Degassing System and Method

Abstract

The degasser includes a gas nucleation medium and a porous barrier. The degasser may include a growth medium between the gas nucleation medium and the porous barrier. The degasser may be part of a system for removing gas from a fluid, the system including a tank with a fluid inlet and a fluid outlet and having a fluid flow path from the fluid inlet to the fluid outlet, the degasser being within the fluid flow path. A method for removing gas from a fluid includes passing the fluid through a degasser defining the fluid flow path.

Description

Technical Field

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 798,272, filed on January 29, 2019, which is incorporated herein by reference in its entirety.

[0002] This application relates to a fluid degassing system and method.

Background Art

[0003] Various systems that utilize fluids can potentially benefit from the removal of air from the fluids (e.g., degassing). In particular, in systems where the same fluid remains in the system for an extended period of time, air can accumulate within the fluid. For example, in systems where the fluid circulates multiple times within the system, such as a hydraulic system, air can accumulate within the fluid, potentially reducing the performance of the system.

[0004] Hydraulic systems, particularly hydraulic machinery, rely on hydraulic fluid to perform work. Common examples of hydraulic systems include hydraulic machinery, hydraulic drive systems, hydraulic transmission systems, hydraulic brakes, and others. Hydraulic fluid typically remains in the system for an extended period of time and undergoes periods of high and low pressure, allowing air to accumulate within the fluid. The air within the fluid can exist in various forms, such as dissolved air or free air. Free air can include entrained air and bubbles. The presence of air can cause pump cavitation, accompanied by symptoms such as increased wear and noise of components or a decrease in the bulk modulus of the fluid, potentially reducing the efficiency and controllability of the hydraulic system.

[0005] It would be desirable to provide a system and method for degassing fluids. Further, it would be desirable to provide a system and method that is compatible with a hydraulic system for degassing hydraulic fluid.

Summary of the Invention

Means for Solving the Problems

[0006] In accordance with the principles of the present disclosure, a degassing device is provided. The degassing device includes a gas nucleation medium. A growth medium may be disposed adjacent to the gas nucleation medium. A porous barrier is disposed adjacent to the growth medium. The degassing device may be part of a system for removing gas (e.g., air) from a fluid, the system including a tank having a fluid inlet and a fluid outlet and a fluid flow path from the fluid inlet to the fluid outlet, and the degassing device is within the fluid flow path.

[0007] A method for removing gas (e.g., air) from a fluid is provided. The method includes passing the fluid through a degassing device. The degassing device defines a fluid flow path and includes a gas nucleation medium disposed in the fluid flow path. A growth medium is disposed in the fluid flow path downstream of the gas nucleation medium. A porous barrier is disposed in the fluid flow path downstream of the growth medium.

[0008] A system for removing gas from a fluid is provided. The system includes a tank having a fluid inlet and a fluid outlet and a fluid flow path from the fluid inlet to the fluid outlet, and a degassing device. The degassing device includes a gas nucleation medium. A growth medium may be disposed adjacent to the gas nucleation medium. A porous barrier is disposed adjacent to the growth medium.

[0009] The degassing device may include a gas nucleation medium, a porous barrier adjacent to the gas nucleation medium, and a gap between the gas nucleation medium and the porous barrier. The porous barrier may have openings sized 250 μm or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0010]

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Best Mode for Carrying Out the Invention

[0011] The present disclosure relates to systems and methods for removing gases such as air from a fluid. The systems and methods of the present disclosure are particularly useful for removing (e.g., degassing) air from a fluid used in a recirculation system such as a hydraulic system.

[0012] The term "fluid" is used in the present disclosure to describe a substance in the liquid phase. The fluid may contain dissolved or entrained gas compounds.

[0013] The terms "degas" and "degassing" are used herein to refer to the removal of air or other gases from a fluid.

[0014] The term "adjacent" is used herein to mean "next to". "Adjacent" features may or may not be in contact with adjacent features. For example, "adjacent" features may be separated by a gap.

[0015] The term "directly adjacent" is used herein to mean in contact with an adjacent feature. The term "directly adjacent" may be used to indicate the absence of intervening features.

[0016] The term "substantially" as used herein has the same meaning as "significantly" and can be understood to modify the term that follows by at least about 75%, at least about 90%, at least about 95%, or at least about 98%. The term "substantially not" as used herein has the same meaning as "significantly not" and has the opposite meaning of "substantially", i.e., it can be understood to modify the term that follows by 25% or less, 10% or less, 5% or less, or 2% or less.

[0017] The term "nominal" in the context of mesh size, pore size, fiber diameter, or wire diameter is used herein to refer to the stated or reported mesh or pore dimensions of a commercially available product.

[0018] The unit "psi" is used herein to refer to pounds force per square inch. 1 psi corresponds to approximately 6900 Pascals, or approximately 6.9 kPa.

[0019] References to standard methods (e.g., ASTM, TAPPI, AATCC, etc.) refer to the latest available version of that method as of the time of filing of this disclosure, unless otherwise specified.

[0020] The term "about" is used herein in combination with a numerical value to include the normal variation in measurements expected by one of ordinary skill in the art, has the same meaning as "approximately", and is understood to cover typical tolerances such as ±5% of the recited value.

[0021] Words such as "a", "an", and "the" are not intended to refer to only a single entity, but include a general class for which specific examples may be used for illustration.

[0022] The words "a", "an", and "the" are used interchangeably with the term "at least one". The phrases "at least one of" and "comprising at least one of" followed by a list refer to any one of the items in the list, and any combination of two or more of the items in the list.

[0023] As used herein, the term "or" is generally used in its ordinary sense including "and / or" unless the content clearly dictates otherwise. The term "and / or" means one or all of the listed elements, or any combination of two or more of the listed elements.

[0024] The enumeration of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc., or 10 or less includes 10, 9.4, 7.6, 5, 4.3, 2.9, 1.62, 0.3, etc.). When the range of values is a "maximum" specific value or "at least" a specific value, that value is included within the range.

[0025] The terms "preferred" and "preferably" refer to embodiments that may provide certain benefits under certain circumstances. However, in the same or other circumstances, other embodiments may also be preferred. Furthermore, the recitation of one or more preferred embodiments does not mean that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the present disclosure, including the claims.

[0026] According to some embodiments, a gas can be removed from a fluid by inducing nucleation of the gas and allowing the gas to escape. Nucleation can be induced by contacting the fluid with a material that provides nucleation sites for the gas. Free gas cavities can be formed by gas nucleation. The gas cavities can grow and / or coalesce in one or two or more stages to increase the size of the gas cavities, thereby increasing their buoyancy and the rate at which the gas rises within the fluid. The terms "gas cavity" and "bubble" are used interchangeably herein.

[0027] Certain types of vehicles, such as excavators, loaders, skid steer loaders, and the like, include an on-board hydraulic system. For various reasons, such as to improve efficiency, there is a desire to improve the hydraulic system, and in particular to reduce the size of the hydraulic fluid tank. However, when the tank is small, the residence time of the fluid in the tank is short, which may exacerbate the problem of air in the hydraulic fluid (e.g., oil). With a short residence time, the air in the fluid may not escape from the fluid before the fluid is drawn out of the tank again. The apparatus and method of the present disclosure may be advantageous for their ability to remove air, including dissolved air, small air cavities, and entrained air, from a fluid such as a hydraulic fluid or oil. The apparatus and method may be further advantageous for their ability to be miniaturized for use in a smaller hydraulic tank, such as those used in a mobile hydraulic system used in a vehicle, e.g., an excavator, loader, skid steer loader, or for use in other systems with a small hydraulic tank.

[0028] A schematic diagram of a hydraulic system 1 according to the present disclosure is shown in FIG. 1. The hydraulic system 1 includes a tank 10 for containing a hydraulic fluid. The system 1 also includes a pump 20 for transferring fluid from the tank 10 to one or more hydraulic applications 30. Examples of hydraulic applications 30 include hydraulic machinery, hydraulic drive systems, hydraulic transmission systems, hydraulic brakes, and the like. The fluid flows from the tank 10 to the pump 20 via an output line 11, and from the pump 20 to the hydraulic application 30 via an output line 21. The pump 20 applies pressure to the fluid, and thus the fluid in the output line 21 is under a higher pressure than the fluid in the tank 10 or the output line 11. The pressurized fluid can be used to perform work in the hydraulic application. The fluid can return to the tank from the hydraulic application 30 via a return line 31.

[0029] System 1 includes a degassing device 100. The degassing device 100 is configured to remove at least a portion of the gas dissolved and / or trapped in the hydraulic fluid. The degassing device 100 may be positioned within the tank 10 as shown, or may be placed elsewhere in the system 1. For example, the degassing device 100 may be placed in series along the return line 31. According to one embodiment, the degassing device 100 is disposed in the flow path of the hydraulic fluid flowing through or within the tank 10. For example, the degassing device 100 may be disposed in the flow path of the fluid discharged from the return line 31 to the tank 10. The direction of flow may be from top to bottom as shown in FIG. 1, where the fluid from the return line 31 flows into the tank 10 from above. At least a portion of the fluid from the return line 31 can enter the degassing device 100.

[0030] System 1 may include additional components such as additional tanks, lines, pumps, meters, control devices, and the like.

[0031] Schematic cross-sectional views of the degassing device 100 according to the present disclosure are shown in FIGS. 2A - 2D. The degassing device 100 includes a gas nucleation medium 110 disposed in the flow path of the fluid within the tank 10. The degassing device 100 further includes a growth medium 120 downstream of the gas nucleation medium 110. A porous barrier 130 may be disposed downstream of the gas nucleation medium 110 and / or the growth medium 120.

[0032] The gas nucleation medium 110, the growth medium 120, and / or the porous barrier 130 may be disposed in a through-flow configuration within the flow path. In some embodiments, at least one of the layers of the gas nucleation medium 110, the growth medium 120, and / or the porous barrier 130 is disposed in a cross-flow configuration. The term "through-flow configuration" is used herein to refer to an arrangement in which the fluid flows through the medium. The term "cross-flow configuration" is used herein to refer to an arrangement in which the fluid flows across (or over) the medium.

[0033] The degassing device 100 may have an open interior 144 with an inlet 101 for receiving the incoming fluid flow. The inlet 101 may be defined as an opening in the first end cap 141. The particular inlet 101 shown is configured as an upper inlet which is an opening to the open interior 144. Alternative inlet arrangements, positions, and orientations are possible. For example, the inlet 101 may be positioned at the bottom or side of the degassing device 100. However, the upper inlet shown is convenient and advantageous. The inlet 101 may include features for coupling the degassing device 100 to the tank 10 and directing the fluid flow into the open interior 144. The degassing device 100 may further include additional or alternative flow paths such as case drain flow (excess flow from the pump), drain flow, overflow, return flow, and the like. Such additional or alternative flow paths may flow back to the tank 10. In one embodiment, the case drain flow 152 is flowed into the degassing device 100. For example, the case drain flow 152 may be flowed through the secondary inlet 146 of the first end cap 141 into the gap 135 between the porous barrier 130 and the growth medium 120 as shown in FIG. 2D.

[0034] The gas nucleation medium 110 may define the open interior 144 such that the gas nucleation medium 110 at least partially surrounds the open interior 144. The gas nucleation medium 110 may be disposed within the fluid flow path such that at least a portion of the fluid entering the open interior 144 flows through the gas nucleation medium 110. In the example shown, the gas nucleation medium 110 is disposed cylindrically around the open interior 144. The cylinder may have an open upper portion including the inlet 101 and a closed bottom defined by the second end cap 142.

[0035] A layer of the growth medium 120 may be disposed adjacent to the gas nucleation medium 110. The growth medium 120 can be directly adjacent to (e.g., in contact with) the gas nucleation medium 110. The growth medium 120 may be disposed within the fluid flow path such that the fluid flows through the growth medium 120 after flowing through the gas nucleation medium 110. The growth medium 120 is coaxial with the gas nucleation medium 110 and may form a cylinder that at least partially circumscribes it therearound.

[0036] The degassing device 100 may further include a porous barrier 130 that defines an opening 131. The porous barrier 130 may be disposed adjacent to the growth medium 120 as shown in FIGS. 2A and 2B. In some embodiments, the degassing device 100' is similar to the degassing device 100 of FIG. 2A in another aspect and includes a gas nucleation medium 110 and a porous barrier 130, but does not include a growth medium as shown in FIG. 3. In some embodiments, the porous barrier 130 is adjacent to the growth medium 120 or the gas nucleation medium 110, but is not directly adjacent (e.g., not in contact), and a gap 135 is left between the porous barrier 130 and the growth medium 120 or between the porous barrier 130 and the gas nucleation medium 110 as shown in FIGS. 2A and 3, respectively. In some embodiments, the porous barrier 130 is directly adjacent to the growth medium 120 such that there is no gap between the porous barrier 130 and the growth medium 120 as shown in FIG. 2B. In some embodiments, the porous barrier 130 is formed by a strainer at the outlet 18 of the tank 10 as shown in FIG. 2C. In such embodiments, the gap 135 may be formed between the growth medium 120 and the porous barrier 130 of the outlet 18. The porous barrier 130 is coaxial with the growth medium 120 and the gas nucleation medium 110 and may form a cylinder that at least partially circumscribes around it. In some embodiments, the gas nucleation medium 110, the growth medium 120, and the porous barrier 130 define a cylindrical body. The first end (e.g., the upper end) of the cylindrical body may be partially closed by a first end cap 141. The second end (e.g., the bottom) of the cylindrical body may be closed by a closed second end cap 142.

[0037] When the degassing device 100 is in use, fluid is introduced into the open interior 144 through the upper inlet 101. After the fluid enters the open interior 144, it may pass through the gas nucleation medium 110. The gas nucleation medium 110 may nucleate at least some of the dissolved gases in the fluid to form free air such as small gas cavities (first-stage gas cavities). As the fluid further passes through the growth medium 120 downstream of the gas nucleation medium 110, more gas comes out of the solution and is added to the existing gas cavities, which can grow the gas cavities. The gas cavities may also coalesce in the growth medium 120. Growth and / or coalescence forms larger gas cavities (second-stage gas cavities). The second-stage gas cavities may begin to rise upward in the gap 135 between the growth medium 120 and the porous barrier 130. In some embodiments, the openings 131 of the porous barrier 130 may be sized generally smaller than the second-stage gas cavities generated by the growth medium. The porous barrier 130 acts to hold the gas cavities within the gap 135, preventing the gas cavities from prematurely diffusing into the fluid within the tank 10. Without wishing to be bound by theory, it is believed that the porous barrier may further grow and / or coalesce the gas cavities upstream of the porous barrier 130 and cause them to rise upward within the gap 135. If the porous barrier 130 is wet, a gas pocket (a larger gas cavity) may form at the top of the gap 135 from the rising coalesced gas. When the gas pocket becomes large enough, sufficient pressure accumulates for the gas pocket to break through the wet porous barrier 130. When the gas breaks through the porous barrier, the gas may dry the adjacent regions of the porous barrier and allow the air pocket to exit. However, even if that region of the porous barrier remains submerged and wet, the gas cavities at the top of the gap may pass through the porous barrier as large bubbles and rise to the surface. When the degassing device is submerged, the gas pocket may have sufficient buoyancy to rise to the surface and escape from the surface. When the gas pocket is gone, the porous barrier 130 may re-wet and the process may repeat.

[0038] Returning to Figures 2A-2D and 3, the gas nucleation medium 110 can be made of any suitable material capable of inducing gas nucleation. Without wishing to be bound by theory, it is believed that several aspects of the gas nucleation medium affect the effectiveness and efficiency of the medium in inducing nucleation based on the effects of those aspects on the chemical and physical interactions of the medium with the fluid and the gas within the fluid. Aspects that may affect nucleation include, for example: surface area of ​​the fibers in the medium; accessible surface area; fiber size (e.g., diameter or cross-sectional dimension); media pore size; presence of sharp edges or corners; surface roughness; chemical composition of the medium (e.g., fibers and binder); oleophilicity / oleophobicity of the medium; presence and number of fiber crossings; orientation angle of adjacent fibers; orientation relative to the direction of flow; tortuosity of the flow channel; percent solids of the media sheet; permeability of the media sheet; thickness of the media sheet; residence time of the fluid in the media; Peclet number (e.g., ratio of advective to diffusive transfer rates) of dissolved gas from the fluid to the media; and differential pressure of the sheet and individual fibers.

[0039] For example, media with appropriate (accessible) surface area, fiber size, and media pore size are believed to be beneficial for nucleation efficiency. The accessible surface area of ​​a fiber can be measured as the basic fiber surface area of ​​a media, which is the area that a fluid can access (e.g., contact), m 2 m per unit of media sheet bulk surface area 2 The basic fiber surface area of ​​a media may be determined by Branauer-Emmett-Teller (BET) analysis or from the Carmen-Kozeny relationship (described in detail in Examples 3 and 4 below). The bulk surface area of ​​a media sheet is understood to mean the area calculated as the length times the width of the media sheet (for pleated media, the pleat height and number of pleats may be used to calculate the width). The basic fiber surface area of ​​a gas nucleation media is the area calculated as the length times the width of the media sheet when measured by either the BET or Carmen-Kozeny method. 2 / m 2 Over 1.5m 2 / m 2Above, 2m 2 / per medium m 2 Above, 5m 2 / per medium m 2 Above, 10m 2 / per medium m 2 Above, 25m 2 / m 2 Above, 50m 2 / m 2 Above, or 100m 2 / m 2 It can be above. When the surface area of the gas nucleation medium is measured by either the BET method or the Carmen - Kozeny method, it is 200m 2 / m 2 Below, 150m 2 / m 2 Below, 100m 2 / m 2 Below, 50m 2 / m 2 Below, 30m 2 / m 2 Below, 10m 2 / m 2 Below, 6m 2 / m 2 Below, or 4m 2 / m 2 It can be below. In one embodiment, when the basic fiber surface area of the gas nucleation medium is measured by the BET method, it is 1m 2 / m 2 Above, 2m 2 / m 2 Above, 5m 2 / m 2 Above. In one embodiment, when the basic fiber surface area of the gas nucleation medium is measured by the BET method, it is 100m 2 / m 2 Below, 50m 2 / m 2 Below, 20m 2 / m 2 Below. In one embodiment, when the fiber surface area of the gas nucleation medium is measured by the BET method, it is from 1 to 75m 2 / m 2 It is. In one embodiment, when the basic fiber surface area of the gas nucleation medium is measured by the BET method, it is from 5 to 50m 2 / m 2is. In one embodiment, the basic fiber surface area of the gas nucleation medium is 1 m when measured by the Carmen-Kozeny method. 2 / m 2 or more, 5 m 2 / m 2 or more, or 10 m 2 / m 2 or more. In one embodiment, the basic fiber surface area of the gas nucleation medium is 200 m when measured by the Carmen-Kozeny method. 2 / m 2 or less, 100 m 2 / m 2 or less, 50 m 2 / m 2 or less, 20 m 2 / m 2 or less. In one embodiment, the basic fiber surface area of the gas nucleation medium is 5 to 75 m when measured by the Carmen-Kozeny method. 2 / m 2 is. In one embodiment, the basic fiber surface area of the gas nucleation medium is 10 to 50 m when measured by the Carmen-Kozeny method. 2 / m 2 is.

[0040] The fiber size is used here to refer to the diameter or cross-sectional dimension of the fibers of the medium. The diameter or cross-sectional dimension of the fiber can be determined optically for larger fibers and by SEM for smaller fibers. The fiber size of the fibers in the gas nucleation medium can vary from fiber to fiber and along a given fiber. The fiber size can also vary along a gradient from the upstream side to the downstream side of the medium. The fibers in the gas nucleation medium can have a fiber size of at least 10 nm (nanometers), at least 50 nm, or at least 100 nm. The fibers in the gas nucleation medium can have a fiber size of up to 10 μm (micrometers) or up to 100 μm.

[0041] The media pore size is understood to mean the size of the individual pores in the media sheet as determined by ASTM F316-03 or ASTM D6767. The pores in the gas nucleation media can have an average pore size of 0.5 μm or greater, 1 μm or greater, or 5 μm or greater. The pores in the gas nucleation media can have an average pore size of 5 μm or less, 10 μm or less, 20 μm or less, 100 μm or less, or 200 μm or less. For example, the pores in the gas nucleation media can have an average pore size from 5 μm to 100 μm. The pores in the gas nucleation media can have a maximum pore size of 1 μm or greater, 5 μm or greater, or 10 μm or greater. The pores in the gas nucleation media can have a maximum pore size of 10 μm or less, 20 μm or less, 100 μm or less, or 200 μm or less. For example, the pores in the gas nucleation media can have a maximum pore size from 5 μm to 200 μm. The values listed herein are determined by ASTM F316-03.

[0042] The chemical composition of the medium and the lipophilicity / hydrophobicity of the medium are thought to affect nucleation. The chemical composition of the medium can include the chemical composition of the fibers in the medium and / or the chemical composition of any binder or other component used in the medium. The fibers can include any suitable fibrous material, including woven or non-woven media made from organic or inorganic materials or combinations thereof. The medium can include various structures combining different materials, such as core and sheath structures, side-by-side structures, sea-island structures, and others. The fibers can include two or more material components within a single fiber, including a single material component or a mixture of materials. For example, the fibrous material can include one or more of cellulose; regenerated cellulose (e.g., rayon); synthetic materials such as polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF); glass; ceramic; or carbon fiber. In one embodiment, the filtration medium used as the gas nucleation medium is made of microglass and synthetic fibers. Examples of suitable filtration media are described in U.S. Patent Nos. 7,314,497; 7,309,372; 8,057,567; 8,268,033; 8,277,529; 8,512,435; 8,641,796; and 9,795,906, and U.S. Patent Application Publication Nos. 2012 / 0234748 and 2017 / 0225105. The medium can include various binders such as acrylic resin, phenolic resin, or epoxy resin.

[0043] Preferably, the gas nucleation medium has a lipophilicity / hydrophobicity suitable for inducing nucleation and releasing the formed gas cavities into the fluid flow (as opposed to being "trapped" on the surface of the fiber). In one embodiment, the gas nucleation medium is hydrophobic. The hydrophobicity evaluation (oil repellency) of the medium can be measured according to AATCC method 118 (e.g., 118 - 2013) using KAYDOL white mineral oil from Sonnerborn LLC (Petrolia, PA). The range of hydrophobicity based on this test is from 0 to 8, and an evaluation of 0 means that the medium is not hydrophobic. A hydrophobic medium has an evaluation of 1 or more. The gas nucleation medium can have a hydrophobicity evaluation of 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more. The gas nucleation medium can have a hydrophobicity evaluation of 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. In one embodiment, the gas nucleation medium has a hydrophobicity evaluation from 2 to 8 or from 3 to 8. The hydrophobicity of the material can also be expressed as the contact angle of an oil droplet on a single fiber in air, and can be measured by dispensing a bubble or an oil droplet onto the fiber and measuring the contact angle using, for example, a micro - contact angle meter (e.g., the MCA - 3 instrument available from Kyowa Interface Science Co., Ltd. (Shinjuku City, Japan)). The gas nucleation medium can have an oil contact angle of at least 30°, at least 50°, at least 70°, at least 90°, or at least 120°. The gas nucleation medium can have an oil contact angle of at most 120°, at most 150°.

[0044] The gas nucleation medium can be essentially hydrophobic (e.g., made of hydrophobic fibers) and / or can be treated to be hydrophobic using, for example, a hydrophobic treatment compound. Generally, hydrophobic materials are fluorochemicals such as fluoropolymers with a high density of terminal CF3 pendant groups exposed on the surface. In certain embodiments, the gas nucleation medium, or the hydrophobic treatment compound applied as a surface coating to the gas nucleation medium (e.g., a fluorochemical treatment compound), can be made from perfluoropolymers such as perfluoroacrylate, perfluorourethane, perfluoroepoxy, perfluorosilicone, perfluoroalkane, perfluorodioxolane, or copolymers of these materials.

[0045] A gas nucleation medium made of a substantially oleophobic material can be used. Typically, a fluorochemical treatment compound is coated onto a conventional filtration medium to make it oleophobic. The coating material can be, for example, an oleophobic polymer or another polymer that can be made oleophobic through a multi-step process. Typically, a fluorochemical treatment compound dissolved or suspended in a liquid carrier (e.g., an organic solvent or water) is applied to the conventional filtration medium by dipping or spraying. Alternatively, a process such as chemical vapor deposition (CVD) can be used to apply the coating through the gas phase.

[0046] Exemplary fluoropolymers include: perfluoroacrylates dissolved in a solvent, such as those available under the trade names FLUOROPEL series from Cytonix (Beltsville, MD), SRA 450 or SRA 451 from 3M Company (Maplewood, MN), and ADVAPEL 806 from Advanced Polymer Incorporated (Carlstadt, NJ); perfluorodioxolanes dissolved in a solvent, such as those available under the trade name TEFLON AF from Chemours (Wilmington, DE); perfluoroacrylate emulsions suspended in water, such as those available under the trade names UNIDYNE from Daikin (Orangeburg, NY), CAPSTONE from Chemours (Wilmington, DE), PHOBOL from Huntsman (The Woodlands, TX), or ADVAPEL 734 from Advanced Polymer Incorporated (Carlstadt, NJ); and perfluorourethanes suspended in water, such as those available under the trade name SRC220 from 3M Company (Maplewood, MN). The gas nucleation medium can also be made oleophobic by applying a coating of a fluoropolymer, such as a perfluoroacrylate coating from P2i (Savannah, GA), through a plasma polymerization process.

[0047] In certain embodiments, the gas nucleation media is prepared by applying a non-oleophobic coating to a conventional filter media and then modifying it to be oleophobic. For example, a polyalcohol polymer can be applied to a conventional filter media and a perfluorosilane or perfluoroacyl chloride can be grafted onto this polymer. Alternatively, a polyamine can be applied to a conventional filter media and a perfluoroacrylate can be grafted onto this polymer.

[0048] The surface energy of the polymer material can be determined, for example, in accordance with ASTM D7490-13, by creating a Zisman plot using an appropriate fluid. The surface energy of the material may be determined using the Owens-Wendt method. The fibers in the gas nucleation media can have a surface energy of 6 mJ / m 2 (millijoules per square meter) or more, 10 mJ / m 2 or more, 15 mJ / m 2 or more, 20 mJ / m 2 or more, or 40 mJ / m 2 or more. The fibers in the gas nucleation media can have a surface energy of 400 mJ / m 2 or less, 300 mJ / m 2 or less, 200 mJ / m 2 or less, 150 mJ / m 2 or less, 100 mJ / m 2 or less, or 50 mJ / m 2 or less. For example, the fibers in the gas nucleation media can have a surface energy of 10 mJ / m 2 to 200 mJ / m 2 . The values listed herein are determined by ASTM D7490-13.

[0049] The geometric configuration of the fibers in the gas nucleation medium can affect nucleation. For example, the presence of sharp edges or corners and surface roughness can potentially improve nucleation. The configuration of fiber intersections, the orientation angle of adjacent fibers, the orientation of the fiber surface with respect to the flow direction, and the degree of curvature of the flow path can also potentially affect nucleation. According to some embodiments, the gas nucleation medium includes fibers having sharp edges or corners. For example, the fibers can have a cross-section that does not have a smooth shape (e.g., is not circular or elliptical). The cross-section of the fiber can be polygonal or have an irregular shape with corners (e.g., corners less than 180°, less than 120°, or less than 90°). The gas nucleation medium includes fibers having a circular, star-shaped, square, rectangular, three-leaf, clover-shaped, or polygonal cross-section. The cross-section can be constant or vary along the length of the fiber.

[0050] The surface roughness of the material can be determined as the root mean square roughness using atomic force microscopy (AFM), cross-sectional SEM or transmission electron microscopy (TEM), or a surface profilometer. The measurement can be made on a fixed surface area having a dimension of half the fiber diameter, e.g., a square. The fibers of the gas nucleation medium can have a surface roughness of 1 nm or more, 10 nm or more, 25 nm or more, 50 nm or more, or 100 nm or more. The fibers of the gas nucleation medium can have a surface roughness of 1000 nm or less, 500 nm or less, or 200 nm or less. For example, the fibers of the gas nucleation medium can have a surface roughness of from 10 nm to 500 nm. The values listed here are determined by a surface profilometer.

[0051] Surface roughness can also be characterized using various other parameters such as skewness, kurtosis, etc. These surface features can indicate the degree of asymmetry (e.g., showing sharper peaks or deeper pits). Asymmetry can be expressed as skewness measured using AFM, fiber cross-section SEM, or a surface profiler. The skewness of the fiber can be -10 or more, -8 or more, or -6 or more. The skewness of the fiber can be 6 or less, 8 or less, or 10 or less. For example, the skewness of the fiber can be from -8 to 8. The values listed here are determined by a surface profiler.

[0052] Kurtosis is another measure of surface roughness that indicates the sharpness of sharp features. Kurtosis can be measured using AFM, fiber cross-section SEM, or a surface profiler. The fibers of the gas nucleation medium can have a kurtosis of at least -10 or more, -8 or more, or -6 or more. The fibers of the gas nucleation medium can have a kurtosis of 6 or less, 8 or less, or 10 or less. For example, the kurtosis of the fiber can be from -8 to 8. Certain combinations of surface roughness, skewness, and kurtosis may result in favorable nucleation characteristics. For example, high roughness and high kurtosis may be beneficial for nucleation. The values listed here are determined by a surface profiler.

[0053] An increase in the number of fiber intersections is thought to potentially increase nucleation to some extent. A fiber intersection is understood to mean the contact point between two fibers. Additionally, some ranges of the angle of orientation of adjacent fibers and the angle of orientation of the fibers with respect to the direction of flow are thought to potentially be beneficial for nucleation. For example, the fibers in the gas nucleation medium can be randomly oriented such that a certain range of orientation angles is achieved. In some embodiments, adjacent fibers in the gas nucleation medium are not axially aligned with each other.

[0054] Aspects that affect the residence time or differential pressure of the fluid in the medium can also affect nucleation. For example, the superficial velocity, the solid fraction of the medium sheet, the permeability of the medium sheet, the thickness of the medium sheet, the Peclet number of the dissolved gas from the fluid to the medium (e.g., the ratio of the convective transport velocity to the diffusive transport velocity), the degree of curvature of the flow path in the medium, and the orientation (e.g., angle) of the medium sheet with respect to the main flow direction can affect nucleation.

[0055] The superficial velocity of the fluid with respect to the gas nucleation medium sheet can be determined as the volumetric flow rate per unit bulk medium surface area. The superficial velocity can be 0.01 cm / second or more, 0.1 cm / second or more, 0.5 cm / second or more, 1.0 cm / second or more, or 5.0 cm / second or more. There is no desired upper limit for the superficial velocity, but in practice, the superficial velocity can be 50 cm / second or less, 20 cm / second or less, or 10 cm / second or less.

[0056] The solid fraction of a porous material is the ratio of the volume of solids to the total volume of the porous material. The gas nucleation medium sheet can have a solid fraction of 5% or more, 10% or more, or 20% or more. The gas nucleation medium sheet can have a solid fraction of 98% or less, 90% or less, 75% or less, 50% or less, 40% or less, or 30% or less.

[0057] The air permeability of a filter medium is defined as the volumetric flow rate of air passing through a specified filter medium area at a specified pressure drop. The method for measuring air permeability is ASTM D737 - 04. The gas nucleation medium sheet is 1 ft 3 / min / ft 2 or more (0.305 m 3 / min / m 2 or more) at 0.5 inches of water column, 10 ft 3 / min / ft 2 or more (3.05 mm 3 / min / m 2 or more) at 0.5 inches of water column, or 50 ft 3 / min / ft 2 or more (15.2 m 3 / min / m 2It may have breathability as described above. The gas nucleation media sheet has a water column of 0.5 inches at 500 ft 3 / min / ft 2 or less (152 m / min / m at 125 Pa 3 / min / m 2 or less), a water column of 0.5 inches at 400 ft 3 / min / ft 2 or less (123 m / min / m at 125 Pa 3 / min / m 2 or less), or a water column of 0.5 inches at 300 ft 3 / min / ft 2 or less (91.4 m / min / m at 125 Pa 3 / min / m 2 or less). For example, the gas nucleation media sheet may have a permeability of 0.5 m / min / m to 100 m / min / m at 125 Pa 3 / min / m 2 from 3 / min / m 2 .

[0058] The gas nucleation media sheet may have an initial clean differential pressure of 0.01 psi or less, 1 psi or less, or 100 psi or less, as per ISO 16889 performed at an appropriate superficial velocity, e.g., 0.5 cm / sec.

[0059] The Peclet number indicates the ratio of the convective transport rate to the diffusive transport rate of dissolved gas from the fluid to the media and is calculated as length (e.g., fiber diameter) × velocity (e.g., superficial velocity) divided by the diffusion coefficient. The gas nucleation media sheet may have a Peclet number of 0.05 or greater, 0.1 or greater, 0.5 or greater, 1 or greater, or 10 or greater. The gas nucleation media sheet may have a Peclet number of 1000 or less, 2500 or less, 10,000 or less, or 50,000 or less. For example, the gas nucleation media sheet may have a Peclet number from 0.5 to 10,000.

[0060] The angle of the fibers with respect to the stream of flow can be determined as the weight average of the angle of the fibers with respect to the direction of flow, for example, using a CT (computed tomography) scan of the medium. The angle can be 0° (degrees) or more, 10° or more, or 30° or more. The angle can be 90° or less, 80° or less, or 60° or less. For example, the angle can be from 10° to 80°.

[0061] The rigidity of the fibers in the gas nucleation medium can also affect the flow characteristics and thus can affect nucleation. The rigidity can be measured, for example, in accordance with ASTM D790 as the flexural modulus of the fiber or base material. In the case of a non-polymeric material, the flexural modulus is equal to the Young's modulus. The fibers of the gas nucleation medium can have a flexural modulus of 1 GPa (gigapascal) or more, 10 GPa or more, or 50 GPa or more. The fibers of the gas nucleation medium can have a flexural modulus of 500 GPa or less, 400 GPa or less, or 250 GPa or less. For example, the fibers of the gas nucleation medium can have a flexural modulus from 10 GPa to 400 GPa.

[0062] The gas nucleation medium can have any suitable shape. The shape can be determined based on the position of the degassing device within the system. In one embodiment, the gas nucleation medium defines a cylindrical shape. The thickness of the filter medium sheet can be measured using a suitable caliper thickness gauge, such as one that applies a pressure of 1.5 psi and uses a foot with a diameter of 2.87 cm. The thickness of the filter medium sheet can be measured in accordance with the TAPPI T411 test method. The gas nucleation medium can have any suitable thickness. The thickness of the gas nucleation medium can be measured in the direction of fluid flow. For example, in a cylindrical degassing device, the thickness of the gas nucleation medium can be measured in the radial direction perpendicular to the central axis A. The gas nucleation medium can have a thickness of 0.01 mm or more, 0.1 mm or more, or 0.5 mm or more. The gas nucleation medium can have a thickness of 5 mm or less, 2 mm or less, or 1 mm or less. For example, the gas nucleation medium can have a thickness of from 0.1 mm to 2 mm. The gas nucleation medium can be pleated or wound. In either case (pleated or wound), the medium can have one layer or multiple layers. The medium can be repeatedly wound or stacked. When multiple layers are included, the layers can have the same composition and / or structure of a unique composition and / or structure arranged in close contact.

[0063] In some embodiments, the gas nucleation medium includes a filter medium. In one embodiment, the gas nucleation medium is made of a particulate filter medium. In some embodiments, the gas nucleation medium has multiple layers. In some embodiments, the gas nucleation medium is wound or stacked. In one embodiment, the gas nucleation medium is made of a pleated medium. In one embodiment, the gas nucleation medium is made of a non-pleated medium.

[0064] The growth medium can be disposed adjacent to, or directly adjacent to, the gas nucleation medium. The growth medium can be made of any suitable material capable of inducing agglomeration and / or growth of gas cavities. Without wishing to be bound by theory, it is believed that multiple sides of the growth medium can affect the effectiveness and efficiency of the medium for inducing agglomeration. For example, the sides that affect agglomeration can include the chemical composition of the medium (e.g., fibers and binders); the surface energy of the medium; the lipophilicity / hydrophobicity of the medium; the basic fiber surface area of the medium; the solids content of the medium sheet; the average pore of the medium; the maximum pore of the medium; the permeability of the medium sheet; the thickness of the medium sheet; the surface roughness; the differential pressure across the medium. One or more of these properties can exhibit a gradient from the upstream side to the downstream side of the growth medium. In some embodiments, the gas nucleation medium can exhibit bubble growth behavior. In such embodiments, a separate layer of the growth medium can be excluded. For example, a gas nucleation medium having a pore size of 4 μm or more, 5 μm or more, 6 μm or more, or 8 μm or more can potentially exhibit bubble growth behavior. In one embodiment, the gas nucleation medium has a pore size of 4 μm or more, 5 μm or more, 6 μm or more, or 8 μm or more. In such an embodiment, the degassing device does not include the growth medium. In one embodiment, the degassing device includes gas nucleation having a pore size of 5 μm or more and does not include the growth medium.

[0065] The chemical composition of the growth medium can affect agglomeration and growth. The chemical composition of the growth medium can include the chemical composition of the fibers in the medium and / or the chemical composition of any binder or other component used in the medium. The fibers can include any suitable fibrous material, including woven or non-woven media made from one or more of cellulose; regenerated cellulose (e.g., rayon); synthetic materials such as polyamide (e.g., nylon), polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF); glass; ceramic; or carbon fibers. In one embodiment, the growth medium is made of, or includes, polyester, rayon, or a combination thereof. The medium can include various binders such as acrylic resin, phenolic resin, or epoxy resin.

[0066] Preferably, the growth medium has an appropriate surface energy and lipophilicity / hydrophobicity that induces the aggregation and / or growth of gas cavities and releases the formed gas cavities to the fluid flow (as opposed to being "trapped" on the surface of the fibers). According to one embodiment, the growth medium is lipophilic. In some embodiments, the growth medium exhibits a gradient of lipophilicity / hydrophobicity, with the upstream side of the medium being more hydrophobic than the downstream side. In another embodiment, the upstream side is more lipophilic than the downstream side. The hydrophobicity evaluation (oil repellency) of the medium can be measured according to AATCC method 118 (e.g., 118 - 2013). The growth medium can have an oil repellency evaluation of 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more. The growth medium can have an oil repellency evaluation of 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. In one embodiment, the growth medium has an oil repellency evaluation of 2 to 8 or 3 to 8. The hydrophobicity of the material can also be expressed as the contact angle of an oil droplet on a single fiber in air. The growth medium can have an oil contact angle of 0° or more, 10° or more, 20° or more, or 30° or more. The growth medium can have an oil contact angle of 150° or less, 120° or less, 90° or less, or 60° or less. The growth medium can be essentially lipophilic (e.g., made from lipophilic fibers) and / or can be treated to be hydrophobic using, for example, a hydrophobic treatment compound. The growth medium can be constructed from a composite material. The growth medium can be a composite of lipophilic and hydrophobic components. The hydrophobic component has an oil repellency evaluation of 1 or more.

[0067] The fibers in the growth medium have a surface energy of 6 mJ / m 2 or more, 20 mJ / m 2 or more, 50 mJ / m 2 or more, 75 mJ / m 2 or more, or 100 mJ / m 2 or more. The fibers in the growth medium have a surface energy of 400 mJ / m 2 or less, 350 mJ / m 2 or less, 300 mJ / m 2 or less, or 250 mJ / m 2 or less. For example, the fibers in the growth medium have a surface energy of 20 mJ / m 2 to 350 mJ / m2 may have a surface energy. The values listed here are determined by ASTM D7490-13.

[0068] The specific surface area of the medium, and thus the contact area between the medium and the fluid, can affect aggregation and growth. The specific surface area of the medium is understood to mean m 2 per unit bulk surface area of the medium sheet and m 2 per unit total surface area (including the surface area between the fibers). The specific surface area of the growth medium can be 1 m 2 / m 2 or more, 1.5 m 2 / m 2 or more, 1.6 m 2 / m 2 or more, or 2 m 2 / m 2 or more. The specific surface area of the growth medium can be up to 200 m 2 / m 2 up to 50 m 2 / m 2 up to 30 m 2 / m 2 up to 10 m 2 / m 2 up to 6 m 2 / m 2 or up to 4 m 2 / m 2 / m. For example, the specific surface area of the growth medium can be from 1.5 m 2 / m 2 to 50 m 2 / m 2 / m. The values described here are determined by the Carmen-Kozeny method.

[0069] The geometric configuration of the fibers in the growth medium can affect aggregation and growth. For example, the presence of sharp edges or corners and surface roughness, the orientation of the fiber surface with respect to the flow direction, the solids fraction, the permeability, and the pore size of the growth medium can be selected to improve the aggregation and growth of gas cavities and to release the gas cavities into the fluid flow after the gas cavities have grown and / or aggregated.

[0070] The cross-section of the fibers in the growth medium can be polygonal or have an irregular shape with corners (e.g., corners less than 180°, less than 120°, or less than 90°). The growth medium can include fibers having a circular, star-shaped, square, rectangular, three-leaf, clover-shaped, or polygonal cross-section. The cross-section can be constant or vary along the entire length of the fiber.

[0071] The fiber size of the fibers in the growth medium can vary from fiber to fiber and along a given fiber. The fiber size can also vary along a gradient from the upstream side to the downstream side of the medium. The fibers in the growth medium can have a fiber size of 10 nm or more, 50 nm or more, or 100 nm or more. The fibers in the growth medium can have a fiber size of 500 μm or less, 100 μm or less, or 10 μm or less. For example, the fibers in the growth medium can have a fiber size of 50 nm to 100 μm.

[0072] The angle of the fibers with respect to the stream of the flow in the growth medium can be 0° or more, 10° or more, or 30° or more. The angle of the fibers in the growth medium can be 90° or less, 80° or less, or 60° or less. For example, the angle can be from 10° to 80°.

[0073] The rigidity of the fibers in the growth medium can also affect the flow characteristics and thus can affect aggregation and / or growth. The fibers of the growth medium can have a flexural modulus of 1 GPa or more, 10 GPa or more, or 50 GPa or more. The fibers of the growth medium can have a flexural modulus of 500 GPa or less, 400 GPa or less, or 250 GPa or less. For example, the fibers of the growth medium can have a flexural modulus of 10 GPa to 400 GPa.

[0074] The fibers in the growth medium can have a surface roughness of 1 nm or more, 10 nm or more, 25 nm or more, 50 nm or more, or 100 nm or more. The fibers in the growth medium can have a surface roughness of 1000 nm or less, 500 nm or less, or 200 nm or less. For example, the fibers of the growth medium can have a surface roughness of 10 nm to 500 nm. The fibers in the growth medium can have a skewness of -10 or more, -8 or more, or -6 or more. The skewness of the fibers can be 6 or less, 8 or less, or 10 or less. For example, the skewness of the fibers can be -8 to 8. The fibers in the growth medium can have a kurtosis of 6 or less, 8 or less, or 10 or less. The values listed here are determined by a surface profiler.

[0075] The pores of the medium are understood to mean holes (e.g., through-holes) and cavities in the sheet of the medium. The pore size can be determined by ASTM F316-03 or ASTM D6767. The pores of the medium can provide a flow path through the sheet of the medium for fluids. The growth medium can have an average pore size of 0.5 μm or more, 1 μm or more, or 5 μm or more. The growth medium can have an average pore size of 5 μm or less, 10 μm or less, 20 μm or less, 100 μm or less, or 200 μm or less. For example, the pores in the growth medium can have an average pore size of 5 μm to 100 μm. The growth medium can have a maximum pore size of 1 μm or more, 5 μm or more, or 10 μm or more. The pores in the growth medium can have a maximum pore size of 10 μm or less, 20 μm or less, 100 μm or less, or 200 μm or less. For example, the pores in the growth medium can have a maximum pore size of 5 μm to 200 μm. The values listed here are determined by ASTM F316-03.

[0076] The growth medium can have a solids content of 2% or more, 4% or more, 5% or more, 6% or more, 10% or more, or 20% or more at 1.5 psi. The growth medium can have a solids content of 90% or less, 75% or less, 50% or less, 40% or less, 30% or less, 20% or less, 15% or less, 10% or less, 9% or less, or 8% or less at 1.5 psi. For example, the growth medium can have a solids content of 2% to 20%, or 2% to 9% at 1.5 psi. The growth medium can include a woven or non-woven medium having a porous structure.

[0077] The growth media sheet can have any suitable thickness. The thickness of the growth media affects the differential pressure across the media sheet. The thickness of the growth media can be measured in the direction of fluid flow. For example, in a cylindrical degassing device, the growth media forms a coaxial cylinder that at least partially surrounds the gas nucleation media, and the thickness of the growth media can be measured in the radial direction perpendicular to the central axis A. The thickness of the filtration media sheet can be measured using a suitable caliper thickness gauge, such as one that applies a pressure of 1.5 psi and uses a foot with a diameter of 2.87 cm. The thickness of the filtration media sheet can be measured according to the TAPPI T411 test method. The growth media can have a thickness of 0.01 mm or more, 0.02 mm or more, 0.05 mm or more, 0.1 mm or more, or 0.5 mm or more, 0.8 mm or more, 1 mm or more, 2 mm or more, 3 mm or more, or 4 mm or more. The growth media can have a thickness of 25 mm or less, 20 mm or less, 15 mm or less, or 10 mm or less. For example, the growth media can have a thickness of from 0.1 mm to 20 mm or from 0.8 mm to 10 mm.

[0078] The growth media sheet can have a differential pressure of 0.01 psi or less, 1 psi or less, or 100 psi or less, in accordance with ISO 16889, which is carried out at a suitable surface velocity, for example 0.5 cm / second.

[0079] The growth medium can be provided as a plurality of media layers. The plurality of layers of the medium can be applied (e.g., wrapped or laminated) on a gas nucleation medium. An increase in the number of layers of the growth medium can improve the agglomeration of gas cavities. However, an increase in the thickness of the growth medium (e.g., due to an increase in the number of layers of the medium) can also increase the pressure drop across the growth medium and the degassing device as a whole. Furthermore, a high pressure drop can limit the gas that the nucleation stage can release, resulting in nucleation occurring in the latter half of the growth stage and smaller bubbles being released downstream of the growth stage. Therefore, the number of layers of the growth medium can be balanced to provide improved agglomeration without overly increasing the pressure drop across the degassing unit. The growth medium can be provided as 2 or more, 3 or more, 4 or more, or 5 or more layers. The growth medium can be provided as a maximum of 20, a maximum of 15, a maximum of 12, or a maximum of 10 layers. In embodiments where the growth medium includes a plurality of layers, the thickness of the growth medium can refer to the total thickness of the layers, unless otherwise specified. The thickness of an individual growth medium sheet can affect the number of rolls used. For example, a thinner medium may utilize more rolls. In one embodiment, the growth medium is composed of 5 to 10 layers (e.g., 7 layers) of the medium.

[0080] The porous barrier downstream of the growth medium can include any suitable porous material that defines openings or pores extending through the barrier. Without wishing to be bound by theory, it is believed that the plurality of sides of the porous barrier can affect the effectiveness and efficiency of the barrier. For example, the sides that can affect the efficiency of the porous barrier can include the following: pore size and pore shape, and the regularity or uniformity of pore size and shape across the barrier; the chemical composition of the barrier; the lipophilicity / hydrophobicity of the barrier; the surface roughness or smoothness of the barrier; the direction / orientation of the barrier with respect to the direction of flow. One or more of these properties can be different on the upstream and downstream sides, or can exhibit a gradient from the upstream side to the downstream side of the growth medium.

[0081] In some embodiments, the porous barrier comprises a woven or non-woven material. The openings can be of uniform size or non-uniform, including openings of various sizes. The pores of the porous barrier are sometimes referred to as screen openings and are understood to mean the holes (e.g., through-holes) of the barrier. The pore size can be determined by ASTM E11 or optical imaging. The porous barrier can include openings with a size of 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more. The porous barrier can include openings with a size of 1 mm or less, 750 μm or less, 500 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less. In one example, the porous barrier includes openings with a size from 10 μm to 250 μm, from 15 μm to 200 μm, or from 20 μm to 150 μm. In some embodiments, the openings of the porous barrier are of uniform size (e.g., narrow pore size distribution). For example, in some embodiments, when determined by the total opening area of the porous barrier, at least some, most, at least 90%, at least 95%, or at least 99% of the openings of the porous barrier are within the specified size range. The values described herein are determined by optical imaging. In one embodiment, substantially all of the openings of the porous barrier are within the specified size range.

[0082] The openings of the porous barrier can have any suitable shape. For example, the openings can be rectangular, square, circular, elliptical, or any other suitable shape. The shape can be determined by viewing the porous barrier in a direction perpendicular to the plane of the porous barrier. In some embodiments, the openings of the porous barrier are of uniform shape. For example, in some embodiments, at least some, most, at least 90%, at least 95%, or at least 99% of the openings of the porous barrier have the same shape (e.g., rectangular, square, circular, elliptical, etc.).

[0083] The porous barrier 130 can be made of a woven or non-woven material. For example, the porous barrier 130 can be made of a woven mesh. The woven mesh can have a wire diameter (or cross-sectional dimension) of 0.01 mm or more, 0.05 mm or more, or 0.1 mm or more. The woven mesh can have a wire diameter (or cross-sectional dimension) of 10 mm or less, 2 mm or less, 1 mm or less, or 0.5 mm or less. For example, the woven mesh can have a wire diameter (or cross-sectional dimension) from 0.05 mm to 2 mm. In one embodiment, the porous barrier 130 includes a pleated material such as a pleated woven mesh. The porous barrier 130 can be made of any suitable material. For example, the porous barrier can be made of a material having suitable lipophilicity / hydrophobicity to promote further growth of the gas cavity and allow the gas cavity to pass through the barrier. In some embodiments, the porous barrier or a portion of the porous barrier is hydrophobic. According to some embodiments, at least one side of the porous barrier is lipophilic. In some embodiments, the porous barrier exhibits a hydrophobic gradient, and the upstream side of the barrier is more hydrophobic than the downstream side. The hydrophobicity of the material can be represented as a hydrophobicity evaluation measured according to AATCC method 118. The porous barrier can have a hydrophobicity evaluation of 1 or more, 1.5 or more, or 2 or more. The porous barrier can have an oil evaluation of 8 or less or 6 or less. The porous barrier can be constructed from a composite material. The porous barrier can be a composite of a lipophilic component and a hydrophobic component. The hydrophobic component has a hydrophobicity evaluation of 1 or more.

[0084] For example, the porous barrier 130 can be made from a woven or non-woven media made of one or more of a metal such as stainless steel, or cellulose; regenerated cellulose (e.g., rayon); synthetic materials such as polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF); glass; ceramic; or carbon fiber. In one embodiment, the porous barrier 130 is made from a woven metal mesh such as a stainless steel mesh. In some embodiments, fibers (e.g., metal fibers) are coated. A polymeric or non-polymeric coating such as a resin can be used. The porous barrier 130 can be arranged in a cylindrical shape that at least partially surrounds the gas nucleation medium 110 and the growth medium 120.

[0085] The porous barrier can exhibit microtexture and macrotexture. Microtexture is used herein to refer to the surface texture of the barrier at the level of the individual fibers or wires that make up the barrier (e.g., referring to variations less than 1 mm in size). Microtexture is sometimes referred to as surface roughness. Macrotexture is used herein to refer to the surface texture of the entire barrier (e.g., referring to variations greater than 1 mm in size). The porous barrier may exhibit surface roughness. For example, the porous barrier can have a surface roughness of 1 nm or more, 10 nm or more, 25 nm or more, 50 nm or more, or 100 nm or more. The porous barrier can have a surface roughness of 1000 nm or less, 500 nm or less, or 200 nm or less. For example, the porous barrier can have a surface roughness of 10 nm to 500 nm. In some embodiments, the porous barrier has little or no macrotexture, i.e., the porous barrier is "smooth" except that the porous barrier can be pleated.

[0086] Additional characteristics of the porous barrier surface include skewness, kurtosis, and radius of curvature. The skewness of the fibers can be at least -10 or greater, -8 or greater, or -6 or greater. The skewness of the fibers can be 6 or less, 8 or less, or 10 or less. The fibers of the porous barrier can have a kurtosis of -10 or greater, -8 or greater, or -6 or greater. The fibers of the porous barrier can have a kurtosis of 6 or less, 8 or less, or 10 or less. Certain combinations of surface roughness, skewness, and kurtosis may result in favorable capture characteristics. For example, high roughness and high kurtosis may be beneficial for capture. The fibers of the porous barrier can have a radius of curvature that is up to 2 nm, up to 5 nm, up to 10, up to 50, up to 100, or up to 500 nm.

[0087] The porous barrier can have an initial clean differential pressure of 0.01 psi or less, 1 psi or less, or 100 psi or less, as per ISO 16889 executed at an appropriate face velocity, such as 0.5 cm / second.

[0088] The porous barrier can be positioned substantially perpendicular to the direction of flow. For example, the porous barrier can be cylindrical with a cylindrical wall that is coaxial with the nucleation medium. In some embodiments, the porous barrier includes a pleated material where the pleat faces are angled with respect to the direction of flow. The degassing device 100 can include a gap 135 between the gas nucleation medium 110 and the porous barrier 130, or between the growth medium 120 and the porous barrier 130, as shown. The gap 135 can be sized appropriately to accommodate the agglomerated gas cavities (second-stage gas cavities) from the growth medium 120. The gap 135 can be arranged such that the agglomerated gas cavities (second-stage gas cavities) can collect and further agglomerate (third-stage gas cavities). Thus, the gap 135 can be considered, in some respects, as a second growth stage.

[0089] The porous barrier 130 may have an axial length equal to the axial length of the gas nucleation medium 110. Alternatively, the porous barrier 130 may have an axial length longer or shorter than the axial length of the gas nucleation medium 110. In one embodiment, the axial length of the porous barrier 130 is shorter than the axial length of the gas nucleation medium 110.

[0090] The gap 135 may extend axially from the first end cap 141 to a second end cap 142 that defines the axial length of the gap 135. The gap 135 may have a width measured as the radial distance between the gas nucleation medium 110 and the porous barrier 130, or between the growth medium 120 and the porous barrier 130. In some embodiments, the gap 135 extends from the growth medium 120 to the wall of the tank. The gap 135 can be of uniform size along its axial length or one end may be wider than the other. For example, the gap 135 can be constructed to be wider at its bottom and narrower at its top, or narrower at its bottom and wider at its top. The gap 135 may have a width of 0.5 mm or more, 1 mm or more, 1.5 mm or more, 2 mm or more, 2.5 mm or more, or 4 mm or more. The width of the gap 135 can be 25 mm or less, 20 mm or less, 15 mm or less, 10 mm or less, or 5 mm or less. For example, the gap can have a width from 4 mm to 20 mm. In some embodiments where the gap 135 extends from the growth medium 120 to the wall of the tank, the size of the gap can be larger, for example, up to 10 m (meters), up to 5 m, up to 1 m, up to 50 cm (centimeters), up to 25 cm, or up to 10 cm.

[0091] The degassing device 100 may include additional elements. For example, the degassing device 100 may include one or more support liners. Such liners can be disposed adjacent to, or between, the gas nucleation medium 110, the growth medium 120, and / or the porous barrier 130, or any combination thereof. The degassing device 100 may further include one or more of a housing element, a support element, a mounting element, an end cap, a seal, a potting compound, a tube, a line, and the like.

[0092] The degassing device 100 may include removable and / or serviceable parts. For example, one or more of the gas nucleation medium 110, the growth medium 120, and the porous barrier 130 may be independently removable and / or serviceable, or may form a removable and / or serviceable unit. In one embodiment, the gas nucleation medium 110 and the growth medium 120 are removable and / or serviceable. For example, the gas nucleation medium 110 and the growth medium 120 may form a removable and / or serviceable unit. The serviceable unit of the gas nucleation medium 110 and the growth medium 120 may optionally include separate end caps attached to the gas nucleation medium 110 and the growth medium 120. The porous barrier 130 may be permanently attached to the first end cap 141 and / or the second end cap 142. The porous barrier 130 and the first end cap 141 and / or the second end cap 142 may form a frame. In some embodiments, the serviceable unit of the gas nucleation medium 110 and the growth medium 120 may be removably and sealingly coupled to the frame. When the degassing device 100 is assembled, the end caps of the serviceable unit of the gas nucleation medium 110 and the growth medium 120 may be adjacent to the first and second end caps 141, 142 and may include a seal such as an O-ring between the adjacent end caps. The adjacent end caps may be axially aligned with one or more of the end caps including lips that limit the movement of the adjacent end caps.

[0093] The degassing device 100 is configured to be mounted in various orientations, for example, with the central axis A oriented vertically as shown, or with the central axis A oriented horizontally. A horizontal orientation may be advantageous when the degassing device 100 is mounted in series, such as in the return line 31. In a horizontal orientation, the gas nucleation medium 110, the growth medium 120, and the porous barrier 130 may be arranged in a non-cylindrical shape, such as a planar shape.

[0094] In a preferred embodiment, the degassing device 100 is positioned inside the tank 10 in a vertical position (the axis A is vertical or substantially vertical). The degassing device 100 can be arranged below (for example, directly below) the inlet to the tank 10. For example, the degassing device 100 can be attached to the inlet where the return line 31 discharges fluid into the tank 10. The degassing device 100 may be submerged or partially submerged, or may at least sometimes be completely above the fluid level of the tank. For example, the tank 10 can be a hydraulic fluid tank of a hydraulic system, where the fluid level in the tank 10 changes during operation of the hydraulic system. The degassing device 100 can be attached to the upper part of the tank or near it so that the degassing device 100 sometimes, at least sometimes, or always partially submerges in the hydraulic fluid.

[0095] A list of various aspects of the degassing device of the present disclosure is provided below.

[0096] According to a first aspect, the degassing device includes a gas nucleation medium; a growth medium adjacent to the gas-forming medium; and a porous barrier adjacent to the growth medium.

[0097] In aspect 2, the degassing device of aspect 1 further includes a gap between the growth medium and the porous barrier. The gap can have a width of 0.5 mm or more, 1 mm or more, 1.5 mm or more, 2 mm or more, or 2.5 mm or more; or 50 cm or less, 20 cm or less, 25 mm or less, 20 mm or less, 15 mm or less, 10 mm or less, or 5 mm or less. The gap can have a width of 1 mm to 15 mm.

[0098] In aspect 3, according to the degassing device of aspect 1 or aspect 2, the gas nucleation medium includes a particulate filter medium.

[0099] In aspect 4, according to any one of the degassing devices of aspects 1 to 3, the gas nucleation medium includes cellulose, regenerated cellulose, polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), glass, ceramic, carbon fiber, or a combination thereof. The gas nucleation medium may include a combination of glass fiber and polyester.

[0100] In aspect 5, according to any one of the degassing devices of aspects 1 to 4, the gas nucleation medium includes a lipophobic material having an oil contact angle of at least 30°, at least 50°, at least 70°, at least 90°, or at least 120°; or at most 120°, or at most 150°. The gas nucleation medium may have an oil contact angle of 50° to 120°.

[0101] In aspect 6, according to any one of the degassing devices of aspects 1 to 5, the gas nucleation medium includes a lipophobic material having a lipophobicity evaluation of 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more; or 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. The gas nucleation medium may have a lipophobicity evaluation of 2 to 8 or 3 to 8.

[0102] In aspect 7, according to any one of the degassing devices of aspects 1 to 6, the growth medium includes a plurality of medium layers. The growth medium may include 2 or more, 3 or more, 4 or more, or 5 or more layers; or at most 20, at most 15, at most 12, or at most 10 layers. The growth medium may include 2 to 15 layers or 4 to 10 layers. The growth medium may include 7 layers.

[0103] In aspect 8, according to any one of the degassing devices of aspects 1 to 7, the growth medium is directly adjacent to the gas nucleation medium.

[0104] In aspect 9, according to any one of the degassing devices of aspects 1 to 8, the growth medium includes cellulose, regenerated cellulose, polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), glass, ceramic, carbon fiber, or a combination thereof. The growth medium may include a combination of regenerated cellulose fibers and polyester.

[0105] In aspect 10, according to any one of the degassing devices of aspects 1 to 9, the porous barrier includes an opening that forms an outlet.

[0106] In aspect 11, according to any one of the degassing devices of aspects 1 to 10, the porous barrier includes openings having a size of 1 mm or less, 750 μm or less, 500 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less. The porous barrier may include openings having a size of 10 μm to 120 μm, 15 μm to 100 μm, or 20 μm to 80 μm.

[0107] In aspect 12, according to the degassing device of aspect 11, it further includes a liner.

[0108] In aspect 13, according to any one of the degassing devices of aspects 1 to 12, it further includes a first end cap that includes an opening defining an inlet.

[0109] In aspect 14, according to any one of the degassing devices of aspects 1 to 13, it further includes a closed second end cap.

[0110] In aspect 15, according to the degassing device of aspect 14, the second end cap includes a bottom.

[0111] In aspect 16, according to any one of the degassing devices of aspects 1 to 15, the gas nucleation medium surrounds and defines the interior of the open degassing device.

[0112] In Embodiment 17, according to any one of the degassing devices of Embodiments 1 to 16, the gas nucleation medium, the growth medium, and the porous barrier form a cylindrical main body.

[0113] In Embodiment 18, according to any one of the degassing devices of Embodiments 1 to 17, the gas nucleation medium has a basic fiber surface area of 1 m 2 / m 2 or more, 1.5 m 2 / m 2 or more, 2 m 2 / m of medium 2 or more, 5 m 2 / m of medium 2 or more, 10 m 2 / m of medium 2 or more, 25 m 2 / m 2 or more, 50 m 2 / m 2 or more, or 100 m 2 / m 2 or more; or 200 m 2 / m 2 or less, 150 m 2 / m 2 or less, 100 m 2 / m 2 or less, 50 m 2 / m 2 or less, 30 m 2 / m 2 or less, 10 m 2 / m 2 or less, 6 m 2 / m 2 or less, or 4 m 2 / m 2 or less and has the following basic fiber surface area. When measured by the Carmen-Kozeny method, the gas nucleation medium has a basic fiber surface area of 1 m 2 / m 2 ~100 m 2 / m 2 or 5 m 2 / m 2 ~50 m 2 / m 2 and may have a basic fiber surface area of.

[0114] In Embodiment 19, according to any one of the degassing devices of Embodiments 1 to 18, the gas nucleation medium has an average pore size of 0.5 μm or more, 1 μm or more, or 5 μm or more; or 5 μm or less, 10 μm or less, 20 μm or less, 100 μm or less, or 200 μm or less as measured by ASTM F316. The pores in the gas nucleation medium can have an average pore size of 5 μm to 100 μm or 30 μm or less as measured by ASTM F316.

[0115] In Embodiment 20, according to the degassing device of Embodiment 13, the first end cap includes a direct inlet to the gap between the growth medium and the porous barrier.

[0116] In Embodiment 21, according to any one of the degassing devices of Embodiments 1 to 20, the growth medium has a solids content of 2% or more, 4% or more, 5% or more, 6% or more, 10% or more, or 20% or more; or 90% or less, 75% or less, 50% or less, 40% or less, 30% or less, 20% or less, 15% or less, 10% or less, 9% or less, or 8% or less at 1.5 psi. The growth medium can have a solids content of 2% to 20% or 2% to 9% at 1.5 psi.

[0117] In Embodiment 22, according to any one of the degassing devices of Embodiments 1 to 21, the growth medium has a thickness of 0.01 mm or more, 0.02 or more, 0.05 or more, 0.1 mm or more, or 0.5 mm or more, 0.8 mm or more, 1 mm or more, 2 mm or more, 3 mm or more, or 4 mm or more; or 25 mm or less, 20 mm or less, 15 mm or less, or 10 mm or less as measured according to the TAPPI T411 test method. The growth medium can have a thickness of 0.1 mm to 20 mm or 0.8 mm to 10 mm as measured according to the TAPPI T411 test method.

[0118] In Embodiment 23, according to any one of the degassing devices of Embodiments 1 to 22, the growth medium includes a composite of a lipophilic component and a lipophobic component, and the lipophobic component has a lipophobicity evaluation of 1 or more as measured by the AATCC method 118.

[0119] In aspect 24, according to any one of the degassing devices of aspects 1 to 23, the porous barrier includes a lipophobic surface having one or more lipophobicity evaluations when measured by AATCC method 118.

[0120] In aspect 25, according to any one of the degassing devices of aspects 1 to 24, the porous barrier includes a composite of a lipophilic component and a lipophobic component, and the lipophobic component has one or more lipophobicity evaluations when measured by AATCC method 118.

[0121] According to aspect 26, a system for removing gas from a fluid includes a tank having a fluid inlet and a fluid outlet and having a fluid flow path from the fluid inlet to the fluid outlet; and a degassing device within the fluid flow path.

[0122] In aspect 27, according to the system of aspect 26, the degassing device includes a gas nucleation medium; a growth medium downstream of the gas nucleation medium; and a porous barrier downstream of the gas nucleation medium.

[0123] In aspect 28, according to the system of aspect 26 or 27, the degassing device includes a gap between the growth medium and the porous barrier.

[0124] In aspect 29, according to any one of the systems of aspects 26 to 28, the gas nucleation medium includes a particulate filter medium.

[0125] In aspect 30, according to any one of the systems of aspects 26 to 29, the gas nucleation medium includes cellulose, regenerated cellulose, polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), glass, or a combination thereof. The gas nucleation medium can include a combination of glass fibers and polyester.

[0126] In aspect 31, according to any one of the systems of aspects 26 to 30, the gas nucleation medium comprises a lipophobic material having an oil contact angle of at least 30°, at least 50°, at least 70°, at least 90°, or at least 120°; or at most 120°, or at most 150°. The gas nucleation medium can have an oil contact angle of from 50° to 120°.

[0127] In aspect 32, according to any one of the systems of aspects 26 to 31, the gas nucleation medium comprises a lipophobic material having a lipophobicity rating of 1 or more, 2 or more, 3 or more, 4 or more, 5 or more or 6 or more; or 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. The gas nucleation medium can have a lipophobicity rating of from 2 to 8 or from 3 to 8.

[0128] In aspect 33, according to any one of the systems of aspects 26 to 32, the growth medium comprises a plurality of medium layers. The growth medium can comprise 2 or more, 3 or more, 4 or more, or 5 or more layers; or at most 20, at most 15, at most 12, or at most 10 layers. The growth medium can comprise from 2 to 15 layers or from 4 to 10 layers. The growth medium can comprise 7 layers.

[0129] In aspect 34, according to any one of the systems of aspects 26 to 33, the growth medium comprises cellulose, regenerated cellulose, polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), glass, ceramic, carbon fiber, or a combination thereof. The growth medium can comprise a combination of regenerated cellulose fibers and polyester.

[0130] In aspect 35, according to any one of the systems of aspects 26 to 34, the growth medium is in direct adjacency to the gas nucleation medium.

[0131] In aspect 36, according to any one of the systems of aspects 26 to 35, the porous barrier includes openings having a size of 1 mm or less, 750 μm or less, 500 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less. The porous barrier may include openings having a size of 10 μm to 250 μm, 15 μm to 200 μm, or 20 μm to 150 μm.

[0132] In aspect 37, according to any one of the systems of aspects 26 to 36, the degassing device includes a liner.

[0133] In aspect 38, according to any one of the systems of aspects 26 to 37, the degassing device includes a first end cap that includes an opening defining a degassing device inlet.

[0134] In aspect 39, according to any one of the systems of aspects 26 to 38, the degassing device includes a closed second end cap.

[0135] In aspect 40, according to any one of the systems of aspects 26 to 39, the closed second end cap includes a bottom.

[0136] In aspect 41, according to any one of the systems of aspects 26 to 40, the gas nucleation medium surrounds and defines the interior of the open degassing device.

[0137] In aspect 42, according to any one of the systems of aspects 26 to 41, the gas nucleation medium, the growth medium, and the porous barrier form a cylindrical body.

[0138] In aspect 43, according to any one of the systems of aspects 26 to 42, the gas nucleation medium and the growth medium are disposed in a fluid flow path in a through-flow configuration.

[0139] According to aspect 44, a method for removing gas from a fluid includes passing the fluid through a degassing device that defines a flow path for the fluid, the degassing device including any one of the degassing devices of aspects 1 to 25. The fluid may include oil. The fluid may include a hydraulic fluid.

[0140] In aspect 45, according to the method of aspect 44, the method includes removing at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, or at least 60% of the air in the fluid as compared to a baseline without a degassing device.

[0141] According to aspect 46, the degassing device includes: a gas nucleation medium; a porous barrier adjacent to the growth medium, the porous barrier including openings sized 1 mm or less, 750 μm or less, 500 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less; and a gap between the gas nucleation medium and the porous barrier. The porous barrier may include openings sized from 10 μm to 120 μm, from 15 μm to 100 μm, or from 20 μm to 80 μm.

[0142] In aspect 47, according to the degassing device of aspect 46, the gas nucleation medium includes a particulate filtration medium.

[0143] In aspect 48, according to the degassing device of aspect 46 or 47, the gas nucleation medium includes cellulose, regenerated cellulose, polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), glass, ceramic, carbon fiber, or a combination thereof. The gas nucleation medium may include a combination of glass fiber and polyester.

[0144] In aspect 49, according to any one of the degassing devices of aspects 46 to 48, the gas nucleation medium includes a lipophobic material having an oil contact angle of at least 30°, at least 50°, at least 70°, at least 90°, or at least 120°; or a maximum of 120°, or a maximum of 150°. The gas nucleation medium may have an oil contact angle of 50° to 120°.

[0145] In aspect 50, according to any one of the degassing devices of aspects 46 to 49, the gas nucleation medium includes a lipophobic material having a lipophobicity evaluation of 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more; or 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. The gas nucleation medium may have a lipophobicity evaluation of 2 to 8 or 3 to 8.

[0146] In aspect 51, according to any one of the degassing devices of aspects 46 to 50, the gap is 0.5 mm or more, 1 mm or more, 1.5 mm or more, 2 mm or more, 2.5 mm or more, or 4 mm or more; or 25 mm or less, 20 mm or less, 15 mm or less, 10 mm or less, or 5 mm or less. The gap may be from 4 mm to 20 mm.

[0147] In aspect 52, any one of the degassing devices of aspects 46 to 51 further includes a liner.

[0148] In aspect 53, any one of the degassing devices of aspects 46 to 52 further includes a first end cap including an opening defining an inlet.

[0149] In aspect 54, any one of the degassing devices of aspects 46 to 53 further includes a closed second end cap.

[0150] In aspect 55, according to any one of the degassing devices of aspects 46 to 54, the gas nucleation medium surrounds and defines the interior of the open degassing device.

[0151] In aspect 56, according to any one of the degassing devices of aspects 46 to 55, the gas nucleation medium and the porous barrier form a cylindrical body.

[0152] In aspect 57, according to any one of the degassing devices of aspects 46 to 56, the gas nucleation medium has an average pore diameter of 0.5 μm or more, 1 μm or more, or 5 μm or more; or 5 μm or less, 10 μm or less, 20 μm or less, 100 μm or less, or 200 μm or less when measured by ASTM F316. The pores in the gas nucleation medium may have an average pore diameter of 5 μm to 100 μm or 30 μm or less when measured by ASTM F316.

Examples

[0153] Examples 1 and 2 Various aspects of a degassing device configured to be used with hydraulic oil were tested. The performance of the degassing device was tested against a commercially available degassing device and a baseline without a degassing device.

[0154] Test system. To test the performance of the degassing device, pressurized air was used to saturate the hydraulic oil with air. The tests were performed using HY-GARD (trademark) hydraulic / transmission oil available from Deere & Company (Moline, IL). The degassing device was assembled into a tank constructed to simulate the hydraulic oil tank of a hydraulic system. Here, the return hydraulic oil enters the tank and the degassing device from above. During the test, the tank was placed under ambient pressure. The air-saturated oil was circulated through a system including a degassing device tank that houses the degassing device to be tested. The air-saturated oil was pumped through the degassing device and the air removal efficiency was measured.

[0155] The fluid was heated to a target temperature such as 35 ± 1.6 °C, and the flow rate was about 36 L / min at a pressure of 414 kPa. Air was flowed into the air mixing tank at 7.1 L / min.

[0156] Preparation of Samples. The degassing filter elements (Samples C - H) were coaxially constructed with a 0.5 cm gap between the growth medium and the screen barrier as shown in Figure 2A. The elements were sized to target step - by - step media surface velocities: 30 cm / min for the nucleation stage, 130 cm / min for the growth stage, and 30 cm / min for the screen barrier stage. The nucleation medium was a pleated EN0799037 hydraulic medium available from Donaldson Company, Inc. (Minneapolis, MN) used with part numbers P171846 and P171579. The growth medium was a wound needle - punched polyester / rayon blend non - woven fabric medium such as PN - 130 (130 g / m 2 ) manufactured by Precision Custom Coatings, LLC (Totowa, NJ). The screen barrier was composed of a simple woven screen with pleats. The nucleation medium and the screen barrier were supported by support wires.

[0157] A commercially available degassing device (comparative example, Sample A) was miniaturized to match the flow capacity of the test system. In the commercially available degassing device, the flow enters from the bottom, turns, and passes radially outward through the particulate medium from the inside to the outside. The particulate medium is surrounded by a cylindrical metal shell (downstream of the particulate medium). The cylindrical metal shell has a rectangular opening in the lower 1 / 3 of the shell, and a single layer of stainless - steel screen is attached inside the opening so that all the flow passes through the screen. The screen was estimated to have an opening of about 2 mm. It was observed that all small bubbles and many large bubbles passed through the screen without coalescing. The screen provided an outward and slightly upward flow through the rectangular opening.

[0158] The baseline (Sample B) included only the particle filter and no degassing device. The particle filter used as the baseline was the K041774 filter available from Donaldson Company, Inc. (Minneapolis, MN).

[0159] Test method. Air was continuously mixed into the hydraulic oil supplied to the tank for 1800 seconds. The oil-air mixture ratio (%) was measured and recorded throughout the test. The schematic of the data collection setup used in Examples 1 and 2 is shown in Figure 4. The maximum air mixture value for each degassing device was determined by averaging the readings of the oil-air mixture ratio (%) from 600 seconds to 1700 seconds. A lower maximum air mixture value indicates that more air was removed, and thus the degassing performance was improved. Samples were tested against a baseline that did not include a commercially available degassing device designated as "Sample A" and a degassing device designated as "Sample B".

[0160] The air mixture measuring device was an AIR-X sensor from Delta Services Industriels (Froyennes, Belgium).

[0161] Example 1 While maintaining the nucleation and growth stages constant, the sample devices were prepared by varying the mesh opening size of the porous barrier. The growth medium was prepared with a 7-layer (rolled) medium. As shown in Table 1 below, the nominal mesh opening sizes of Samples C to F ranged from 20 μm to 125 μm. The degassing devices were tested as described above. The results, including the differential pressure across the degassing devices, are shown in Table 1 and Figures 5A to 5C.

[0162] [Table 1]

[0163] Figure 5A is a data plot of the oil-air mixture (%) results of various samples. The improvement in the maximum average air mixture (%) with respect to the reference line sample B is shown in Figure 5B. It was observed that the smaller the mesh opening size of the porous barrier, the better the degassing results compared to the larger size. The reduction in the maximum average air mixture of sample C was 61%, while that of sample D was 22%, and those of samples E and F were 15%. Furthermore, it was observed that each of samples C to F was superior to the commercially available sample A and the reference line sample B. In Figure 5C, the maximum average air mixture (%) and the differential pressure are compared.

[0164] Example 2 Sample apparatuses C, G, and H were prepared as follows, that is, while maintaining the mesh opening sizes of the nucleation medium and the porous barrier constant, they were prepared with various thicknesses of the growth medium by applying various numbers of layers of the growth medium. As shown in Table 2 below, sample C had a growth medium of the same thickness as in Example 1 (7-layer medium), sample G had a growth medium of half the thickness (3-layer medium), and sample H had no growth medium. The degassing apparatus was tested as described above. The results including the differential pressure across the degassing apparatus are shown in Table 2 and Figures 6A to 6C.

[0165]

Table 2

[0166] Figure 6A is a data plot of the oil-air mixture (%) results of various samples. The improvement in the maximum average air mixture (%) with respect to the reference line sample B is shown in Figure 6B. It was observed that a thicker growth medium resulted in better degassing results. The reduction in the maximum average air mixture of sample C was 61% of the reference line, while sample G achieved a 46% reduction in the maximum average air mixture, and sample H achieved a 27% reduction. Furthermore, it was observed that each of samples C, G, and H was superior to the commercially available sample A and the reference line sample B. In Figure 6C, the maximum average air mixture (%) and the differential pressure are compared.

[0167] Examples 3 to 5 Preparation of Samples. The media hand sheets were manufactured by dispersing fibers in water and then formed in an ADIRONDACK FORMAX 12’’×12’’ stainless steel sheet mold available from Adirondack Machine Corp. (Hudson Falls, NY). Specific details of the furnish are provided in Example 3 below. The media tested was cut to fit the media holder with an effective area of 71 mm 2 and immersed in the test oil and placed in a series media housing.

[0168] The term “basic fiber surface area” is used herein to refer to the surface area of the fibers per unit bulk media surface area.

[0169] Surface Area Analysis. The surface area of the media can be determined by Brunauer-Emmett-Teller (BET) analysis or from the Carmen-Kozeny relationship. Examples 3 and 4 used the Carmen-Kozeny relationship.

[0170] BET Analysis: The basic fiber surface area of the media per m 2 per unit bulk surface area of the media sample can be determined from the following relationship from the surface area per unit mass using ISO 9277 and the dry basis weight of the media determined by ASTM D646: 2 For low surface area materials (e.g., fiber surface area less than 1 m [Number]

[0171] / g), BET measurements are preferably performed using krypton gas. For high surface area materials (e.g., fiber surface area greater than 1 m 2 / g), BET measurements are preferably performed using nitrogen gas. When the basic fiber surface area of only a single layer of the media composite is measured, that layer is removed from the composite and the mass and basis weight of the layer are used in the calculations. 2

[0172] Carmen-Kozeny method: The basic fiber surface area of the medium can be calculated based on the Carmen-Kozeny relational expression, where the pressure drop of the fluid flowing through the solid porous material is calculated based on an equation derived by combining Darcy's law and Poiseuille's law when modeling the flow of fluid through a packed bed of spheres. The general form of the equation is as follows: [Number] This equation can be processed into the following equation: [Number] In the formula, d = nominal diameter of the cylinder constituting the porous structure (sometimes called the nominal fiber diameter size) ΔP = pressure drop across the filled porous bed L = length of the porous bed v = directional velocity of the fluid through the porous bed μ = viscosity of the fluid ε = porosity of the porous bed φ = shape factor of the spherical particles. A shape factor of φ = 1 was used.

[0173] The fibers used in the most typical filter media, including the examples here, have a large aspect ratio of 100 to 1000, so the end surface area can be considered negligible and the surface area of the fiber can be regarded as the surface area of a single long fiber or cylinder. Next, the basic fiber surface area of the medium can be calculated based on the total mass of the filter medium sample and the density of the material. In the case of fibers made of multiple materials, the mass fraction weighted density is used. The identification of the fiber materials and their mass fractions can be determined by methods known to those skilled in the art. The surface area is reported as the basic fiber surface area according to the Carmen-Kozeny method. If the basic fiber surface area is measured for only a single layer of the medium composite, that layer is removed from the composite before testing.

[0174] Test Procedure. To test the performance of the nucleation media, a nucleation test bench was constructed from a tank connected to an air supply source via a series of valves and piping. The air supplied to the tank was controlled by two different pressure control valves to maintain a specific pressure within the tank. The tank was connected to a media test housing that also incorporated a bypass loop. Both the housing tube and the bypass were connected to a CANTYVISION camera, which was then connected to a collection flask positioned on a digital mass scale. Images obtained from the video recording of the CANTYVISION camera were analyzed using CANTYVISION intelligent analysis software to record and analyze the nucleation function of the media sheet under test. The CANTYVISION camera and software are available from JM Canty, Inc. (Buffalo, NY).

[0175] At the start of the test, the tank was filled with approximately 1.5 gallons of test oil. An air flow loop was created through the tank to entrain air into the hydraulic oil by bubbling. The tank pressure was maintained at 25 psi to entrain air into the oil. After entraining air into the oil, excess free air was released from the oil.

[0176] To conduct the nucleation test, air-entrained hydraulic oil from the tank was flowed through the test media while adjusting the tank pressure to drive the flow at the desired experimental superficial velocity as observed by recording data from the scale. The test was run for 7 minutes. The oil flow was imaged at 5 frames per second using a CANTYVISION camera, and the data was processed using CANTYVISION software to calculate the average air volume and average bubble diameter per video frame.

[0177] Image data processing. Image processing was performed using IMAGEJ software (available from the U.S. Dept. of Health and Human Services, National Institutes of Health). The following routine was applied uniformly to all experiments for the last 1000 frames captured per experiment.

[0178] The images were trimmed to areas that exclude experimental artifacts such as the walls of the window and circular objects that are not bubbles, as necessary. The images were converted to 8-bit grayscale images. The "Otsu" automatic thresholding algorithm (described in Otsu, N., A Threshold Selection Method from Gray-Level Histograms, 9 IEEE Transactions on Systems, Man, and Cybernetics 62 (1979)) was applied to convert the images to black-and-white images, where black is set as the background color. The contours of the un-filled objects in the images were filled using the "fill holes" routine, and then the "watershed" routine (described in Soille, P. and Vincent, L., "Determining Watersheds in Digital Pictures via Flooding Simulations", 1360 Proc. SPIE 240 (1990)) was applied to detect and split overlapping objects. Next, using these processed images, bubbles with an area of at least 1203 μm 2 , roundness (defined as 4 * area / [π * major_axis 2 ) of 0.95 were counted. The volume of the bubbles was estimated from the ferret diameter of the bubbles. The ferret diameter is defined as the longest distance between any two points along the selected boundary (also known as the maximum caliper). In the nucleation stage, the term "bubble diameter" refers to the ferret diameter.

[0179] Aperture measurement. The aperture of the medium can be measured using an automated air permeability porometer, such as those manufactured by Porous Materials, Inc. (Ithaca, NY). In these examples, the model number APP-1200-AEXSC of the porous material was used with CAPWIN software. The test type was capillary flow porometry, dry-up / wet-up, the test liquid was a silicone liquid with a fluid surface tension of 20.1 dynes / cm, and the effective test size of the sample was 1 cm in diameter.

[0180] Example 3 Various nucleation medium samples were tested in a monolayer configuration. The medium samples were prepared from micro glass fiber and sheath / core two-component polyester according to Table 3 below. The two-component polyester fiber was ADVANSA 271P available from Advansa GmbH, Germany, with a nominal average diameter of 14 μm and a nominal average length of 6 mm. Various drying techniques including an oven and a sheet dryer and compression were used to create various thicknesses and solid fractions in the samples. The air flow oven is known to create a structure with a lower solid fraction than the sheet dryer.

[0181] [Table 3]

[0182] The characteristics of the media tested are shown in Table 4.

[0183] [Table 4]

[0184] The average air volume per frame (proportional to the total air released) and the average bubble diameter were determined as functions of the average pore diameter, the basic fiber surface area, the solids fraction of the media measured at 1.5 psi, and the thickness of the media. The basic fiber surface area was determined by the Carmen-Kozeny method. The parameters showing trends are shown in the figures. Data comparing the average air volume per frame with the average pore diameter, the total nucleation surface area, the solids fraction of the media measured at 1.5 psi, and the thickness of the media are shown in FIGS. 7A-7D. Data comparing the average bubble diameter with the average pore diameter, the basic fiber surface area, the solids fraction of the media measured at 1.5 psi, and the thickness of the media are shown in FIGS. 8A-8D.

[0185] ANOVA analysis was performed to determine the most important regressors for the average air volume per frame. Based on this analysis, more air is released as the basic fiber surface area increases and the average pore diameter decreases. A similar ANOVA analysis was performed to determine the most important regressors for the average bubble diameter. Based on this analysis, the average bubble diameter increases as the average pore diameter increases. The average bubble diameter decreases as the basic fiber surface area increases.

[0186] Example 4 In another example, media samples from Example 3 were stacked into a multi-layer media sample. The media properties of the media samples used for layering are shown in Table 5. The multi-layer media sample included 1 to 8 media samples.

[0187] [Table 5]

[0188] The average air volume per frame (proportional to the total air released) and the average bubble diameter were determined as functions of the number of layers. The average air volume per frame as a function of the number of layers is shown in FIG. 9A. The average bubble size as a function of the number of layers is shown in FIG. 9B. First, it was observed that as the number of layers increased, the average air volume per frame increased and the average bubble size decreased. As the number of layers increases, the average air volume per frame levels off, but the average bubble size continues to decrease.

[0189] Example 5 In another example, the media hand sheet was produced by a wet laid process by dispersing 200 mg of sheath / core bicomponent polyester fibers (ADVANSA 271P) with a nominal average diameter of 14 μm and a nominal average length of 6 mm in water, and then formed on a circular stainless steel sheet mold with a diameter of 90 mm. The dried media hand sheet patch was fused at 115 °C.

[0190] Samples of the media hand sheet were coated to be oleophobic. The oleophobic coating was applied by manually dipping a screen sample into a 5% aqueous solution of DAIKIN UNIDYNE TG-5502 obtained from Daikin America Inc. (Orangeburg, NY). The samples were dried in an oven at 120 °C for 10 minutes. The oleophobic-treated media had an oleophobic rating of at least 6 when tested by the AATCC method 118.

[0191] The nucleation performance of the oleophobic-coated media was compared with that of the uncoated media as in Examples 3 and 4. The average air generation rate was calculated by summing the volumes of all individual bubbles during the experiment and dividing by the length of the experiment in seconds.

[0192] The results are shown in Table 6. It was observed that the oleophobic treatment increased the air generation rate and the total released air. After the oleophobic treatment, the average bubble diameter decreased.

[0193] [Table 6]

[0194] Example 6 Various aspects of the growth layer were tested in Example 6.

[0195] Preparation of Samples. The media handsheets were manufactured by dispersing fibers in water and then formed in an ADIRONDACK FORMAX 12’’×12’’ stainless steel sheet mold available from Adirondack Machine Corp. (Hudson Falls, NY). Specific details of the finished materials are shown in Table 7 below. The media tested were cut to fit the media holder with an effective area of 12.9 cm 2 and placed in a series media housing.

[0196] Test Procedure. To test the performance of the growth media, a test bench was constructed and used to challenge media samples containing small bubbles (nominal average diameter 600 μm) in oil and monitor the ability of the media to grow the bubbles. The bench was constructed so that the size and number of bubbles could be monitored both upstream and downstream of the test media sample.

[0197] The test bench included an oil storage tank, a gear pump to regulate the flow of oil from the tank, a pressure gauge, and lines connecting the oil storage tank to the test cell. A flow meter placed in the line was used to determine the superficial velocity of the oil in the media within the test cell. A bubble injection fitting was attached in series immediately before the test cell. Air injection was controlled by a series of flow meters and pressure regulators to create a consistent bubble challenge upstream of the test media. The test cell was constructed of clear acrylic so that images could be captured on both the upstream and downstream sides of the test media. A return line led back from the test cell to the oil storage tank. A Nikon D90 camera was attached to a vertical slide rail and used to capture image sequences on both the upstream and downstream sides of the test media.

[0198] To conduct the test, first the flow of oil was started and when the oil filled the test cell, the bubble injector was turned on. After reaching a steady state, a series of images were captured on both the upstream and downstream sides of the test media. After a while, the image capture was repeated.

[0199] Image data processing. The images were processed in the same manner as in Examples 3 and 4 (nucleation stage) over all experiments (20 frames per experiment) until the application of the "watershed" routine. Next, the processed images were used to count bubbles with an area of at least 10,000 μm 2 (23.42 μm / pixel) and a circularity (defined as 4π * area / perimeter 2 ) of 0.5. The volume of the bubbles was calculated from the bubble area using the following conditions: When the Feret diameter of the bubble is greater than 3 mm, the diameter is estimated from the bubble area as follows: Volume = π / (7.5 * 10 8 ) * ([area] / π) (3 / 2)

[0200] Otherwise, when the Feret diameter is 3 mm or less, the diameter is considered the Feret diameter, and the volume of the bubble is calculated as a typical sphere.

[0201] The difference in the calculation method is due to the fact that visual inspection of bubbles larger than about 3 mm suggests that these large bubbles are actually clusters of bubbles, thus giving an artificially large volume when calculated by the Feret diameter.

[0202] Data analysis. The performance was evaluated using the growth performance parameter D50. D50 is defined as the median of the calculated bubble volumes, i.e., 50% of the number of bubbles is below this size.

Number

[0203] When the performance increase rate of D50 is 0%, it is interpreted that there is no improvement in performance. Less than 0% is interpreted as insufficient performance of bubble growth, and more than 0% is interpreted as an improvement in bubble growth.

[0204] Tests and Results. To evaluate the influence of the media structure, various growth media samples were tested. The media samples were composites of rayon and a sheath / core bicomponent polyester fiber (ADVANSA 271P) with a nominal mean diameter of 14 μm and a nominal mean length of 6 mm. The design variables of the finished materials are shown in Table 7 and were mixed to create various media samples. The parameters of the finished materials were changed to target various media characteristics shown in Table 8.

[0205]

Table 7

[0206]

Table 8

[0207] The increase rate of D50 was determined as a function of the solids content of the media, the thickness of the media, and the fiber size. The results are shown in FIGS. 10A - 10B respectively.

[0208] Note that the solids content and the thickness are not independent of each other. To prepare a media with a higher solids content, the media was compressed, thereby reducing the thickness. It may be difficult to distinguish the effects caused by the solids content and the thickness. However, it was observed that a decrease in the solids content with an increase in thickness resulted in better growth performance.

[0209] It was observed that benefits in growth performance were obtained at thicknesses greater than 1 mm. Furthermore, it was observed that benefits in growth performance were obtained at solids contents less than 7.5%, especially less than 9%.

[0210] Example 7 Various aspects of the woven stainless - steel screen and other variables were tested in Example 7 for the porous barrier stage. Such aspects included the size of the openings, the chemical nature of the surface, the superficial velocity, and the size of the bubbles reaching the upstream porous barrier.

[0211] Preparation of samples. Various screens were obtained from commercial sources. The screen samples were cut to fit the media holder with an effective area of 12.9 cm 2 . The screen samples were placed in a series test cell.

[0212] Test procedure. The test procedure was the same as in Example 6 above.

[0213] Image data processing. Image processing was performed as in Examples 3 - 5 above. The volume of the bubbles was estimated from the Feret diameter of the bubbles. The Feret diameter is referred to as the "bubble diameter" in this document with respect to the screen barrier stage.

[0214] Data analysis. The performance of the screen was calculated as follows:

Number

[0215] The performance of the screen is the percent difference in the average of the 10 largest bubbles downstream compared to the average of the 10 largest bubbles upstream for each test.

[0216] A performance of 0% is interpreted as no change in the bubble volume across the screen. Less than 0% is interpreted as insufficient performance, greater than 0% but less than 100% is interpreted as a moderate increase in size, greater than 100% but less than 250% is interpreted as a significant improvement in size, and greater than 250% is interpreted as a major improvement in size.

[0217] Tests and results. The screen was a stainless - steel plain - weave screen. With the application of the oleophobic treatment, various screens with various characteristics as shown in Table 9 below were tested. The screens were obtained from McMaster - Carr (Elmhurst, Illinois).

[0218]

Table 9

[0219] Screen samples were run at different surface velocities of 0.5 cm / sec, 1.25 cm / sec, and 5.0 cm / sec to test the effect of surface velocity on screen performance.

[0220] Bubble challenges were classified as either "coarse" with an average nominal Feret diameter of 550 μm or "fine" with an average nominal Feret diameter of 350 μm. Air flow was adjusted to account for changes in surface velocity to maintain similar upstream bubble challenge sizes.

[0221] The results of the tests are shown in Figure 11A. Generally, it was observed that as the surface velocity increased, the performance of the screen decreased.

[0222] The effect of oleophobic surface treatment on screen performance was also tested. The screens were treated with trichloro(1H,1H,2H,2H-perfluorooctyl)silane (available from Millipore Sigma (St. Louis, MO)) using chemical vapor deposition. Briefly, the screens were placed under vacuum for at least 10 minutes and the treatment chemical was applied to the screens in the form of a vapor. After treatment, the oleophobicity of the samples was tested by the AATC118 method. All treated samples had an oleophobicity rating of at least 6.

[0223] The results of the tests are shown in Figure 11B. It was observed that at lower surface velocities of 0.5 cm / sec and with oleophobic treatment, screen performance was improved, particularly with regard to fine bubbles.

[0224] All references and publications cited in this specification are hereby expressly incorporated by reference in their entirety, except where they may directly conflict with the present disclosure. Although specific embodiments have been illustrated and described herein, those skilled in the art will understand that various alternatives and / or equivalent implementations may be substituted for the specific embodiments illustrated and described without departing from the scope of the present disclosure. It is not intended that the present disclosure be overly limited by the exemplary embodiments and examples described herein, and such examples and embodiments are presented merely as examples, and it is to be understood that the scope of the present disclosure is intended to be limited only by the claims set forth herein.

Claims

1. A degassing device comprising: A gas nucleation medium configured to induce nucleation of gas in a fluid to form gas cavities, having a basic fiber surface area of at least 10 m² / m² when measured by the Carman-Kozeny method and an average pore diameter of 30 µm or less when measured by ASTM F316; A growth medium adjacent to and downstream of the gas nucleation medium, having a solids fraction of 20% or more at 1.5 psi and capable of inducing aggregation or growth of gas cavities, or both aggregation and growth of gas cavities; A porous barrier adjacent to and downstream of the growth medium; The degassing device comprising the above components.

2. The degassing device according to claim 1, further comprising a gap between the growth medium and the porous barrier.

3. The degassing device according to claim 1 or 2, wherein the gas nucleation medium comprises a hydrophobic material having an oil contact angle of at least 30° and a hydrophobicity evaluation of 1 or more when measured by AATCC method 118.

4. The degassing device according to any one of claims 1 to 3, wherein the porous barrier comprises openings with a size of 250 µm or less.

5. The degassing device according to any one of claims 1 to 4, wherein the gas nucleation medium comprises cellulose, regenerated cellulose, polyamide, polyester, polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), glass, ceramic, carbon fiber, or a combination thereof.

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