Method and Apparatus for Separation of Components of Differing Buoyancy Mixed into a

Flowing Fluid

BACKGROUND

1. Technical Field

This is related to systems for separating flowing fluid into separate portions, and in particular, to systems for separating solid particles or gases from a liquid or liquids of differing buoyancies.

2. Related Technology

The separation of mixtures into their component parts for the purposes of clarification, cleaning, and removal of undesirable portions of the mixture is a major function in many industries. In many cases it is desired to perform this function rapidly, at high flow rates and in an "on-line" operating mode. In many applications this function is performed by conventional centrifuges, often augmented with a settling or decanting process to overcome the inherent limitations of current centrifuges to achieve the desired level of end product purity needed. In addition, the removal of air or other gases from fluid flows is widely applicable in cases in which the entrained gases may interfere with the function and performance of equipment. One prevalent application is in the removal of air from liquid coolant to improve the heat exchange performance of radiators. Another such application is the removal of air from lubricating fluid to improve the lubrication and cooling performance of the fluid. Yet another application is the removal of air from hydraulic fluid to improve the force transfer of hydraulic actuators. In all of these applications, the separated air or gas is typically removed, since recombination would tend to defeat the purpose of the removal. In these cases, air removal is the primary function and any suspended particles in the fluid are of little or no interest. In other cases, recombination after separation may be desirable, for example, to retain oil fumes that are entrained in the airflow in order to preserve the total oil content of the system. In certain particle monitoring applications, such as that disclosed by U.S. Patent No. 4,282,016 to Tauber et al., a goal is to remove particles above a certain size for analysis. Real time suspended particle monitors are disclosed in U.S. Patent No. 5,572,320, U.S. Patent No. 6.049,381, U.S. Patent No. 7,921,739, and U.S. Patent No. 8,056,400.

BRIEF SUMMARY

A system for separating a multicomponent fluid into two or more flow channels, each containing components with different buoyancy, comprising a housing having a fluid inlet at a first end and at least two outlets; a first member configured to fit within the housing at the first end of the housing and having a passageway from the inlet through the member, the first member having a concave inner surface; a second member having a convex surface at one end that fits into the concave inner surface, the second member having at least one helical channel in an outer cylindrical surface extending from the convex surface to an opposite end of the second member; and a third member having a central fluid passageway for carrying higher buoyancy fluid and extending through the member along a central axis, and at least one other fluid passageway for carrying lower buoyancy fluid with an inlet positioned radially outward of the inlet of the central fluid passageway; the first member, the second member, and the third member configured to fit within the housing and aligned along a central longitudinal axis.

A system for separating a multicomponent fluid into two or more flow channels, each containing components with different buoyancy, comprising a housing having a fluid inlet at a first end and at least two outlets; a flow forming member configured to fit within the housing at the inlet end of the housing and having a flow passage therethrough with at least one helical channel in an outer cylindrical surface that directs the fluid into a helical flow direction near the outer circumference of the flow forming member as the fluid exits the flow forming member; and a flow receiving member configured to fit within the housing at an opposite end of the housing, having a central fluid passageway for carrying higher buoyancy fluid and extending through the member along a central axis, and at least one other fluid passageway for carrying lower buoyancy fluid with an inlet positioned radially outward of the inlet of the central fluid passageway; wherein a separation chamber is formed between faces of the flow forming member and the flow receiving member. In operation, the helical flow enters the separation chamber, and more buoyant portions of the flow move toward a central axis of the chamber and enter the central fluid passageway, and less buoyant portions of the flow continue in a helical path near the outer part of the chamber and bypass the entrance of the central fluid passageway and exit the system through the at least one other fluid passageway. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a flow separation system for separating a fluid flow into two or more channels based on the fluid buoyancy. FIG. IB, 1C, and ID show further detail of some internal components of the flow separation system of FIG. 1 A. FIG. 2A and FIG. 2B show a front view and a back view of three components of a flow separation system.

FIG. 3 shows some details of the geometry of one of the components of the flow separation system.

FIG. 4A illustrates an example of a flow separation system as a part of a real time fluid analysis system. FIG. 4B is a cross sectional view of a viewing window suitable for use in the real time fluid analysis system of FIG. 4A.

FIG. 5 illustrates an example of two flow separators arranged in sequence to create multiple flow channels, each having a fluid component of different buoyancy.

FIG. 6 illustrates an example of a fluid separation system as a part of a system for removing foreign material from a fluid reservoir.

FIG. 7 illustrates an example of a fluid separation system as a part of a real-time optically based fluid analysis system.

DESCRIPTION OF MODES OF OPERATION

The fluid separation systems described herein are suitable for separating fluids or fluids with entrained particles into two or more components based on their densities or buoyancies into separate flow channels. In particular, fluid flow can have entrained or suspended components such as solid particles, gases, or fluids of different densities. The components in either or both channels can be analyzed in real time with an on-line monitor. Alternatively, the entrained components in either of the separated channels can be permanently removed from the flow. Following analysis or removal of the entrained particles, the flows in the two channels can be recombined, allowing reconstitution of the full flow at a downstream location. The fluid separation system described herein can retain the suspended particles in an oil flow while separating the aerated gas. This feature can be an advantageous addition to the operation of real time suspended particle monitors, such as those described in 5,572,320, U.S. Patent No. 6.049,381, U.S. Patent No. 7,921,739, and U.S. Patent No. 8,056,400, by making these systems operable with aerated flows, thereby expanding their applicability.

In general in the following discussion, the term fluid is intended to encompass liquids and aerated liquids with or without solid particles in the fluid. The liquid can be, but is not limited to oil, hydraulic fluid, or water. The solid particles can be debris from engine wear, such as but not limited to metal shavings, ceramic particles, or non-metallic particles, can be biological contaminants, can be other contaminants or other solid particles. Entrained gas can be air or another gas.

Entrained solid particles typically are heavier than the liquid in which they are carried. Air or other gases entrained in a liquid are typically lighter than fluid in which they are carried. In some circumstances, it is desired to deaerate a flowing fluid, without discarding the gaseous portion, by separating the flow into a less dense portion containing a high fraction of the gases and into a denser portion containing a low fraction of the gases, then recombining the flows. In some instances, it is desired to separate a flowing fluid into a first portion containing a high portion of entrained solid particles into one portion of the flow, and a second portion containing few entrained solid particles. In other circumstances, it is desired to separate two different fluids, one heavier than the other, that have been mixed together, into two different channels.

FIG. 1A is a cutaway view of a fluid separation system 100 for separating a fluid flow into two more separate flows based on buoyancy of the flow components. FIG. IB, 1C, and ID show further detail of some internal components of the fluid separation system 100. In this example, the separation system 100 is suitable for separating a flowing fluid that has entrained or suspended components such as solid particles and gases. Thus, the separation system 100 shown in FIG. 1A is also suitable for deaerating fluid, that is, for separating the gases within a liquid from the liquid itself.

In the exemplary fluid separation system 100, a plurality of components are aligned along a common axis and positioned within a housing 110. In this example, the housing 110 has a generally cylindrical interior surface an approximately constant inner diameter D3 and an inlet opening 112 at first end along the central axis for receiving the fluid flow to be separated. Note that in FIG. 1 A, the front half of the housing 110 is not shown. The outer surface of the housing can have various shapes depending on the application, including cylindrical and rectangular. FIG. 2A and FIG. 2B show three components 120, 140, 160 of the flow separation system 100 that fit within the housing 110. FIG. 3 shows some details of the geometry of the member 140. The first of the three components positioned within the housing 110 is a cup- shaped member 120 having an outer cylindrical surface 121 shaped to fit within the inner diameter D3 of the housing 110. A central axial passageway 123 with a diameter Dl extends from the inlet end 122 that abuts the inner surface of the inlet end 116 of the housing 110 and opens into a concave internal surface 124 that extends to the far end 125 of the member 120. The internal surface 124 forms a cavity and has a diameter that increases in the flow direction.

The cup-shaped member 120 should fit within the housing tightly enough that little or no flow will bypass the passageway 123 by flowing between the outer surface of the member 120 and the inner surface of the housing 110, but loose enough that it can easily be inserted and removed from the housing 110. In this example, the cup-shaped member is inserted into the housing 110 through the inlet end 116 of the housing 110 and held inside the housing by an end cap 118, although other configurations are also envisioned.

Also positioned within the housing is a second member 140 with a convex portion 141 having an apex that faces toward the inlet end and a generally cylindrical portion 143 with an outer diameter sized to fit within the housing 110. In this example, the outer diameter of the cylindrical portion is approximately equal to that of the member 120. When the components are assembled, the convex portion 141 extends at least partially into the cavity of the cup-shaped member 120, with a gap of a predetermined size between the surfaces 124 and 141. The convex portion 141 of the member 140 has an maximum diameter that is less than the outer diameter of the member 140One or more helical slots or channels 144 and 144' extend from one end 154 to the far end of the cylindrical portion 143 of the member 140. The fluid can flow from the gap 126 into the channels 144 formed by the side walls 147, 148, the cylindrical bottom surface 149, and the cylindrical surface of the housing 110. The channels 144 and 144' are opposite each other, and extend approximately one time around the member 140, but in other embodiments, the channels could extend several times around the member. As seen in FIG. 2, 3, and 4, the wide apertures that narrow to a channel width Wl, with the narrower channel portion extending at a helix angle A2 around the member 140 to the other end of the member 140.

In one example, the aperture mouth of each channel 144 and 144' is almost half the circumference of the cylinder, as seen in FIG. 2 A, with a small end surface 142 formed between the mouths of the channels 144 and 144'. When the member 140 is inserted into the housing 110 the end surface 142 comes into contact with the end 125 of the cup-shaped member 120, maintaining the desired spacing between the surfaces 141 and 124. As seen in FIG. 1A, a gap 126 is formed between the concave internal surface 124 and the convex surface 141. In this embodiment, the gap 126 extends completely around the convex surface 141 of the member 140. In operation, fluid flows from the inlet 112 in the inlet end 116 of the housing 110, through the passageway 123, and through a gap 126 or space formed between the inner concave surface 124 and the convex surface 141. FIG. 1A and IB show the passageway 123 and the gap 126 formed between the members 120 and 140. The gap between the member 140 and the member 120 is of such dimension that the diameter of the flow area in the gap region is greater than the diameter of the inlet. For example, for any point along the gap 126 in FIG. IB, the flow's radial position, shown in FIG. ID, will be larger than flow's radial position in the inlet passageway 123 shown in FIG. 1C. The maximum diameter D2 of the convex portion of the member 140 and the angle Al can be determined based on flow rates, allowable pressure drops, mounting space restrictions, and the required amount of separation between fluid components. In this example, both the internal concave surface 124 and the convex surface 141 are cones. Here, the convex portion of the member 140 has a vertex angle Al. In this example, the conical surfaces of the member 120 and the member 140 have equal vertex angles, so the gap has approximately the same radial distance between surfaces 124 and 141 over the length of the conical portion 141. However, the gap's radial distance between surfaces 124 and 141 separation could be increased or decreased by setting the vertex angles to be different, depending on the design parameters discussed above. In addition, the surfaces and 141 can be other shapes instead of cones, with constant, increasing, or decreasing gap radial separation. It is suitable to select the shape and dimensions of the surfaces to prevent or minimize increases in turbulence of the fluid flow FL1 as it moves through this region and approaches the channels 144 and 144'. As the fluid FL1 passes through the passageway 123 and through the gap 126, it has moved radially outward along the length of the member 120, and has taken on an annular flow shape. The member 140 should be locked into position to prevent it from spinning under the force of the fluid flow. In this example, a pin or protuberance 114 extends outward from the inside cylindrical surface of the housing 110. The cylindrical portion of the member 140 has a groove 146 that engages the pin or protuberance and prevents the member 140 from spinning when the fluid flows through the channel 144. Other locking mechanisms are also possible.

The convex portion 141 of the member 140 collects and directs the flow to enter the helical channels 144 and 144'. Each channel has a depth and width DEI, Wl, DE', and Wl', respectively, that can be different but are typically equal. As seen in FIG. 3, one side of a helical channel has a curvature with a radius of curvature R. The channel depths DEI, the widths Wl, and helix angles A3 can be calculated based on the speed of the fluid flow FLl at the inlet and the centrifugal "g-force" to be exerted upon the flow FLl needed to create the desired amount of flow separation in the separation chamber 150. In this example, the depth DEI of the channel is defined by the inner diameter of the housing 110 and the cylindrical inner surface of the channel 144, and is approximately constant throughout its length. However, in other embodiments, the channel depth can be varied depending on the design requirements of the application.

A third member 160 is positioned within the housing, with the member 140 being arranged between the member 120 and the member 160, with a separation chamber 150 between the member 140 and the member 160. The chamber is defined by the facing surfaces of the members 140 and 160 and the inner surface of the housing 110. The outer cylindrical surface of the member 160 has a diameter that is approximately the same as that of the members 120 and 140, so it fits within the inner cylindrical surface of the housing 110.

The member 160 has at least two fluid channels. One channel 161 is a centrally arranged passageway 161 with a wide collector 166 facing into the chamber 150, and another channel 162 has an inlet 163 that is located radially outward and downstream of the collector 166. The centrally arranged passageway 161 has an inlet that in this example is a horn shaped collector 166 that extends into the chamber 150and an outlet 169 at the far end 168 of the member 160. The fluid flow channel 162 has an inlet 163 at the end of the member 160 that faces the chamber 150, at or near the outer surface of the member 160. The fluid flow channel 162 can have a bottom surface formed in the member 160, a top surface defined by the inner surface of the housing 110, and side walls. In this example, the fluid flow channel 162 extends at least partially around the circumference of the member 160 to a second end 165 positioned to direct the fluid flow through an aperture 113 in the housing 110. As discussed in later paragraphs, the horn shaped collector 166 receives a portion of the fluid flow passing through the chamber 150, and the channel opening 163 receives the remaining portion of the fluid flow passing through the chamber 150. In operation, the fluid with entrained particles or gases enters the inlet passage 123, and flows through the passage 123, through the cone shaped gap and over the conical surface 141 of the member 140. The gap surfaces 124 and 141 direct the fluid into the mouths of the channels 144 and 144', and the fluid continues through the channels 144 and 144'. The helical shape of the channels forces the flow into a helical or spiral flow direction, which continues as the fluid moves from the channels into the chamber 150. The centrifugal force resulting from the spiral flow path of the fluid in chamber 150 causes the heavier, particulate-enhanced portion FL3A of the fluid to flow outward toward the cylindrical wall of the chamber 150while the more buoyant portion of fluid flow (e.g., the gaseous portion) separates and forms gaseous partial flow FL2A, which is driven by the generated force toward the center axis 153 of the chamber 150. In this example, the end of the horn shaped collector 166 is positioned at a distance L from the entrance to the chamber 150. The horned shaped collector 166 collects the more buoyant portion of the flow FL2A that has been driven toward the central part of the chamber. The heavier portion of the flow FL3A is collected from the region adjacent to the cylindrical wall of the chamber 150 by the opening 163 of the fluid flow channel 162 in the member 160. The distance L affects the dwell time of the flow within the chamber 150, and together with the angle and dimensions of the channel 144 and the helix angle A3, affects the amount of separation between the partial flows FL2A and FL3A. The distance M between the outer rim 167 of the horn shaped collector 166 and the inner wall of the housing 110 affects amount of the more buoyant component in the flow (FL2A) collected by the horn-shaped collector 166, and the amount of the less buoyant component in the remaining flow that enters the fluid flow passage 162 (FL3A).

In this example, the channels 144 and 144' in the member 140 and the channel 162 in the member 160 can each turn in the same direction. In this example, if viewing the members from the apex end 151 of the member 140, flow through all the channels will be in the counterclockwise direction and toward the far end 168 of the member 160. Further, it will be clear that the fluid moves generally in a single direction from the inlet 112 at one end of the system toward the outlets 165 and 169 at or near the far end of the member 160 without reversing course.

The spiral shape of the channel 162 can provide a low-resistance flow path to a side outlet in the housing, which can be suitable for a compact particle analysis system discussed in later paragraphs. However, the channel can extend more directly to the side of the housing, or to the end of the housing, and can be a shape other than spiral or curved.

In this example, the member 160 is held at the desired axial distance from the member 140 and prevented from spinning by an end portion 172 that extends in a radial direction past the inner diameter of the housing, or by another securing mechanism. The design parameters L and M can be selected so the system provides a desired amount of separation efficiency, a desired size range of particles collected in the heavier FL3A flow, and

concentration efficiency of the FL3A flow. Thus, the system is widely applicable for a wide range of values of viscosity, particle density, and sizes.

In this example, a single channel 162 is shown radially outward of a single horn shaped opening 166 with a single axial passageway. In other embodiments, additional horn shaped openings and passageways can surround the first horn shaped opening, to collect intermediate buoyancy flow portions. Further, more channels 162 can be included in the member 160 to collect the heavier portion of the fluid flow.

The aperture or mouth 166 of the axial passageway 161 tapers outward, and can be curved in an outward direction as shown in FIG. 1A, 2A, and 2B or can increase linearly in diameter. It may also be suitable to use a straight pipe extending into the chamber in some circumstances, however, such a straight pipe is expected to collect less of the more buoyant flow component.

The system 100 is intended to introduce a multicomponent flow along the axis of the device and form the flow into an annular ring, then introduce this flow into spiral channels without constricting the flow area. This allows the centrifugal separation area to be achieved without the disadvantageous large pressure drop effects associated with directional changes and flow area constriction associated with previous "cyclone" designs. The separated flows FL2 and FL3 can be analyzed or processed separately, as discussed in later paragraphs. The flows can then be discarded, maintained separately for further processing, or one or both can be reintroduced into the original system flow path. In this example, the fluids leaving the flow separation system 100 have different buoyancies. For example, FL-3 can be denser (less buoyant) with more solid particles, while FL2 can be more buoyant (less dense) due to the presence of more entrained gases. The system 100 can deaerate fluids, that is, can separate most or all of the air or other gases from a fluid flow FL1 into a flow FL2 having most or all of the air or other gases and a flow FL3 having little entrained gas or air. This is suitable for many applications, including particle analysis systems. For example, in some particle sensors the detection sensitivity depends on the pipe diameter of the flow. Deaerating or increasing the concentration of particles in the oil flow allows a smaller diameter pipe and a smaller sensor to be used, providing improved particle detection sensitivity. The deaeration can reduce the noise in the sensor caused by air in the flow.

Some presently available real time optical fluid particle analysis systems, e.g., that described in U.S. Patent No. 5,572,320, are best able to image particles located in the optical near field of the imaging system. For these systems, the conduit size necessary to carry the fluid viewed by that sensor is such that the particles size range is limited. Deaerating the flow with a flow separation system can broaden the applicability and effectiveness of the oil analysis system.

FIG. 4 A shows the flow separation system 100 as a part of a larger fluid monitoring system 400. The flow separation system 100 separates the flow into a denser flow FL3 containing the majority of the particles in the flow, and a more buoyant flow FL2. The particle enhanced flow FL3 can be introduced into a particle analysis system 410 directly or by way of connecting tubing or other fluid conduits. The particle enhanced flow FL3 flows through a passageway 420 and past an optional fluid sampling port 440, and the sample of flow FL3b can be extracted through conduit 450. The remaining flow FL3c, which is not removed at the sampling port, can be passed to a real time oil analysis system 430. In some embodiments, the oil analysis system can automatically analyze the size distribution of particles carried in the fluid. In this example, the flow FL3c that has passed through the real time oil analysis system is recombined with the higher buoyancy flow FL2 in a chamber 460 to form a re-aerated flow FL4. In this example, the higher buoyancy flow FL2 can be transmitted directly from the flow separation system 100 to the chamber 460, or can be further processed or analyzed by fluid analysis devices before passing into the chamber 460. The recombined flow FL4 flows out of the chamber 460 and exits the particle analysis system 410 through an exit port 470. The flow FL4 can be reintroduced into the fluid flow system to maintain total system volume, or discarded. FIG. 4B shows the details of one embodiment of a viewing port as positioned in the flow conduit 420 for the optical analysis system. Here, the heavier fluid flow FL3c flows through the conduit 420. Sets of windows 432 formed of suitably transparent and strong material are aligned opposite each other across the channel 420 in one or more pairs. The windows surfaces 438 are preferably flush with the interior walls of the channel 420 and are secured by a compressing seal system 436 against a lock mechanism 434 such that pressure variations in the channel will not cause the windows 432 to move. In one embodiment, the real time oil analysis system is an optical debris monitor such as that described in U.S. Patent No. 5,572,320, U.S. Patent No. 6,049,381, U.S. Patent No. 8,582,100, or U.S. 8.654,329, and the disclosures of which are incorporated by reference in their entireties. The remaining components of the oil analysis system are not shown.

FIG. 5 illustrates a system in which two flow separators 100 are arranged in series. Here, the input flow FLl is separated by separator 100 into a denser (less buoyant) flow FL3 and a more buoyant (less dense) flow FL2. In this example, the denser flow FL3 is then input into a second separator 100', which separates this flow into a denser flow FL5 and a less dense flow FL4. The separators 100 and 100' can have different design parameters. Additional separators can be added in-line with any of the output flows FL4, FL5, and FL2 to further separate the fluids. The separated flow channels can be recombined in a chamber or the flow in one or more of the final channels can be permanently isolated, with the remaining flows being recombined and returned to the original fluid system. For example, the most particle-laden flows could be permanently removed from the fluid system. In other examples, the more buoyant flow FL2 is input to an additional fluid separator.

FIG. 6 illustrates a system for removing foreign material from a fluid reservoir contaminated with the foreign material. Here, a positive displacement pump 620 draws contaminated fluid from a reservoir 610. The contaminated fluid enters the fluid separator 100, where the fluid is separated into flows FL2 and FL3, with the less buoyant (denser) fluid flow FL3 containing the particles of foreign material. The cleaned, more buoyant, fluid flow FL2 is returned to the reservoir by way of conduit 670. The particle-laden flow FL3 is directed to a residual slurry separation unit 630 by conduit 660, and the particles are removed from the slurry separation unit 630 by a foreign material removal unit 640. The reclaimed fluid from the slurry separation unit 630 is returned to the reservoir 610 via conduit 680. The removed particles removed from the flow can be transported to a foreign material compactor and treatment unit 640 for disposal. Fluid from which the particles have been removed is returned to the fluid reservoir 610. Although only one separation system 100 is shown, more than one separation system can be arranged in the system in series to remove a broader range of particle sizes. Several separation systems 100 can also be arranged in parallel, to clean a high volume of fluid more rapidly. This system 600 provides continuous operation of the separators without loss of fluid from the main reservoir. The fluid reservoir 610 can be, for example, a fuel storage tank. Fuel storage tanks can have a tendency to contain microbial contamination.

FIG. 7 illustrates the flow and viewing components of a compact, optical oil analysis system. The flow separation module 700 can be as shown in FIG. 1A - ID and FIG. 2A-2B above, configured to separate an oil flow FL1 into a more buoyant flow FL2 and a more dense flow FL3. The more buoyant flow is introduced into a connector module 710, which physically connects the flow separation module 700 to the viewing and recombination module 720. The connector module 710 can receive the axial flow FL2 and redirect it toward another component (e.g., toward a optical viewing and recombination module 720). The module can be integral with or affixed to the third member 160, and its size can keep the member 160 from sliding too far into the housing 110, thus maintaining the desired distance L between the member 140 and the horn 166. The connector module 710 can be integral with the separation module 700, with the viewing and recombination module 720, or can be a separate component.

The viewing and recombination module has a passageway 722 that receives the particle laden flow FL3 and passes it through a viewing window 724, and subsequently into a recombination chamber 726. The viewing window can be as shown in FIG. 4 A and 4B, and can be part of an optical oil analysis system described above. In this example, two passageways 728 and 730 transmit the lower density fluid FL2 into the recombination chamber. A passageway 734 and outlet port 732 output the recombined fluid. In real time oil analysis systems, the recombined fluid can be returned to the main fluid reservoir, to avoid loss of system fluid. This embodiment can operate at pressures typical for oil lubrications systems of gas turbine engines, typically 80 - 150 psi, with an oil flow through the analysis system of approximately 10 gallons per minute.

The system 100 can also be considered to include three main components: the housing, a flow forming member, and a flow receiving member, with a separation chamber between the flow forming element and the flow receiving element. The flow forming member takes the input flow and gives it a helical or spiral shape that continues in the separation chamber. The flow receiving member can be considered to be the member 140 or the member 140 together with the member 120, because it receives the flow from the chamber. It is also noted that the member 120 and 140 do not have to be separate elements, but can be a single unitary element, either integral with each other or formed separately and subsequently joined together. The flow receiving member can be considered to correspond to the member 160.

Thus, the system for separating a multicomponent fluid into two or more flow channels, each containing components with different buoyancy, can comprise a housing having a fluid inlet at a first end and at least two outlets; a flow forming member configured to fit within the housing at the inlet end of the housing and having a flow passage therethrough with at least one helical channel in an outer cylindrical surface that directs the fluid into a helical flow direction near the outer circumference of the flow forming member as the fluid exits the flow forming member; and a flow receiving member configured to fit within the housing at an opposite end of the housing, having a central fluid passageway for carrying higher buoyancy fluid and extending through the member along a central axis, and at least one other fluid passageway for carrying lower buoyancy fluid with an inlet positioned radially outward of the inlet of the central fluid passageway; wherein a separation chamber is formed between faces of the flow forming member and the flow receiving member. In operation, the helical flow enters the separation chamber, and more buoyant portions of the flow move toward a central axis of the chamber and enter the central fluid passageway, and less buoyant portions of the flow continue in a helical path near the outer part of the chamber and bypass the entrance of the central fluid passageway and exit the system through the at least one other fluid passageway.

The components of the flow separation system are preferably formed of a strong material that is impervious to corrosion or other degradation from the fluid being carried. Some suitable materials include aluminum, stainless steel, and some plastics.