Abstract:
According to one aspect of the invention, a coalescer cartridge for separating a first fluid from a second fluid includes a pleated filter media portion including a pleated fluid separation layer configured to separate a first fluid from a second fluid, the first fluid forming relatively small droplets of fluid suspended in the second fluid; and a wrap filter media portion downstream of the pleated media portion including a droplet growth layer configured to coalesce the relatively small droplets of the first fluid into relatively larger droplets of the first fluid.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/878,946 filed Sep. 17, 2013, which is hereby incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates generally to filtration, and more particularly to a high flow coalescer for use with hydrocarbon fuels. 
       BACKGROUND 
       [0003]    Coalescer cartridges are employed as the first stage in filter/separator vessels for hydrocarbon fluids. Coalescers filter-out particulate contaminants and coalesce (combine) highly dispersed, emulsified water particles into larger water drops. 
         [0004]    Tiny droplets of water in the fuel contact and adhere to strands of a filter (for example, fiberglass). Flow pushes the droplets along the strand until they reach an intersection of strands where they combine with other droplets (coalesce) into large drops. 
         [0005]    These large drops are then carried to the outside surface of the cartridge in a conventional inside-out flow arrangement, although outside-in flow arrangements are also possible. Having a higher specific gravity than the hydrocarbon fluid, the water droplets release and settle to the bottom of the vessel containing the filtration media. The larger the drops, the faster and more efficiently they fall out. 
         [0006]    The largest single application of a fuel coalescer is the filtration of aviation jet fuel, however they are also used with other types of fuels, process streams in refineries and petrochemical plants, and condensate streams where natural gas is produced. 
         [0007]    Other liquids can be separated if they are immiscible, the specific gravities differ, and high concentrations of surface active agents are not present. As a rule of thumb, if a sample of the mixture readily separates in an hour or two, a coalescer can probably be used. If the mixture hasn&#39;t separated after 24 hours, coalescing probably will not work. 
         [0008]    In conventional coalescers, combination fiberglass and pleated media coalescers remove particles primarily in the high surface area pleated core. They typically contain 6-8 layers of pleated media inside a cylinder of molded fiberglass laminations to provide an extended surface area for particulate filtration. Pleat corrugation and separation materials are used to keep pleats open for full utilization. The outer wrap layers are used for water separation and growth of water droplets. Conventional coalescers can achieve flow rates of about 2.5 gallons per minute per square inch. In a 1000 gpm system, this requires a 400 square-inch coalescer. 
       SUMMARY OF INVENTION 
       [0009]    Exemplary embodiments provide for a significantly higher flow rate—about 6.6 gallons per minute (gpm) per square inch. In a 1000 gpm system, the coalescer requires less than about 150 square inches, resulting in a filter about one-half the size of conventional filters. The reduced size and weight of the coalescer (and the associated housing) creates clear advantages, especially in the aerospace industry. 
         [0010]    To achieve these higher flow rates, exemplary coalescers include a first layer of pleated filter media used to capture particulates and a second co-pleated layer of pleated filter media to separate water. The wrap layers can then be dedicated to water droplet growth in order to speed flow rates. Exemplary wrap layers may include about three layers of needle polyester wrap with large fiber diameters. 
         [0011]    According to one aspect of the invention, a coalescer cartridge for separating a first fluid from a second fluid includes a pleated filter media portion including a pleated fluid separation layer configured to separate a first fluid from a second fluid, the first fluid forming relatively small droplets of fluid suspended in the second fluid; and a wrap filter media portion downstream of the pleated media portion including a droplet growth layer configured to coalesce the relatively small droplets of the first fluid into relatively larger droplets of the first fluid. 
         [0012]    Optionally, the pleated media portion includes two layers of co-pleated material. 
         [0013]    Optionally, the pleated filter media portion includes a solids retention layer configured to filter particulate matter from the first and second fluid. 
         [0014]    Optionally, the pleated filter media portion includes a cellulose or glass filter media. 
         [0015]    Optionally, the fluid separation layer includes an open structure relative to the dense structure of the solids retention layer. 
         [0016]    Optionally, the wrap filter media portion includes first, second, and third droplet growth layers. 
         [0017]    Optionally, a first droplet growth layer is upstream of a second droplet growth layer and includes a fine distribution of fibers relative to the second droplet growth layer having a coarse distribution of fibers relative to the first droplet growth layer. 
         [0018]    Optionally, the wrap filter media portion includes a needle polyester wrap. 
         [0019]    Optionally, the wrap filter media portion includes fibers having a diameter greater than a diameter of fibers in the pleated filter media portion. 
         [0020]    Optionally, the coalescer cartridge further includes a first endcap having a fluid inlet in fluid communication with a central chamber of the pleated filter media portion defined by an inner layer of filter media. 
         [0021]    Optionally, the coalescer cartridge further includes a second endcap closing an end of the central chamber of the pleated filter media portion defined by an inner layer of filter media. 
         [0022]    Optionally, the first endcap includes an internal gasket for sealing against a fluid port when installed in a filtration assembly. 
         [0023]    Optionally, the first fluid is water. 
         [0024]    Optionally, the second fluid is jet fuel. 
         [0025]    Optionally, the second fluid is diesel fuel. 
         [0026]    According to another aspect of the invention, a method of filtering a primary fluid with a coalescer includes the steps of filtering particles from the primary fluid by passing a fluid mixture through a pleated filter media portion of the coalescer; separating a secondary fluid from the primary fluid by passing the fluid mixture through a pleated fluid separation layer of the pleated filter media portion of the coalescer, thereby forming relatively small droplets of the secondary fluid; and growing the relatively small droplets of the secondary fluid into relatively large droplets of the secondary fluid by passing the mixture through a wrap filter media portion downstream of the pleated media portion and thereby coalescing the relatively small droplets into relatively large droplets. 
         [0027]    Optionally, the method further includes the step of releasing and settling the relatively large droplets into a vessel containing the filter media. 
         [0028]    The foregoing and other features of the invention are hereinafter described in greater detail with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a perspective view of an exemplary coalescer cartridge wherein successive layers of filter media are partially broken away to illustrate the interior structure of the cartridge; 
           [0030]      FIG. 2  is a cross-sectional schematic view of the exemplary coalescer cartridge; 
           [0031]      FIG. 3  is a side elevation view of an exemplary coalescer cartridge wherein successive layers of filter media are partially broken away to illustrate the interior structure of the cartridge; 
           [0032]      FIG. 4  is a partial cross-sectional view of a pleated media portion showing exemplary pleated media portion layers; and 
           [0033]      FIG. 5  is a partial cross-sectional view of a wrap media portion showing exemplary wrap media portion layers. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    As mentioned, coalescers have two primary functions, solids retention and water removal. Conventional coalescers include a pleated section and a wrap section. Conventionally, the primary purpose of the pleated section was for the removal of solid particulate, which was accomplished by a thin dense microglass or cellulose media for solids retention. The wrapped section, downstream of the pleated section, was used solely for the separation of fuel from water to begin the coalescing process and growth of water droplets. The maximum flow rate achieved by a coalescer is driven by the total surface area of the pleated section. Maximum water removal efficiency is achieved via matching the right glass fiber diameters and number of layers of same for separation and coalescing/growth of water droplets. Another important factor for completeness of coalescence is dwell time of the fuel in the fiber matrix. Limitations of flow and effective coalescence are directly related to surface area of the pleated section and dwell time in the fiber matrix. 
         [0035]    Exemplary coalescers have much higher flow rates than these conventional coalescers and include a co-pleated, more open fiber matrix (than the primary filtration media) water-separation media that is positioned downstream of the primary filtration media. The primary function of this water-separation media is to begin the water coalescing process by separating the water from the fuel. Therefore, in exemplary coalescers, the pleated filtration media is both an efficient solids retainer and a water separator. This co-pleated material is a far less dense (than conventional pleated section) filtration material that begins the coalescing process by separation of the primary phase, (fuel) from the secondary phase, (free water), before the flow reaches the wrap section. Exemplary media include the use of a very lofty air filtration media (e.g., an open-structured cellulose or glass). Because the pleated section has 5-10× the surface area of the wrap section, this secondary coalescing pleated material is very effective at beginning the water separation. 
         [0036]    As previously mentioned, conventionally, the wrap section alone performed the separation and growth process. The advantage of exemplary configurations is a significant increase in the amount of water droplet growth media thereby greatly enhancing the quality of the coalescence even in the presence of problematic low interfacial tension fuel. The wrap section now has one primary role and that is to achieve droplet growth, where previously, in conventional coalescer designs, it was tasked with separation and growth of water droplets. 
         [0037]    Referring first to  FIGS. 1 and 2 , shown is an exemplary coalescer cartridge  100 . The coalescer cartridge  100  includes a generally cylindrical coalescer media  110  that extends along a longitudinal axis  112  and has an inner diameter  114  and an outer diameter  116 . The inner diameter defines a central chamber  118  into which fuel flows before passing through the media  110 . The media  110  is sealingly secured (for example, by adhesive) to and extends from a first end cap  120  to a second end cap  130  to which the media  110  is also sealingly secured. 
         [0038]    Exemplary cartridges may be any appropriate size, but are preferably about 6 inches in diameter and range from approximately 14 inches long (11 inches of media) to approximately 56 inches long (53 inches of media) resulting in outer surface areas of about 65-320 square inches. 
         [0039]    The first end cap  120  may be generally ring-shaped and include a port  122  opening onto the central chamber  118  of the media. The port  122  may be configured to attach to a filtration assembly (filter head) of the vehicle or other assembly for which the coalescer cartridge is made to be installed in. The port may include one or more seal members  124  such as a gasket for sealing the cartridge  100  to the filtration assembly. Optionally, the end cap  120  may include internal or external threads (for example, in the port  122 ) for attaching the cartridge to the filtration assembly, although other attachment may be used. 
         [0040]    The second end cap  130  may close off the central chamber  118  of the media, and may be generally disk-shaped. The end cap  130  may include a fixing element  132  to fix the cartridge  100  to a structure, for example by a spider bolt. 
         [0041]    Referring now to  FIG. 3 , the coalescer cartridge  100  is shown with layers of the media  110  stripped away to show more detail. Shown as an inner most section in  FIG. 3  is a pleated filter media portion  140  (pleated portion). Radially outward of the pleated portion  140  are, successively, a perforated center tube  170 , a wrap filter media portion  180 , polyester batting  190 , and an outer sock  195 . 
         [0042]    The pleated portion  140  is shown in cross-section in  FIG. 4 , revealing the layers of the pleated portion  140 . The pleated portion may be either normally pleated or M-pleated, but is preferably normally pleated as shown. Although the number of pleats in the pleated portion  140  may be any amount, depending on the application, exemplary portions  140  include approximately 60 pleats. Similarly, pleat height may vary depending on the application, but exemplary height is preferably about 1 inch, and is more preferably about 0.9375 inches. 
         [0043]    Optionally, the pleated portion  140  includes an epoxy coated screen mesh  141  as a radially innermost layer. This screen  141  may provide very coarse filtering but mainly acts to provide structural rigidity to the media  110 . Additionally or alternatively, the pleated portion  140  may include an epoxy coated screen  142  as a radially outermost layer. Again, this screen  142  mainly provides structural integrity to the media  110 . 
         [0044]    The pleated portion  140  includes a solids-retention portion  150  and a water separation portion  160  downstream (in this case, radially outward) of the solids-retention portion  150 . The solids-retention portion  150  is configured to filter out particulate matter from the fluid passing through the coalescer cartridge  100 . The water separation portion  160  is configured to begin the coalescing process by separating water from the fuel in the fluid passing through the coalescer cartridge  100 . 
         [0045]    The solids-retention portion  150  includes a micro-glass solids retention layer  152 . The micro-glass layer  152  is preferably a non-woven glass. Optionally, the layer  152  has a fiber diameter of between about 0.5 and 2 microns. Optionally, the fiber diameter is between 1 and 2 microns. Preferably, the micro-glass layer  152  is a denser media layer than the fiberglass layer  162  described below. 
         [0046]    Upstream (in this case radially inside) of the micro-glass layer  152  may be a spun-bonded polyester layer  154 . This polyester layer  154  is primarily used to filter larger particulates before reaching the micro-glass layer  152 . 
         [0047]    The water separation portion  160  includes a fiberglass layer  162  for beginning separation of the water from the fuel passing through the cartridge  100 . Preferably, the fiberglass layer  162  is AFS-3 fiberglass(fiberglass with cured phenolic binder). Preferably, the fiberglass layer  162  is a non-woven glass. Optionally, the fiberglass layer  162  has a fiber diameter of between about 0.5 and 2 microns. Optionally, the fiber diameter is between 1 and 2 microns. Preferably, the fiberglass layer  162  includes a more open structure than the micro-glass solids retention layer  152 . 
         [0048]    Optionally, downstream (in this case, radially outward) of the fiber glass layer  162  is a layer of spun bonded polyester  164 . This polyester layer  164  is primarily used to further separate the water from the fuel. Some water droplet growth may begin in this layer. 
         [0049]    Referring now to  FIG. 5 , an exemplary wrap filter media portion  180  (wrap portion) is shown in cross-section. The wrap portion may include one, two, three, or more layers. Preferably the wrap portion  180  includes two or three layers. Preferably, the wrap portion  180  includes one or two droplet growth layers  182  and  184  at the upstream side (radially inward in this case) of the wrap portion  180 . The one or two droplet growth layers are fine relative to the downstream (radially outward in this case) droplet growth layer  186 . For example, the fine layer(s) may be made of fibers having a diameter of between about 0.5 and 2 microns. Optionally, a first fine layer  182  has a fiber diameter of about 0.5 microns. Optionally, a second fine layer  184  has a fiber diameter of about 1-2 microns. Optionally, the downstream droplet growth layer  186  (considered coarse relative to the fine layers) includes fibers having a diameter of approximately 50 microns. 
         [0050]    These wrap layers  182 ,  184 ,  186  are preferably AFS-3 fiberglass, although other types are possible. Preferably, the wrap layers  182 ,  184 ,  186  are cured fiberglass which, although typically more expensive, has been found to improve droplet growth performance. 
         [0051]    Preferably, at least one, and more preferably all, of the fiberglass wrap layers are hydrophilic as contrasted with conventional hydrophobic wraps such as a polyester wrap. 
         [0052]    Preferably, at least one, and more preferably all, of the fiberglass wrap layers are fully wettable, as contrasted with conventional non-fully wettable wraps such as a polyester wrap. 
         [0053]    Preferably, at least one, and more preferably all, of the fiberglass wrap layers are nonwoven as contrasted with conventional precisely woven wraps. The nonwoven nature of exemplary wraps has been found to aid in droplet growth efficiency. 
         [0054]    Referring back to  FIG. 3 , between the pleated portion  140  and the wrap portion  180  may be a perforated center tube  170 . The center tube  170  is used to add rigidity to the cartridge, keeping the cartridge from bending and ensuring proper spacing between the end caps. The center tube  170  may be made of any appropriate material known in the art. The center tube  170  is perforated to allow flow from the pleated portion  140  to the wrap portion  180 . 
         [0055]    Downstream (radially outward in this case) of the wrap portion  180  is a polyester batting  190  layer. Optionally, the polyester batting is a coarser medium than the coarse layer  186  of the wrap portion  180 , and is configured to further grow the water droplets. 
         [0056]    Downstream of the polyester batting  190  layer is an outer sock  195 . Preferably the outer sock is made of woven cotton and is configured to protect the polyester batting during handling of the cartridge before installation and to further grow water droplets and to release the water droplets from the coalescer cartridge outer surface. The outer sock preferably has even larger fiber diameters (coarser) than the polyester batting  190 . Optionally, the outer sock may be treated to mitigate microbial growth. 
         [0057]    Exemplary coalescers increase flow rate 2-3 times verses conventional products. This increased flow rate through the coalescer allows for increased flow rates on vessel or to provide the same flow rate on smaller filter vessels. 
         [0058]    Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.