WO2006083279A2

WO2006083279A2 - Filter dehydrator

Info

Publication number: WO2006083279A2
Application number: PCT/US2005/018963
Authority: WO
Inventors: Gregory S Sprencer
Original assignee: Velcon Filters, Inc.
Priority date: 2004-09-13
Filing date: 2005-05-31
Publication date: 2006-08-10
Also published as: WO2006083279A3

Abstract

A filter dehydrator for sensing and separating water from hydrocarbon fluid is disclosed. The filter dehydrator utilizes water insoluble cross-linked superabsorbent of a range of particle sizes to provide faster water absorption and swelling. This results in a filter dehydrator with better absorption of water that contains soluble substances typically present in field use.

Description

TITLE

FILTER DEHYDRATOR

FIELD OF THE INVENTION

[0001] The present invention relates to a filter dehydrator with improved performance in separating water that contains dissolved compounds. More particularly, the invention is directed to a filter dehydrator including cross-linked superabsorbents such as carboxymethyl cellulose (CMC) for removal of water from fuels, wherein the water may contain inorganic salts, alcohols, and other compounds.

BACKGROUND OF THE INVENTION

[0002] It is critical that aviation fuel be supplied to aircraft free from solid particles and water. The literature discloses processes for the removal of contaminants from aviation fuel, and discloses apparatus which may be utilized in seeking the objective.

[0003] Filter dehydrators have been used for over 20 years in this application, utilizing special absorbent materials called superabsorbents. These compounds can absorb hundred of time their own weight in distilled water, and can retain up to 50 times their own weight under applied pressure. However, water containing high levels of dissolved compounds adversely affect the efficacy of superabsorbents under these conditions, the rate of swell and the amount of water absorbed is reduced.

[0004] Although carboxymethyl cellulose has been used as an absorbent in the past, polyacrylates presently are the mainstay. This is primarily due to lower material cost and availability. Polyacrylates are used extensively in the disposable baby diaper industry, and as such are produced in very high volumes world wide. However, recent testing indicates that CMC chemistry may be better suited to absorb water containing soluble compounds.

[0005] There are only a few sources worldwide for carboxymethyl cellulose. Most carboxymethyl cellulose is uncross-linked, which makes it water-soluble. It is critical in the treatment of aviation fuel that the CMC be cross-linked, and as a result, water-insoluble. In most cases, uncross-linked compounds are used for applications other than filtration; primarily in pharmaceuticals, food, and oil production. For example, an uncross-linked CMC is marketed under the trade name of AGUALON. This product is unsuitable for filter dehydration use. [0006] The rapidity of water absorption is also critical in the dehydration of fuels. This is due to the fact that fuel exposure to the superabsorbents is very short. [0007] It would be desirable to prepare a filter dehydrator having improved performance for quickly absorbing substantially all of the water from aviation fuel.

SUMMARY OF THE INVENTION

[0008] Accordant with the present invention, an improved filter dehydrator has surprisingly been discovered. It comprises at least one layer of cross-linked superabsorbent having a particle size ranging from about 15 to about 600 microns.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Objects and advantages of the invention will become manifest to those skilled in the art from reading the following detailed description of an embodiment of the invention, when considered in the light of the accompanying Drawings, in which:

[0010] Fig. 1 is a sectional view of a filter dehydrator embodying the features of the present invention, wherein superabsorbent powder forms a layer within the filter dehydrator; and

[0011] Fig. 2 is an enlarged fragmentary sectional view of another embodiment of a filter dehydrator embodying the features of the present invention, wherein superabsorbent powder is applied between layers of other support media. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0012] Referring to the Drawings, and particularly to Fig. 1, there is shown at 10 a filter dehydrator according to the present invention. The filter dehydrator 10 comprises at least one layer 12 of cross-linked superabsorbent having an average mean particle size ranging from about 15 to about 600 microns. [0013] A typical filter dehydrator 10, useful for absorbing contaminated water from a jet fuel stream, includes a cylindrical, perforated support tube 14, an inner support layer 16, a fine particle filtering layer 18, a coarse particle filtering layer 20, and an outer, perforated support tube 22. Fuel, to be filtered and dehydrated, is passed under pressure radially inwardly through the successive structures 22 through 14. As will be readily apparent to one ordinarily skilled in the art, the filter dehydrator optionally may include additional or different layers (not shown). The present invention contemplates all such filter dehydrators, as long as they comprise at least one layer of cross-linked superabsorbent having an average mean particle size ranging from about 15 to about 600 microns. [0014] Fig. 2 illustrates at 24 one of many alterative embodiments of the filter dehydrator according to present invention, comprising multiple layers 26 of cross- linked superabsorbent having an average mean particle size ranging from about 15 to about 600 microns. The multiple layers 26 of cross-linked superabsorbent may be embedded between layers of support media which together form a support matrix layer 28 for retaining the particles of superabsorbent 26. Additionally, the filter dehydrator may contain conventional components such as a cylindrical, perforated support tube 30, an inner support layer 32, a fine particle filtering layer 34, and an outer, perforated tube 36.

[0015] The inner and outer support tubes may be prepared from conventional materials such as metal, ceramic, plastic, fiberglass, and the like. The various other layers, including the particle filtering layers, the support layers, and support matrix layer, may be prepared from conventional particulate filtering materials such as plastic, fabric, fiberglass, paper, and the like, as well as fibrous marts made from these materials. [0016] Methods for assembling filter cartridges and filter dehydrators, utilizing support structures and layers of filtering media, are well-known in the art. [0017] Properly sized superabsorbent particles are those small enough to provide high surface area/material weight and fast water absorption, but large enough to be retained in a filter. The particle filtering media in these types of filters will retain particles as small as 1 micron in diameter. However, very small water absorbent particles will act as contaminants in filter dehydrators, and compromise service life. Therefore, a minimum size for water absorbing particles is approximately 15 microns in diameter.

[0018] Surprisingly, it has been discovered that an effective range for superabsorbent particles is from about 15 to about 600 microns in diameter. Effective minimum size cross-linked superabsorbent fibers may be about 5 microns in diameter, as long as the fibers are at least 15 microns in length. Carboxymethyl cellulose fibers are unlikely to be much larger in diameter than 5 microns, due to the cellulose fibers which are used as the raw material to make the CMC fibers.

[0019] Suitable superabsorbent particles may be prepared from polymers selected from, but not necessarily limited to, carboxymethyl cellulose, hydroxyalkylated celluloses such as hydroxyethyl cellulose and methyhydroxypropyl cellulose, polyethylene glycol, polyethylene oxide, partially or fully hydrolyzed polyvinyl alcohol, polyvinyl pyrrolidone, polyethyloxazoline, polyethylene oxide-co-polypropylene oxide block copolymers, polyoxamines, polypeptides, polysaccharides, carbohydrates, proteins such as gelatin, collagen, albumin, or ovalbumin, or mixtures, copolymers, or blends of any of the above. A preferred superabsorbent is carboxymethyl cellulose. These superabsorbents are well-known, conventional materials that may be obtained through commercial channels.

[0020] The superabsorbent polymers according to the present invention may be comminuted by conventional processing equipment to prepare particles ranging in size from about 15 microns to about 600 microns. EXAMPLE

[0021] An industry test called a water slug test is performed, whereby a neat slug of water is injected into a flowing fuel stream. The filter dehydrator receives the water, the superabsorbent absorbs the water and swells, and the flow is restricted to almost zero. The flow leakage rate is then recorded. [0022] Two difficult conditions are tested, using water with dissolved substances in the neat slug of water. One condition uses a 50/50 mixture of DiEGME and water. DiEGME is an anti-icing inhibitor, routinely used in military fuels. This additive is preferentially water soluble, so that when water is present in the fuel, the water extracts the DiEGME from the fuel. This creates a water/DiEGME mixture, which can reach a ratio of 1 to 1. The second condition is a 3% salt water solution. This is similar in concentration to sea water, which can enter fuel supplies when transported by ocean tanker.

TABLE Leakage Rate; Percent of Rated Flow Leakage Rate

Filter Dehydrator DiEGME/water 3% salt water

Standard Particulate 30%+ 30%+ Filter

Particulate Filter With Carboxymethyl Cellulose 2.7% 0.9% Particles Having Diameters More Than 600 Microns

Particulate Filter With Carboxymethyl Cellulose 0.2% 0.2% Particles Having Diameters Ranging From 15 - 600 Microns [0023] The inventive filter dehydrator removes significantly more contaminated water than either a standard particulate filter or a particulate filter including commercially available carboxymethyl cellulose particles having diameters greater than 600 microns.

[0024] In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be understood that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.

Claims

WHAT IS CLAIMED IS:

1. A filter dehydrator, comprising at least one layer of cross-linked superabsorbent having a particle size ranging from about 15 to about 600 microns.

2. The filter dehydrator according to Claim 1, wherein the cross-linked superabsorbent is selected from the group consisting of carboxymethyl cellulose, hydroxyalkylated celluloses such as hydroxyethyl cellulose and methyhydroxypropyl cellulose, polyethylene glycol, polyethylene oxide, partially or fully hydrolyzed polyvinyl alcohol, polyvinyl pyrrolidone, polyethyloxazoline, polyethylene oxide-co- polypropylene oxide block copolymers, polyoxamines, polypeptides, polysaccharides, carbohydrates, proteins such as gelatin, collagen, albumin, or ovalbumin, and mixtures, copolymers, and blends thereof.

3. The filter dehydrator according to Claim 1, wherein the cross-linked superabsorbent comprises carboxymethyl cellulose.

4. A filter dehydrator, comprising at least one layer of cross-linked carboxymethyl cellulose having a particle size ranging from about 15 to about 600 microns.