• 专利附录
  • 专利说明
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  • 类似技术
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    • 专利摘要:
    This invention relates to a coalescence filter for purifying a fluid containing a carrier and at least one liquid contaminant, by coalescing the at least one contaminant. The filter element contains a primary coalescence medium which is provided to coalesce the at least one contaminant in the primary coalescence medium. The primary coalescence medium includes at least one layer of a porous material. The primary coalescence medium has a total thickness of at least 3.5 mm, measured at a pressure of 2N / cm2. FIG. 1.
    公开号:BE1022383B1
    申请号:E2014/0669
    申请日:2014-09-08
    公开日:2016-03-18
    发明作者:
    申请人:Atlas Copco Airpower, N.V.；
    IPC主号:
    专利说明:

    Coalescence filter.
    This invention relates to a coalescence filter for purifying a fluid containing a carrier and at least one liquid contamination by coalescence the at least one contamination, the coalescence filter comprising an inlet for supplying the fluid to a fluid contained in the coalescence filter filter element, wherein the filter element contains a primary coalescing medium which is provided for coalescence the at least one contamination in the primary coalescing medium during the displacement of the fluid through the primary coalescing medium, the coalescing filter further comprising an outlet for discharging the coalesced contamination from the filter element, wherein the primary coalescing medium comprises at least one layer of a porous material, according to the preamble of the first claim.
    The use of coalescing filters for coalescing a disperse phase from a mixture of two immiscible phases, a continuous and a disperse phase, is known per se. Examples of practical applications include separating oil aerosol drops from compressed air from air compressors and crankshafts, separating water as a disperse phase from fuel as a continuous phase in fuel-water systems, or separating oil as a disperse phase from a water-oil system with water as a continuous phase.
    Coalescence is induced by a coalescing medium, which usually comprises a plurality of layers of one or more porous, fibrous substrates, which may be wetting (oleophilic or fluid attracting or adsorbent) or non-wetting (oleophobic or fluid repellent). The fibrous material has a surface that induces aggregation or coalescence of the disperse phase. A dispersed fluid with drops of a dispersed phase is moved through the continuous phase or carrier of the fluid through the coalescing medium, for example oil contaminated with air. The disperse phase often already coalesces in the first layers on the fibers of the coalescing medium. With continuous supply of fluid, the smaller drops grow into larger drops. The droplets are transported through the filter with the air stream, and as soon as they reach a size that no longer adheres to the fibers of the coalescing medium, they leave the filter, usually under the influence of gravity. After being in use for some time, the filter usually reaches a stationary state, where the accumulation rate of the dispersed phase of fluid droplets in the coalescing medium corresponds to the draining rate from the filter. Coalesced drops typically have a drop diameter of 5 to 500 µm.
    Various types of materials are used to produce coalescing filters, for example organic and inorganic fibrous or porous materials. These materials are available in various forms, for example as homogeneous, heterogeneous, layered or folded or rolled up materials, composites, laminates and combinations thereof. Shapes suitable for use as a coalescing filter are typically a fleece, cloth, cylinder, cube or other simple or complex geometric shape. The separation capacity of a filter material depends on numerous parameters including the composition and orientation of the fibers in the filter or coalescing medium, the yield of the filter material under the practical conditions, the concentration of the impurities (disperse phase) in the carrier (continuous phase), the pressure to which the filter material is subjected and the volume of continuous phase to which the filter is exposed over time.
    Numerous attempts have been made to improve the resolving power of a coalescing filter unit, including through the use of complex fiber structures or porous structures in the coalescing medium. US8,114,183 describes a coalescing filter for separating a non-miscible continuous and disperse phase. The coalescing filter includes an axially extending coalescence element with a coalescing medium that includes a plurality of fibers oriented in the gravity direction. Because the fibers of the coalescing medium extend tangentially around the circumference of the coalescence element, the flow resistance is lowered and drainage to the lower outlet is promoted. The coalescence element has a cross-section with respect to its axis in the form of a closed loop with an inner cavity. To achieve the highest possible drainage pressure, the vertical dimension is as large as possible and the transverse dimensions of the coalescence element decrease towards the bottom. US8,114,183 further describes to decrease the average fiber diameter and / or the porosity of the coalescence element towards the center of the coalescence element, with the aim of contaminants with larger dimensions that can cause blockage of the coalescence element , in the initial, open, less restrictive layers.
    It is known from US8,409,448 to build up a coalescing filter for removing an immiscible lipophilic or hydrophilic liquid from a continuous hydrophilic or lipophilic liquid phase, from a mixture of fibers with varying hydrophobic and hydrophilic surface properties. Coalescence and wetting can be controlled by controlling the amount of hydrophobic and hydrophilic fibers.
    However, the coalescence filters known from the prior art have the disadvantage that the pressure drop across the filter is often still too large, i.e. a large pressure drop occurs over the filter, whereby the filter performance is adversely affected. A known measure for reducing the pressure drop is the removal or reduction of the number of layers of filter material. However, this has an adverse effect on the filter efficiency. By filter efficiency is meant the amount of fluid that is filtered through the coalescing filter as opposed to the amount of fluid at the inlet of the filter. Thus, there is a need for a coalescing filter that exhibits the highest possible filter efficiency in use.
    It is therefore an object of the present invention to provide a coalescing filter with improved filter efficiency.
    This is achieved according to the invention with a coalescing filter which has the technical features of the feature of the first claim.
    To this end, the coalescing filter of this invention is characterized in that the primary coalescing medium has a total thickness of at least 3.5 mm, preferably at least 4 mm, preferably at least 5 mm, more preferably at least 6 mm, most preferably at least 7 mm, in particular at least 7.5 mm, measured in the flow direction of the fluid to be coalescribed, at a pressure of 2 N / cm 2. In the context of this invention, by "total thickness" is meant that the thickness of the primary coalescing medium is measured in the direction in which the fluid flows through the coalescing filter and thus the coalescing medium, while the primary coalescing medium is subjected to an ambient pressure of 2 N / cm 2
    The large layer thickness of the primary coalescence medium according to this invention in comparison with the coalescence filters known from the prior art makes it possible to improve the filter efficiency. The large layer thickness makes it possible in particular to considerably increase the coalescence yield, i.e. the amount of contamination filtered through the primary coalescing medium or coalesced in the primary coalescing medium, relative to the amount of contamination at the inlet of the filter.
    The inventors have furthermore found that in the coalescing medium of this invention, the capillary pressure is hardly influenced by the greater layer thickness of the primary coalescing medium, and that also the resistance to be overcome by the fluid as it travels through the primary coalescing medium (the so-called channel pressure) remains limited and low compared to capillary pressure. This is surprising since it is customary in the prior art to increase or decrease the layer thickness of the coalescing filter in order to increase the filter performance, for example by applying a limited number of layers of porous material, in order to reduce the pressure drop across the filter layer. to keep. This invention now makes it possible not only to improve the filter efficiency, but also to reduce the pressure drop across the coalescing filter, and thus improve the filter performance.
    Because of practical utility in existing filter devices and from a cost point of view, the primary coalescing medium preferably has a total thickness of at most 50 mm, preferably at most 40 mm, more preferably at most 30 mm, most preferably at most 25 mm, in particular at most 20 mm. Namely, the inventors have found that the filter efficiency is not significantly improved with greater thickness of the primary coalescing medium and that the material cost threatens to become disproportionately high.
    Moreover, with increasing thickness, there is a risk that the pressure that must be overcome by the coalesced contamination in order to move through the primary coalescing medium, the so-called channel pressure, becomes too high. Namely, the inventors have found that once coalescence of the contamination into larger drops has taken place, transport through the primary coalescing medium takes place under the influence of the transport of the carrier present in the fluid through the coalescing medium. It has been found that the pressure that must be overcome to transport the coalesced drops through the primary coalescing medium, in the form of channels that extend over the entire thickness of the coalescing medium, depends on the thickness of the primary coalescing medium
    The primary coalescing medium of this invention can be easily manufactured, for example, by processing a fibrous material, for example glass fibers, such that a layer-shaped or sheet-like material is provided with pores or openings between the fibers. The pores in the fibrous material of the coalescing medium through which the fluid travels and in which coalescence takes place are mainly formed by the spaces present between the fibers of the fibrous material. Suitable techniques that make this possible are known to those skilled in the art and include, inter alia, the manufacture of one or more sheets, for example woven or non-woven fibrous materials, knits, braided fibers, films, webs and combinations of the aforementioned materials or laminates or composites thereof. Fiber-like materials suitable for use in a primary coalescing medium of this invention are known to those skilled in the art, and are preferably selected such that they are capable of effecting the capture and coalescence of the contamination in the coalescing medium. However, other porous materials can also suitably be used as a primary coalescing medium.
    The primary coalescing medium is preferably a porous material with pores with an average diameter between 2 and 100 µm, preferably between 3 and 70 µm, more preferably between 5 and 50 µm, in particular between 5 and 35 µm, more in particular between 5 and 30 pm
    A primary coalescing medium whose porosity is provided by pores as described above has an open structure.
    A primary coalescing medium made from a fibrous material will usually contain substantially fibers with an average diameter of 0.25-20 µm, preferably 0.5-10 µm, although fibers with an even smaller or larger diameter may be present. The primary coalescing medium will usually be composed of a plurality of fibers, the diameter of which varies within the aforementioned limits.
    The primary coalescing medium of this invention preferably has an air permeability of at least 30 l / m2.s, preferably at least 50 l / m2.s, more preferably at least 60 l / m2.s, most preferably at least 80 l / m2.s, in particular at least 100 l / m2.s or more. The air permeability can vary within wide limits and in practice will usually not exceed 2000 l / m2.s, preferably a maximum of 1750 l / m2.s. The air permeability is measured at 2 mbar according to DIN and ISO 9237.
    A primary coalescing medium with such an air permeability has an open structure.
    According to the invention it is thus possible to obtain a primary coalescing medium with an improved performance, which is able to provide a better separation yield of the contamination present in the fluid, by using a primary coalescing medium with a greater total thickness in combination with a more open structure than is known so far. -
    The open structure contributes to the fact that the coalescence yield, i.e. the amount of contamination filtered through the primary coalescing medium or coalesced in the primary coalescing medium, can be considerably increased with respect to the amount of contamination at the inlet of the filter. This is in contrast to the prior art which teaches to use a primary coalescing medium with a smaller thickness in which the pores have a smaller average diameter to increase the filtering efficiency.
    The inventors have further found that when using a primary coalescing medium with an open structure as described above, also the capillary pressure to be overcome by a coalescing fluid upon entering the pores of a non-wetting primary coalescing medium (e.g. an oil repellent or oleophobic coalescing medium) can be considerably reduced, as well as the capillary pressure to be overcome by the coalesced liquid upon leaving a wetting primary coalescing medium (e.g. an oil-adsorbing or oleophilic coalescing medium). This lower capillary pressure offers the advantage that the primary coalescing medium can have a much larger thickness and a more open structure than previously thought possible, so that the coalescence yield can be increased considerably, and yet the pressure drop across the coalescing filter can be kept sufficiently low. to become. The thickness is thereby measured in the flow direction of the fluid to be coalescribed. In practice, this can mean that the primary coalescing medium can be built up from a much larger number of layers of filter material than has been the case hitherto, and that at the same time the pressure drop across the coalescing filter can be kept sufficiently low.
    Namely, the inventors have found that when using a primary coalescing medium with smaller pores and thus a more closed structure, the pressure drop across the coalescing medium appears to be considerably higher. Consequently, when using a coalescing medium with smaller pores, it is necessary to keep the thickness low to ensure a sufficiently low pressure drop across the coalescing filter.
    A reduced capillary pressure further offers the advantage that the energy required for supplying a contaminant into the pore system of a non-wetting primary coalescing medium can be lowered, as well as the capillary pressure that must be overcome when leaving a contaminant from a wetting primary coalescing medium. By a non-wetting primary coalescing medium it is meant that the coalescing medium has a low affinity for the coalescence fluid, or in other words that substantially repulsion forces occur between the two materials. Examples of a non-wetting primary coalescing medium are an oleophobic and / or hydrophobic primary coalescing medium. By a wetting primary coalescing medium is meant that the primary coalescing medium has a high affinity for the coalescence fluid or in other words that substantial attraction forces occur between the primary coalescence medium and the coalescence fluid. Examples of a wetting primary coalescing medium are an oleophilic and / or hydrophilic primary coalescing medium.
    The person skilled in the art is able to adjust the thickness of the primary coalescing medium taking into account the nature of the primary coalescing medium, in particular taking into account the average pores of the coalescing medium and / or the air permeability and / or density of the coalescing medium, to make the intended performance possible.
    The primary coalescing medium may be composed of a plurality of densely stacked or closely wound abutting layers of a sheet-shaped porous filter material, although the use of a single layer with a desired thickness is also possible. By densely stacked is meant that successive layers are in contact with each other, or in other words that successive layers are arranged adjacent. Adjacent layers of sheet-like coalescing medium are preferably stacked in such a way that a sheet of the coalescing medium is wound such that successive layers of the coalescing medium are positioned adjacent such that the distance between successive layers is minimal, and that any air layer present between successive layers is minimal has a thickness or is preferably even absent. This makes it possible to keep the capillary pressure to be overcome at the transition of the fluid from one layer to the other as low as possible. This also makes it possible to minimize the risk of fluid flowing out between successive layers.
    In one embodiment, successive layers of the primary coalescing medium can be made of the same porous material. By stacking layers of the same material, it is possible to prevent an additional capillary pressure from having to be overcome when the fluid enters a subsequent layer from a previous layer, and it is therefore possible to increase the risk of a pressure drop across the coalescing filter due to material transitions. In another embodiment, two or more consecutive layers of the primary coalescing medium are composed of different materials, in particular materials with a different average porosity and / or a different average pore diameter and / or a different density and / or a different air permeability. It is also possible to construct the primary coalescing medium from a first primary coalescing medium and a second primary coalescing medium, the first primary coalescing medium being made up of one or more layers of a first material, for example a wetting, oleophilic or hydrophilic coalescing medium, and the second coalescing medium is made up of one or more layers of a second material, for example a non-wetting, oleophobic or hydrophobic coalescing medium.
    In case the primary coalescing medium is composed of a plurality of layers, the layer thickness of the individual layers can vary within wide limits. The layer thickness of the individual layers of the primary coalescing medium can, for example, vary from 0.1 to 1 mm, preferably 0.4 mm, more preferably 0.5 mm, most preferably 0.6 mm. The person skilled in the art is able to choose the desired layer thickness taking into account the total layer thickness intended for the coalescing medium.
    The primary coalescing medium of this invention preferably contains at least 4 consecutive layers of the same porous material to ensure a sufficient degree of coalescence, more preferably at least 6 layers, most preferably at least 10 layers. The number of layers will usually not be more than 30 since the filter efficiency is not significantly improved if the primary coalescing medium contains more layers, and the material cost threatens to become disproportionately high. Moreover, with a further increasing number of layers, there is a risk that the channel pressure becomes too high, as explained above. Preferably, the number of layers of material from which the primary coalescing medium is built up is no more than 25, most preferably no more than 20.
    The inventors have further found that upon flowing through a multi-layer primary coalescing medium as described above, the contamination present in the fluid coalesces into the pores or openings present in the primary coalescing medium. The pores of successive layers appear to form quasi-continuous channels that extend in the flow direction of the fluid, through the coalescing medium, and provide preferred pathways along which the fluid travels.
    Without wishing to be bound by this theory, the inventors assume that the pores of successive layers of material from which the primary coalescing medium is composed overlap at least partially, whereby pores from a previous layer at least partially connect and thus provide access to pores in a subsequent low. Thus, a kind of channels or preferred ranges are formed that extend through multiple layers of the primary coalescing medium, through which the fluid moves. Preferred trajectories in successive layers will usually not be perfectly congruent. Rather, it is likely that preferred pathways connect partly, to a greater or lesser extent, but sometimes also entirely, and thus form quasi-continuous channels in which the contamination can settle. These quasi-continuous channels extend through the entire thickness of the material of the primary coalescing medium, in the flow direction of the fluid. The inventors further assume that these quasi continuous channels in the primary coalescing medium exhibit a higher permeability to the fluid than the surrounding material, or in other words form channels with a higher flow capacity for the fluid.
    The inventors have further found that the quasi-continuous channels described above are in successive layers, laterally in the primary coalescing medium, in proximity to one another, and also laterally connected to each other. Without wishing to be bound by this theory, the inventors assume that a contamination present in a layer of the coalescing medium spreads somewhat laterally and forms a spot locally, or in other words a local continuous phase. The contamination is believed to travel along preferred pathways where the least resistance is to be overcome. The coalesced contamination thus forms a continuous phase which extends both laterally in the coalescing medium and in the depth or flow direction of the fluid. The process described above is repeated in the direction of thickness and / or in successive layers of the primary coalescing medium.
    The assumption that preferred ranges are present in the layered structure of the coalescing medium of this invention is plausible. Porous filter materials, in particular sheet-shaped filter materials constructed from fibrous materials, even if carefully manufactured, exhibit regions that are not homogeneous on a micro-scale and exhibit locally varying permeability with openings between the fibers. Air or any other fluid will preferably travel through areas of higher / better permeability. In these areas with better permeability, a contamination will first precipitate in the pores and coalescence into larger drops. These droplets are moved with the air flow through areas of better permeability. Because the areas of high permeability in successive layers at least partially connect with each other, quasi-continuous channels are created.
    In the context of this invention, therefore, by "channels" is meant the use of a preferred range by an amount of coalescence fluid that is periodically displaced through the primary coalescing medium under the influence of fluid flow, e.g., air. These routes have a random shape and can extend in all directions. According to this invention, "channels" does not necessarily mean cylindrical tubes or pipes. In the case of non-wetting coalescing media, these channels lead to the formation of droplets at the exit of the filter, in the case of wetting coalescing media, these channels spread into a film which must be pushed out of the primary coalescing medium under the influence of capillary force and leads to capillary pressure drop.
    In a preferred embodiment of this invention, the primary coalescing medium has a density in the range of 0.05 to 0.90 g / cm 3, preferably 0.05 to 0.75 g / cm 3, more preferably from 0.08 to 0.50 g / cm 3. The density is measured by weighing a quantity of material from the primary coalescing medium with an area of 1 m2, and multiplying this by the thickness of this material, measured with a digital micrometer at a pressure of 2 N / cm 2.
    The coalescing filter of this invention preferably includes, adjacent to a surface of the primary coalescing medium, a drainage layer, preferably along a downstream surface of the primary coalescing medium along which coalesced contamination leaves the primary coalescing medium, for receiving and removing coalesced contamination and promoting of its disposal. This downstream drainage layer is also intended to provide a barrier that counteracts reflux of coalesced contamination to the coalescing medium and / or in particular to the carrier present in the fluid. Without wishing to be bound by this hypothesis, it is believed that the drainage layer forms a boundary zone or transition zone along the boundary surface of the primary coalescing medium along which drainage occurs, thereby counteracting build-up of contamination at the boundary surface, by forming large drops caused by the driving force of driven by gravity and deposited in the filter housing for discharge from the filter. If desired, a protective layer can also be arranged upstream of the primary coalescing medium, adjacent to a surface of the primary coalescing medium along which fluid is supplied to the primary coalescing medium in a manner such that both materials are in contact. Downstream, a protective layer can also be added adjacent to a surface of the primary coalescing medium, which can have an additional drainage function in addition to a protective effect.
    The invention also relates to a coalescing medium as described above as part and / or for use in a coalescing filter as described above.
    The invention further relates to a method for purifying a fluid containing a carrier and at least one impurity, wherein the fluid is passed through a coalescing filter as described above, for reducing the concentration of the at least one impurity by coalescence of the at least one impurity in the coalescence filter, in particular in the primary coalescence medium. Thereby, the fluid may be selected, for example, from the group of compressed air contaminated with one or more hydrocarbons, contaminated water or contaminated hydrocarbons, but other fluids may also be suitably used. The coalescing filter of this invention is suitable for use in a continuous process in which a continuous supply of fluid to the primary coalescing medium takes place. However, it is also possible to supply the fluid in one or more discrete batches.
    The invention also relates to the use of the coalescing filter described in this patent application for separating one or more liquid impurities from a carrier, wherein the carrier can be a gas or a liquid. The invention relates in particular to the use of the coalescing filter described in this patent application for separating oil aerosol drops from compressed air originating from air compressors and crankshafts, separating water as a dispersed phase of fuel as a continuous phase in fuel-water systems or separating oil as a disperse phase from a water-oil system with water as a continuous phase.
    The invention is further explained below in the accompanying figures and description of these figures.
    FIG. 1 shows a view of the inner volume of a representative coalescing filter for compressed gas.
    FIG. 2a is a schematic cross-section of a primary coalescing medium relative to a drainage layer, wherein a carrier liquid (CF) is supplied at an angle of 90 ° and the coalescing medium and the drainage layer are disposed adjacent.
    FIG. 2b is a schematic representation of a primary coalescing medium relative to a drainage layer, wherein a carrier liquid (CF) is supplied at an angle between 1 ° and 90 ° and the coalescing medium and the drainage layer are arranged adjacent.
    FIG. 3 shows a cross section of a quasi-continuous channel formed in the primary coalescing medium, as shown by a higher concentration of deposited liquid.
    FIG. 4 shows an isometric view of a plurality of quasi-continuous channels formed in the primary coalescing medium, as shown by regional regions showing a higher concentration of deposited liquid.
    FIG. 5 is a graphical representation of the pressure drop of a carrier fluid through a coalescing medium containing wetting (oleophilic) fibers in accordance with this invention, in a carrier fluid stream with deposition of a liquid, oil-containing contaminant as a function of time.
    FIG. 6 is a graphical representation of the pressure drop of a carrier fluid through a coalescing medium containing oleophobic fibers in accordance with this invention, at a carrier fluid stream with deposition of a liquid impurity as a function of time.
    The coalescing filter 10 shown in Figure 1 comprises a closed housing 24 with a filter head 12 at the top. Filter head 12 contains an inlet 16 along which a fluid containing a carrier of liquid and at least one impurity is introduced into the coalescing filter. The housing 24 comprises an outlet 18 for draining a fluid and / or carrier fluid which has flowed through the filter element. Filter head 12 is detachably connected to housing 24, so that the interior of the coalescing filter is accessible for replacing the filter element if necessary. The releasable connection can be established in any way deemed suitable by a person skilled in the art, for example by means of a screw connection, by means of pressure, friction, clamps, etc. Inlet 16 is connected to a filter element in such a way that a fluid flows to the filter element can be fed. The filter element is preferably detachable with the filter head 12, so that the filter element can be replaced periodically, or can be replaced if necessary.
    The coalescing filter shown in Figure 1 is intended for coalescence one or more liquid contaminants present in a liquid or gaseous carrier of a fluid. The one or more impurities may, for example, be an inert or reactive substance. The one or more impurities may, for example, belong to the group of liquids, aerosols, macro-drops or mixtures of two or more of these materials. An example of a fluid suitable for use with the coalescing filter of this invention is compressed air contaminated with an oil aerosol.
    The filter element comprises at least one primary coalescing medium 22, for coalescing one or more liquid contaminants present in the fluid in the coalescing medium and separating these contaminants from a carrier present in the fluid. Depending on the intended application, in particular if coalescence of several contaminants is envisaged, one can choose to install two or more different primary coalescing media, each with a desired affinity for the contaminant to be removed.
    In a preferred embodiment the filter element, adjacent to the coalescing medium 22 and downstream of the coalescing medium 22, also comprises at least one porous drainage layer 30. This drainage layer is disposed adjacent to a surface of the coalescing medium, with or without air layer or other physical separation between the two media, preferably without air layer. The aim is to enable an energy-efficient flow of fluid, carrier and / or contamination from the coalescing medium to the drainage layer. This is shown in Figures 2a and 2b. The drainage layer is usually arranged downstream of the primary coalescing medium.
    A downstream drainage layer 30 is intended to maximize the transfer of delivery / discharge of the contamination separated from the fluid by the primary coalescing medium, on the one hand by the driving force of the fluid and / or the carrier present therein which is moved through the filter. Materials that make this possible are known to those skilled in the art. The material of the drainage layer 30 also preferably provides a barrier that resists reflux or return of the coalesced contamination to the primary coalescing medium 22, but in particular to the support. Without wishing to be bound to this, it is believed that the drainage layer 30 provides a boundary or transition zone for the adjacent surface of the coalescing medium 22, which counteracts any build-up of coalesced contamination on this contact surface by inhibiting the formation of macroscopic drops of the contaminating liquid stimulates. These drops are then driven from the drainage layer 30 by an additional driving force, such as gravity, and are deposited or deposited, for example, in the housing and discharged from the filter. If desired, two or more drainage layers 30 can be provided. An example of a suitable material is an open polymer foam.
    If desired, a protective layer 25 may be provided upstream but also downstream of the primary coalescing medium 22. This protective layer 25 can also serve as a drainage layer or direct the fluid flow in a desired direction. An example of a suitable material for use as a protective layer 25 is an open polypropylene layer, but other materials can also be used. The filter element preferably also comprises a core 20. The at least one primary coalescing medium 22 is arranged downstream of the filter core 20.
    The coalescing filter 10 preferably contains one or more internal supporting structures 26, which support integration of the filter element as one mechanical whole, which minimize and protect the risk of mechanical deformation of the filter materials including the coalescing medium 22 under the influence of fluid loading against the impact of unexpected or sudden impact.
    The housing 24 may further comprise a drainage mechanism 32. A suitable drainage mechanism 32 can contain automatic, semi-automatic or manually operating valves, along which a coalesced and drained contamination retained in the housing is removed.
    The coalescing filter 10 may further contain optional components, which further improve the use and yield of the filter. For example, filter head 12 may include a status indicator 14, which gives an indication of the status of the coalescing filter, including the potential need for a periodic replacement. The status indicator 14 may be provided for directly or indirectly measuring the yield of the coalescing filter and may include an indicator which gives an impression of the condition of the coalescing filter 10, by means of, for example, a visual, auditory or electronic signal or a combination thereof. The indicator 14 can operate pneumatically or electrically or according to any principle deemed suitable by the person skilled in the art.
    The primary coalescing medium 22 used in the coalescing filter of this invention has a porous structure that can induce aggregation or coalescence of one or more contaminants present in the fluid. The surface of the pores present in the porous structure of the primary coalescing medium can be wetting for one or more of the impurities to be coalescribed, or non-wetting. The surface can be, for example, oleophobic or hydrophobic, or oleophilic or hydrophilic. In applications where the removal of oil from a liquid or gas stream is intended, the coalescing medium may be oleophilic or oleophobic. The material for the primary coalescing medium 22 is preferably chosen such that it displays a high affinity for the impurity to be removed.
    To allow successively different contaminants to be removed, the coalescing filter of this invention may contain two or more primary coalescing media 22 with different affinity selectively for the contaminant to be removed. Preferably, however, in order to keep the capillary pressure as low as possible, the coalescing filter contains only one primary coalescing medium.
    The primary coalescing medium is a porous material that may contain one or more layers of a porous material, and is preferably layered. The primary coalescing medium is preferably composed of one or more layers of the same layer-shaped fibrous material. In an alternative embodiment, the coalescing filter comprises two or more filter elements with different coalescing media, i.e., several coalescing media with different affinity selectively for the contamination to be removed.
    Suitable layered materials for use as primary coalescing medium 22 include substrates or materials made up of finite-length fibers, continuous filaments and combinations thereof. The primary coalescing medium preferably contains suitable materials that can withstand the pressure exerted to allow movement of the fluid through the primary coalescing medium, against the liquid impurities present in the fluid and the static and dynamic load to which the material is exposed during manufacturing the filter, assembling it and using it. Examples of suitable layered fibrous materials include woven or non-woven fibrous materials, knits, braiding, filming, and combinations of the aforementioned materials or laminates or composites thereof.
    The primary coalescing medium is preferably a multilayer material, which preferably contains at least 4 layers, more preferably at least 6 layers, most preferably at least 10 layers. Usually the number of layers of fibrous material will not exceed 20. The thickness of the individual layers of the coalescing medium is not critical to this invention and can vary within wide limits. The thickness of a layer can be, for example, a thickness of 0.4 mm, 0.5 mm, 0.6 mm, 0.75 mm or 1 mm. On the other hand, the primary coalescing medium can also be composed of one layer of the desired material, in the desired thickness.
    A multi-layer primary coalescing medium can be produced in various ways, for example by stacking, folding or rolling up or wrapping a plurality of layers of a fibrous material, so that the desired number of layers is obtained. However, any other method can suitably be used. The layers of the fibrous material are preferably arranged adjacent to each other, such that an air layer with the smallest possible layer thickness is present between adjacent layers. Adjacent layers are preferably arranged such that no air layer is present between them.
    This can be achieved, for example, by compressing or clamping a plurality of stacked layers, for example along one or more sides of the fibrous material. Preferably, however, the fibrous material is wound to minimize the risk of damage.
    Examples of fibrous materials that are particularly suitable for manufacturing a layered material for use in the primary coalescing medium of this invention include thermoplastic materials, thermosetting materials, organic or inorganic materials, metallic materials or alloys, blends, and chemically modified materials, for example manufactured by drawing, spinning, sewing, cross-linking, melt spinning (e.g. spinning, nanofiber, meltblowing), wet laying, electrospinning, solvent spinning, point bonding, adhesive bonding, continuous fabrics - knits, casting, co-extruding etc. Particularly preferred materials include glass fibers, silicate-based wet-laid thermosetting adhesive bonded non-woven fabrics, for example a finite-length borosilicate glass fiber, due to their thermal and hydrothermal resistance, load by the fluid, the carrier liquid and the contamination, without chemical mo for example by a fluorocarbon surface treatment.
    Primary coalescing media suitable for use in this invention have a density that preferably ranges between 0.05 - 0.90 g / cm 3, more preferably 0.05 - 0.75 g / cm 3, most preferably 0.08 - 0.50 g / cm 3. Materials with a density between 0.10 - 0.25 g / cm3 or 0.12 - 0.17 g / cm3 can also be suitable and are preferred with specific fluids and / or impurities.
    The average diameter of the pores present in the material from which the primary coalescing medium is constructed (measured by microscopy) is preferably in the range of 2 to 100 µm, preferably between 3 and 70 µm, more preferably between 5 and 50 µm, most preferably between 5 and 35 pm, in particular between 5 and 30 pm.
    Materials for use in the drainage layer 30 can be, for example, woven or non-woven materials, knits, films, open cell foams, molded or spun webs, open nets and combinations or laminates or composites of the aforementioned materials. Materials for use in the drainage layer 30 can be selected, for example, from the group of thermoplastic or thermosetting plastics, organic or inorganic substances, metallic materials or alloys, mixtures of the aforementioned materials and chemically modified forms thereof. The aforementioned materials can be produced in any way that is suitable for those skilled in the art, for example by pulling, spinning, sewing, cross-linking, melt spinning (e.g. spin binding, nano fibers, melt blowing), wet laying, electro spinning, solvent spinning, point binding, through-air bond , adhesive bonding, continuous fabrics - knits, casting, co-extruding, expansion, solvent casting and the like. Polyurethane foams are particularly preferred since they are resistant to thermal stress by the fluid and / or the carrier and contaminating liquid contained in the fluid, but at the same time prevent the return of the contaminants, for example hydrocarbon-based contaminants, to the coalescing medium, without it is necessary to pre-treat one or more components of the coalescing filter or drainage layer with fluorine-containing substances.
    The primary coalescing medium 22, the drainage layer 30 and the barrier layer can be mounted in the coalescing filter 10 as separate layer-shaped materials. However, it is also possible to combine the aforementioned materials in a laminate, so that they form a whole and optimum contact between adjacent layers is guaranteed and optimum fluid flow can be obtained from one layer to the other.
    This invention offers the advantage that the primary coalescing medium is composed of one or more porous layered materials or structures with a high bulk volume and low density, with a large pore volume, the pores having a relatively large average pore diameter. Such an open structure makes it possible to keep both the capillary pressure and the channel pressure during the transport of the fluid and the coalesced contamination through the primary coalescing medium low and to keep the pressure drop across the coalescing filter low. Capillary pressure means the resistance that a contamination must overcome to enter a non-wetting coalescing medium, but also the resistance that a contamination must overcome when leaving a wetting coalescing medium. With channel pressure is meant the resistance that a coalesced contamination must overcome when it travels through the pore system of the coalescing medium.
    The coalesced fractions of the liquid impurity typically occur in the coalescing medium as quasi-continuous channels with an increased concentration of coalesced fluid. These channels form separate, observable areas which extend through the thickness of the filter material as shown in Figure 4. The driving force of the carrier that is forced through the coalescing filter, for example by pumping, ensures the transport of the contaminants through the coalescence medium in the direction of the outlet or the rear, downstream outer surface of the primary coalescence medium, where the impurities have reached a sufficient aggregation as liquid fraction to leave the carrier as macroscopic drops under the influence of gravity. It is believed that the relatively large pores, low density, and high air permeability of the primary coalescing medium of this invention work together to allow for dynamic development of quasi-continuous channels during the service life of the filter and to minimize the pressure drop across the filter.
    Without wishing to be bound by this theory, it is believed that it is possible that upon first contact of a fluid, for example compressed gas, with the primary coalescing medium 22 a first population of separate quasi-continuous channels 50 is formed. As additional fluid is supplied, the accessibility of one or more of the quasi-continuous channels 50 may decrease, by the formation of aggregates or immiscible complexes, by gel formation and occlusion by solids and / or particles in these channels. With a continuous flow of fluid, it is possible that a quasi-continuous channel 50 develops in a different direction from the primary coalescence medium 22, along a route that offers less resistance. This way new quasi-continuous channels can arise. Without wishing to be bound by this hypothetical model, it is assumed that when a compressed stream of, for example, air containing oil aerosol as an impurity is transported through a primary coalescing medium, the transport passes through one or more quasi-continuous channels 50. In these channels 50, an effective reduction in the amount of oil in the air is achieved by coalescence the oil in these channels 50.
    Figure 5 shows a practical situation for a coalescing medium composed of an oleophilic fibrous structure. The inventors have found that coalescence of a liquid impurity from the fluid proceeds according to a step-by-step process, with at least a first and second discrete step, each discrete step being associated with a reduction in pressure across the coalescing medium. A second discrete step was observed when the contamination leaves the coalescing medium and is associated with an energy barrier that must be overcome upon exiting the coalescing medium to overcome an attractive force. A first discrete step was observed during the movement of the contamination through the coalescing medium in the form of one or more quasi-continuous channels because the liquid has to be pumped through the coalescing medium.
    Figure 6 shows a practical situation for a coalescing medium composed of an oleophobic fibrous structure. The inventors have found that coalescence of fluid contamination from the fluid is accompanied by a step-by-step pressure reduction across the coalescing medium, with at least a first and second discrete step. A first discrete step occurs when the contamination enters the coalescing medium to overcome the repulsive force. A second small discrete step occurs during the transport of the contamination through the coalescing medium through one or more quasi-continuous channels.
    The present invention thus provides a coalescing filter with a coalescing medium comprising a plurality of layers of a fibrous material with pores with a relatively large average diameter, whereby the fluid with carrier and at least one impurity moves. The fibrous material has high air permeability, low density and contains a pore system whose pores have a relatively large diameter. This makes it possible to provide a primary coalescing medium that ensures a higher separation yield of a contamination present in the fluid. This higher separation yield is accompanied by a considerable reduction in the capillary pressure that must be overcome by the fluid when entering or leaving the coalescing medium, but also by a substantial reduction in the channel pressure, this is the pressure that must be overcome during transport of the fluid and the coalesced contamination through the pore system of the primary coalescing medium. Because the pressure drop over the coalescing medium can be reduced, the energy requirement of the filter system can be considerably improved. The present invention thus provides a coalescing filter with an improved separation yield in combination with a reduced energy requirement. This is surprising since in the systems known from the prior art an improved separation yield is at the expense of the energy requirement.
    With the coalescing filter of this invention, in particular when used as a coalescing filter for a compressed air stream, a separation yield for polluting liquid present in the air can be obtained of at least 40 pg liquid per m3 of carrier fluid or carrier gas per 1.0 mbar pressure difference, preferably at least at least 44 pg, more preferably at least 46 pg.
    The invention is further illustrated with reference to the examples below.
    The fibrous materials described below were tested as a coalescing filter for purifying oil-contaminated air, as described in ISO 12500-1 and ISO 8573-2. The initial oil concentration was 10 mg / m3.
    Comparative experiments A-B.
    A filter material was used comprising the indicated number of layers of a conventional, commercially available oleophobic filter material with properties as described in Table 1.
    Example 1-2.
    A coalescing medium was used comprising 14 and 8 layers of oleophilic or oleophobic glass fiber material, respectively, with the material properties as described below. The permeability to air was determined in accordance with DIN EN ISO 9237.
    Table 2.
    The comparison of example 1 with comparative experiment A shows that the filter efficiency of a thick, open package of filter material is better than that of a thin, densely stacked package. The pressure drop over the thick open package appears to be even lower.
    The comparison of comparative experiment B with example 2 teaches that the filtering efficiency is comparable for a thick, open package and a thin, densely packed package. However, the pressure drop over the thick open package is lower than the pressure drop over the thin, packed package.
    权利要求:
    Claims (21)
    [1]
    CONCLUSIONS
    A coalescence filter for purifying a fluid containing a carrier and at least one liquid contamination by coalescence the at least one contamination, the coalescence filter comprising an inlet for supplying the fluid to a filter element present in the coalescence filter, the filter element includes a primary coalescing medium that is provided for coalescence the at least one contaminant in the primary coalescing medium during the movement of the fluid through the primary coalescing medium, the coalescing filter further comprising an outlet for discharging the coalesced contaminant from the filter element , wherein the primary coalescing medium comprises at least one layer of a porous material, characterized in that the primary coalescing medium has a total thickness of at least 3.5 mm, preferably at least 4 mm, preferably at least 5 mm, more preferably at least 6 mm, most preferably at least 7 mm, in particular at least 7.5 mm measured at a pressure of 2 N / cm 2.
    [2]
    A coalescing filter according to claim 1, wherein the primary coalescing medium has a thickness of at most 50 mm, preferably at most 40 mm, more preferably at most 30 mm, most preferably at most 25 mm, in particular at most 20 mm.
    [3]
    A coalescing filter according to any one of the preceding claims, wherein the pores in the primary coalescing material have an average pore diameter between 2 and 100 µm, preferably between 3 and 70 µm, more preferably between 5 and 50 µm, most preferably between 5 and 50 µm 35 pm, in particular between 5 and 30 pm.
    [4]
    A coalescing filter according to any one of the preceding claims, wherein the primary coalescing medium has an air permeability of at least 30 l / m2.s, preferably at least 50 l / m2.s, more preferably at least 100 l / m2.s.
    [5]
    A coalescing filter according to any one of the preceding claims, wherein the primary coalescing medium has an air permeability of at most 2000 l / m2.s, preferably at most 1750 l / m2.s.
    [6]
    A coalescing filter according to any of the preceding claims, wherein the primary coalescing medium contains a plurality of layers of the same porous material, preferably at least 4 layers, more preferably at least 6 layers, most preferably at least 10 layers.
    [7]
    A coalescence filter according to any of claims 1 to 5, wherein the primary coalescence medium contains one or more layers of a first coalescence medium and one or more layers of a second coalescence medium that is different from the first coalescence medium.
    [8]
    A coalescing filter according to claim 7, wherein the first coalescing medium is wetting for the contamination to be coalesced, and the second coalescing medium is non-wetting for the contamination to be coalesced.
    [9]
    A coalescing filter according to any one of the preceding claims, wherein the primary coalescing medium has a density between 0.08 and 0.50 g / cm 3, preferably between 0.10 and 0.25 g / cm 3, preferably between 0.12 and 0.17 g / cm 3.
    [10]
    A coalescing filter according to any one of the preceding claims, wherein the primary coalescing medium is made up of one or more layers of a porous fibrous material, which essentially contains fibers with an average diameter of 0.25-20 µm, preferably 0.5-10 pin.
    [11]
    A coalescing filter according to any one of the preceding claims, wherein the coalescing filter, adjacent a surface of the primary coalescing medium, comprises a layer of a drainage material, preferably along a downstream surface of the primary coalescing medium along which coalesced contamination leaves the primary coalescing medium, for the uptake and drainage of coalesced contamination.
    [12]
    A coalescing filter according to the preceding claim, wherein the drainage layer is made of a thermoplastic or thermosetting plastic, an organic or inorganic material, a metallic material or alloy, or a mixture of two or more of said materials and chemically modified forms thereof.
    [13]
    A coalescing filter according to any one of the preceding claims, wherein the coalescing filter, adjacent to a surface of the primary coalescing medium, comprises a layer of a protective material, along an upstream surface of the primary coalescing medium along which the fluid is supplied to the primary coalescing medium.
    [14]
    A coalescing filter according to any one of the preceding claims, wherein the primary coalescing medium is made from a material selected from the group of hydrophobic, hydrophilic, oleophobic or oleophilic fibrous materials or a mixture of two or more thereof.
    [15]
    A coalescing filter according to any one of the preceding claims, wherein the primary coalescing medium is made from an oleophilic or oleophobic fiber-like material or a mixture thereof.
    [16]
    A coalescing medium according to any of claims 1-15 for use in a coalescing filter according to any of claims 1 to 15.
    [17]
    A method of purifying a fluid containing a carrier and at least one contaminant, the fluid being passed through a coalescing filter according to any of claims 1 to 15, for reducing the concentration of the at least one contaminant by coalescence this contamination in the coalescing filter.
    [18]
    A method according to claim 17, wherein the fluid is selected from the group of compressed air contaminated with one or more hydrocarbons, contaminated water or contaminated hydrocarbons.
    [19]
    A method according to claim 17 or 18, wherein the at least one impurity belongs to the group of liquids, aerosols, macro-drops or mixtures of two or more of these materials.
    [20]
    A method according to any of claims 17-19, wherein the supply of fluid is continuous.
    [21]
    A method according to any of claims 17-20, wherein at least a fraction of said fluid is supplied to the coalescing medium at an angle of 1 to 90 °
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    法律状态:
    优先权:
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