FR2699420A1 - Process for separating an immiscible liquid / liquid mixture and system for its implementation - Google Patents

Abstract

The present invention relates to a method and to a system for separating a first liquid from a second liquid in which the first liquid is partially or totally immiscible. The system includes a housing (12), a fluid inlet (14) in said housing (12), a first liquid outlet (24) in said housing (12), a second liquid outlet (34) in said housing ( 12) at least one coalescing assembly for coalescing said first liquid and at least one separating assembly for separating drops of said first liquid from said second liquid, said coalescing and separating assemblies being disposed in superimposed relationship in said housing (12). This system and this separation method find application in particular in all systems for purifying an immiscible liquid / liquid mixture. In particular, they find application in the purification of an organic fuel containing drops of water.

Description

The present invention relates to a method for separating small

  quantities of a first liquid which are immiscible but suspended in a second liquid and a system used for this purpose More particularly, the present invention relates to a method for separating and removing a discontinuous liquid phase of a continuous liquid phase and a coalescence / separation system

used for that.

  Many industrial processes and apparatus, as well as household devices, relate to the separation of a liquid phase from another phase. In some cases, particularly when water is the phase present in minor amounts, chemical means can be used. These means for removing moisture, however, require the replacement and / or regeneration of the reagents used in the process. The reagents employed and the products formed frequently introduce complications in the handling and rejection Due to the concomitant cost and, in some cases, inconvenience associated with such processes, physical methods and devices have been preferred to chemical means for removing small amounts of a phase

liquid of other phases.

  A method for coalescing an immiscible liquid suspended in another phase and a coalescing device, frequently called a "coalescer", have found widespread use in the removal of a liquid from both a gaseous phase, such as aerosols, and a suspension of a liquid in another liquid. Such devices are particularly effective when the volume of liquid is decreased and small in size.

  compared to the volume of the phase from which it is eliminated.

  Typically, the equipment needed to remove a liquid aerosol from a gas tends to be less complicated than that used to separate two liquid phases in which a first liquid phase is immiscible and suspended in a second liquid phase. This is generally true because in air / liquid suspensions, gravitational effects tend to be more significant while surface energy, surface tension or interfacial tension effects tend to be less significant than with liquid / liquid suspensions. The spectrum of indications or coalescers has been used to remove minor amounts of a first liquid phase, known as a "discontinuous phase" or "suspended phase", from a second liquid phase in which it is suspended, known as the "liquid phase". Continuous phase "or" suspending phase "covers a considerable range of situations. For example, coalescers have been used most often to remove or separate small amounts of moisture from petroleum fuels, including gasoline, fuels for diesel and aviation, such as kerosene; to remove moisture from the cleaning fluid; to separate cooling oil and parts cleaners; to eliminate oil contamination found in the natural bodies of water; to separate immiscible solvent systems used in extraction processes, etc. Many mechanisms and models have been proposed to describe the coalescence of a drop of the discontinuous phase of the continuous phase and the ease or difficulty of separation of immiscible phases Factors that affect the coalescence process include the physical properties of the phases, such as density, viscosity, surface tension, and interfacial tension (IFT). In addition, the properties of the system, such as the size drop, interface curvature, temperature, concentration gradients, and vibrations also significantly affect coalescence. Although some or all of these factors may be significant in a particular situation, properties such as density drop size and interfacial tension appear to be among the most ignificatives and often over which the least control can be exercised in difficult separations of immiscible liquids Thus, all other things being equal, where the densities of two liquids differ only slightly, the separation becomes more difficult This is also true for the interfacial tensions of the liquids involved In these situations in which the drops are larger than 10 (primary emulsions) coalescence and separation are much easier to perform frequently with the discontinuous phase settling by gravity after coalescence to form a heterogeneous layer When the drops are less than 10 p, especially less than 1 in diameter, secondary emulsions or secondary mists result from the fact that the discontinuous phase is much more difficult to coalesce The latter occurs frequently when the emulsion is to be formed by stirring vigoureu If an emulsification to form the secondary mist occurs purely by mechanical means, coalescence can be accomplished much more easily

  by conventional coalescence methods and apparatus.

  When the secondary mist results from surface active materials, which influence the interfacial tensions of

  liquids, separation becomes more difficult.

  The type of coalescer used depends on the difficulty of separation or coalescence, as influenced by the factors identified above. Thus, in some situations, the equipment can be very simple, such as that employing baffles, and goes up to More complex devices, containing different types of packings The type of fluid to be separated frequently determines the packing used Thus, both the shape of the packing material and its composition influence the efficiency of coalescence and separation For example, Coalescing apparatus used to separate an oil and water typically contains tubes, plates, discs, rods, rods, fibers or other internal structures designed to trap the oil Conventionally, the glass has was the most commonly used packing material and although in some cases membranes were used in the coalescers, although ssages listed above,

  fibers have been the preferred form of packing.

  Currently, glass fibers seem to have found the most common application in coalescers. In recent years, both industrial and household requirements have led to a demand for purer liquids, including drinking water, solvents, liquids used in industrial processes, and fuels. more stringent requirements for such materials, the requirements have increased in relation to the efficiency and capacity of the equipment used to purify these liquids Manufacturers of such equipment have also endeavored to give a longer life and longer periods of time. longer intervals between maintenance, regeneration or replacement of components In the field of liquid / liquid separation, coalescers are often expected to have a filtration function to remove particulate matter, in addition to the function

  primary coalescence of a discontinuous phase.

  A typical, conventional separation apparatus

  coalescence is illustrated in Figure 1 The coalescence unit 10

  separator includes a housing 12 having a divided base An inlet 14 is provided for introducing a contaminated liquid through the housing, the liquid then passing through an inlet chamber 16 and thereafter through an inlet 18 of the coalescer into a cartridge 20 After passing in an inner / outer flow direction through a suitable packing which defines the walls 22 of the coalescer cartridge, the fluid passes into the housing body and thereafter through the walls 32 of the cartridge 30 of the coalescer. separator in an outer-inner flow path The outer surfaces of the walls of the separator are provided with a material having a surface energy such that due to the surface tensions of the continuous and discontinuous phases, the liquid forming the continuous phase may pass through the walls of the separator and into the separator body while the liquid that is immiscible with it is In fact, the liquid forming the discontinuous phase, which is coalesced into wider drops by the coalescer, is pushed into the vicinity of the wall 32 of the separator. The continuous phase which enters the cartridge 30 of the separator, through the wall 32 of the separator, thereafter passes through the outlet 28 of the separator into the outlet chamber 26 and finally exits through the outlet 24 of the housing Coalesced drops of liquid originally in the discontinuous phase flow to the bottom or base 36 of the housing unit, located above the inlet chamber 16 and the outlet chamber 26, and leaves the phase

  discontinuous by the outlet or drain 34.

  In some industries, requests for increased capacities resulted in increased size of coalescer units. Figure 2 shows a plan view

  from the inside of a conventional coalescence

  Separation to be expected to provide a larger scale capability for the separation of a discontinuous phase As can be noted, while the apparatus includes only two separator elements, many coalescer units are provided. inlet 14 of housing 12 where it then flows, by separate paths, into the inlets (not shown) of the different coalescer units and thereafter through the lining of each coalescer unit 20 in the housing. in the housing section containing the separator elements 30 where the fluid, largely separated from the liquid of the discontinuous phase, passes through the walls 32 of the separator units, into the body of the separator units, thereafter passing through the outlet of the separator unit. each of the separator units and exiting through the outlet 24 of the housing While the capacity of the apparatus shown in Fig. 2 has been increased relative to the type illustrated in FIG. 1, such an arrangement results in a non-uniform flow distribution. That is, a fluid flow or a velocity gradient exists between the different regions in the housing. arrangement shown in Figure 2, the gradient exists as a side-by-side gradient in which the row of coalescer units closest to the separators treats more fluid than does the remaining units of the coalescer At the same time, the units of the separator have a non-uniform flow distribution around their circumference due to their

  proximity with coalescer units.

  As stated above, secondary emulsions or mists present one of the most difficult separation problems where physical methods are used exclusively to separate and eliminate the discontinuous phase

  or scattered While coalescer-

  separator have been used with varying degrees of success to purify the continuous phase in such applications, the method and the apparatus are accompanied by various weak points Firstly, it is difficult to obtain 100% coalescence and elimination of the discontinuous phase simply because of the very small size of the dispersed phase, which itself may be partly caused

  by the presence of a surface active substance.

  Secondly, in those situations in which a surface active material is present, which is a common situation, the surface tension change attributable to the surface active substances makes coalescence difficult, unless these surface active substances are removed before Coalescence treatment Third, after a period of use, the surface active substances found in many of these chemically induced emulsions are believed to coat the active surfaces of the coalescer lining, which is commonly most commonly made of glass fibers, "disarming" In this way coalescer-separator devices do not provide the desired degree of purity of liquids containing such surface active substances and / or require the frequent change of

coalescer elements.

  This type of problem is encountered much more frequently in industries related to fuels. Oil-based fuels tend to take moisture,

  especially during storage.

  coalescer-separator have been conventionally used to remove entrained water from such fuels In recent years, however, additives, especially surfactants, have been used in increasing amounts in such fuels Therefore, to achieve the same minimum concentrations of moisture, treatments to remove moisture after mixing, transport and storage of such fuels required more frequent changes of coalescing units Although the inclusion of phenolic or acrylic resins that act primarily as binding agents for Fiberglass packing has had a collateral effect in reducing disarmament somewhat, but disarmament is still occurring in

  liquids containing a lot of surfactants.

  The present invention relates to a coalescer-separator apparatus which overcomes many of the defects of conventional coalescer devices. Due to the improved flow distribution resulting from the present invention, the useful life of the coalescer units employed is significantly increased and effective separation of a discontinuous phase, such as typically found water

  in oil-based fuels, is greatly increased.

  In addition, because of the arrangement of the components of the present invention, a more compact unit can be prepared that achieves an identical or improved level of performance as compared to larger conventional units. To achieve these results, a liquid purification system is provided by the present invention that includes at least one coalescing assembly each of which includes at least one coalescing element or unit for coalescing the discontinuous or suspended (rather than dissolved) phase of a mixture of drop-immiscible liquid and at least one separation assembly, each of which includes at least one element or unit for separating coalesced drops from the continuous phase In one aspect of the present invention, the assemblies and / or element (s) ) coalescing (s) and assemblies and / or element (s)

  separation are placed in stacked or superimposed relationship.

  Typically the coalescing element (s) and the separating element (s) are enclosed in a housing having fluid inlet and outlet passages, particularly liquid ports. The housing includes an outlet for the liquid which originally formed the continuous phase and usually an outlet for the liquid that formed

  originally the discontinuous liquid phase.

  Another aspect of the present invention relates to a system for the separation of two partially or totally immiscible liquids including at least one coalescing element and at least one separation element in which the coalescing element (s) include a porous material having a surface energy (or surface tension of critical wetting) which is greater than the surface tension of the continuous liquid phase but less than the surface tension of the discontinuous liquid phase. Preferably, the material forming the portion separating the phase

  coalescer has a fibrous configuration.

  Another aspect of the present invention relates to a method of separating a liquid discontinuous phase, such as water, from a liquid continuous phase, particularly an organic liquid, such as a fuel. a mixture of the discontinuous and continuous phase liquid to at least one coalescing element which includes a packing material having a critical wetting surface energy intermediate to that of the critical wetting surface tension of the discontinuous and continuous phase liquid to form After this, the mixing of the liquid in the continuous phase and the drops of the discontinuous phase liquid are fed to at least one separation element which allows the passage of the continuous liquid phase but resists or substantially prevents the passage of the drops. of liquid of the discontinuous phase, whereby the liquid in continuous phase is separated from the drops of liquid in phase discontinuous. More specifically, the invention provides a liquid purification system capable of separating a first liquid from a second liquid, wherein the first liquid is completely or partially immiscible and forms a discontinuous phase with a second liquid forming a continuous phase, characterized in that it comprises (a) a housing, (b) a fluid inlet in said housing; (c) a first liquid outlet in said housing; (d) a second liquid outlet in said housing; (e) at least one coalescing assembly for coalescing said first liquid; and (f) at least one separation assembly for separating drops of said first liquid from said second liquid, said at least one coalescing assembly and said at least one separation assembly being arranged in relation to

superimposed in said housing.

  According to one characteristic of this liquid purification system, said at least one coalescence assembly comprises at least one coalescing element and said at least one coalescence assembly comprises at least one separation element. According to another feature of this liquid purification system, said at least one coalescing member includes a packing material having an intermediate critical wetting surface tension between

  the surface tensions of said first and second liquids.

  In this case, said packing material comprises a

  polyester, preferably a polybutylene terephthalate.

  According to yet another characteristic of this liquid purification system, said at least one coalescence assembly includes at least one coalescing element having a functional portion and said at least one separation assembly includes at least one separation element having a functional portion. , the ratio of the effective surface area of the functional portion of each of said at least one coalescence assembly to the effective surface area of the functional portion of each of said at least one separation assembly being in the range of about

0.25: 1 to about 10: 1.

  In particular said ratio is about 5: 1 to

about 10: 1.

  Said ratio may also be about 0.25: 1 to

about 4: 1.

  According to one embodiment of this liquid purification system, said at least one coalescence assembly comprises a plurality of coalescence elements, each of which is arranged in said coalescence assembly

in parallel relation.

  According to another embodiment of this liquid purification system, said at least one coalescence assembly comprises a plurality of coalescence elements, each of which is arranged in said at least one assembly of

coalescence in serial relation.

  According to yet another embodiment of this liquid purification system, said at least one coalescence assembly comprises a coalescing element and said at least one separation assembly comprises a

separation.

  The invention also proposes a liquid purification system capable of separating a first liquid from a second liquid in which the first liquid is totally or partially immiscible and forms a discontinuous phase with a second liquid forming a continuous phase, characterized in that that it includes (a) a dwelling; (b) a fluid inlet in said housing; (c) a first liquid outlet in said housing; (d) a second liquid outlet in said housing; (e) a plurality of coalescing elements for coalescing said first liquid; and (f) a plurality of separating members for separating the drops of said first liquid from said second liquid, said plurality of coalescing elements and said plurality of separating elements being disposed in

  superimposed and alternating relationship in said housing.

  The invention also proposes a liquid purification system capable of separating a first liquid from a second liquid in which the first liquid is totally or partially immiscible and forms a discontinuous phase with a second liquid forming a continuous phase, characterized in that it comprises: at least one coalescing assembly for coalescing said first liquid; and at least one separation assembly for separating the drops of said first liquid from said second liquid, said at least one coalescing assembly and said at least one separation assembly being arranged in superimposed relationship

  and in fluid communication relation.

  According to one embodiment of the liquid purification system of the invention, said at least one coalescence assembly is superimposed above said separation assembly. In another embodiment of the liquid purification system of the invention, said at least one separation assembly is superimposed over said

coalescence assembly.

  More specifically, according to one embodiment of the liquid purification system of the invention, each of said at least one coalescing element is disposed coaxially with respect to each of said at least one element.

of seperation.

  On the other hand, the liquid purification system is characterized in that it comprises at least one coalescing element in said at least one coalescence assembly having a functional portion and at least one separation element in said at least one separating assembly having a functional portion, said at least one coalescing member being arranged coaxially with said separating member and having a packing material formed of polybutylene terephthalate wherein the ratio of its effective surface area to that of the functional portion said at least one separating element is

  in the range of about 0.25: 1 to about 10: 1.

  The invention also provides a method of removing water from a liquid organic fuel in which it is substantially immiscible, characterized in that it comprises the steps of: (a) introducing a mixture of water and liquid organic fuel to at least one coalescing assembly which includes at least one coalescing element with a packing material having a critical intermediate wetting surface tension between the surface tensions of the water and said liquid organic fuel to form a mixture of drops of water and said liquid organic fuel; (b) bringing the mixture of drops of water and organic liquid fuel to at least one separation assembly which includes at least one separation element, which allows the passage of said liquid organic fuel but resists or substantially prevents the passage of said drops of water whereby the organic liquid fuel is separated from said drops

of water.

  In this method, said packing material is a

  polyester, preferably a polybutylene terephthalate.

  According to a characteristic of this method, said fuel has

  a high concentration of surface active substances.

  According to another characteristic of this method, said

  Fuel is an oil-based fuel.

  According to yet another characteristic of this method, said at least one coalescence assembly and at least one separation assembly are arranged in superimposed relationship. According to still another feature of the method, said polyester packing material comprises a structure formed as a mass of nonwoven microfibers which are substantially free of fiber-to-fiber bonding and are attached to one another by a mechanical entanglement, said structure having a substantially constant void volume over at least a substantial portion of the structure and said polyester structure being of

  graduated preference, as measured in the radial direction.

  Another object of the invention is a liquid purification system, characterized in that said at least one separation element includes a porous, calendered fibrous structure which comprises polytetrafluoroethylene fibers, preferably having

  up to about 70 micrometers, and a fluorocarbon binder.

  Yet another object of the invention is a separating element for separating a first liquid from a second liquid in which the first liquid is totally or partially immiscible and forms a discontinuous phase with the second liquid forming a continuous phase, characterized in that it comprises a fibrous, porous, calendered structure including polytetrafluoroethylene fibers having diameters of up to 70

  micrometers and a fluorocarbon binder.

  According to a feature of this separating member, it further includes a metal or polymeric support sleeve and a metal support core, each of the support cores, support sleeve and fibrous structure having a cylindrical configuration, and in concentric relation and end caps sealingly attached to said support core, support sleeve and fibrous structure. Still an object of the invention is a separation medium characterized in that it comprises a fibrous structure, porous, calendered including polytetrafluoroethylene fibers having diameters of up to about 70 micrometers and a fluorocarbon binder. The invention will now be described and illustrated in greater detail with reference to the accompanying figures, in which: Figure 1 illustrates an elevational sectional view with a partial stoppage of a conventional coalescer-separator liquid separation system; Fig. 2 illustrates a plan view of the interior of a conventional coalescer-separator liquid separation system having a plurality of separating elements and a plurality of coalescing elements; Figure 3a illustrates an embodiment of the present invention in which the coalescing elements are superimposed above the separating elements; FIG. 3b is a sectional view of the mode of

  embodiment of Figure 3 taken along the line III-III; and Figure 4 illustrates another embodiment of the present

  invention in which the separating elements

  are superimposed above the coalescing elements.

  As indicated above, the present invention relates to an immiscible liquid / liquid separation and coalescence system, which in comparison to the conventional liquid separation-coalescence system, provides a longer service life of the coalescer elements. , can be formed as a smaller unit than a similar conventional system of comparable capacity and performance and, because of the arrangement of the elements, results in an improved flow distribution that is more efficient in separating liquid components by describing In the present invention, terms such as "coalescer", "coalescing element", "coalescing unit" and analogous terms, both singular and plural, have been used to describe the device or article that coalesces the discontinuous or polydivisized phase of a mixture of immiscible liquid to form drops Regardless of the term used, the coalescence step using such a device occurs in the same way while the term "coalescer" generally describes such a device and that the term "coalescing element" describes a unit of components or a cartridge of a system that may contain multiple units of coalescence and separation, the present invention can be considered as containing also

  little more than a unit of coalescence in a separator system.

  In addition, such coalescing units can be fixed and not removable (without causing significant damage to the system), or preferably contain easily removable and replaceable elements. In a similar manner, terms such as "separator", "separating element", "separator units" and similar terms have similar meanings to each other as they are

  relating to coalescers, discussed above.

  When a liquid is brought into contact with the surface downstream of a porous medium and a small pressure differential is applied, flow into and through the porous medium may or may not occur. does occur is the one in which the liquid does not wet the material whose porous structure

Is made.

  A series of liquids can be prepared, each with a surface tension of about 3 x 10-3 N / m (3 dynes / cm) higher compared to the previous one. A drop of each can then be placed on a porous surface and observed to determine whether it is absorbed rapidly, or remains on the surface. For example, by applying this technique, with a 0.2 micron porous polytetrafluoroethylene (PTFE) filter sheet, an instantaneous wetting was observed for a liquid with a surface tension of 26 x 10-3 N / m (26 dynes / cm) However, the structure remains wet when a liquid with a

  Surface tension of 29 10-3 N / m (29 dynes / cm) is applied.

  Similar behavior is observed for porous media made using other synthetic resins, with wet-non-wetted values depending primarily on the surface characteristics of the material from which the porous medium is made, and secondarily, size characteristics of the material. porous medium pore For example, sheets of a polyester

  fiber, specifically polybutylene terephthalate (hereinafter

  after "PBT"), which have pore diameters less than about 20 micrometers, were wetted with a liquid with a surface tension of 50 x 10-3 N / m (50 dynes / cm), but did not been wet by a liquid with a voltage of

  area of 54 x 10-3 N / m (54 dynes / cm).

  In order to characterize this conduct on a porous medium, the term "critical wetting surface tension" (CWST) was defined as described below. The CWST of a porous medium can be determined by individually applying to its surface, preferably drip, a series of liquids with surface tensions ranging from 2 to 4 x 10-3 N / m (2 to 4 dynes / cm), and observing the absorption or non-absorption of each liquid The "CWST" of a porous medium, in units of 10-3 N / m (dynes / cm), is defined as the average value of the surface tension of the liquid that is absorbed and that of a

  neighboring surface tension liquid that is not absorbed.

  Thus, in the examples of the two preceding paragraphs, the "CWST" are respectively 27.5 and 52 x 10-3 N / m (27.5 and

52 dynes / cm).

  By measuring CWST, a series of test standard liquids are prepared with surface tensions varying sequentially from about 2 to about 4 × 10 -3 N / m (about 2 to about 4 dynes / cm). Ten drops of each of at least two of the sequential surface tension sample liquids are placed independently on representative portions of the porous medium and left for 10 minutes The observation is made after 10 minutes Wetting is defined as the evident absorption or wetting of porous medium by at least nine of the ten drops within 10 minutes Non-wetting is defined as the non-absorption or non-wetting of at least nine of the ten drops within 10 minutes The test is continued using surface tension liquids successively higher or lower, until

  that a pair has been identified, a wetting and a non

  wetting, which are the closest in surface tension.

  The CWST is then within this range and, for convenience, the average of the two surface tensions is used

  as a unique number to specify the CWST.

  Suitable solutions with varying surface tensions can be prepared in a variety of ways, however, those used in the development of the described product were

Table 1.

  Solution or Fluid Surface Voltage N / m (dynes / cm) Sodium Hydroxide in 94-110 x 10-3 (94-110) Water Calcium Chloride in 90-94 x 10-3 (90-94 ) water Sodium nitrate in 75- 87 x 10-3 (76-87) water Pure water 72.4 x 10-3 (72, 4) Acetic acid in water 38-69 x 10 -3 (38-69) Ethanol in water 22-35 x 10-3 (22-35) n-hexane 18.4 x 10-3 (18.4) FC 77 (3 M Corp) 15x10 -3 (15) FC 84 (3 m Corp) 13 x 10-3 (13) A first aspect of the present invention relates to a separation-coalescence system employing both a coalescence assembly that includes at least one element of coalescence and a separation assembly which includes at least one separating element in which the assembly or coalescing element is placed relative to the assembly or

  separating element in stacked or superimposed relation.

  When cylindrical coalescing and separating elements are employed, the cylindrical axes of the elements are placed substantially vertically. In its simplest form, the present invention may include a single coalescing or coalescer element and a single separator or separating element. be used for coalescers and separators formed from any suitable medium, which media are placed in any suitable configuration In its simplest form, the media serving as a coalescer may be supplied in sheet form and placed in close proximity but spaced relationship of the separator, which may also be in the form of a sheet In such an embodiment, both the coalescing element and the separating element, independent of each other, may be formed of either sheets flat or folded or wavy leaves in which the peaks and troughs of ch The preferred configuration of the coalescer and separator is cylindrical in which the functional portion of the coalescer and separator (i.e. that portion of the coalescer or separator which performs the function coalescence or separation, respectively) is independently formed as a cylinder around the axis of the element In both cases, the working part of the element can be arranged in cylindrical sheets or mats, sheets or cylindrical mats pleated, or sheets or mats wound helically or spirally, the latter being particularly relevant for coalescers In the case of separators, the working part of the element can also be a band, or, preferably, a screen Coalesceurs and separators or separating and coalescing elements of the present invention may be manufactured as a single unit. With one or more stages or portions of coalescence and one or more stages or portions of separation Most preferably, the coalescing and separating elements are manufactured and assembled as separate units. In practice, this allows the removal and replacement of

separate elements.

  Figure 3a illustrates an embodiment of the present invention in which a plurality of coalescing elements 20 are individually superimposed over a plurality of separating elements 30 Coalescing elements 20 and separating elements 30 , illustrated in the embodiment of Figure 3a, are located in the housing 12 A liquid inlet is provided in a housing wall for introducing a liquid, in this embodiment, above the coalescing elements The inputs 18 of liquid are provided in the upper end of each cylindrical coalescence member 20

  for the introduction of a contaminated liquid into it.

  Each coalescing member has a lining which defines the cylindrical wall 22 of the coalescing member The lining contains a material which has a surface wetting surface critical energy of the surface tensions

  fluids forming the continuous and discontinuous phases.

  Similarly, each separating member includes a perforated wall 32 that is formed from, or has an outer surface coating, a material that repels (or is not wet with) a discontinuous phase liquid. , which may be called the "discontinuous phase barrier material" Such material should not react with any liquid or other substance present in the mixture of immiscible liquids When used as a coating on the wall of the separator, such material must remain substantially immobilized thereon Typically, the critical wetting surface energy of this material is chosen to allow a passage of the liquid forming the continuous phase through the small pores of the material defining the wall of the separator element, and when the separator is a cylindrical element, as shown in Figure 3a, thereby allowing the entry of this liquid in the separator but to repel or prevent For example, in systems in which the water is the discontinuous phase, the materials are chosen as, or are applied to, the wall of the separator which has the discontinuous phase. critical surface or CWST below water surface tension For applications in which water or a liquid with a similar surface tension is the discontinuous phase, the preferred materials for use as a continuous phase barrier material to form or cover the wall of the separating member include silicones, such as silicone-treated paper, and preferably fluoropolymeric materials among which fluorocarbon or perfluorocarbon or perfluoro resins are particularly preferred. Examples of preferred materials for use as a trimmer or coating in the separator include polytetrafluoroethylene (PTFE) or other polyfluorinated polymers such as fluorinated resins

ethylene propylene (FEP).

  One preferred embodiment includes a coating of one of these materials on a stainless steel screen, or a package of pleated papers. Other suitable materials include those described in the US Patent owned by Miller et al (US Patent No. 4,759 782), specifically incorporated herein by reference Generally, the portion of the discontinuous or functional phase barrier material, which is also the liquid passing part of the continuous phase, of the separator is chosen to have pores smaller than a substantial amount. Initially, the pore size of the functional portion of the wall of the separator is selected to be from about 5% to about 1%, preferably from about 40% to about 100%. more preferably, and particularly when the discontinuous phase is water, the pore size is about 80%. Other suitable media for use as a discontinuous or functional phase barrier material part of the separating element are porous, fibrous fluorocarbon structures of the type described in Hurley et al. US Patent No. 4,716,074. Specifically incorporated herein by reference, such materials are porous, fibrous structures having good structural integrity which include fluorocarbon polymer fibers and a fluorocarbon binder. Such media, while suitable for use in the present invention, are primarily intended for use in the present invention. as layers of

  drainage and support in the filter cartridges.

  While sharing some of the compositional and preparative similarities with the structures described by Hurley et al, the most preferred medium in the present invention is a fibrous, porous, calendered, fluorocarbon structure which includes PTFE fibers in a fluorocarbon binder, Preferably, the fibers used are water-bleached and bleached PTFE fibers having diameters of up to about 70 micrometers, preferably from about 54 to about 70 micrometers. Most preferred are PTFE fibers having a diameter. This material is prepared to have a sheet weight of about 15 to about 35 grams / 0.0929 m 2 (about 15 to about 35 grams / ft 2), preferably about 15 to about 25 grams. / 0.0929 m 2 (about 15 to about 25 grams / ft 2) The most preferred medium is a medium having a sheet weight of about 21.5

  grams / 0.0929 m 2 (21.5 grams / ft 2).

  As noted above, although similarities exist both in the preparation and the composition between the preferred fluorocarbon, fibrous, porous media used as the discontinuous phase barrier material of the present invention and the media described in the patent. No. 4,716,074, major distinctions also exist between these materials. Thus, the material which is most preferred in the present application is calendered to a thickness of about 50 to about 90%, preferably about 75%, of its thickness. Such calendering increases both the AP and the bubble points of the media and produces a more efficient separation medium that achieves a substantially uniform flow velocity perpendicular to and in contact with all portions of the downstream surface in contrast. , a non-calendered material shows both a high transverse flow (movement or diffusion in a direction edge rather than a surface-to-surface direction) and a substantially imperceptible resistance to fluid flow in

  an upstream-downstream direction through the middle.

  Essentially, fluids passing through such media take the path of least resistance and may not contact all portions of the medium. Thus, the method of calendering the medium provides the desirable qualities for the medium of the present invention while rendering such Substantially unsuitable medium as a support and drainage layer In the same way, a material which shows a suitability as a support and drainage layer is frequently particularly

  effective as a discontinuous phase barrier material.

  This preferred medium having an average calender thickness of about 0.015 x 0.02540 m (0.015 inches) to about 0.025 x 0.0254 m (0.025 inches), preferably about 0.018 x 0.0254 to about 0.022 x 0, 0254 m (about 0.018 to about 0.022 inches) and most preferably about 0.019 x 0.0254 m (0.019 inches) is calendered to a thickness of about 0.004 x 0.0254 m to about 0.009 x 0.0254 m (about 0.004 to about 0.009 inches), preferably about 0.005 x 0.0254 to about 0.007 to about 0.007 inches, and most preferably about 0.006 to 0.0254 meters (0.006 to 0.007 inches). The calendering is carried out at ambient temperature under appropriate pressure to achieve compression and reduction in thickness to produce the AP and the desired bubble point. The calendered product has a first bubble point (which reflects the size of the pore the larger), measured in ethyl alcohol about 0.5 x 0.254 to about iron 4 x 0.0254 m (about 0.5 to about 4 inches or about 1.3 to about 10.2 cm) of water, preferably about 2 x 0.254 to about 3.5 x 0.254 m (about 2 to about 3.5 inches or about 5.1 to about 8.9 cm) of water, preferably about 2.75 x 0.0254 m (about 2.75 inches or about 7 cm) of water. The calendered medium also has a mean pore bubble point measured in ethyl alcohol of about 2 x 0.0254 to about 10 x 0.0254 m (about 2 to about 10 inches or about 5.1 at about 25.4 cm) of water, preferably about 3.5 x 0.0254 to about 6 x 0.254 m (about 3.5 to about 6 inches or about 8.9 to about 15.2 cm) Most preferably the average pore bubble point is about 4.5 x 0.254 m (about 4.5 inches or about 11.4 cm) of water. The calendered PTFE fiber sheet bonded with a binder FEP has a pressure drop across the medium (AP) as measured with an air face velocity at 28 x 0.3048 m / min (28 ft / min) ), from about 0.5 x 0.0254 to about 12 x 0.0254 m (about 0.5 to about 12 inches or about 28 to about 1.17 Frazier number or 1.3 to about 30.5 cm ) water, preferably from about 1 x 0.0254 to about 5 x 0.0254 m (about 1 to about 5 inches or about 14 to about 2.8 Frazier number or about 7.6 to about 12, 7 cm) of water and most preferably 1.4 x 0.0254 m (1.4 inches or

  about 10 Frazier numbers or about 3.5 cm) of water.

  After passing through the separator 30 through the wall 32 in an outer-inner direction, the liquid forming the continuous phase exits through the outlet 28 of the separator and enters the outlet chamber 26. After this, the liquid which originally formed the continuous phase exiting the device through the outlet 24 The liquid that formed the discontinuous phase in the original liquid mixture gathers in the bottom or the base 36 and is removed from the device

  by the outlet or drain 34 of discontinuous phase.

  In operation, a mixture of immiscible liquids is introduced into the housing 12 through the inlet 14 of immiscible liquid. After entering the housing, the mixture flows in the direction of the arrows shown in FIGS. 3a and 4b. the liquid enters each coalescing element through the inlet portion 18 into one of the end caps and, since the other end cap seals the unit completely, the liquid flows through the porous lining which defines the wall 22 of each coalescing element Each coalescing element is held in a fixed position relative to the other coalesced element juxtaposed and / or the wall of the housing This can be achieved by a specific means of rental and / or fixing (not shown) or, alternatively, at least in part, using liquid barriers 38a, located between the elements, or by liquid barriers 38b, located between the elements and the wall int. These barriers can be formed in separate sections or as a single unit. These liquid barriers act primarily as a sealing element for liquid and ensure that a liquid flowing into the housing under the force of gravity or under additional pressure can flow only downwardly from the housing by first entering through the inlet portion 18 of each of the coalescing elements and flowing through the walls of the coalescing elements.

  wall of the coalescing element in an inner direction-

  outside, the liquid flows into each separating element through a wall portion 32 in an outer-inner direction Due to the composition of which the outer wall of the separating element is composed or on which a coating is placed, only the continuous phase enters the separating element, leaving many drops of discontinuous phase liquid formed by the coalescing elements to fall on the bottom portion 36 located between and below the separating elements (in the embodiment shown in FIG. FIG. 3 a) This liquid is then removed from the housing by the discontinuous phase or drain outlet 44. The discontinuous phase liquid leaves each separation element through an outlet 28 in the outlet chamber 26 where it passes from the housing through the outlet 24. continuous phase. Figures 3a and 3b illustrate an embodiment of the present invention containing an assembly of seven liquid coalescence elements superimposed over an assembly of seven liquid separators. However, although this is a method of In a preferred embodiment and arrangement, the present invention is not limited to this and other embodiments and variations are possible. The number and particular arrangement of the separation and coalescence elements depend on the specific mixture to be separated. The arrangement shown in FIG. 3a is the most suitable, and is preferred, for liquid mixtures in which the discontinuous phase is denser than the continuous phase, such as, for example, a mixture in which the water is suspended in a In such a situation, the denser discontinuous phase would tend to move in the direction of the separating elements after changing to Through the coalescence elements When the discontinuous phase is less dense than the continuous phase, for example water suspended in CC 14, it is preferred to position the separating elements above the coalescing elements. Such as is illustrated in FIG. 4 Although the foregoing represents the preferred arrangements, when the discontinuous phase is present at very low input concentrations, e.g., concentrations of about to about 0.02, the reverse orientation to that of FIG. 4 has been shown to be relatively effective even when the discontinuous phase is less dense. Also, rather than a single coalescence element being arranged in superimposed relation to each separating element, an assembly of coalescence composed of a plurality of coalescing elements may be superimposed in series with respect to each separating element. The series relationship could take a variety of forms. In these embodiments, in which a plurality of coalescing elements are used for each separation element employed, and more than one separate element can be used, the coalescing elements are arranged, for example, in an assembly, in parallel relationship with each other and collectively in superimposed relationship and in series with one or more of the separating members employed In this arrangement, a row of coalescence elements, arranged in parallel with each other, could be placed above or below one or more separation elements in this embodiment, although a coalescing element can be disposed coaxially with respect to each element. employee separation, such

arrangement is not required.

  In another embodiment of the present invention, the coalescence (C) and separation (S) elements are placed in alternating series, and preferably

  coaxial, in a head-to-tail arrangement (ie, C-S-C-

  S) Such an arrangement could be used with mixtures that are difficult to separate With this arrangement, the liquid originally present in the discontinuous phase, which did not coalesce sufficiently to be rejected by the walls of the separator, passed over the next coalescer series, the drops of liquid that were formed from the discontinuous liquid growing in size after passage to

through each successive stage.

  In another embodiment of the present invention, one which is preferred, a coalescence assembly is formed from a plurality of coalescing elements which are arranged in stacked and coaxial arrangement in series with each other and are collectively positioned in series with a separating member (eg CCCS). More than

  details of such an arrangement are given below.

  In addition, while FIG. 3b shows six superimposed coalescence-separation elements placed radially around a central coalescence-separation element, the number of coalescence and separation elements placed radially in superposed relation can be increased or decreased as can centrally positioned coalescence and separation elements Although the radially placed elements result in the most compact liquid purification device with the best flow distribution, other arrangements, such as a linear arrangement or rectangular can be

  used for particular purposes.

  In those cases in which the coalescing and separating elements are manufactured as separate units, the closed or blind end caps of the separation and coalescence elements may be designed so that they interconnect with one another. with each other Alternatively, a means can be provided to place each item in the

  housing so that it stays in superimposed position.

  When a plurality of coalescing elements are employed for each separation element used, the coalescing elements may be arranged in series relative to each other (for example, CCCS), preferably in stacked or superimposed arrangement In such an arrangement, the coalescing elements may be interconnected in a number of ways. For example, those coalescing elements that first prevent entry of the mixture of immiscible liquids may be joined to successive coalescing elements downstream in an arrangement. at the top end by conduits joining an outlet portion of each coalescing member (which differ from the blind end caps of the coalescing members of Figures 3a and 4 in that there are fluid outlets in the

  end caps downstream) to a next downstream element.

  In such an arrangement, the output end of each conduit could be connected to the input portion of the next coalescing element in series and all the coalescing elements in series could have both input and output portions except for the last coalescing elements in each series which are located in stacked relation to the separating elements and could have only one fluid inlet. These latter elements or end-of-series coalescence elements could be essentially as shown in FIG. end cap with an inlet, a waterproof end cap

  or blind at the other end of the coalescing element.

  In an alternative arrangement, rather than using conduits between successive coalescing elements, the fluid outlet portion of a coalescing member may be constructed to engage in sealing in the portion of

  the element of coalescence upstream.

  In still another embodiment using a plurality of coalescing elements for each separation element, the coalescing elements, either individually or as an assembly of a plurality of coalescing elements could be placed above In this embodiment, all of the coalescing elements would include inlet portions and blind end caps of the present invention. opposite end of

  each element, such as those shown in Figures 3a and 4.

  Rather than a liquid flowing continuously from a coalescing element to the downstream coalescing element in series, through the center of each element and out through the lining defining the walls of the last coalescing element, as in the embodiment discussed immediately above, each coalescing element could be provided with a closed or sealed end cap and the liquid would flow only outward through the walls of each coalescing element and in the portion

  of the next succeeding downstream coalescing element.

  In such a case, it may be preferable to use multiple barriers, such as 38a and 38b, to separate each successive coalescing element or stack of coalescing elements to direct the flow of liquid passing through the walls of the the coalescing element in this stack or assembly to the input of the element

  coalescing in the next downstream stack.

  FIG. 3a illustrates a device in which the liquid mixture inlet 14 is located in the wall of the housing immediately above the coalescing elements while the outlet 24 of purified continuous liquid is located in the bottom of the housing communicating with the output chamber 26 Although these are preferred arrangements, the inputs and outputs may be located elsewhere in the housing. For example, in the embodiment shown in FIG. 3a, an inlet 14 may be located in the top of the housing. housing 38 while the output of

  liquid 24 could be located in the housing wall.

  In the latter case, the device would preferably have a flat bottom rather than the spherical bottom illustrated in FIG. 3a and the outlet 24 could be located near the base of the device. In the embodiments in which the separating elements are positioned at above the coalescence elements as in FIG. 4, the relative positions of the inputs and outputs can be reversed with respect to those described for the embodiment shown in FIG. 3. For example, the liquid mixture inlets 14 and located in the bottom portion along the housing below the coalescing elements while the continuous phase liquid outlet 24 is located at the

superior housing.

  In embodiments of the present invention in which the coalescing elements and / or the separating elements are intended for easy removal of the device for replacement or regeneration, the housing is designed so that either the top or the bottom of the housing Since the coalescing elements most frequently will be discarded and replaced, the preferred system for the embodiment illustrated in FIG. 3 in which the coalescent elements are superimposed above the separating elements includes a housing with a vertex or a portion The most preferably, the top is an upwardly tilting cover, but alternatively, the top could include tappings or needles to engage a bayonet base portion or a similar tapping in the wall 42 of the housing or could be a hinged lid, counterbalanced, loaded by spring such as described in Miller et al, US Pat. No. 4,419,234. In these systems, in which the separating elements are located above the coalescing elements, the housing can be constructed to

include a removable bottom.

  In some cases, therefore, the wall of the housing may be provided with vents and pressure release valves, as well as adjustment for pressure gauges.

inlet and outlet pressure.

  As noted above, while in many cases a separation can be adequately achieved by using equal numbers of coalescing elements and separating elements, to provide as compact a unit as possible with the housing of the smallest possible volume, and adequate separation and satisfactory capacity in terms of flow velocity, in many situations it is desirable to increase the ratio of the number of coalescing elements to the number of separation elements employed. Substantially identical to the ratio of coalescing elements to separating elements, in many situations the most relevant parameter is the ratio of the effective surface area of the coalescing elements to the effective surface area of the separation elements up to a certain number of times. point, it depends on the size, shape and configuration of the functionally effective parts of separation and coalescence elements In many situations this corresponds to the planar surface area or cylindrical surface area (the eighth of the circumference of the functionally effective part), also known as the

  "projected surface area" of the cylindrical element.

  When a woven element is used either in the coalescing element or in the separating element, a more relevant measure is the "effective surface area". This specific surface measurement differs somewhat from the measurement of the planar surface area or cylindrical since it is the real surface of the material as measured when the folds or corrugations are removed and the material is extended (or the height that multiplies the number of folds that multiplies the depth of the folds that multiplies 2) This surface measurement specific is greater than the cylindrical specific surface. This can be taken into account in

  determining the effective surface area.

  In these cases, in which the shape and configuration of both the separating elements and the coalescing elements are the same, it is simply necessary to express the ratio of the specific surfaces as the ratio of the number of the units. Alternatively, when the configuration and diameter of both the separating elements and coalescing elements are identical, it may only be necessary to compare the height of the coalescing element with that of the separating element. As suggested above, the ratio of the effective surface area of the coalescer or coalescing element to which the separation element or separator varies with the separation to be carried out. The factors to be taken into account in determining the appropriate ratio are the nature of the liquids which form the discontinuous or suspended phase and the continuous or suspending phase, the nature of the packing and discontinuous phase liquid barrier and the volume and / or the flow rate of the liquid mixture These factors take into account the chemical and of both liquids and dissolved materials (such as surface active substances) and the functional part of the elements of coalescence and separation, as well as their interaction with each other For many purposes, however, this ratio is in the range of about 0.25 to about 10 to 1 When the water forms the discontinuous phase and the liquid forming the continuous phase a high viscosity, preferably, the ratio is from about 5 to 1 to about 10 to 1 Alternatively, when the liquid in the continuous phase has a low viscosity, the ratio is preferably from about 0.25 to about 1 to about As used in discussing the present invention, "high viscosity" means about 50 cp or more and "low viscosity" is

refers to less than about 5 cp.

  In the stacked separator-coalescer arrangement of the present invention, any packing may be employed to form the coalescer wall through which the immiscible mixture of liquids passes and does not react chemically.

  with or absorbing only one of the components of the liquid mixtures.

  Typically, this would include materials such as glass, cork, and nylon. However, other materials, such as those cited in Pall et al. US Pat. No. 3,266,442, specifically incorporated herein by reference could be used in the stacked arrangement of the present invention. In a particular aspect of the present invention which is not restricted to the superimposed arrangement of the coalescer and separator, but which is preferably used therewith to provide even other benefits, the packing material is selected for the coalescer having properties

specific surface energy.

  In this preferred aspect of the present invention, the lining is chosen with consideration of the mixing of the liquids to be separated. In particular, the surface energy or CWST of the lining material is chosen to be less than the surface tension of the liquid phase. discontinuous and superior to the surface tension of the continuous phase Suitable for use in the present invention, as packing materials for the coalescing member are those having a pore size in the range of about 0.5 at about 25 M, preferably about 0.5 to about 3 M (especially for liquids with low IFTs) and more preferably about 3 percent. This is particularly preferred as a pore size of the preferred packing material discussed below. In general, the effective pore size can be selected on the basis of the relationship y = 50 / BP = pore size effective in microns and BP = end bubble point opening of the material in inches of water using the ethanol-containing liquid (the constant is determined, in part, by the thickness and nature of the material used and the measurement conditions and is known as capture efficiency "For the preferred material, as a

  As packing in the present invention, the value is 50.

  For fiberglass packings, this value could typically be 150). In many situations, and particularly in those situations where water is present as a discontinuous phase, polyesters, including polycarbonates are preferred as the material. Among the preferred polyesters, polyethylene terephthalate and polybutylene terephthalate are preferred with the latter being the most preferred. Due to cost considerations and pressure drop across the packing (AP), these materials are preferably used in the form of fibers, although in

  in some cases the membranes can be used.

  The fibers can be used as woven mats but nonwoven mats are generally preferred. It has been found that materials with the critical wetting surface tensions described above, and particularly polyesters, are much less easily disarmed than materials. Conventional and their use results in extended lifetimes for the coalescing elements In addition, such materials are effective in the separation of liquid with very low IFT, typically at or below 20 x 10 -3 N / m ( 20 dynes / cm) and preferably below 10 x 10 -3 N / m

(10 dynes / cm).

  As preferred fibrous mats used as packing in the coalescing members of the present invention, mats containing uniform fiber diameters as well as mats having graduated or stepwise fiber diameters across the depth of the mat (i.e., a parallel surface surface) may be used Preferred are nonwoven mats containing at least one partially graduated fiber diameter structure and the most preferred are mats arranged in fibrous structures cylindrical having a graded fiber diameter structure in at least a portion of the structure in the radial direction. It is also preferred that such a structure has a substantially constant void volume at least over a substantial portion of the structure, also as mentioned above, in the radial direction. One of the preferred embodiments inc read fiber diameters constant in the downstream part with the upstream part being profiled from the fiber diameter of the upstream portion to a larger diameter The fibers used to make such mats are of

  preferably substantially free of fiber-to-fiber bonds

  The fibers used to make the nonwoven mats are preferably polymeric, synthetic microfibers, most preferably of the thermoplastic nature. Examples of such thermoplastic microfibers include polyolefins. Such packing material and such cylindrical structures provided with such materials are available from Pall Corporation and are described in US Pat. Nos. 4,594,202 and 4,726,901, specifically incorporated herein by reference.

  empty of such materials are in the range of about 60-

  %, most preferably about 75 to 85%. They also typically have ring thicknesses of about 0.4 x 0.254 to about 1 x 0.0254 m (about 0.4 to about 1 inch or about 1.0 to about 2.5 cm) The fiber diameter is in the range of about 1.5 p or less to about 20 p or more When the product is prepared to obtain a void volume in the range of about From about 75% to about 85%, the fiber diameters are preferably selected to be below about 20%. The packing may also include a "final coalescence layer" of fine fibers having diameters of no greater than about 5μ and preferably These fine coalescence fibers are present in a downstream layer having a thickness of about 0.1 x 0.0254 to 0.5 x 0.0254 m (about 0.1 to about 0.5 inches or about 2.5 to about

12.7 mm).

  Each coalescing element may be provided with an upstream or downstream support and / or an upstream or downstream drainage material. When many elements of the cylindrical coalescer are employed in situations in which the flow is in an inner direction, exterior, measures are generally taken to protect the downstream surface of the damage lining from a compression induced by

  high pressures or turbulent flow states.

  Thus in order to maintain the structural integrity and to allow the free flow of the liquid, a plastic (eg PVC coated glass) or stainless steel is placed or wrapped around the lining. Downstream of the lining, a roller This element, which has very large pores, that is to say significantly larger than those of the packing, is provided to reduce turbulence can be placed in air or knitted fibers, preferably formed of polyester. and to orient or "reduce" the flow of fluid Optionally, a "sock" or outer sleeve formed from Remay, Orlon or cotton may be located downstream of the turbulence-reducing layer to prevent fiber migration from the last In addition, an upstream filter material may be provided to trap the particulate material before it contacts the lining of the coalescing member. Preferably, the latter is a professional filter. With a preferred embodiment, as discussed above, the packing used in the coalescing element has a larger effective pore diameter significantly greater than the coalescer packing material so as to inhibit flow in the coalescer. may be of a profiled type with graduated pores that tap into cones from the surface upstream to the downstream surface This type of structure works to trap dirt or particulate material in larger pores and perform a function coalescence in the nearest downstream pores All these cylindrically configured layers are included in the

end caps.

  The end cap, the core and any support member may be made from materials that are inert to the liquids to be treated Typically, these may be formed of glass fibers, a metal such as steel

  stainless or, preferably plastic.

  The separator may include elements similar to those of the coalescing elements, such as end caps, hearts and to a lesser extent, drainage and support layers. These may also be formed from the same materials as used to form like elements in the coalescing elements The separator may be formed as or include a porous liner or a coated member which allows free flow of the continuous phase liquid but regrows

  the liquid that originally formed the discontinuous phase.

  Preferably, it is a stainless steel screen, for example, a 100 x 100 mesh screen, coated with PTFE. More preferably, the functional portion of the separating element is formed of the medium described above, a calendered fabric of fibrous fibers. PTFE and a FEP binder The separating element may be provided with a plastic or metal core downstream Any plastic that is inert or highly resistant to liquids to be treated or contaminants found in liquids, and that has satisfactory strength and rigidity can be used to form the core Examples are polyesters, including polycarbonates such as Lexan, polyamides and Delrin As for coalescing elements, the separating elements can be provided with an open pore sleeve to assist dispensing of fluid flow along the dimension of the height of the intermediate unit between the discontinuous phase barrier or repellent layer and the Preferred is a pleated material known as Epocel (available from Pall Corporation) which is formed of cellulose and a phenolic binder. A preferred embodiment of the present invention employs, from an upstream to downstream direction, a sleeve. a calendered medium formed of PTFE fiber and a FEP binder (as described above), a polymeric or metallic mesh support sleeve and a

metal support heart.

  In the present invention, the critical surface energy or CSWT of the functional portion of the separator coating or lining is less than the surface tension of the discontinuous phase. Thus, in cases where water is present, the present invention is effective primarily to remove water in a discontinuous phase of another liquid having a surface tension lower than that of water Generally, since the water is in the continuous phase and the liquid to be removed constitutes the suspended or discontinuous phase and has a surface tension lower than that of water, a separator having a coating or lining with a surface energy lower than the surface tension of the water could be ineffective since it would prevent the passage of water but would allow the flow of the liquid in the discontinuous phase through the walls of the

  separator without improving the coalescence thereof.

  Using a coating with a surface energy greater than the surface tension of water would allow both discontinuous phase liquids and continue to pass

  through the separator, being also ineffective.

  The following example indicates the manner in which the present invention is used. The invention should not, however, be considered to be in any way

it is limited to this one.

Example

  A separator-coalescer system of the present invention has been tested to remove water from gasoline. An apparatus has been constructed as described above. A housing containing a single coalescing element superimposed in a coaxial arrangement on a single separation member. effective surface area ratio of the element

  coalescing to the separating element was about 3 to 1.

  The lining which defined the walls of the coalescing element was formed of a polybutylene propyl terephthalate fiber mat in which the upstream portion of 0.10 x 0.254 m (0.10 inches) was formed of coarse fibers (approximately 40 to 60 p) and the remaining portion downstream of the mat was formed of fine fibers (about 3 to about 5 μ) having an effective pore size of about 3 μ and a void volume of about 75%. Coalescer element was equipped with end caps made of stainless steel and a 1.815 x 0.0254 m (1.815 inch) inner diameter stainless steel core. A support cage formed of a network of glass fibers covered with polyvinylchloride and fixed with nylon hot-melt beads which were attached downstream of the element and upstream of a polyester cake left in the air The separating elements contained a Teflon discontinuous phase liquid barrier covered on a t 100 x 100 stainless steel friends The separator included the same end caps and core as the coalescer A corrugated padding of Epocel was provided in

* downstream of the Teflon coating of the separator.

  The separator-coalescer housing was connected to a 500-gallon gasoline storage tank by means of a closed-loop system with valves (disc and conventional) flow controllers (Kates) and fluid pumps to control the pressure and flow of liquid in the system as well as to create an emulsion of water and fuel The system was also equipped with an Aqua Glo device (available from Gammon Technical Products Company) to determine the concentration of water in

the system.

  The gasoline used in the tests contained a commercial additive mixture that included, among other things, a surfactant or engine detergent. The additive composition was blended with a high test gasoline at three times the typical concentration. commercially available gasoline to create a process stream of

extreme disarmament.

  After initiating the flow of gasoline into the system and blowing air from a vent into the housing, the flow of fuel through the system was set at 5 gallons per minute. The water was then introduced into the system. rotameter-adjusted system After reaching equilibrium (as determined by an AP constant) and water started to be collected, downstream water concentrations were determined with the Aqua-Glo La concentration upstream of the water was then readjusted to approximately

  intervals of 10 minutes and the procedure was repeated.

  The water concentration was increased by 2-7% (vol / vol) to the indicated values and with the results shown in Table 2, below. The upstream and downstream fuel samples were

  taken for clarity and gloss analysis.

Table 2.

  Time (minutes) Water injection% Aqua-Glo (vol / vol) (ppm water) At equilibrium 2 5

3 5

4 8

5 8.5

6 12

7 18

7 16

7 19

Claims (18)

  A liquid purification system capable of separating a first liquid from a second liquid, wherein the first liquid is completely or partially immiscible and forms a discontinuous phase with a second liquid forming a continuous phase, characterized in that it comprises (a) a housing (12), (b) a fluid inlet (14) in said housing (12); (c) a first liquid outlet (24) in said housing (12); (d) a second liquid outlet (34) in said housing (12); (e) at least one coalescing assembly for coalescing said first liquid; and (f) at least one separation assembly for separating drops of said first liquid from said second liquid, said at least one coalescing assembly and said at least one separation assembly being arranged in relation to   superimposed in said housing (12).   2 liquid purification system according to claim 1, characterized in that said at least one coalescence assembly comprises at least one coalescing element (20) and said at least one assembly of   coalescence comprises at least one separating element (30).   The liquid purification system according to claim 2, characterized in that said at least one coalescing member (20) includes a packing material having a critical wetting surface tension intermediate the surface tensions of said first and second liquids.   The liquid purification system according to claim 3, characterized in that said packing material comprises a polyester, preferably a polybutylene terephthalate.   A liquid purification system according to claim 1, characterized in that said at least one coalescence assembly includes at least one coalescing member (20) having a functional portion and said at least one separation assembly includes at least one member (30). ) having a functional portion, the ratio of the effective surface area of the functional portion of each of said at least one coalescence assembly to the effective surface area of the functional portion of each of said at least one separation assembly being in the range from about 0.25 to 1: 1. The liquid purification system according to claim 5, characterized in that said ratio is from about 5: 1 to about 10: 1.   Liquid purification system according to claim 5, characterized in that said ratio is from about 0.25: 1 to about 4: 1.   The liquid purification system according to claim 2, characterized in that said at least one coalescence assembly comprises a plurality of coalescing elements (20) each of which is arranged in said   coalescence assembly in parallel relation.   The liquid purification system according to claim 2, characterized in that said at least one coalescence assembly comprises a plurality of coalescing elements (20), each of which is arranged in said at least one   least a coalescence assembly in series relation.   A liquid purification system according to claim 2, characterized in that said at least one coalescence assembly comprises a coalescing member and said at least one separation assembly comprises a separation element.   A liquid purification system capable of separating a first liquid from a second liquid in which the first liquid is totally or partially immiscible and forms a discontinuous phase with a second liquid forming a continuous phase, characterized in that it comprises a) a housing (12); (b) a fluid inlet (14) in said housing (12); (c) a first liquid outlet (24) in said housing (12); (d) a second liquid outlet (34) in said housing (12); (e) a plurality of coalescing elements (20) for coalescing said first liquid; and (f) a plurality of separating elements (30) for separating the drops of said first liquid from said second liquid, said plurality of coalescing elements (20) and said plurality of separating elements (30) being arranged in relation to each other; superimposed and alternating in said housing (12).   A liquid purification system capable of separating a first liquid from a second liquid in which the first liquid is totally or partially immiscible and forms a discontinuous phase with a second liquid forming a continuous phase, characterized in that it comprises: at least one coalescing assembly for coalescing said first liquid; and at least one separation assembly for separating the drops of said first liquid from said second liquid, said at least one coalescing assembly and said at least one separation assembly being arranged in superimposed relationship   and in fluid communication relation.   13 liquid purification system according to claim 1, characterized in that said at least one coalescence assembly is superimposed above said separation assembly.   The liquid purification system according to claim 1, characterized in that said at least one separation assembly is superimposed above said coalescence assembly.   A liquid purification system as claimed in claim 2, characterized in that each of said at least one coalescing member (20) is disposed coaxially with respect to each of said at least one separating member (30). Liquid purification system according to claim 1, characterized in that it comprises at least one coalescing element (20) in said at least one coalescence assembly having a functional portion and at least one separation element (30) in said at least one separation assembly having a functional portion, said at least one coalescing member (30) being disposed coaxially with said separating member (30) and having a packing material formed of polybutylene terephthalate in which the ratio of its effective surface area to that of the functional portion of said at least one separation element (30) is in the range of about 0.25: 1 to about 10: 1.   Method for removing water from a liquid organic fuel in which it is substantially immiscible, characterized in that it comprises the steps of: (a) introducing a mixture of water and liquid organic fuel to minus a coalescing assembly which includes at least one coalescing element with a packing material having a critical wetting surface tension intermediate between the surface tensions of the water and said liquid organic fuel to form a mixture of water drops and said liquid organic fuel; (b) bringing the mixture of drops of water and organic liquid fuel to at least one separation assembly which includes at least one separating element (30), which allows the passage of said liquid organic fuel but substantially resists or prevents the passage of said drops of water whereby the liquid organic fuel is separated from said water drops.   Method according to claim 17, characterized in that said packing material is a polyester,   preferably a polybutylene terephthalate.   19 Method according to claim 17, characterized in that said fuel has a high concentration of susbtances active surface.   Method according to claim 17, characterized in   what said fuel is a petroleum fuel.   Method according to claim 17, characterized in that said at least one coalescence assembly and at least one separation assembly are arranged in superimposed relationship. Method according to claim 18, characterized in that said polyester packing material comprises a structure formed as a mass of non-woven microfibers which are substantially free of fiber-to-fiber bonding and are attached to each other by a mechanical entanglement, said structure having a void volume substantially constant over at least a substantial portion of the structure and said polyester structure being of   graduated preference, as measured in the radial direction.   The liquid purification system according to claim 2, characterized in that said at least one separation element (30) includes a porous, calendered fibrous structure which comprises polytetrafluoroethylene fibers, preferably having   up to about 70 micrometers, and a fluorocarbon binder.   Separating element (30) for separating a first liquid from a second liquid in which the first liquid is totally or partially immiscible and forms a discontinuous phase with the second liquid forming a continuous phase, characterized in that it comprises a fibrous, porous, calendered structure including polytetrafluoroethylene fibers having diameters of up to 70   micrometers and a fluorocarbon binder.   Separating element according to claim 24, characterized in that it further includes a support sleeve 46 2699420   metal or polymeric core and a metal support core, each of the support cores, support sleeve and fibrous structure having a cylindrical configuration, and in concentric relation, and end caps sealingly attached to said support core, support sleeve and structure fibrous. Separating medium characterized in that it comprises a fibrous, porous, calendered structure including polytetrafluoroethylene fibers having   up to about 70 micrometers and a fluorocarbon binder.