is a non-volatile liquid selected from the group consisting of glycerol, polyethylene glycol, and polypropylene glycol.

15. The cabin air filtration system of claim 12 further including means for receiving the air-borne material absorbing liquid and absorbed materials from the means for conveying and for separating the absorbed materials from the liquid whereby the liquid may be returned to the liquid inlet for re-use.

16. The cabin air filtration system of claim 15 wherein the internally wicking fibrous material is made of at least one material selected from the group consisting of:

nylons, polyesters, and polyolefins.

17. Apparatus for removing molecules from a fluid stream comprising:

a plurality of elongated fibers each having a longitudinally extending hollow internal cavity including an opening extending longitudinally along said fiber from the internal cavity to the outer fiber surface;

a liquid which can absorb the molecules disposed within the internal cavities of said plurality of elongated fibers;

a flow path for the fluid stream, containing the molecules to be removed, directed over a portion of said plurality of elongated fibers whereby the molecules to be removed are absorbed by said liquid;

means for directing said fluid stream along said flow path and,

removing means for removing the absorbed molecules from said liquid at a position on said plurality of elongated fibers displaced from said flow path.

18. Apparatus as claimed in claim 17 wherein the longitudinally extending internal cavity in each of said plurality of elongated fibers is sized so that said liquid is retained within the cavity by capillary forces.

19. Apparatus as claimed in claim 17 wherein the molecules to be removed which are absorbed by said liquid are moved from said flow path to said removing means by a concentration factor induced molecular migration which effectively conveys the absorbed molecules away from the fluid stream.

20. Apparatus as claimed in claim 17 wherein the fluid stream is air.

21. Apparatus as claimed in claim 17 wherein a plurality of internal cavities, each including an opening to the outer fiber surface, are formed in each fiber.