WO2015143155A1 - Droplet coalescers - Google Patents

Droplet coalescers Download PDF

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Publication number
WO2015143155A1
WO2015143155A1 PCT/US2015/021465 US2015021465W WO2015143155A1 WO 2015143155 A1 WO2015143155 A1 WO 2015143155A1 US 2015021465 W US2015021465 W US 2015021465W WO 2015143155 A1 WO2015143155 A1 WO 2015143155A1
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WIPO (PCT)
Prior art keywords
coalescer
fluid
droplets
coalescing element
flow
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PCT/US2015/021465
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French (fr)
Inventor
Andrew W. Rabins
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3M Innovative Properties Company
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Publication of WO2015143155A1 publication Critical patent/WO2015143155A1/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D17/00Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/02Separation of non-miscible liquids
    • B01D17/04Breaking emulsions
    • B01D17/045Breaking emulsions with coalescers

Definitions

  • This disclosure relates to droplet coalescers that aggregate droplets of a discontinuous phase dispersed in a continuous phase.
  • the coalescers have one or more fluid transport layers that comprise at least one structured surface that has a plurality of longitudinal grooves where droplets may aggregate or coalesce as the continuous phase flows tangentially to the surface.
  • oil droplets in a water stream or water droplets in an oil stream wick into the longitudinal grooves and coalesce; flow is under laminar conditions.
  • the devices disclosed herein are particularly useful in mining as well as oil & gas applications.
  • emulsions can be formed at various points throughout the operation.
  • SX solvent extraction
  • EW electrowinning
  • emulsions can form between the various aqueous streams such as leach solution or electrolyte for electrowinning and the organic phase used for solvent extraction.
  • This organic is a kerosene based fluid containing a 20-30% mixture of aldoxime and ketoxime moieties that chelate the target metal, such as copper or nickel.
  • the emulsions form when the organic phase is contacted with either the pregnant leach solution (PLS) or electrolyte in the electrowinning circuit.
  • PLS pregnant leach solution
  • electrolyte in the electrowinning circuit.
  • the residence time in the settling tanks may not be sufficient for the phases to completely disengage.
  • Phase separation is also difficult in the presence of an interphase containing solid & particulates, degraded organic, and other contaminants.
  • a device or element that coalesces discontinuous droplets into larger sizes will make industrial unit operations for separation, such as hydrocyclones, flotation units, and walnut shell filters, more efficient and effective, resulting in increased throughput, capital avoidance, and reduction in the use of chemicals such as flocculants and de-emulsifiers, particularly upstream of the flotation units.
  • the likelihood of violating discharge conditions is decreased and fewer production interruptions are expected.
  • droplets having a diameter in the range of less than 50 ⁇ can be coalesced and removed. Reduction of oil content by up to 99% was achieved, with a corresponding reduction in turbidity. Because this is a coalescing device and not a filter, at steady state, the amount of each of oil and water entering the coalescer is the same as the amount exiting it.
  • This devices and elements provided herein have industrial utility in treating produced water from enhanced oil recovery (EOR) and fracking operations, as well as recovering the ketoxime solvents used for copper extraction in hydrometallurgical mining.
  • a coalescer for aggregating droplets of a discontinuous phase dispersed in a continuous phase comprises: a housing; a coalescing element located in the housing, the coalescing element comprising at least one flow channel defined by a cap layer arrayed with a fluid transport layer that comprises at least one structured surface that has a plurality of longitudinal grooves; and a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
  • An additional aspect is a method for aggregating droplets of a discontinuous phase dispersed in a continuous phase, the method comprising: contacting with a feed having the droplets of the discontinuous phase dispersed in the continuous phase with an embodiment of any coalescing element or coalescer disclosed herein; a fluid inlet and a fluid outlet in fluid communication with the coalescing element; wherein the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet.
  • flow into the fluid inlet is laminar having a Reynolds number of Re ⁇ 10.
  • the discontinuous phase is oil and the continuous phase is water and the Dso droplet particle size in the feed into the fluid inlet is in the range of 10-25 micrometers and the Dso droplet particle size upon flow out of the fluid outlet is in the range of at least 30-75 micrometers.
  • a further aspect is a method of making a coalescer, the method comprising: forming a coalescing element comprising flow channels defined by a cap layer arrayed with a fluid transport layer, at least one of which comprises at least one structured surface that has a plurality of longitudinal grooves; locating the coalescing element in a housing; and providing or forming a fluid inlet and a fluid outlet to the flow channels.
  • coalescer for aggregating oil droplets dispersed in an aqueous phase
  • the coalescer comprising: a coalescing element comprising a fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves, the structured surface being hydrophobic and comprising peaks and minor features; and a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
  • the longitudinal grooves of the coalescer may be horizontal and the combination of peaks and minor features may narrow away from the direction of gravity.
  • the cap layer may comprise a second fluid transport layer that comprises at least one structured surface.
  • One or both of the first and the second fluid transport layers may comprise two structured surfaces.
  • One or more additional fluid transport layers may be present in the coalescer.
  • the fluid transport layers may be microreplicated. Both the first and the second fluid transport layers may comprise a microfluidic film.
  • the coalescing element may comprise a plurality of layers in a stacked relation.
  • the coalescing element may comprise a plurality of layers in a spiral-wound configuration.
  • the plurality of layers may be assembled with a frame.
  • the cap layer may comprise a polymeric material that comprises a non-permeable material, a web material, an apertured polymeric film, a wet-laid material, a nonwoven material, a woven material, or combinations thereof.
  • the structured surface may be hydrophilic, hydrophobic, or amphiphilic.
  • the structured surface may have at least two regions of different wettabilities, wherein a first region is hydrophilic, hydrophobic, or amphiphilic and a second region is hydrophobic, amphiphilic, or hydrophilic while having a different wettability from the first region.
  • the structured surface may comprise peaks and minor features.
  • the grooves may have an average width ranging from 1 micrometer to 500 micrometers and an average depth ranging from 1 to 500 micrometers, and wherein the flow channel has a height ranging from 100 to 1500 micrometers. More specifically, the average width of the grooves may range from 25 to 100 micrometers, and wherein the height of the flow channel may range from 250 to 500 micrometers.
  • the grooves may have a minimum aspect ratio in the range of 10:1 (or 100:1 , or 1000:1 ) and a hydraulic radius no greater than 300 ⁇ (or less than 100 ⁇ or even less than 10 ⁇ ).
  • the fluid transport layers may have a thickness in the range of 100-1000 micrometers (or 100-500 micrometers, or even 100-350 micrometers).
  • the flow in the coalescer may be laminar having a Reynolds number of Re ⁇ 10, and the flow is such that residence time of the droplets allows for the droplets to have agglomerated such that the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet.
  • the flow channel may comprise a porous spacer between the layers.
  • the housing may be pressure-rated.
  • the housing may comprise two end plates mechanically fastened together or a pipe.
  • FIG. 1 is an expanded schematic of a coalescing element where nominally small droplets coalesce into larger droplets
  • FIG. 2 is an end view schematic of an exemplary coalescing element that is in a stacked relation with the grooves facing downwards;
  • FIG. 3 is end view schematic of an exemplary coalescing element that is in a spiral-wound configuration
  • FIGS. 4a, 4b, and 4c provide end views of exemplary flow transport layers
  • FIG. 5 is a perspective view of an exemplary coalescer in a horizontal orientation
  • FIG. 6 is an expanded cross-sectional view of an exemplary coalescer through line 6-6 of FIG. 5;
  • FIG. 7 is a flow schematic of a system utilizing a coalescer.
  • the coalescers comprise a coalescing element located in a housing, the coalescing element comprising at least one flow channel defined by a cap layer arrayed with a fluid transport layer that comprises at least one structured surface that has a plurality of longitudinal grooves.
  • a fluid inlet and outlet in fluid communication with the coalescing element.
  • Exemplary fluid transport layers comprise microreplicated films that have surface structures that are designed for contact with droplets in a continuous phase. Such microreplicated films may be stacked or spiraled together alone or with other layers, some of which may provide additional functionality such as spacing and/or flow enhancement.
  • nominally small droplets entering a coalescing element agglomerate upon contact with the structured surface of the fluid transport layer, thereby forming droplets of a larger size.
  • droplets generally agglomerate such that the D50 droplet particle size is bigger, by for example at least a factor of 3 (or 10 or 100), upon flow out of the fluid outlet relative to the D50 droplet particle size upon flow into the fluid inlet.
  • An expanded schematic of a coalescing element is provided in FIG.
  • nominally small droplets 12 are carried by a liquid (e.g., oil droplets of a contaminated water stream) the direction of the arrow into a coalescing element 10, and upon contact with the structured surfaces (not shown) of fluid transport layers 16 (shown in expanded form for clarity) that form flow channels 18, larger droplets 14 are formed.
  • Reference to nominally small droplets means less than 50 ⁇ (e.g. 1 -50 ⁇ or even 10-20 ⁇ ). Specifically, the droplets wick into the longitudinal grooves of the structured surface, and then move downstream with the flow. Residence time in the coalescing element is inversely related to flow rate and directly related to the length of the channels and their cross-sectional area, which are designed as needed for particular applications.
  • Cross-sectional area is impacted by the design of the structured surface. As the droplets progress through the channel, they coalesce into larger droplets. These larger droplets (>100 ⁇ ) easily separate from the continuous phase due to Stokes' Law, often in a settling tank without further assistance.
  • the coalescers may be used, for example, in O&G and mining applications, where coalescence of oil-phase droplets from water or water-phase droplets from oil will facilitate operations. For example, coalesced droplets would lead to easier separation in downstream operations.
  • costly chemicals such as flocculants & de-emulsifiers are added to help break these emulsions.
  • a device that coalesces the oil without the need for these chemicals would have immediate impact.
  • mining the use of a coalescer would allow for recovery of the valuable organic that is either lost or collected from a raffinate pond, where expensive re-processing is subsequently required.
  • coalescers disclosed herein can accommodate large amounts of flow at low pressure drop (up to 10,000 Liters/(m 2* hr) at less than 5 psig), which means that the coalescers are a practical technical solution that fits into existing operations, such as hydraulics of the mine.
  • An "emulsion” is a two-phase mixture where droplets of a discontinuous phase are dispersed in a continuous phase.
  • an oil-in- water emulsion comprises discontinuous oil droplets dispersed in a continuous aqueous phase.
  • a water-in-oil emulsion comprises discontinuous water droplets dispersed in a continuous oil phase.
  • a "coalescing element” is a module of the coalescers, comprising at least one fluid transport layer with a structured surface in conjunction with a cap layer to define a flow channel.
  • the coalescing element is located in a housing that has mechanical strength, and usually the housing is pressure-rated to endure conditions during industrial use. The coalescing element is replaced as needed.
  • a “fluid transport layer” is a fundamental structure of the coalescing element. Reference to “fluid transport” means that liquid flow is tangential to the surface of the layer. Fluid transport layers are generally a film formed from a polymeric material that is substantially impermeable and/or resistant to diffusion of the liquid. Specifically, on a microscopic level, liquid flow is not perpendicular through the layer. Thus, the fluid transport layers are non-filtering. Holes or openings may be provided in fluid transport layers to facilitate different flow patterns on a macroscopic level. At least one surface of the fluid transport layer has a structured surface with a plurality of longitudinal grooves to facilitate wicking and aggregating of droplets.
  • a plurality of layers may be formed from a continuous source of material that is rolled or spiraled to form an array of layers.
  • layers may be formed from individual pieces of material that are arrayed together, possibly in a stack or in a framework. Design of each layer may be independent, allowing for various configurations of: structured surfaces and location of the same; materials; hydrophilic, hydrophobic, or amphiphilic nature; and the like.
  • the layers in some embodiments may be identical, and in other embodiments, they may be different. [0039] Reference to "wick” or “wicking” means movement by capillary action due to intermolecular forces between a liquid and nearby solid surfaces.
  • wicking of the emulsion itself within the longitudinal grooves is achieved in the longitudinal direction upon entry into the individual grooves from the inlet.
  • wicking of the droplets in both the longitudinal and the axial direction is also expected based on the interactions of the droplets themselves with the structured surface. Without intending to be bound by theory, it is thought that a hydrophobic surface will facilitate separation and coalescence of oil droplets from an aqueous phase. Likewise, it is thought that a hydrophilic surface will facilitate separation and coalescence of water droplets from an oil phase.
  • Enhanced wicking may be achieved by orienting the structured surface to take advantage of gravity and/or density differences. For example, when separating oil droplets from a continuous water phase through a horizontally- positioned coalescer, locating the narrowest part of the structured surface at the top of the flow channel facilitates direct contact of the structured surface with the oil droplets, which rise and will readily coalesce upon contact with the structured surface and with other dispersed oil droplets.
  • Reference to "arrayed” means an assembly of layers to receive liquid flow and to achieve coalescing, where the layers may or may not be in direct contact with each other.
  • a “cap layer” is a layer that provides a surface (or cap) to the flow channels.
  • the cap layer may any polymeric film that is present arrayed with a fluid transport layer.
  • the cap layer may in fact be another fluid transport layer or a spacer layer or some other functional layer.
  • Flow channels are passages that direct a fluid along a particular path. When flow channels are discrete, the flow of each channel is independent.
  • Longitudinal grooves run along the length of an element or device. The grooves are not necessarily parallel along the length, longitudinal in this case mean the grooves generally run in the lengthwise direction.
  • Fluid means a volume of gas and/or liquid.
  • Hydraulic radius is the wettable cross-sectional area of a channel divided by the length of its wettable perimeter. For a circular channel, the hydraulic radius is one-fourth its diameter.
  • Flexible layers refer to structures that are non-rigid and can be rolled onto itself and unrolled without damage. Also, upon bending or flexing, there is not significant flow channel constriction. Generally, the fluid transport layers are flexible. In one or more embodiments, such layers may be rolled around a 1 cm radius. Each layer is typically 350-500 ⁇ thick.
  • the longitudinal grooves of the structures surface may be aligned in a manner best suited for flow and aggregation.
  • the grooves may be axially aligned or aligned along the spiral path.
  • Axial alignment may help reduce the Reynolds number, depending on total flow channel area as compared to an inlet cross-section.
  • Spiral flow may increase the flow resistance and pressure drop while enhancing aggregation by increasing the acceleration force on the droplets, which in turn enhances the effect of Stoke's Law.
  • a minimum bend radius may be 1 cm.
  • Spiraled layers may utilize one roll of material, or it may be desired to provide two or more dissimilar layers that are spiraled together.
  • the additional layers may or may not have structured surfaces and may provide additional functionality such as providing spacing.
  • Weightability means a characteristic of a material by reference to what liquids are capable of wetting or maintain contact with the structure.
  • hydrophilicity, hydrophobicity, oleophilicity, oleophobicity, and amphiphilicity describe the wettability of a material.
  • Hydrophilic refers to a material that is wettable by water, which is the continuous phase in an oil-in-water emulsion, but the discontinuous phase in a water-in-oil emulsion.
  • Water generally has a contact angle of less than 90° with hydrophilic materials. Exemplary such structures are hydrophilic by virtue of the materials used to fabricate the layer and/or by treatment.
  • Hydrophobic refers to a material that is not wettable by water. Water generally has a contact angle of 90° or greater with hydrophobic materials. Exemplary such structures are hydrophobic by virtue of the materials used to fabricate the layer and/or by treatment.
  • Oleophilic refers to a material that is wettable by oil. Oil generally has a contact angle of less than 90° with oleophilic materials. Exemplary such structures are oleophilic by virtue of the materials used to fabricate the layer and/or by treatment. For the purposes of this disclosure, materials that are oleophilic are also hydrophobic.
  • Oleophobic refers to a material that is not wettable by oil. Oil generally has a contact angle of 90° or greater with oleophobic materials. Exemplary such structures are oleophobic by virtue of the materials used to fabricate the layer and/or by treatment. For the purposes of this disclosure, materials that are oleophobic are also hydrophilic.
  • Amphiphilic layer refers to a material that is wettable by both oil and water. Exemplary such structures are amphiphilic by virtue of the materials used to fabricate the layer and/or by treatment.
  • Combination layers may provide designs of different hydrophobic, hydrophilic, and/or amphiphilic regions in the same layer.
  • the conditions for the coalescers herein are Re ⁇ 1000.
  • Re ⁇ 10 completely laminar flow is expected.
  • Re ⁇ 10, or ⁇ 3, or even ⁇ 2 may be desired.
  • Dso particle size refers to a median droplet size where 50% of the total volume of the discontinuous phase is in droplets which have a diameter that is less than the recited Dso particle size and 50% of the volume has droplet diameters which are greater.
  • Dio particle size refers to a median droplet size where 10% of the total volume of the discontinuous phase is in droplets which have a diameter that is less than the recited Dio particle size and 90% of the volume has droplet diameters which are greater.
  • D90 particle size refers to a median droplet size where 90% of the total volume of the discontinuous phase is in droplets which have a diameter that is less than the recited D90 particle size and 10% of the volume has droplet diameters which are greater.
  • Structured surface means has a nonplanar surface that has defined features in a predetermined arrangement.
  • An exemplary disclosure for providing a structured surface on a substrate is commonly-assigned WO201 1/056496, the disclosure of which is incorporated herein by reference.
  • a surface having "peaks” and “minor features” is one where the peaks are higher than the minor features. As such, varying surfaces for contacting droplets and directing flow are provided. Both peaks and minor features are the result of the structure molded, extruded, or cast into the microfluidic film.
  • Microreplication or “microreplicated” means the production of a microstructured surface through a process where the structured surface features retain individual feature fidelity during manufacture, from product-to product, that varies no more than about 50 ⁇ .
  • Microstructured channels or “microstructured flow channels” refer to channels that have a minimum aspect ratio of about 10:1 and a hydraulic radius no greater than about 300 ⁇ .
  • housing means a structure with mechanical strength that is adequate to withstand at least a desired pressure rating and/or assembly into an industrial setting.
  • pressure-rated means the housing can withstand pressures greater than or less than atmospheric.
  • the fluid transport layers used herein made from a material that is substantially impermeable and/or resistant to diffusion of a fluid, e.g., liquid. Specifically, on a microscopic level, liquid flow is not perpendicular through the layer. Thus, the fluid transport layers are non-filtering and are for fluid transport.
  • a fluid e.g., liquid.
  • the fluid transport layers are non-filtering and are for fluid transport.
  • An exemplary disclosure of microchanneled active fluid transport devices that may be suitable herein is commonly-assigned U.S. Patent No. 6,290,685 (Insley), the disclosure of which is incorporated herein by reference.
  • Fluid transport layers for any of the embodiments in accordance with the present invention can be formed from a variety of polymer materials such as polymers and copolymers including thermoplastic, thermoset, and curable polymers.
  • thermoplastic as differentiated from thermoset, refers to a polymer which softens and melts when exposed to heat and re-solidifies when cooled and can be melted and solidified through many cycles.
  • thermoset polymer on the other hand, irreversibly solidifies when heated and cooled.
  • a cured polymer system, in which polymer chains are interconnected or crosslinked, can be formed at room temperature through use of chemical agents or ionizing irradiation.
  • polystyrene resin e.g., polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene resin, polystyrene (PVdF)), acrylate polymers (e.g., polymethyl methacrylate), polycarbonate polymers, polyesters (e.g., polyethylene terephthalate), polyamides (e.g., Nylon), polyurethanes, polysaccharides (e.g.
  • vinyl polymers e.g., polyvinyl chloride, polyvinyl alcohol, vinyl chloride/vinyl alcohol copolymers, polyvinylidene chloride, polyvinylidine difluoride (PVdF)
  • Other functional layers may be provided to facilitate flow through the coalescers by reducing pressure drop and/or encourage wicking and/or promote uniform flow. It may be desirable to provide a porous spacer, for example, such as a nonwoven polymeric material, e.g., a blown melt fiber(BMF) web, in order to control pressure drop through the coalescer.
  • a porous spacer for example, such as a nonwoven polymeric material, e.g., a blown melt fiber(BMF) web
  • Another possible spacer or flow enhancer may be a polymeric material that comprises an extruded web material or an apertured polymeric film, or combinations thereof.
  • An exemplary aperture polymeric film is 10 mil polypropylene Delnet.
  • An exemplary extruded web is 30 mil polypropylene Naltex (nettings).
  • the coalescing element 10 comprises at least one flow channel 18 defined by a first fluid transport 16a arrayed in a stacked relation with a cap layer 20.
  • a plurality of fluid transport layers 16a, 16b, 16c, 16d, 16e are provided in this embodiment, where layers 16a, 16b, 16c, and 16d functionally serve as cap layers to layers 16b, 16c, 16d, and 16e respectively.
  • Each fluid transport layer 16a-16e as shown here has a major surface 23 opposite the structured surface.
  • the major surface 23, also referred to as "land” may have a thickness in the range of 4-6 mils. Different embodiments may provide that the fluid transport layer has two structured surfaces.
  • the coalescing element comprises a cassette frame to which the layers are glued.
  • the layers may comprise different channel configurations and/or number of channels, depending on a particular application.
  • the fluid transport layers 16 have structured surfaces on one surface only, but it is contemplated that both surfaces of one or more of the fluid transport layers may be structured in the same or different patterns.
  • holes or openings may be provided in fluid transport layers or cap layers or any additional layers to facilitate different flow patterns on a macroscopic level. For example, it may be beneficial to provide holes through one layer to divert flow to another layer, should channels of one layer become fouled and/or shut down.
  • FIGS. 4a, 4b, and 4c provide end views of exemplary flow transport layers.
  • FIG. 4a represents the fluid transport layers 16a-e exemplified in FIG. 2, that is, fluid transport layer 16 has a structured surface comprising multiple inverted v-shaped peaks 26 that define flow channels 18.
  • Other configurations are contemplated.
  • channels 18' have a wider flat valley between slightly flattened peaks 26'.
  • a cap layer can be arrayed along one or more of the peaks 26' to define discrete channels 18'.
  • FIG. 4c illustrates a configuration where wide channels 28 are defined between peaks 26", but instead of providing a flat surface between channel sidewalls, a plurality of minor features 33 are located between the sidewalls of the peaks 26". These minor features 33 thus define secondary channels 34 therebetween. Minor features (or small peaks) 33 may or may not rise to the same level as peaks 26", and as illustrated create a first wide channel 28 including smaller channels 34 distributed therein. The peaks 18" and 33 need not be evenly distributed with respect to themselves or each other. The smaller channels 34 may be used to control fluid flow through the wider channels 32 by modifying frictional forces along the channel's length.
  • FIGS. 2 and 4a-4c illustrate elongated, linearly configured channels
  • the channels may be provided in other configurations.
  • the channels could have varying cross-sectional widths along the channel length—that is, the channels could diverge and/or converge along the length of the channel.
  • the channel sidewalls could also be contoured rather than being straight in the direction of extension of the channel, or in the channel height.
  • any channel configuration that can provide at least multiple discrete channel portions that extend from a first point to a second point within the coalescing element are contemplated.
  • the channels may be configured to remain discrete along their whole length if desired.
  • the structured surface may be a microstructured surface that defines discrete flow channels that have a minimum aspect ratio (length/hydraulic radius) of 10:1 , in some embodiments exceeding approximately 100:1 , and in other embodiments at least about 1000:1 .
  • the hydraulic radius of a channel is no greater than about 300 ⁇ . In many embodiments, it can be less than 100 ⁇ , and may be less than 10 ⁇ . Although smaller is generally better for many applications (and the hydraulic radius could be submicron in size), the hydraulic radius typically would not be less than 1 mm for most embodiments.
  • channels defined within these parameters can provide efficient bulk fluid transport through a coalescer or device.
  • Microstructured surfaces in accordance with the present invention provide flow systems in which the volume of the system is highly distributed. That is, the fluid volume that passes through such flow systems is distributed over a large area. Microstructure channel density from about 10 per lineal cm (25/in) and up to 1 ,000 per lineal cm (2500/in) (measured across the channels) provide for high fluid transport rates. Generally, when a common manifold is employed, each individual channel has an aspect ratio that is at least 400 percent greater, and more preferably is at least 900 percent greater than a manifold that is disposed at the channel inlets and outlets.
  • the coalescers are assembled by arraying fluid transport layers and/or cap layers, as needed, into a coalescing element which is placed in a housing. Fluid inlets and outlets are provided to the housing and in fluid communication to the flow channels of the coalescing element. As needed, one or more end caps may be affixed to the coalescing element to facilitate fluid communication to and from the coalescing element and into and out of the housing, respectively.
  • a coalescer 100 in a horizontal orientation is provided, where the coalescer 100 comprises a housing 102 that is made from two end plates 104a, 104b with mechanical fasteners 106 that sandwich a coalescing element therein.
  • FIG. 6 shows an expanded cross-sectional view of an exemplary coalescer 100 through line 6-6 of FIG. 5, where the coalescing element comprises a plurality of fluid transport layers 16 that are affixed by glue 19 to a cassette frame 21 .
  • the coalescing element is located between the two end plates 104a, 104b and a gasket 15 provides a liquid tight seal.
  • Gasket materials should be compatible with ingredients of the emulsion.
  • An exemplary gasket material is a fluoroelastomer, which is compatible with many components of crude oil.
  • Suitable materials for housing the coalescing elements have mechanical strength, providing adequate structure to withstand at least a desired pressure rating and/or assembly into an industrial setting.
  • Housings may be formed by two end plates that are mechanically fastened together with coalescing elements being sandwiched therebetween.
  • Other suitable housing may be pipes or self- supporting or braided hoses.
  • the housings may be rigid or semi-rigid.
  • the housings may be "pressure-rated" to withstand pressures greater than atmospheric.
  • coalescers provided herein are included in a system that handles emulsions. Output of the coalescers may be supplied to any desirable process tank of any purpose that is a part of the overall emulsion handling system, usually a separator tank.
  • FIG. 7 provided is a flow schematic that shows a system utilizing a coalescer, where the system 150 has a source of emulsion 130, which for this example is an oil-in-water emulsion that feeds a pump 140 that in turn supplies a coalescer 100. Oil droplets entering the coalescer 100 are nominally small and are larger upon exiting the coalescer.
  • the output of the coalescer 100 having nominally large oil droplets is sent to a separation vessel 160, which is generally set up for settling, where an oil-free aqueous phase is drawn off the bottom to a receptacle 170 or other location and the oil phase from above the aqueous phase is supplied to another receptacle 180 or location.
  • the coalescers may be used in mining applications at locations where emulsions form such as in mixers upstream of settling tanks. Thus, the coalescer would receive flow from one or more mixers. This coalescer could also be positioned at points further downstream or even within the settler. In O&G applications, coalescers may be located downstream of a gravity separation tank (e.g., a "gunbarrel tank"). For such applications, it is noted that fouling challenges may be present, such as particulates, scale, and tarlike organic compounds such as asphaltenes, and there may be a need for ancillary equipment such as a pre-filter upstream of the coalescer.
  • a gravity separation tank e.g., a "gunbarrel tank”
  • fouling challenges may be present, such as particulates, scale, and tarlike organic compounds such as asphaltenes, and there may be a need for ancillary equipment such as a pre-filter upstream of the coalescer.
  • a coalescer for aggregating droplets of a discontinuous phase dispersed in a continuous phase comprising:
  • coalescing element located in the housing, the coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves;
  • Item 2 The coalescer of item 1 , wherein the cap layer comprises a second fluid transport layer that comprises at least one structured surface.
  • Item 3 The coalescer of item 2, wherein at least one of the first and the second fluid transport layers comprise two structured surfaces.
  • Item 4 The coalescer of any one of items 2-3 further comprising one or more additional fluid transport layers arrayed with the first and second fluid transport layers.
  • Item 5 The coalescer of any one of items 1 -4, wherein the first fluid transport layer is microreplicated.
  • Item 6 The coalescer of any one of items 2-5, wherein both the first and the second fluid transport layers comprise a microfluidic film.
  • Item 7. The coalescer of any one of items 1 -6, wherein the coalescing element comprises a plurality of layers in a stacked relation.
  • Item 8. The coalescer of any one of items 1 -6, wherein the coalescing element comprises a plurality of layers in a spiral-wound configuration.
  • Item 9 The coalescer of any one of items 1 -8, wherein the cap layer comprises a polymeric material that comprises a non-permeable material, a web material, an apertured polymeric film, a wet-laid material, a nonwoven material, a woven material, or combinations thereof.
  • Item 10 The coalescer of any one of items 1 -9, wherein the structured surface is hydrophilic, hydrophobic, or amphiphilic.
  • Item 1 1 The coalescer of any one of items 1 -10, wherein the structured surface has at least two regions of different wettablilities, wherein a first region is hydrophilic, hydrophobic, or amphiphilic and a second region is hydrophobic, amphiphilic, or hydrophilic while having a different wettability from the first region.
  • Item 12 The coalescer of any one of items 1 -1 1 , wherein the grooves have an average width ranging from 1 to 500 micrometers and an average depth ranging from 1 to 500 micrometers, and wherein the flow channel has a height ranging from 100 to 1500 micrometers.
  • Item 13 The coalescer of item 12, wherein the average width of the grooves ranges from 25 to 100 micrometers, and wherein the height of the flow channel ranges from 250 to 500 micrometers.
  • Item 14 The coalescer of any one of items 1 -13, wherein the grooves have a minimum aspect ratio in the range of 10:1 and a hydraulic radius of no greater than 300 micrometers.
  • Item 15 The coalescer of any one of items 2-14, wherein the fluid transport layers have a thickness in the range of 100- 1000 micrometers.
  • Item 16 The coalescer of any one of items 1 -15, wherein upon receipt of flow into the fluid inlet, the flow is laminar having a Reynolds number of R e ⁇ 10, and the flow is such that residence time of the droplets allows for the droplets to have agglomerated such that the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet.
  • Item 17 The coalescer of any one of items 1 -16, wherein the flow channel comprises a porous spacer between the layers.
  • Item 18 The coalescer of any one of items 1 -17, wherein the structured surface comprises peaks and minor features.
  • Item 19 The coalescer of any one of items 1 -18, wherein the housing is pressure-rated.
  • Item 20 The coalescer of any one of items 1 -19, wherein the housing comprises two end plates mechanically fastened together or a pipe.
  • Item 21 A system for aggregating of a discontinuous phase dispersed in a continuous phase comprising:
  • coalescer that receives the discontinuous phase dispersed in a continuous phase, the coalescer comprising:
  • coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves;
  • Item 22 The system of item 21 further comprising a process tank that receives flow from the coalescer.
  • Item 23 The system of any one of items 21 -22, wherein the coalescer further comprises a housing that contains the coalescing element.
  • Item 25 A method for aggregating droplets of a discontinuous phase dispersed in a continuous phase, the method comprising:
  • coalescer that comprises; a coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves;
  • Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet.
  • Item 26 The method of item 25, wherein flow into the fluid inlet is laminar having a Reynolds number of R e ⁇ 10.
  • Item 27 The method of any one of items 25-26, wherein the discontinuous phase is oil and the continuous phase is water and the Dso droplet particle size in the feed into the fluid inlet is in the range of 10-25 micrometers and the Dso droplet particle size upon flow out of the fluid outlet is in the range of at least 30-75 micrometers.
  • coalescing element comprising a fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves, the structured surface being hydrophobic and comprising peaks and minor features;
  • Item 30 The coalescer of item 29, wherein the longitudinal grooves are horizontal and the combination of peaks and minor features narrow away from the direction of gravity.
  • Item 31 The coalescer of an one of items 29-30, wherein the coalescing element comprises a plurality of fluid transport layers assembled with a frame.
  • hot melt glue When hot melt glue was used, it was generally Hot Melt Adhesive #3761 (3M Company, St. Paul, MN). When a glue gun was used, it generally was a Model Scotch-Weld Hot Melt Applicator EC (3M Company St. Paul, MN).
  • the fluoroelastomer gasket used in the examples was part #86075K32, McMaster-Carr Corporation, Elmhurst, IL.
  • Turbidity was measured with a Hach AN-2100 turbidimeter (Hach Corporation Loveland, CO). Particle size distribution (PSD) was measured by laser light scattering (LA-300, Horiba Corporation, Kyoto, Japan).
  • PSD particle size distribution
  • FeSO 4 iron sulfate
  • Testing apparatus A supply beaker contained an emulsion to be tested. A mixing apparatus was available to mix the emulsion in the beaker. The emulsion flowed from the beaker to a pumping system (FilterTec pumping system (SciLog Corporation, Madison, Wl)) and into the coalescer. For the O&G surrogate emulsions, effluent of the coalescer was supplied to a separator funnel having an internal volume of roughly 3 liters. The effluent traveled up a tube to the approximate midpoint of this separatory funnel. This vessel was kept liquid-full, and the overflow was discharged from the bottom of the vessel while the oil coalesced at the top of the dome. For the mining surrogate emulsions, the effluent was directed to a beaker.
  • a pumping system FrterTec pumping system (SciLog Corporation, Madison, Wl)
  • O&G surrogate emulsions effluent of the coalesc
  • hexane extraction analysis reagent grade hexane was Spectrophotometric grade n-Hexane (Alfa Aesar Co. Ward Hill MA). Effluent was contacted with the hexane in a vial overnight on a rocker (Vari-Mix Test Tube Rocker, Thermo-Scientific, Waltham, MA). The hexane phase was measured by colorimetric visible spectrometry. A characteristic peak of around 326 nm was observed (DR-3900 spectrometer, Hach Corporation, Loveland, CO) to determine oil content.
  • a coalescing element was made from 15 layers of a microreplicated film having longitudinal grooves spaced on about 60 ⁇ centers and having 54 degree peaks and valley with a 50 micrometer pitch polypropylene, made by 3M Company, St. Paul, MN using an extrusion replication process). Each layer was formed from a sheet that was cut to 2.75" wide by 5" long. The sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 3/8" high with an internal opening of 3"x 6". This left 1 ⁇ 2" of open area at each end for flow distribution and collecting the effluent. The long edges were sealed with 3M hot melt, applied with a glue gun. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
  • An O&G surrogate oil-in-water emulsion was prepared as follows.
  • a surfactant package was made up with the following ingredients: oleic acid (technical grade, Sigma-Aldrich Co. St. Louis, MO), naphthenic acid (TCI Co, LTD, Toshima, Japan), and ethanol (200 proof pure Ethanol, Koptec Co. King of Prussia, PA) in a 2:4:15 ratio (by wt).
  • An organic (oil) phase contained a mixture of: mineral oil (Nujol light oil, Alfa Aesar, Ward Hillm MA), kerosene (Low Odor Kerosene, Alfa Aesar), and xylene (Xylenes ACS grade, EMD Co (Merck) Darmstadt, Germany) in a 2:3:1 ratio by weight.
  • a 1 % saline solution was used for the aqueous phase.
  • the surfactant package, organic (oil) phase, and aqueous phase were mixed to form an emulsion using a IKA Turrax T-18 mixer (VWR Corporation, Radnor, PA).
  • a coalescing element was made from 14 alternating layers of the same microreplicated film as Example 1 and spacer layers (a 25 grams/m 2 85/25 w/w polyethylene/polypropylene (PE/PP) blown melt fibers (BMF) in a cassette frame (polypropylene). Each layer was formed from a sheet that was cut to 2.75" wide by 5" long. The sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 3/8" high with an internal opening of 3"x 6". This left 1 ⁇ 2" of open area at each end for flow distribution and collecting the effluent. The long edges were sealed with hot melt glue applied with a glue gun. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
  • spacer layers a 25 grams/m 2 85/25 w/w/w/w polyethylene/polypropylene (PE/PP) blown melt fibers (B
  • Inlet flow of the emulsion started at 30 ml/min, and then was gradually increased to 50 ml/min such that about 5 L of emulsion was processed through the coalescer.
  • the pressure drop (delta P) was observed to be less than 2 psi throughout the run. Oil was observed coalescing in the separator about an hour after flow was started, first as droplets on the walls, and then as a red layer on top. PSD data showed that the coalescer was taking out virtually all droplets larger than 2 ⁇ .
  • the flow rate was increased to 75 ml/min (4.5 L/hr).
  • the cassette had a cross sectional area of approximately 4 cm 2 , of which most of the space was taken up by the microreplicated film, which was 420 ⁇ thick.
  • Residence time for fluid flowing through the stack of sheets for two exemplary void fractions is provided as follows.
  • a mining (SX) surrogate oil-in-water emulsion was prepared as follows. This is derived from BASF monograph D/EVH 017e "Standard quality control test of LIXTM reagents", dated August 2012 which is the basis of design for the "mix vessel”
  • steps 6-9) was repeated roughly every 20-40 minutes, depending on flow rate, in order to keep the system supplied with feed.
  • the coalescing element comprised a microreplicated riblet film was used having a geometry identical to what is shown in Figure 4a, with the grooves having a pitch and depth of approximately 65 ⁇ . 10 pieces of film were cut into 2-3/4" x 5" dimensions with the grooves oriented along the 5" edge. These pieces were alternated with a similarly sized piece of 32 gsm polypropylene BMF web with an EFD of 1 1 .4 microns. . A coalescer was formed with the pieces as described in Example 1 . Note, the spacer material was added on day 2 of the experiment, as it was quickly evident that the microreplicated film on its own had too high a pressure drop (greater than 35 psig).
  • the feed typically had a Dso of 18.8 ⁇ . Late in the experiment, analysis showed that the apparatus was coalescing the droplets from a Dso of approximately 25 ⁇ up to a Dso of 250 ⁇
  • a coalescing element was made from 10 layers of a microfluidic film having peaks and minor features in accordance with FIG. 4c (5 mil land, 8 mil peaks polypropylene, made by 3M Company, St. Paul, MN) in a cassette frame (polypropylene). Each layer was formed from a sheet that was cut to 2.5" wide by 5" long. The sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 1/8" high with an internal opening of 3"x 6". Note that no additional layers were inserted between the microreplicated sheets. This left 1 ⁇ 2" of open area at each end for flow distribution and collecting the effluent. The long edges were sealed with hot melt glue applied with a glue gun. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
  • a surrogate oil-in-water emulsion was prepared in a manner similar to that of Example 1 , except that for the organic/oil phase, 500 ppm of actual crude oil (containing at least paraffins, aromatics, and asphaltenes) was used. This emulsion was pumped through the coalescer at flow rates in the range of 30-70 ml/min. Given the dimensions of the coalescer, this corresponds to a flux of 9,000-20,000 LMH.
  • a coalescing element was made in a similar manner to Example 4 except that the number of layers was reduced from 15 layers of the same media down to 3 layers.
  • the layers, with the channels facing down, were placed in between two pieces of the same McMaster-Carr gasket material (except that this sheet stock was slightly thicker than 1/8") that was slightly shorter than the film to reduce the possibility of closing off the passageway and creating a bypass (Note: for flux calculation purposes, only two layers are considered. It is assumed that the bottom layer was sealed off against the gasket material). This increased the flux by a factor of 5-6, enabling the system to more quickly achieve steady state.
  • Each layer was formed from a sheet that was cut to 3" wide by 5" long.
  • the sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 3/8" high with an internal opening of 3"x 6". Note that no additional layers were inserted between the microreplicated sheets. This left 1 ⁇ 2" of open area at each end for flow distribution and collecting the effluent. Because of the additional gasket material and the wider film it was not necessary to seal the longitudinal edges with hot melt adhesive. A small bead of hot melt was applied at the upstream junction of the film/elastomer and the frame to eliminate. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
  • the effluent from the coalescer was collected directly in a beaker.
  • the system was run for 4-6 hours a day for four days.
  • the flow rate was 20 ml/min throughout, although with the minimized number of layers the flux was 23,000LMH.
  • the turbidity of the surrogate feed was routinely between 400-470 NTU.
  • the effluent turbidity from the coalescer was typically in the 100-150 NTU range, which corresponds to roughly a 65% reduction.
  • the outlet turbidity was noted to drop to the 43-47 NTU range, which is a 90% reduction.

Abstract

Coalescers having one or more fluid transport layers that comprise at least one structured surface that has a plurality of longitudinal grooves are provided. Discontinuous droplets in a continuous phase aggregate or coalesce as the continuous phase flows tangentially to the surface. Specifically, oil droplets in a water stream or water droplets in an oil stream wick into the longitudinal grooves and coalesce; flow is under laminar conditions. The coalesced droplets are discharged from the coalescer in much larger form relative to the size upon entry to the coalescer. For example, upon entry of 10-25 µm droplets in the discontinuous phase, droplets are 30-75 µm or even 100-250 µm or larger upon exit.

Description

DROPLET COALESCERS
TECHNICAL FIELD
[0001] This disclosure relates to droplet coalescers that aggregate droplets of a discontinuous phase dispersed in a continuous phase. The coalescers have one or more fluid transport layers that comprise at least one structured surface that has a plurality of longitudinal grooves where droplets may aggregate or coalesce as the continuous phase flows tangentially to the surface. Specifically, oil droplets in a water stream or water droplets in an oil stream wick into the longitudinal grooves and coalesce; flow is under laminar conditions. The devices disclosed herein are particularly useful in mining as well as oil & gas applications.
BACKGROUND
[0002] Effective separation of oil droplets from water or water droplets from oil has commercial significance in both mining and oil & gas (O&G) applications. In O&G, the presence of emulsified oil in produced water and other waste streams presents a challenge to both onshore and offshore operations. Regulations for offshore oil platforms dictate that, for example, the oil content must be reduced below 30 ppm (or less) in order to discharge produced water or other waste streams back into the ocean, and restrictions are also imposed for surface discharge onshore. A number of unit operations such as hydrocyclones, flotation units, and walnut shell filters have historically been used to remove the oil with varying degrees of effectiveness. One of the keys for separating oil droplets from water or water droplets from oil is droplet size. Stokes' Law dictates that an immiscible droplet will settle (or rise) at a velocity that is inversely proportional to the square of the droplet diameter. For example, a 100 m droplet will separate two orders of magnitude faster than a 10 μιτι droplet. And most of the aforementioned unit operations depend on a gravity field to effect the separation. Discontinuous phase droplets, e.g. the oil, in emulsions found in O&G operations are routinely as small as 1 μιτι in size (there are smaller droplets, but generally these do not contribute significantly to the total oil content).
[0003] In hydrometallurgical mining operations, also known as leaching, solvent extraction (SX), and electrowinning (EW), emulsions can be formed at various points throughout the operation. During SX, emulsions can form between the various aqueous streams such as leach solution or electrolyte for electrowinning and the organic phase used for solvent extraction. This organic is a kerosene based fluid containing a 20-30% mixture of aldoxime and ketoxime moieties that chelate the target metal, such as copper or nickel. The emulsions form when the organic phase is contacted with either the pregnant leach solution (PLS) or electrolyte in the electrowinning circuit. The residence time in the settling tanks may not be sufficient for the phases to completely disengage. Phase separation is also difficult in the presence of an interphase containing solid & particulates, degraded organic, and other contaminants. Presently there is not an effective process solution for separating this type of emulsion. This leads to significant organic losses as the organic is carried back to the heap leaching, as well as into the electrowinning circuit where it can degrade the copper cathodes (the actual production of the mine) and cause other processing problems. These organic losses require makeup chemicals, which are costly for mines.
[0004] There is a need to provide efficient, compact, and cost-effective methods for handling and processing emulsions.
SUMMARY
[0005] A device or element that coalesces discontinuous droplets into larger sizes will make industrial unit operations for separation, such as hydrocyclones, flotation units, and walnut shell filters, more efficient and effective, resulting in increased throughput, capital avoidance, and reduction in the use of chemicals such as flocculants and de-emulsifiers, particularly upstream of the flotation units. In addition, the likelihood of violating discharge conditions is decreased and fewer production interruptions are expected. Upon coalescence of droplets to a diameter size of several hundred microns or even millimeter size, they can easily be separated by gravity alone. For example, droplets having a diameter in the range of less than 50 μιτι (e.g., 1 -50 μιτι, 20-50 μιτι and/or smaller than 10 μιτι) can be coalesced and removed. Reduction of oil content by up to 99% was achieved, with a corresponding reduction in turbidity. Because this is a coalescing device and not a filter, at steady state, the amount of each of oil and water entering the coalescer is the same as the amount exiting it. This devices and elements provided herein have industrial utility in treating produced water from enhanced oil recovery (EOR) and fracking operations, as well as recovering the ketoxime solvents used for copper extraction in hydrometallurgical mining.
[0006] Provided are droplet coalescers and systems that utilize the droplet coalescers, and methods of making and using the same.
[0007] In a first aspect, a coalescer for aggregating droplets of a discontinuous phase dispersed in a continuous phase comprises: a housing; a coalescing element located in the housing, the coalescing element comprising at least one flow channel defined by a cap layer arrayed with a fluid transport layer that comprises at least one structured surface that has a plurality of longitudinal grooves; and a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
[0008] Another aspect provides a system for aggregating of a discontinuous phase dispersed in a continuous phase comprising: a source of the discontinuous phase dispersed in a continuous phase; a coalescer that receives the discontinuous phase dispersed in a continuous phase, an embodiment of any coalescing element or coalescer disclosed herein; a fluid inlet and a fluid outlet in fluid communication with the coalescing element. The system may further comprise a process tank that receives flow from the coalescer. The system may further comprise a pre-filter that receives the discontinuous phase dispersed in a continuous phase from the source and supplies a filtered flow to the coalescer.
[0009] An additional aspect is a method for aggregating droplets of a discontinuous phase dispersed in a continuous phase, the method comprising: contacting with a feed having the droplets of the discontinuous phase dispersed in the continuous phase with an embodiment of any coalescing element or coalescer disclosed herein; a fluid inlet and a fluid outlet in fluid communication with the coalescing element; wherein the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet. In an embodiment, flow into the fluid inlet is laminar having a Reynolds number of Re< 10. In a detailed embodiment, the discontinuous phase is oil and the continuous phase is water and the Dso droplet particle size in the feed into the fluid inlet is in the range of 10-25 micrometers and the Dso droplet particle size upon flow out of the fluid outlet is in the range of at least 30-75 micrometers.
[0010] A further aspect is a method of making a coalescer, the method comprising: forming a coalescing element comprising flow channels defined by a cap layer arrayed with a fluid transport layer, at least one of which comprises at least one structured surface that has a plurality of longitudinal grooves; locating the coalescing element in a housing; and providing or forming a fluid inlet and a fluid outlet to the flow channels.
[0011] Another aspect is a coalescer for aggregating oil droplets dispersed in an aqueous phase, the coalescer comprising: a coalescing element comprising a fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves, the structured surface being hydrophobic and comprising peaks and minor features; and a fluid inlet and a fluid outlet in fluid communication with the coalescing element. The longitudinal grooves of the coalescer may be horizontal and the combination of peaks and minor features may narrow away from the direction of gravity.
[0012] Other features that may be used individually or in combination with respect to any aspect of the invention are as follows.
[0013] The cap layer may comprise a second fluid transport layer that comprises at least one structured surface. One or both of the first and the second fluid transport layers may comprise two structured surfaces. One or more additional fluid transport layers may be present in the coalescer.
[0014] The fluid transport layers may be microreplicated. Both the first and the second fluid transport layers may comprise a microfluidic film.
[0015] The coalescing element may comprise a plurality of layers in a stacked relation. The coalescing element may comprise a plurality of layers in a spiral-wound configuration. The plurality of layers may be assembled with a frame.
[0016] The cap layer may comprise a polymeric material that comprises a non-permeable material, a web material, an apertured polymeric film, a wet-laid material, a nonwoven material, a woven material, or combinations thereof. [0017] The structured surface may be hydrophilic, hydrophobic, or amphiphilic. The structured surface may have at least two regions of different wettabilities, wherein a first region is hydrophilic, hydrophobic, or amphiphilic and a second region is hydrophobic, amphiphilic, or hydrophilic while having a different wettability from the first region. The structured surface may comprise peaks and minor features.
[0018] The grooves may have an average width ranging from 1 micrometer to 500 micrometers and an average depth ranging from 1 to 500 micrometers, and wherein the flow channel has a height ranging from 100 to 1500 micrometers. More specifically, the average width of the grooves may range from 25 to 100 micrometers, and wherein the height of the flow channel may range from 250 to 500 micrometers. The grooves may have a minimum aspect ratio in the range of 10:1 (or 100:1 , or 1000:1 ) and a hydraulic radius no greater than 300 μιτι (or less than 100 μιτι or even less than 10 μιτι). The fluid transport layers may have a thickness in the range of 100-1000 micrometers (or 100-500 micrometers, or even 100-350 micrometers).
[0019] During operation, upon receipt of flow into the fluid inlet, the flow in the coalescer may be laminar having a Reynolds number of Re< 10, and the flow is such that residence time of the droplets allows for the droplets to have agglomerated such that the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet.
[0020] The flow channel may comprise a porous spacer between the layers.
[0021] The housing may be pressure-rated. The housing may comprise two end plates mechanically fastened together or a pipe.
[0022] These and other aspects of the invention are described in the detailed description below. In no event should the above summary be construed as a limitation on the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings are included to provide a further understanding of the invention described herein and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments. Certain features may be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof, and wherein:
[0024] FIG. 1 is an expanded schematic of a coalescing element where nominally small droplets coalesce into larger droplets;
[0025] FIG. 2 is an end view schematic of an exemplary coalescing element that is in a stacked relation with the grooves facing downwards;
[0026] FIG. 3 is end view schematic of an exemplary coalescing element that is in a spiral-wound configuration;
[0027] FIGS. 4a, 4b, and 4c provide end views of exemplary flow transport layers;
[0028] FIG. 5 is a perspective view of an exemplary coalescer in a horizontal orientation;
[0029] FIG. 6 is an expanded cross-sectional view of an exemplary coalescer through line 6-6 of FIG. 5; and
[0030] FIG. 7 is a flow schematic of a system utilizing a coalescer.
[0031] The figures are not necessarily to scale. Like numbers used in the figures refer to like components. It will be understood, however, that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.
DETAILED DESCRIPTION
[0032] Provided are droplet coalescers and systems that utilize the droplet coalescers, and methods of making and using the same. The coalescers comprise a coalescing element located in a housing, the coalescing element comprising at least one flow channel defined by a cap layer arrayed with a fluid transport layer that comprises at least one structured surface that has a plurality of longitudinal grooves. There are a fluid inlet and outlet in fluid communication with the coalescing element. Exemplary fluid transport layers comprise microreplicated films that have surface structures that are designed for contact with droplets in a continuous phase. Such microreplicated films may be stacked or spiraled together alone or with other layers, some of which may provide additional functionality such as spacing and/or flow enhancement. [0033] In operation, nominally small droplets entering a coalescing element agglomerate upon contact with the structured surface of the fluid transport layer, thereby forming droplets of a larger size. For example, droplets generally agglomerate such that the D50 droplet particle size is bigger, by for example at least a factor of 3 (or 10 or 100), upon flow out of the fluid outlet relative to the D50 droplet particle size upon flow into the fluid inlet. An expanded schematic of a coalescing element is provided in FIG. 1 to depict what happens in the coalescing element, where nominally small droplets 12 are carried by a liquid (e.g., oil droplets of a contaminated water stream) the direction of the arrow into a coalescing element 10, and upon contact with the structured surfaces (not shown) of fluid transport layers 16 (shown in expanded form for clarity) that form flow channels 18, larger droplets 14 are formed. Reference to nominally small droplets means less than 50 μιτι (e.g. 1 -50 μιτι or even 10-20 μιτι). Specifically, the droplets wick into the longitudinal grooves of the structured surface, and then move downstream with the flow. Residence time in the coalescing element is inversely related to flow rate and directly related to the length of the channels and their cross-sectional area, which are designed as needed for particular applications. Cross-sectional area is impacted by the design of the structured surface. As the droplets progress through the channel, they coalesce into larger droplets. These larger droplets (>100 μιτι) easily separate from the continuous phase due to Stokes' Law, often in a settling tank without further assistance.
[0034] The coalescers may be used, for example, in O&G and mining applications, where coalescence of oil-phase droplets from water or water-phase droplets from oil will facilitate operations. For example, coalesced droplets would lead to easier separation in downstream operations. In the O&G industry, costly chemicals such as flocculants & de-emulsifiers are added to help break these emulsions. A device that coalesces the oil without the need for these chemicals would have immediate impact. In mining, the use of a coalescer would allow for recovery of the valuable organic that is either lost or collected from a raffinate pond, where expensive re-processing is subsequently required. The coalescers disclosed herein can accommodate large amounts of flow at low pressure drop (up to 10,000 Liters/(m2*hr) at less than 5 psig), which means that the coalescers are a practical technical solution that fits into existing operations, such as hydraulics of the mine.
[0035] The following terms shall have, for the purposes of this application, the respective meanings set forth below.
[0036] An "emulsion" is a two-phase mixture where droplets of a discontinuous phase are dispersed in a continuous phase. For example, an oil-in- water emulsion comprises discontinuous oil droplets dispersed in a continuous aqueous phase. Likewise, a water-in-oil emulsion comprises discontinuous water droplets dispersed in a continuous oil phase.
[0037] A "coalescing element" is a module of the coalescers, comprising at least one fluid transport layer with a structured surface in conjunction with a cap layer to define a flow channel. The coalescing element is located in a housing that has mechanical strength, and usually the housing is pressure-rated to endure conditions during industrial use. The coalescing element is replaced as needed.
[0038] A "fluid transport layer" is a fundamental structure of the coalescing element. Reference to "fluid transport" means that liquid flow is tangential to the surface of the layer. Fluid transport layers are generally a film formed from a polymeric material that is substantially impermeable and/or resistant to diffusion of the liquid. Specifically, on a microscopic level, liquid flow is not perpendicular through the layer. Thus, the fluid transport layers are non-filtering. Holes or openings may be provided in fluid transport layers to facilitate different flow patterns on a macroscopic level. At least one surface of the fluid transport layer has a structured surface with a plurality of longitudinal grooves to facilitate wicking and aggregating of droplets. A plurality of layers may be formed from a continuous source of material that is rolled or spiraled to form an array of layers. Alternatively, layers may be formed from individual pieces of material that are arrayed together, possibly in a stack or in a framework. Design of each layer may be independent, allowing for various configurations of: structured surfaces and location of the same; materials; hydrophilic, hydrophobic, or amphiphilic nature; and the like. The layers in some embodiments may be identical, and in other embodiments, they may be different. [0039] Reference to "wick" or "wicking" means movement by capillary action due to intermolecular forces between a liquid and nearby solid surfaces. When forces of adhesion (attraction of liquid to a surface) are stronger than cohesion (like- molecules stay close together), movement by capillary action is achieved. For example, wicking of the emulsion itself within the longitudinal grooves is achieved in the longitudinal direction upon entry into the individual grooves from the inlet. In addition, wicking of the droplets in both the longitudinal and the axial direction (normal to the longitudinal direction) is also expected based on the interactions of the droplets themselves with the structured surface. Without intending to be bound by theory, it is thought that a hydrophobic surface will facilitate separation and coalescence of oil droplets from an aqueous phase. Likewise, it is thought that a hydrophilic surface will facilitate separation and coalescence of water droplets from an oil phase. Enhanced wicking may be achieved by orienting the structured surface to take advantage of gravity and/or density differences. For example, when separating oil droplets from a continuous water phase through a horizontally- positioned coalescer, locating the narrowest part of the structured surface at the top of the flow channel facilitates direct contact of the structured surface with the oil droplets, which rise and will readily coalesce upon contact with the structured surface and with other dispersed oil droplets.
[0040] Reference to "arrayed" means an assembly of layers to receive liquid flow and to achieve coalescing, where the layers may or may not be in direct contact with each other.
[0041] A "cap layer" is a layer that provides a surface (or cap) to the flow channels. The cap layer may any polymeric film that is present arrayed with a fluid transport layer. The cap layer may in fact be another fluid transport layer or a spacer layer or some other functional layer.
[0042] "Flow channels" are passages that direct a fluid along a particular path. When flow channels are discrete, the flow of each channel is independent. "Longitudinal grooves" run along the length of an element or device. The grooves are not necessarily parallel along the length, longitudinal in this case mean the grooves generally run in the lengthwise direction.
[0043] "Fluid" means a volume of gas and/or liquid. [0044] "Hydraulic radius" is the wettable cross-sectional area of a channel divided by the length of its wettable perimeter. For a circular channel, the hydraulic radius is one-fourth its diameter.
[0045] "Aspect ratio" is the ratio of a channel's length to its hydraulic radius.
[0046] "Flexible layers" refer to structures that are non-rigid and can be rolled onto itself and unrolled without damage. Also, upon bending or flexing, there is not significant flow channel constriction. Generally, the fluid transport layers are flexible. In one or more embodiments, such layers may be rolled around a 1 cm radius. Each layer is typically 350-500 μιτι thick.
[0047] When the layers are spiraled to form a "spiral-wound configuration," the longitudinal grooves of the structures surface may be aligned in a manner best suited for flow and aggregation. For example, the grooves may be axially aligned or aligned along the spiral path. Axial alignment may help reduce the Reynolds number, depending on total flow channel area as compared to an inlet cross-section. Spiral flow may increase the flow resistance and pressure drop while enhancing aggregation by increasing the acceleration force on the droplets, which in turn enhances the effect of Stoke's Law. With reference to a spiral alignment, a minimum bend radius may be 1 cm. Spiraled layers may utilize one roll of material, or it may be desired to provide two or more dissimilar layers that are spiraled together. The additional layers may or may not have structured surfaces and may provide additional functionality such as providing spacing.
[0048] "Wettability" means a characteristic of a material by reference to what liquids are capable of wetting or maintain contact with the structure. Thus, the specific characteristics of hydrophilicity, hydrophobicity, oleophilicity, oleophobicity, and amphiphilicity describe the wettability of a material.
[0049] "Hydrophilic" refers to a material that is wettable by water, which is the continuous phase in an oil-in-water emulsion, but the discontinuous phase in a water-in-oil emulsion. Water generally has a contact angle of less than 90° with hydrophilic materials. Exemplary such structures are hydrophilic by virtue of the materials used to fabricate the layer and/or by treatment.
[0050] "Hydrophobic" refers to a material that is not wettable by water. Water generally has a contact angle of 90° or greater with hydrophobic materials. Exemplary such structures are hydrophobic by virtue of the materials used to fabricate the layer and/or by treatment.
[0051] Oleophilic" refers to a material that is wettable by oil. Oil generally has a contact angle of less than 90° with oleophilic materials. Exemplary such structures are oleophilic by virtue of the materials used to fabricate the layer and/or by treatment. For the purposes of this disclosure, materials that are oleophilic are also hydrophobic.
[0052] Oleophobic" refers to a material that is not wettable by oil. Oil generally has a contact angle of 90° or greater with oleophobic materials. Exemplary such structures are oleophobic by virtue of the materials used to fabricate the layer and/or by treatment. For the purposes of this disclosure, materials that are oleophobic are also hydrophilic.
[0053] "Amphiphilic layer" refers to a material that is wettable by both oil and water. Exemplary such structures are amphiphilic by virtue of the materials used to fabricate the layer and/or by treatment.
[0054] "Combination layers" may provide designs of different hydrophobic, hydrophilic, and/or amphiphilic regions in the same layer.
[0055] Reference to Reynolds number (Re) is a dimensionless number that defines fluid flow in a pipe, where Re = Dvp/μ, D is pipe diameter, v is fluid velocity, p is fluid density, and μ is fluid viscosity. Generally, the conditions for the coalescers herein are Re < 1000. For Re < 10, completely laminar flow is expected. In certain embodiments, Re < 10, or < 3, or even < 2 may be desired.
[0056] Reference to Dso particle size refers to a median droplet size where 50% of the total volume of the discontinuous phase is in droplets which have a diameter that is less than the recited Dso particle size and 50% of the volume has droplet diameters which are greater. Dio particle size refers to a median droplet size where 10% of the total volume of the discontinuous phase is in droplets which have a diameter that is less than the recited Dio particle size and 90% of the volume has droplet diameters which are greater. D90 particle size refers to a median droplet size where 90% of the total volume of the discontinuous phase is in droplets which have a diameter that is less than the recited D90 particle size and 10% of the volume has droplet diameters which are greater. [0057] "Structured surface" means has a nonplanar surface that has defined features in a predetermined arrangement. An exemplary disclosure for providing a structured surface on a substrate is commonly-assigned WO201 1/056496, the disclosure of which is incorporated herein by reference.
[0058] A surface having "peaks" and "minor features" is one where the peaks are higher than the minor features. As such, varying surfaces for contacting droplets and directing flow are provided. Both peaks and minor features are the result of the structure molded, extruded, or cast into the microfluidic film.
[0059] "Microreplication" or "microreplicated" means the production of a microstructured surface through a process where the structured surface features retain individual feature fidelity during manufacture, from product-to product, that varies no more than about 50 μιτι.
[0060] "Microstructured channels" or "microstructured flow channels" refer to channels that have a minimum aspect ratio of about 10:1 and a hydraulic radius no greater than about 300 μιτι.
[0061] "Polymeric material" means a material that is formed by combining monomers to produce a natural or synthetic organic molecule(s) that contains one or more repeating units regularly or irregularly arranged in the organic molecule(s).
[0062] "Microfluidic film" refers to a material that contains channels that by design handles small amounts of fluid with precise control. Such films move, mix, and otherwise process amounts of fluids through channels having diameters on the order of around 100 nanometers to several hundred micrometers (e.g., microchannels). For industrial purposes, therefore, a large magnitude of microchannels is needed in practice.
[0063] Reference to "housing" means a structure with mechanical strength that is adequate to withstand at least a desired pressure rating and/or assembly into an industrial setting. Reference to "pressure-rated" means the housing can withstand pressures greater than or less than atmospheric. MATERIALS
[0064] Fluid Transport Layers
[0065] By definition, the fluid transport layers used herein made from a material that is substantially impermeable and/or resistant to diffusion of a fluid, e.g., liquid. Specifically, on a microscopic level, liquid flow is not perpendicular through the layer. Thus, the fluid transport layers are non-filtering and are for fluid transport. An exemplary disclosure of microchanneled active fluid transport devices that may be suitable herein is commonly-assigned U.S. Patent No. 6,290,685 (Insley), the disclosure of which is incorporated herein by reference.
[0066] Fluid transport layers for any of the embodiments in accordance with the present invention can be formed from a variety of polymer materials such as polymers and copolymers including thermoplastic, thermoset, and curable polymers. As used here, thermoplastic, as differentiated from thermoset, refers to a polymer which softens and melts when exposed to heat and re-solidifies when cooled and can be melted and solidified through many cycles. A thermoset polymer, on the other hand, irreversibly solidifies when heated and cooled. A cured polymer system, in which polymer chains are interconnected or crosslinked, can be formed at room temperature through use of chemical agents or ionizing irradiation.
[0067] Polymers useful in forming a structured layer in articles of the invention include but are not limited to polyolefins such as polyethylene and polyethylene copolymers, polypropylene, ethylene/vinyl acetate polymers, ethylene/ethyl acrylate polymers. Other useful polymeric materials include vinyl polymers (e.g., polyvinyl chloride, polyvinyl alcohol, vinyl chloride/vinyl alcohol copolymers, polyvinylidene chloride, polyvinylidine difluoride (PVdF)), acrylate polymers (e.g., polymethyl methacrylate), polycarbonate polymers, polyesters (e.g., polyethylene terephthalate), polyamides (e.g., Nylon), polyurethanes, polysaccharides (e.g. cellulose acetate), polystyrenes (e.g., polystyrene/methyl methacrylate copolymer), polysiloxane polymers (e.g., polysiloxane and organopolysiloxane polymers). Fluid transport members can be cast from curable resin materials (monomer and prepolymer mixtures) such as acrylates or epoxies and cured through free radical polymerization pathways promoted chemically, by exposure to heat, UV, gamma or electron beam radiation. Plasticizers, fillers or extenders, antioxidants, ultraviolet light stabilizers, surfactants, and the like may be utilized within the polymers of the invention.
[0068] The making of structured surfaces, and in particular microstructured surfaces, on a polymeric layer such as a polymeric film are disclosed in US. Pat. Nos. 5,069,403 and 5,133,516, both to Marentic et al. Structured layers may also be continuously microreplicated using the principles or steps described in US. Pat. No. 5,691 ,846 to Benson, Jr. et al. Other patents that describe microstructured surfaces include US. Pat. Nos. 5,514,120 to Johnston et al., 5,158,557 to Noreen et al., 5,175,030 to Lu et al., and 4,668,558 to Barber.
[0069] Structured polymeric layers produced in accordance with such techniques can be microreplicated. The provision of microreplicated structured layers is beneficial because the surfaces can be mass produced without substantial variation from product-to-product and without using relatively complicated processing techniques. The microreplicated surfaces preferably are produced such that the structured surface features retain individual feature fidelity during manufacture, from product-to-product, which varies no more than 25 μιτι.
[0070] Optional Additional Functional Layers
[0071] Other functional layers may be provided to facilitate flow through the coalescers by reducing pressure drop and/or encourage wicking and/or promote uniform flow. It may be desirable to provide a porous spacer, for example, such as a nonwoven polymeric material, e.g., a blown melt fiber(BMF) web, in order to control pressure drop through the coalescer. Another possible spacer or flow enhancer may be a polymeric material that comprises an extruded web material or an apertured polymeric film, or combinations thereof. An exemplary aperture polymeric film is 10 mil polypropylene Delnet. An exemplary extruded web is 30 mil polypropylene Naltex (nettings).
[0072] Another possible additional layer is a structured surface with high aspect ratio protruding features, such features being present on one or both surfaces of the layer. The high aspect ratio features generally are structures where the ratio of the height to the smallest diameter or width is greater than 0.1 , preferably greater than 0.5 theoretically up to infinity, where the structure has a height of at least about 20 microns and preferably at least 50 microns. If the height of the high aspect ratio structure is greater than 2000 microns the film can become difficult to handle and it is preferable that the height of the structures is less than 1000 microns. The features can be in the shape of upstanding stems or projections, e.g., pyramids, cube corners, J-hooks, mushroom heads, or the like.
[0073] Coalescing Element
[0074] Turning to FIG. 2, the coalescing element 10 comprises at least one flow channel 18 defined by a first fluid transport 16a arrayed in a stacked relation with a cap layer 20. A plurality of fluid transport layers 16a, 16b, 16c, 16d, 16e are provided in this embodiment, where layers 16a, 16b, 16c, and 16d functionally serve as cap layers to layers 16b, 16c, 16d, and 16e respectively. Each fluid transport layer 16a-16e as shown here has a major surface 23 opposite the structured surface. The major surface 23, also referred to as "land" may have a thickness in the range of 4-6 mils. Different embodiments may provide that the fluid transport layer has two structured surfaces. Optionally, the coalescing element comprises a cassette frame to which the layers are glued.
[0075] A coalescing element in a spiral-wound configuration is shown in FIG. 3, where the coalescing element 10 is formed from a single polymeric film that is arranged in a corkscrew or helical alignment around a central axis 24 forms a plurality of fluid transport layers 16 having a structured surface 22.
[0076] As the number of layers increases, the ability of the element to transport fluid clearly increases due to the increased flow capacity. The layers may comprise different channel configurations and/or number of channels, depending on a particular application. As show, the fluid transport layers 16 have structured surfaces on one surface only, but it is contemplated that both surfaces of one or more of the fluid transport layers may be structured in the same or different patterns.
[0077] As needed, holes or openings may be provided in fluid transport layers or cap layers or any additional layers to facilitate different flow patterns on a macroscopic level. For example, it may be beneficial to provide holes through one layer to divert flow to another layer, should channels of one layer become fouled and/or shut down.
[0078] The fluid transport layers comprise at least one structured surface having a plurality of longitudinal grooves. [0079] FIGS. 4a, 4b, and 4c provide end views of exemplary flow transport layers. Specifically, FIG. 4a represents the fluid transport layers 16a-e exemplified in FIG. 2, that is, fluid transport layer 16 has a structured surface comprising multiple inverted v-shaped peaks 26 that define flow channels 18. Other configurations are contemplated. For example, as shown in FIG. 4b, channels 18' have a wider flat valley between slightly flattened peaks 26'. Like the FIG. 4a embodiment, a cap layer can be arrayed along one or more of the peaks 26' to define discrete channels 18'. In this case, bottom surfaces 30 extend between channel sidewalls 31 , whereas in the FIG. 4a embodiment, sidewalls 17 connect together along lines. FIG. 4c illustrates a configuration where wide channels 28 are defined between peaks 26", but instead of providing a flat surface between channel sidewalls, a plurality of minor features 33 are located between the sidewalls of the peaks 26". These minor features 33 thus define secondary channels 34 therebetween. Minor features (or small peaks) 33 may or may not rise to the same level as peaks 26", and as illustrated create a first wide channel 28 including smaller channels 34 distributed therein. The peaks 18" and 33 need not be evenly distributed with respect to themselves or each other. The smaller channels 34 may be used to control fluid flow through the wider channels 32 by modifying frictional forces along the channel's length.
[0080] Although FIGS. 2 and 4a-4c illustrate elongated, linearly configured channels, the channels may be provided in other configurations. For example, the channels could have varying cross-sectional widths along the channel length— that is, the channels could diverge and/or converge along the length of the channel. The channel sidewalls could also be contoured rather than being straight in the direction of extension of the channel, or in the channel height. Generally, any channel configuration that can provide at least multiple discrete channel portions that extend from a first point to a second point within the coalescing element are contemplated. The channels may be configured to remain discrete along their whole length if desired.
[0081] The structured surface may be a microstructured surface that defines discrete flow channels that have a minimum aspect ratio (length/hydraulic radius) of 10:1 , in some embodiments exceeding approximately 100:1 , and in other embodiments at least about 1000:1 . The hydraulic radius of a channel is no greater than about 300 μιτι. In many embodiments, it can be less than 100 μιτι, and may be less than 10 μιτι. Although smaller is generally better for many applications (and the hydraulic radius could be submicron in size), the hydraulic radius typically would not be less than 1 mm for most embodiments. As more fully described below, channels defined within these parameters can provide efficient bulk fluid transport through a coalescer or device.
[0082] Microstructured surfaces in accordance with the present invention provide flow systems in which the volume of the system is highly distributed. That is, the fluid volume that passes through such flow systems is distributed over a large area. Microstructure channel density from about 10 per lineal cm (25/in) and up to 1 ,000 per lineal cm (2500/in) (measured across the channels) provide for high fluid transport rates. Generally, when a common manifold is employed, each individual channel has an aspect ratio that is at least 400 percent greater, and more preferably is at least 900 percent greater than a manifold that is disposed at the channel inlets and outlets.
[0083] Coalescers
[0084] In general terms, the coalescers are assembled by arraying fluid transport layers and/or cap layers, as needed, into a coalescing element which is placed in a housing. Fluid inlets and outlets are provided to the housing and in fluid communication to the flow channels of the coalescing element. As needed, one or more end caps may be affixed to the coalescing element to facilitate fluid communication to and from the coalescing element and into and out of the housing, respectively. With specific reference to FIG. 6, a coalescer 100 in a horizontal orientation is provided, where the coalescer 100 comprises a housing 102 that is made from two end plates 104a, 104b with mechanical fasteners 106 that sandwich a coalescing element therein. Inlet 108 is at one end of the housing 102 in this embodiment and receives a source of emulsion. An optional pressure gauge 1 12 is to measure inlet pressure. Outlet 1 10 is at the other end of this embodiment, providing coalesced droplets in the continuous phase for further separation in, for example, a settling tank. [0085] FIG. 6 shows an expanded cross-sectional view of an exemplary coalescer 100 through line 6-6 of FIG. 5, where the coalescing element comprises a plurality of fluid transport layers 16 that are affixed by glue 19 to a cassette frame 21 . The coalescing element is located between the two end plates 104a, 104b and a gasket 15 provides a liquid tight seal. Gasket materials should be compatible with ingredients of the emulsion. An exemplary gasket material is a fluoroelastomer, which is compatible with many components of crude oil.
[0086] Housings
[0087] Suitable materials for housing the coalescing elements have mechanical strength, providing adequate structure to withstand at least a desired pressure rating and/or assembly into an industrial setting. Housings may be formed by two end plates that are mechanically fastened together with coalescing elements being sandwiched therebetween. Other suitable housing may be pipes or self- supporting or braided hoses. Thus, the housings may be rigid or semi-rigid. The housings may be "pressure-rated" to withstand pressures greater than atmospheric.
UTILITY
[0088] In practice, the coalescers provided herein are included in a system that handles emulsions. Output of the coalescers may be supplied to any desirable process tank of any purpose that is a part of the overall emulsion handling system, usually a separator tank. Turning to FIG. 7, provided is a flow schematic that shows a system utilizing a coalescer, where the system 150 has a source of emulsion 130, which for this example is an oil-in-water emulsion that feeds a pump 140 that in turn supplies a coalescer 100. Oil droplets entering the coalescer 100 are nominally small and are larger upon exiting the coalescer. The output of the coalescer 100 having nominally large oil droplets is sent to a separation vessel 160, which is generally set up for settling, where an oil-free aqueous phase is drawn off the bottom to a receptacle 170 or other location and the oil phase from above the aqueous phase is supplied to another receptacle 180 or location.
[0089] The coalescers may be used in mining applications at locations where emulsions form such as in mixers upstream of settling tanks. Thus, the coalescer would receive flow from one or more mixers. This coalescer could also be positioned at points further downstream or even within the settler. In O&G applications, coalescers may be located downstream of a gravity separation tank (e.g., a "gunbarrel tank"). For such applications, it is noted that fouling challenges may be present, such as particulates, scale, and tarlike organic compounds such as asphaltenes, and there may be a need for ancillary equipment such as a pre-filter upstream of the coalescer.
[0090] Coalescence of oil-phase droplets from water or water-phase droplets from oil will facilitate operations of downstream equipment in both mining and O&G applications.
[0091] Exemplary items of the present disclosure are listed as follows:
[0092] Item 1 . A coalescer for aggregating droplets of a discontinuous phase dispersed in a continuous phase, the coalescer comprising:
a housing;
a coalescing element located in the housing, the coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
[0093] Item 2. The coalescer of item 1 , wherein the cap layer comprises a second fluid transport layer that comprises at least one structured surface.
[0094] Item 3. The coalescer of item 2, wherein at least one of the first and the second fluid transport layers comprise two structured surfaces.
[0095] Item 4. The coalescer of any one of items 2-3 further comprising one or more additional fluid transport layers arrayed with the first and second fluid transport layers.
[0096] Item 5. The coalescer of any one of items 1 -4, wherein the first fluid transport layer is microreplicated.
[0097] Item 6. The coalescer of any one of items 2-5, wherein both the first and the second fluid transport layers comprise a microfluidic film.
[0098] Item 7. The coalescer of any one of items 1 -6, wherein the coalescing element comprises a plurality of layers in a stacked relation. [0099] Item 8. The coalescer of any one of items 1 -6, wherein the coalescing element comprises a plurality of layers in a spiral-wound configuration.
[00100] Item 9. The coalescer of any one of items 1 -8, wherein the cap layer comprises a polymeric material that comprises a non-permeable material, a web material, an apertured polymeric film, a wet-laid material, a nonwoven material, a woven material, or combinations thereof.
[00101] Item 10. The coalescer of any one of items 1 -9, wherein the structured surface is hydrophilic, hydrophobic, or amphiphilic.
[00102] Item 1 1 . The coalescer of any one of items 1 -10, wherein the structured surface has at least two regions of different wettablilities, wherein a first region is hydrophilic, hydrophobic, or amphiphilic and a second region is hydrophobic, amphiphilic, or hydrophilic while having a different wettability from the first region.
[00103] Item 12. The coalescer of any one of items 1 -1 1 , wherein the grooves have an average width ranging from 1 to 500 micrometers and an average depth ranging from 1 to 500 micrometers, and wherein the flow channel has a height ranging from 100 to 1500 micrometers.
[00104] Item 13. The coalescer of item 12, wherein the average width of the grooves ranges from 25 to 100 micrometers, and wherein the height of the flow channel ranges from 250 to 500 micrometers.
[00105] Item 14. The coalescer of any one of items 1 -13, wherein the grooves have a minimum aspect ratio in the range of 10:1 and a hydraulic radius of no greater than 300 micrometers.
[00106] Item 15. The coalescer of any one of items 2-14, wherein the fluid transport layers have a thickness in the range of 100- 1000 micrometers.
[00107] Item 16. The coalescer of any one of items 1 -15, wherein upon receipt of flow into the fluid inlet, the flow is laminar having a Reynolds number of Re< 10, and the flow is such that residence time of the droplets allows for the droplets to have agglomerated such that the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet. [00108] Item 17. The coalescer of any one of items 1 -16, wherein the flow channel comprises a porous spacer between the layers.
[00109] Item 18. The coalescer of any one of items 1 -17, wherein the structured surface comprises peaks and minor features.
[00110] Item 19. The coalescer of any one of items 1 -18, wherein the housing is pressure-rated.
[00111] Item 20. The coalescer of any one of items 1 -19, wherein the housing comprises two end plates mechanically fastened together or a pipe.
[00112] Item 21 . A system for aggregating of a discontinuous phase dispersed in a continuous phase comprising:
a source of the discontinuous phase dispersed in a continuous phase;
a coalescer that receives the discontinuous phase dispersed in a continuous phase, the coalescer comprising:
a coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
[00113] Item 22. The system of item 21 further comprising a process tank that receives flow from the coalescer.
[00114] Item 23. The system of any one of items 21 -22, wherein the coalescer further comprises a housing that contains the coalescing element.
[00115] Item 24. The system of any one of items 21 -23, further comprising a pre-filter that receives the discontinuous phase dispersed in a continuous phase from the source and supplies a filtered flow to the coalescer.
[00116] Item 25. A method for aggregating droplets of a discontinuous phase dispersed in a continuous phase, the method comprising:
contacting with a feed having the droplets of the discontinuous phase dispersed in the continuous phase with a coalescer that comprises; a coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element;
wherein the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet.
[00117] Item 26. The method of item 25, wherein flow into the fluid inlet is laminar having a Reynolds number of Re< 10.
[00118] Item 27. The method of any one of items 25-26, wherein the discontinuous phase is oil and the continuous phase is water and the Dso droplet particle size in the feed into the fluid inlet is in the range of 10-25 micrometers and the Dso droplet particle size upon flow out of the fluid outlet is in the range of at least 30-75 micrometers.
[00119] Item 28. A method of making a coalescer, the method comprising: forming a coalescing element comprising flow channels defined by a cap layer arrayed with a fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; locating the coalescing element in a housing; and
providing or forming a fluid inlet and a fluid outlet to the flow channels.
[00120] Item 29. A coalescer for aggregating oil droplets dispersed in an aqueous phase, the coalescer comprising:
a coalescing element comprising a fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves, the structured surface being hydrophobic and comprising peaks and minor features; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
[00121] Item 30. The coalescer of item 29, wherein the longitudinal grooves are horizontal and the combination of peaks and minor features narrow away from the direction of gravity. [00122] Item 31 . The coalescer of an one of items 29-30, wherein the coalescing element comprises a plurality of fluid transport layers assembled with a frame.
[00123] Before describing several exemplary embodiments of the invention, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced or being carried out in various ways.
EXAMPLES
[00124] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, and all reagents used in the examples were obtained, or are available, from general chemical suppliers such as, for example, Sigma-Aldrich Company, Saint Louis, Mo., or may be synthesized by conventional methods.
[00125] When hot melt glue was used, it was generally Hot Melt Adhesive #3761 (3M Company, St. Paul, MN). When a glue gun was used, it generally was a Model Scotch-Weld Hot Melt Applicator EC (3M Company St. Paul, MN). The fluoroelastomer gasket used in the examples was part #86075K32, McMaster-Carr Corporation, Elmhurst, IL.
[00126] Turbidity was measured with a Hach AN-2100 turbidimeter (Hach Corporation Loveland, CO). Particle size distribution (PSD) was measured by laser light scattering (LA-300, Horiba Corporation, Kyoto, Japan).
[00127] The following abbreviations are used to describe measurements referenced in the examples:
AU: Absorbance units
cm: centimeters
cm2: square centimeters
EFD: effective fiber diameter
g: gram
g/hr: grams per hour
g/L: grams per liter
L: Liter LMH: Liters per m2 per hour
L/hr: Liters per hour
min: minutes
ml: milliliter
ml/min: milliliters per minute
mm: millimeter
NTU: Nephelometric Turbidity Units
PSD: particle size distribution
ppm: parts per million
psi: pounds per square inch
rpm: revolutions per minute
sec: seconds
μιτι: micrometer
wt weight
[00128] The following abbreviations are used to describe ingredients referenced in the examples:
BMF blown melt fiber
CuSO4: copper sulfate
DIW: deionized water
FeSO4: iron sulfate
H2O: water
H2SO4: sulfuric acid
O&G: Oil and gas applications
SX: solvent extraction
[00129] Testing apparatus: A supply beaker contained an emulsion to be tested. A mixing apparatus was available to mix the emulsion in the beaker. The emulsion flowed from the beaker to a pumping system (FilterTec pumping system (SciLog Corporation, Madison, Wl)) and into the coalescer. For the O&G surrogate emulsions, effluent of the coalescer was supplied to a separator funnel having an internal volume of roughly 3 liters. The effluent traveled up a tube to the approximate midpoint of this separatory funnel. This vessel was kept liquid-full, and the overflow was discharged from the bottom of the vessel while the oil coalesced at the top of the dome. For the mining surrogate emulsions, the effluent was directed to a beaker.
[00130] For hexane extraction analysis, reagent grade hexane was Spectrophotometric grade n-Hexane (Alfa Aesar Co. Ward Hill MA). Effluent was contacted with the hexane in a vial overnight on a rocker (Vari-Mix Test Tube Rocker, Thermo-Scientific, Waltham, MA). The hexane phase was measured by colorimetric visible spectrometry. A characteristic peak of around 326 nm was observed (DR-3900 spectrometer, Hach Corporation, Loveland, CO) to determine oil content.
EXAMPLE 1
[00131] A coalescing element was made from 15 layers of a microreplicated film having longitudinal grooves spaced on about 60 μιτι centers and having 54 degree peaks and valley with a 50 micrometer pitch polypropylene, made by 3M Company, St. Paul, MN using an extrusion replication process). Each layer was formed from a sheet that was cut to 2.75" wide by 5" long. The sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 3/8" high with an internal opening of 3"x 6". This left ½" of open area at each end for flow distribution and collecting the effluent. The long edges were sealed with 3M hot melt, applied with a glue gun. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
[00132] An O&G surrogate oil-in-water emulsion was prepared as follows. A surfactant package was made up with the following ingredients: oleic acid (technical grade, Sigma-Aldrich Co. St. Louis, MO), naphthenic acid (TCI Co, LTD, Toshima, Japan), and ethanol (200 proof pure Ethanol, Koptec Co. King of Prussia, PA) in a 2:4:15 ratio (by wt). An organic (oil) phase contained a mixture of: mineral oil (Nujol light oil, Alfa Aesar, Ward Hillm MA), kerosene (Low Odor Kerosene, Alfa Aesar), and xylene (Xylenes ACS grade, EMD Co (Merck) Darmstadt, Germany) in a 2:3:1 ratio by weight. A 1 % saline solution was used for the aqueous phase. The surfactant package, organic (oil) phase, and aqueous phase were mixed to form an emulsion using a IKA Turrax T-18 mixer (VWR Corporation, Radnor, PA).
[00133] Flow rate to the coalescer approximately 25 ml/min. After about one hour of operation, the flow was terminated due to a pressure drop of about 40 psi. Despite the high pressure drop, improvements in turbidity and PSD were observed. Turbidity was reduced by about 97-98 % during the run. The coalescer removed virtually all oil droplets larger than 10 m as measured by laser light scattering. The D50 of the feed solution was 9-10 μιτι. Much of the early effluent samples showed D50 values in the 1 -2 μιτι range, indicating that larger droplets were being coalesced out as expected. Late in the experiment it was observed that the effluent had a D50 centered on 200 μιτι, demonstrating that the droplets discharging in the effluent had coalesced by a factor of 20x or more.
While this configuration demonstrated the desired coalescence, the geometry of the microreplication pattern created too high a pressure drop on its own. It was decided to combine the microreplicated film with a spacer layer, which is described in Example 2.
EXAMPLE 2
[00134] A coalescing element was made from 14 alternating layers of the same microreplicated film as Example 1 and spacer layers (a 25 grams/m2 85/25 w/w polyethylene/polypropylene (PE/PP) blown melt fibers (BMF) in a cassette frame (polypropylene). Each layer was formed from a sheet that was cut to 2.75" wide by 5" long. The sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 3/8" high with an internal opening of 3"x 6". This left ½" of open area at each end for flow distribution and collecting the effluent. The long edges were sealed with hot melt glue applied with a glue gun. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
[00135] The surrogate oil-in-water emulsion of Example 1 was used.
[00136] The emulsion was pumped through the coalescer at various flow rates to process various amounts of emulsions as follows:
[00137] Run A 30-50 ml/min— 5 L of emulsion [00138] Run B 75 ml/mi n— 15 L emulsion
[00139] Run C 100 ml/min - 20 L emulsion
[00140] Run A
[00141] Inlet flow of the emulsion started at 30 ml/min, and then was gradually increased to 50 ml/min such that about 5 L of emulsion was processed through the coalescer. The pressure drop (delta P) was observed to be less than 2 psi throughout the run. Oil was observed coalescing in the separator about an hour after flow was started, first as droplets on the walls, and then as a red layer on top. PSD data showed that the coalescer was taking out virtually all droplets larger than 2 μιτι.
[00142] Run B
[00143] The flow rate was increased to 75 ml/min (4.5 L/hr). The cassette had a cross sectional area of approximately 4 cm2, of which most of the space was taken up by the microreplicated film, which was 420 μιτι thick. Residence time for fluid flowing through the stack of sheets for two exemplary void fractions is provided as follows.
Figure imgf000028_0001
[00144] At 75 ml/min, the pressure drop across the module was 3 psi for most of the run. It did increase at one point, but by loosening the bolting slightly the pressure came back down to 3 psi. Significant amounts of oil were observed to coalesce throughout the run. Approximately 15 L of emulsion was processed. The feed had a Dso of 7 μιτι by PSD analysis. By the end of the day as steady state was achieved it was noted that the effluent had a Dso at 39.6 μιτι, indicating that coalescence was occurring. This corresponds to a coalescing factor of over 5x.
[00145] The PSD of the continuous phase of the effluent directly off of the coalescer showed increased droplet size, which was in addition to the oil phase that was separating and could be visibly detected. This was also detected in the bulk effluent; the liquid collected off of the separator. This indicates that the oil that did not physically disengage in the separatory funnel (approx. 40 minutes residence time @75ml/min) was about 5x larger median droplet size than the feed, which would translate to a 25x increase in separation velocity per Stokes' law.
[00146] Run C
[00147] During this run, the flow rate was increased to 100 ml/min (6 L/hr). Approximately 20 L of emulsion were passed through the system. Pressure drop remained at 3 psi throughout most of the run, although it rose up to about 4 psi towards the end. The PSD showed that all droplets larger than 10 μιτι were being coalesced. It was observed that periodically (about once every 1 -2 minutes) a large oil droplet was seen to be entering the separatory vessel. This oil all separated by gravity in the upper dome of this separator. Since the Horiba by nature only sees snapshots of the flow these droplets would not be detected. Also the Horiba has an upper limit of 600 μιτι droplet size, and most of the droplets visually observed in the effluent were larger than that.
[00148] Turbidity of the samples of Run C was still down around 5 NTU throughout most of the run. The bulk effluent was run neat through the Horiba, whereas the feed was diluted about 16:1 . Droplets several millimeters in diameter were observed entering the separatory funnel every few seconds. At 100 ml/min, the coalescer was being challenged with 3 g/hr of oil at a flow rate of 14,000 LMH (based on facial area, no accounting for void fraction).
EXAMPLE 3
[00149] A mining (SX) surrogate oil-in-water emulsion was prepared as follows. This is derived from BASF monograph D/EVH 017e "Standard quality control test of LIX™ reagents", dated August 2012 which is the basis of design for the "mix vessel"
[00150] 1 . Add 2 L of DIW to a 2 L beaker;
[00151] 2. Adjust pH to 1 .8 with 50% H2SO4 (Alfa Aesar, Ward Hill, MA);
[00152] 3. Add 20.6 g of FeSO4 *7H20 granular (J.T. Baker, Center Valley, PA); [00153] 4. Add 48.6g of CuSO4 *5H2O (Alfa Aesar, Ward Hill, MA) to give a copper level of 6 g/L;
[00154] 5. Dissolve the powders by mixing on a stir plate. Heat to 60°C if necessary;
[00155] 6. Combine 450 of this aqueous phase with 135 ml of organic mixture in in the mix vessel. This organic mixture is an 80:20 (by volume) blend of Orform SX-12 Diluent (Chevron Corp, San Ramon, CA) and LIX-84-I ketoxime (BASF SE, Ludwigshafen, Germany);
[00156] 7. Mix at 2000 rpm for 3 m in;
[00157] 8. Turn off mixer and allow to phase separate for 5 min;
[00158] 9. Drain off aqueous phase and measure turbidity, conduct PSD, and set aside 20 ml for n-Hexane extraction.
[00159] 10. This procedure (steps 6-9) 'was repeated roughly every 20-40 minutes, depending on flow rate, in order to keep the system supplied with feed.
[00160] For this experiment, the coalescing element comprised a microreplicated riblet film was used having a geometry identical to what is shown in Figure 4a, with the grooves having a pitch and depth of approximately 65 μιτι. 10 pieces of film were cut into 2-3/4" x 5" dimensions with the grooves oriented along the 5" edge. These pieces were alternated with a similarly sized piece of 32 gsm polypropylene BMF web with an EFD of 1 1 .4 microns. . A coalescer was formed with the pieces as described in Example 1 . Note, the spacer material was added on day 2 of the experiment, as it was quickly evident that the microreplicated film on its own had too high a pressure drop (greater than 35 psig).
[00161] Over the course of 5 days, the surrogate emulsion flowed through the coalescer at flow rates in the range of 10-15 ml/minute. Pressure drop of through the coalescer was below 4psig. Over the course of 5 days, a cumulative total of almost 14 L of surrogate emulsion passed through the coalescer. Inlet turbidity typically ranged between 350-375 NTU. Outlet turbidities were uniformly in the 5-10 NTU range. Starting on the fourth day of the experiment, large (~1 mm) droplets of oil were observed to be discharging out of the module with the clarified effluent.
[00162] On the last day of the experiment, 50 mg/L of Arizona Road Dust (Powder Technologies, Inc. Burnsville, MN) was added to the surrogate emulsion in the aqueous phase (in step 1 above) to form a challenge solution. No change in pressure drop was observed in the apparatus from the addition of this foulant.
[00163] Based on the amount of organic mixture consumed in the test, it is estimated that averaged approximately 3,500 ppm of organic. Several samples of the effluent were analyzed per the EPA Method 1664 Revision A (February 1999) using an Empore™ Oil & Grease Disk (3M Company, St. Paul, MN) . This gave results of 38.9 ppm & 29.8 ppm for the two liters of effluent tested. This equates to a 99% removal of organic from the feed solution.
[00164] The feed typically had a Dso of 18.8 μιτι. Late in the experiment, analysis showed that the apparatus was coalescing the droplets from a Dso of approximately 25 μιτι up to a Dso of 250 μιτι
EXAMPLE 4
[00165] A coalescing element was made from 10 layers of a microfluidic film having peaks and minor features in accordance with FIG. 4c (5 mil land, 8 mil peaks polypropylene, made by 3M Company, St. Paul, MN) in a cassette frame (polypropylene). Each layer was formed from a sheet that was cut to 2.5" wide by 5" long. The sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 1/8" high with an internal opening of 3"x 6". Note that no additional layers were inserted between the microreplicated sheets. This left ½" of open area at each end for flow distribution and collecting the effluent. The long edges were sealed with hot melt glue applied with a glue gun. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
[00166] A surrogate oil-in-water emulsion was prepared in a manner similar to that of Example 1 , except that for the organic/oil phase, 500 ppm of actual crude oil (containing at least paraffins, aromatics, and asphaltenes) was used. This emulsion was pumped through the coalescer at flow rates in the range of 30-70 ml/min. Given the dimensions of the coalescer, this corresponds to a flux of 9,000-20,000 LMH.
[00167] The particle size distribution of the oil droplets and the turbidity were monitored in the effluent. The turbidity decreased by 45-51 % depending on flow rate, with the reduction decreasing as the flow rate was increased from 30 to 70 ml/min. The coalescer coalesced out virtually all oil droplets larger than 10 μηη. The D50 of the feed solution was characterized at 25 μηη.
[00168] Another indication of the effectiveness of the coalescer was via hexane extraction of the feed and effluent fluids. 40 ml of feed or effluent sample was contacted with 15 ml of reagent grade hexane in a 60 ml vial overnight on a rocker. All of the organic emulsion droplets were extracted into the hexane phase. 10 ml of the hexane were measured via colorimetric visible spectrometry. For the feed solution an absorbance of 2.403 AU at 326 nm was recorded. For the effluent, this value was 0.482 AU, which demonstrates an 80% reduction in oil content. Note that this differs from the approximately 50% reduction in turbidity. While turbidity is heavily influenced by a large population of small droplets, actual oil content (ppm) is determined largely by the population of large droplets remaining in the effluent. Towards the end of experiment, larger droplets of oil were observed coming off the discharge of the module, indicating that the system was approaching steady state. These larger droplets (1 mm or larger) quickly separated by gravity in the separator vessel.
EXAMPLE 5
[00169] A coalescing element was made in a similar manner to Example 4 except that the number of layers was reduced from 15 layers of the same media down to 3 layers. The layers, with the channels facing down, were placed in between two pieces of the same McMaster-Carr gasket material (except that this sheet stock was slightly thicker than 1/8") that was slightly shorter than the film to reduce the possibility of closing off the passageway and creating a bypass (Note: for flux calculation purposes, only two layers are considered. It is assumed that the bottom layer was sealed off against the gasket material). This increased the flux by a factor of 5-6, enabling the system to more quickly achieve steady state. Each layer was formed from a sheet that was cut to 3" wide by 5" long. The sheets were oriented with the grooves facing downwards and substantially centered within the cassette frame that was 3/8" high with an internal opening of 3"x 6". Note that no additional layers were inserted between the microreplicated sheets. This left ½" of open area at each end for flow distribution and collecting the effluent. Because of the additional gasket material and the wider film it was not necessary to seal the longitudinal edges with hot melt adhesive. A small bead of hot melt was applied at the upstream junction of the film/elastomer and the frame to eliminate. The coalescing element was sandwiched between two polycarbonate blocks with sheets of 1/16" thick Viton fluoroelastomer gasket to form the coalescer.
[00170] The mining surrogate oil-in-water emulsion of Example 3 was supplied to the coalescer.
[00171] In this example, the effluent from the coalescer was collected directly in a beaker. The system was run for 4-6 hours a day for four days. The flow rate was 20 ml/min throughout, although with the minimized number of layers the flux was 23,000LMH. The turbidity of the surrogate feed was routinely between 400-470 NTU. Over the first 3 days the effluent turbidity from the coalescer was typically in the 100-150 NTU range, which corresponds to roughly a 65% reduction. In day four after steady state was achieved the outlet turbidity was noted to drop to the 43-47 NTU range, which is a 90% reduction. During the last two days large droplets (greater than 1 mm in diameter) of organic were observed to be discharging from the module. It is assumed the inlet oil emulsion was coalescing on the microfluidic film, and large droplets were "spalling" off of the trailing edge of the media stack.
[00172] Another indication of the effectiveness of the coalescer was via hexane extraction of the feed and effluent fluids. Similar to Example 4, 20 ml of feed or effluent sample was contacted with 15 ml of reagent grade hexane in a 40 ml vial overnight on a rocker. All of the organic emulsion droplets were extracted into the hexane phase. 10 ml of the hexane were measured via colorimetric visible spectrometry. Over the first three days of the experiment the organic content of the feed was reduced by 60-80% as the coalescer was adjusted. On day 4 after steady state was achieved, the reduction dramatically increased to 96%. As with Example 4 the reduction in organic content was greater than the reduction in turbidity. The reasoning is the same as described in Example 4: the large drops had coalesced out, and the smaller drops which still lent the effluent some turbidity comprised a significantly smaller volume of oil. Note that the larger droplets that were observed to have coalesced out were not part of the sample subjected to the n-Hexane extraction. [00173] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
[00174] Reference throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.
[00175] Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

What is claimed is:
1 . A coalescer for aggregating droplets of a discontinuous phase dispersed in a continuous phase, the coalescer comprising:
a housing;
a coalescing element located in the housing, the coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
2. The coalescer of claim 1 , wherein the cap layer comprises a second fluid transport layer that comprises at least one structured surface.
3. The coalescer of claim 2, wherein at least one of the first and the second fluid transport layers comprise two structured surfaces.
4. The coalescer of any one of claims 1 -3, wherein the first fluid transport layer is microreplicated.
5. The coalescer of any one of claims 1 -4, wherein the coalescing element comprises a plurality of layers in a stacked relation or in a spiral-wound configuration.
6. The coalescer of any one of claims 1 -5, wherein the structured surface has at least two regions of different wettablilities, wherein a first region is hydrophilic, hydrophobic, or amphiphilic and a second region is hydrophobic, amphiphilic, or hydrophilic while having a different wettability from the first region.
7. The coalescer of any one of claims 1 -6, wherein the grooves have a minimum aspect ratio in the range of 10:1 and a hydraulic radius of no greater than 300 micrometers.
8. A system for aggregating of a discontinuous phase dispersed in a continuous phase comprising:
a source of the discontinuous phase dispersed in a continuous phase;
a coalescer that receives the discontinuous phase dispersed in a continuous phase, the coalescer comprising:
a coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
9. A method for aggregating droplets of a discontinuous phase dispersed in a continuous phase, the method comprising:
contacting with a feed having the droplets of the discontinuous phase dispersed in the continuous phase with a coalescer that comprises; a coalescing element comprising at least one flow channel defined by a cap layer arrayed with a first fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element;
wherein the Dso droplet particle size is bigger by at least a factor of 3 upon flow out of the fluid outlet relative to the Dso droplet particle size upon flow into the fluid inlet.
10. A method of making a coalescer, the method comprising:
forming a coalescing element comprising flow channels defined by a cap layer arrayed with a fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves; locating the coalescing element in a housing; and
providing or forming a fluid inlet and a fluid outlet to the flow channels.
1 1 . A coalescer for aggregating oil droplets dispersed in an aqueous phase, the coalescer comprising:
a coalescing element comprising a fluid transport layer that comprises at least one structured surface having a plurality of longitudinal grooves, the structured surface being hydrophobic and comprising peaks and minor features; and
a fluid inlet and a fluid outlet in fluid communication with the coalescing element.
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