EP0069729A1

EP0069729A1 - Industrial coolant fluid recovery system

Info

Publication number: EP0069729A1
Application number: EP81901219A
Authority: EP
Inventors: Darrel D. Jahn; Robert D. Quam
Original assignee: Donaldson Co Inc
Current assignee: Donaldson Co Inc
Priority date: 1981-01-15
Filing date: 1981-01-15
Publication date: 1983-01-19
Also published as: EP0069119A1; DE3152669A1; WO1982002343A1; EP0069119B1; WO1982002344A1; EP0069119A4; JPS603850B2; AU535134B2; JPS57502093A; AU7173281A; GB2103962A; AU7170581A; GB2103962B

Abstract

Systeme (10) de recuperation d'un fluide refrigerant a partir d'un melange de fluides contamine. Le systeme (10) comprend un recipient (20) structure pour permettre la creation d'un tourbillon de fluide a l'interieur. Le recipient (20) comprend une ouverture de sortie de fond et un moyen d'entree tangentiel (25). Une conduite (30) relie un separateur (35) a l'ouverture de sortie (24) du recipient Une seconde conduite (33, 34) recycle le fluide decharge du conteneur (20) et le renvoie dans le conteneur (20) par l'intermediaire du moyen d'entree (25) pour maintenir le tourbillon de fluide cree a l'interieur du recipient (20). Le liquide plus leger dans le melange monte vers la surface du tourbillon puis est porte par les forces tourbillonnantes sur cette surface vers l'orifice de sortie (24), le liquide plus leger etant alors 'ecume' du fluide refrigerant dans le conteneur (20).System (10) for recovering a refrigerant from a mixture of contaminated fluids. The system (10) comprises a container (20) structured to allow the creation of a vortex of fluid inside. The container (20) comprises a bottom outlet opening and a tangential inlet means (25). A line (30) connects a separator (35) to the outlet opening (24) of the container A second line (33, 34) recycles the discharge fluid from the container (20) and returns it to the container (20) via the intermediate the inlet means (25) for maintaining the vortex of fluid created inside the container (20). The lighter liquid in the mixture rises towards the surface of the vortex then is carried by the swirling forces on this surface towards the outlet orifice (24), the lighter liquid then being 'scum' of the refrigerant fluid in the container (20 ).

Description

INDUSTRIAL COOLANT FLUID RECOVERY SYSTEM

Technical Background The present invention pertains to fluid recovery systems and in particular to industrial recovery systems applying rotational fluid flow principles for removing a coolant fluid from a contaminated mixture.

Background In industries such as the machine-tooling indus¬ try, one of the end results of the industrial process is a contaminated fluid mixture. The contaminated mixture typically includes a coolant fluid, generally water-based, lighter liquids such as free and mechanically emulsified oils, and various solids particulate and other impurities. The valuable component is the coolant fluid which acquires a build-up of free or tramp oil within it from leaks in the lubricating and hydraulic systems of the industry and further contamination from the oil-wetted parts being machined.

Due to stringent government regulations for the disposal of such contaminated mixtures as well as the desire by those in the industries for continued, indef¬ inite use of the coolant fluid in more than one application, efforts have been spent in creating a system capable of recovering the valuable coolant fluid from the contaminated mixture. Not only must the metal solids, foreign objects and other impurities be removed from the mixture, but just as important is the removal of the free and mechanically emulsified oils which have accumulated in the coolant fluid during the machining processes. Also, the removal of oils must occur without resulting damage to the composition of the recovered coolant fluid.

Prior art recovery systems have addressed the problem of solids and impurities removal but their removal

O P1 of free or tramp oils have generally been accomplished with various complex structural arrangements requiring substantial floor areas for operation which are often as expensive to maintain as they are to construct. The present invention is a much simplified recovery system design which achieves a high degree of recovered coolant clarity by methods unknown at present in the art. Further, the present invention answers the pressing needs of modern industries for a recovery system which will significantly increase the useful life of the coolant fluid while eliminating the disposal difficulties involved with the contaminated fluid mixtures.

Summary of the Invention The present invention is a system for separating a heavier coolant fluid from lighter contaminating liquids and various types of solid matter accumulating in the coolant fluid during the particular industrial process. Primary elements of the system include a fluid container having a generally circular cross-section. The container is adapted to receive the contaminated mixture through a top portion of the container. A downwardly sloping bot¬ tommost portion extends inwardly to the container's centrally located bottom outlet opening. Along a side of the container is a tangentially directed inlet means through which fluid is returned into the container — together the inlet means and outlet opening impart a fluid vortex to the container's fluid contents. A conduit means connected to the container outlet opening and a separator transfers the fluids discharged from the container to an inlet means in the separator. The transfer is aided by a pump. The separator is generally of the centrifugal type such that a heavier fluid, a lighter liquid and relatively small solids particulates can be separated from each other and separately discharged from the separator. A final primary aspect of the system is the structural means for returning fluid from various locations in the system back to the container through the tangential inlet means. The returned fluid flows into the container from the inlet means in a manner which maintains the fluid vortex so that the free oil or tramp oil is carried upon the surface of the heavier coolant as it is carried out of the container outlet opening by the forces of the fluid vortex.

Accordingly, one aspect of the present invention provides a versatile recovery system compatible for use in most types of industries using water-based type coolant fluids. According to another aspect of the present invention, there is provided a fluid recovery system design which is successful in achieving a high degree of coolant fluid recovery for reuse of the fluid in the industry on a continuing basis. A further aspect of the present invention mini¬ mizes the industrial disposal problems by reclaiming the valuable industrial fluids for reuse and discharging separated contaminants for convenient disposal or other use. A still further aspect of the present invention provides removal of contaminating liquids and solids from the coolant fluid in an efficient and quick manner without damage to the chemical composition of the coolant fluid.

Brief Description of the Drawings Figure 1 is a schematic, elevational view of one embodiment of the present invention with portions broken away and shown in cross-section.

Figure 2 is a cross-sectional view of the present invention as seen along lines 2-2 in Figure 1. Figure 3 is a schematic, elevational view of a second embodiment of the present invention.

Figure 4 is an elevational view of one aspect of the present invention with portions broken away and shown in cross-section. Figure 5 is a greatly enlarged view of a portion of the present invention seen in Figure 4.

OMP1 Detailed Description of the Preferred Embodiment Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to Figure 1, the recovery system is indicated generally by the reference number 10. A solids dragout arrangement first receives the contaminated fluid mixture into the system 10. The dragout arrangement generally includes a holding tank 11, a standard dragout assembly 12 which removes the solids settling out from the fluid held in the tank 11, and a solids discharge opening 13 through which the "dragged-out" solids are removed from the tank 11. The contaminated fluid leaves the tank 11 by overflowing a portion of the tank 14 through a grid-like screen 15 which prevents foreign objects floating on the surface of the mixture from overflowing the tank 14 with the fluid mix¬ ture.

- From the receiving container 11, the contami¬ nated mixture flows into a recovery container 20 through or along a conduit 16 or other suitable transfer struc¬ ture. The recovery container 20 in the preferred embodi¬ ment has a cylindrical shape with an open top 23 upon which a cover (not shown) can be placed. The bottom portion of the tank is typically frusto-conical in shape or a rounded dish shape so that the walls 22 of the con¬ tainer slope downwardly towards a central portion of the container's bottom wall. A circular outlet opening 24 is formed in the central portion of the container's bottom wall. The vertical axis 18 of the container 20 passes through the center of the outlet opening 24. Located along an upper portion of a side 21 of the container 20 is an inlet means 25 which in the preferred embodiment, seen most clearly in Figure 2, is a tube or pipe 34 positioned tangential to the container so that fluid entering the container 20 through the pipe 34 is directed tangentially along a side wall 21 of the container 20. A standard fluid tap 27 is disposed in a lower portion of the con-

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OMPI tainer side wall 21. The tap 27 is essentially a combina¬ tion valve 28 and pipe 29, an arrangement which allows the removal of clarified, recovered coolant fluid from the recovery container 20. Secured to the container outlet opening 24 is a conduit 30, e. g. pipe or tubing, which receives fluid flow from the container outlet opening 24 and transfers the fluid to a remote location. Disposed in the conduit 30 of the preferred embodiment is a pump 31. The pre- ferred pump 31 is an air-operated diaphragm pump which is capable of transferring a fluid being carried upon the surface of a second fluid without substantial agitation of the fluids or causing a substantial remixing of the two fluids during the transfer. In the second embodiment shown in Figure 3, a standard two-way valve 32 is located upstream from the pump 31 in the conduit 30. The valve 32 is operable to return a portion of the container's dis¬ charged fluid to the container's inlet means 25 through a suitable conduit 33, e. g., pipe or tubing allowing a substantial portion of the fluid to pass through into the conduit 30, or all of the discharged fluid can be passed through the valve and into the conduit 30, preventing then any portion from returning to the container.

The conduit 30 transfers the container's dis- charged fluids with the assistance of the pump 31 to a separator 35 positioned generally above and proximate to the recovery container 20. Referring now to Figure 4, the separator 35 used in the preferred embodiment is a liquid/liquid/solid centrifugal separator. The separator has a drum 36 including a cylindrical side wall 37, a top wall member 38, and a frustoconical bottom member 39. The periphery of the bottom member 39 is attached to the bottom edge of the side wall 37 and the center extends into the drum 36. The rotor assembly includes a portion of the stationary inlet manifold 40, a shaft 41, a disc assembly mounted to the shaft 41, and radial spacers 42 secured within the disc assembly. The inlet manifold 40 is fixed to a portion of the housing cover 53, and extends downwardly from the housing cover 53 through the drum top wall member 38 and into the rotor disc assembly. In the embodiment shown, the disc assembly is a nested arrange- ment of spaced apart truncated cone discs 44, including a topmost and bottommost disc 45, 46, respectively. The shape of each disc 44, 45 , 46 is basically a central flat circular portion from which extends downwardly a sloping annular peripheral portion. The sloping portion is the frusto-conical surface of the disc and is shown sloped at a 50° angle from the plane of the flat surface portion. The radial spacers 42 maintain the spaced apart relation¬ ship between adjacent discs. As can be understood from FIGURE 5, each spacer is a finger plate secured between adjacent discs. Each of the discs 44, not including the topmost and the bottommost discs 45, 46, has a circular arrangement of holes or apertures 47 along its conical surface. The topmost disc 45 has its openings 47 formed in the horizontal upper portion thereof generally in vertical alignment with openings 47 of discs 44. The circular patterns of disc apertures 47 are aligned within the assembly to allow a light liquid to flow upward as the disc assembly rotates. The bottommost disc 46 has attached along the underside of its conical portion a set of three fins 48 extending generally downward from the disc surface in the flow path of the incoming contaminated fluid. The fins 48 are spaced apart at substantially equal intervals along the disc surface. A set of paddles 49 is mounted to a rotor shaft head 50 positioned below the truncated portion of the bottommost disc 46 of the rotor assembly. The rotor shaft head 50 is mounted in the drum 36 for coaxial rotation with the rotor assembly. Each paddle 49 is of rectangular shape and extends upward towards the bottommost disc 46 and radially outward from the rotor shaft 41. The paddles 49 are mounted at sub¬ stantially equal intervals with respect to each other about the rotor shaft head 50. Referring again to FIGURE 4, the drum 36 and the rotor assembly are mounted in a housing 51 having a gener¬ ally cylindrical body 52, a top cover 53 and a bottom portion 54. The assembly of nested discs 44, 45, 46 is secured to the rotor shaft head 50 by a plurality of shoulder screws 55. The drum and the rotor assembly are concentrically mounted and rotate independently about a vertical axis 56. It can be seen that the drum 36 rotates on bearings 57 mounted in the housing cover 53 and bear- ings 58 mounted between a drum hub portion 83 and bearing sleeve 84. The rotor assembly is rotatably mounted by bearings 59 mounted between bearing sleeve 84 and rotor shaft 41. A motor (not shown) drives the rotor assembly by means of a belt 60 and a pulley 61 mounted on the rotor shaft 41. The directions of rotation for the drum 36 and rotor assembly are generally counterclockwise when viewed from the top.

The contaminated fluid mixture containing liquids of differing density, a light liquid, e.g., a mechanically emulsified oil, a heavier liquid, e.g., a water-based coolant, and solid particles, e.g., metal chips, enters the separator through the inlet manifold 40 extending to the bottom of the disc assembly. The con¬ taminated fluid drops onto the rotor shaft head 50 where it is thrown or directed outwardly by the rotating set of paddles 49, into contact with the rotating fins 48 extending below the bottommost disc 46 where it is further accelerated towards the drum side wall 37. The drum 36 is then driven by the viscous or shear forces associated with the rotating fluid. In steady state operation, the rotor assembly is driven at about 3600 rpm. The rotation rate of the drum 36 lags behind that of the rotor assembly by 100-300 rpm. As the drum 36 and rotor assembly rotate a wall of fluid is built up along the side wall 37 of the drum 36. Centrifugal forces cause the solid particles in the fluid to be thrown radially outward to accumulate in the portion of the fluid wall closest to the side wall 37 of the drum 36 can be seen in FIGURE 5. As the wall of fluid builds upward and flow continues to enter the separator 35, the solids heavier than the fluid separate and move to the drum side wall 37. The lighter liquid separates from the heavier liquid within the disc assembly and flows upward along the sur¬ faces of the individual discs 44, 46. As the light liquid collects towards the central portion of each disc, it eventually overflows into the apertures 47 of the discs 44, 46 and proceeds upward towards the upper portion of the disc assembly where it then overflows out of the top disc apertures 47 and is guided upward to the drum top wall member 38 by a downwardly extending annular baffle member 62, best seen in FIGURE 5. As the clarified light liquid moves upward along the baffle member 62, it over- flows out of the drum through light liquid discharge openings 47' provided in the top wall member 38 of the drum 36. The clarified light liquid then flows along a second baffle-like member 63 extending upward from the drum top wall member 38 where it is guided to an upper collection chamber 64 and then removed through an outlet 65 in its clarified state. The topmost disc 45 of the rotor assembly has a greater diameter than the other discs 44, 46. The lip portion formed by the greater diameter prevents the light liquid flow from proceeding to the heavier liquid discharge openings 66 in the drum top wall 38, by trapping the light liquid flow within the disc assembly.

The heavier liquid separated from both the light liquid and the solids flows upward near the outer side edges of the disc assembly. When the flow has reached the level of the top disc 45 it flows radially inward between the top disc 45 and a parallel portion 81 of an extension means 80. See FIGURE 5. The extension means 80 is a fixed structural member for preventing carryover of con- taminated fluid and solids into the disc assembly and liquid discharge openings 47', 66 during the purge cycle. Generally it is an angled, annular member mounted between

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OMPI the drum side wall 37 and the heavier liquid openings 66 in the drum top wall member 38. A portion 81 of the means 80 extends substantially parallel and close to a portion of- the conical surface of the topmost disc 45 in the rotor assembly. It is in this gap between the parallel exten¬ sion portion 81 and the conical surface of the top disc 45 that the clarified heavier liquid flows upward and inward. As it passes the parallel portion 81 of the extension means 80 it then proceeds generally upward in the space between the baffle member 62 and an extension portion 82 where it overflows the drum 36 through the circular ar¬ rangement of heavier liquid openings 66 in the drum top wall member 38. As the clarified heavier liquid passes through the openings 66, it enters a lower collection chamber 67 from which it is subsequently -released from the centrifuge through an outlet 68. In the preferred embodi¬ ment of Figure 1 the separator outlet 68 is connected to the conduit 34 for returning the separated heavier coolant fluid to the container 20 through inlet means 25. The upper collection chamber 64 is defined by the area between housing 51 and the drum top wall member 38. The lower collection chamber 67 is defined by the centrifuge housing body 52 and an internal wall 52' of the housing as shown in FIGURE 5. Each chamber is separate from the other. An air brake 69 shown in FIGURE 4 is used to slow and stop the drum 36 when the purge cycle is ini¬ tiated. When the brake 69 is actuated, a shoe 70 is driven- upwards and held against a projection 71 which is in effect an extension of the drum 36. An annular wall or baffle 72 extends from the bottom of the drum side wall 37. An opposite apex thereof defines an edge or lip opening 75 into which the fluid containing the resuspended particles flows during the purge cycle. The edge opening 75 is formed inwardly of the baffle 72 and beyond the centers of the clarified light liquid openings 47' in the drum top wall 38. Note also in FIGURES 4 and 5 that the peripheral edges of the

' _OMP1 rotor disc assembly extend beyond the outermost edges of the clarified heavier liquid openings 66. Particles, as stated above, accumulate during the separation process on the drum side wall 37 between the drum top wall member 38 and the baffle 72.

A pair of purge rods 73 are bolted to the inside of the drum 36 near the side wall 37 so as to extend from the drum top wall member 38 to the inner edge of the baffle 72. The rods 73 are positioned opposite each other in the drum 36. Each rod 73 has a generally circular cross-section, but a longitudinal flat surfaced portion 74 along the rod length is also provided. Each rod's flat surface faces opposite the directions of rotation of the drum and rotor assembly. When the drum 36 is stopped or_.slowed, the rotor assembly continues to rotate. The fluid is disrupted and the accumulated particles are penetrated by fluid flow diverted as a result of impacting the flat surfaces 74 of the purge rods 73. The particles are then resuspended in the fluid. As the purge cycle continues, the fluid and the resuspended particles flow inwardly and downwardly along the upper surface of the baffle 72, downwardly through the lip openings 75 and downwardly through an opening 76 leading from the solids collection chamber 77. The purged fluid and solids then exit the centrifuge through a ramp-like outlet 78, only partially shown in FIGURE 4. ■ ■ Operation of the Preferred Embodiment

The contaminated fluid mixture is initially held in the receiving tank 11 where the relatively heavy solids particulate settle out and are removed by the slow-moving dragout 12 which ultimately discharges the solids particu¬ late in a relatively dry state through the discharge opening 13 into a collection chamber (not shown). Any floating foreign objects are collected along the grid-like screen 15 in the overflow portion 14 of the receiving tank 11 and can subsequently be removed from the tank 11. As the contaminated fluid mixture overflows the tank 11, it flows into the top portion 23 of the recovery container 20. When the container is partially filled, the pump 31 is turned on thus starting the process of recover- ing the coolant fluid. The pump draws the fluid mixture out the opening 24 and on into the separator 35 where the separation of mixture is carried on as discussed above in the description of the centrifugal separator 35. Sepa¬ rated tramp or free oil is discharged from the separator 35 through outlet means 65 where it is deposited into an oil concentrator for further recovery and concentration or into a collection container for disposal. During the purge cycle of the separator, the separated solids par- ticulate exit the separator 35 through outlet means 67 where the material is collected and disposed of. More importantly, however, is" the route of the recovered cool¬ ant fluid which is released from the separator 35 through outlet 68 into conduit 34. Conduit 34 carries the recovered coolant fluid flow into inlet means 25 where the flow enters the tank in a plane substantially perpen¬ dicular to the vertical axis 18 and near the liquid surface level of the container's contents either just below or just above the fluid surface level.

In combination with the downwardly sloping side walls 21 of the container 20 and the bottom outlet opening 24 through which the container's vertical axis 18 passes, the entering tangential flow of the returning coolant fluid, imparts a rotational velocity to the container's fluid contents. This rotational velocity in combination with the natural tendency of draining liquid to swirl creates a fluid vortex and whirlpool in the container. The free oil within the contaminated mixture will natur¬ ally separate and rise to the top of the container fluid's surface. In the prior art, various mechanical skimming devices were used to remove the accumulated oil from the surface of the fluid held in prior art settling tanks. A direct result, however, of the vortex forces created within the container 20 of the present invention is the quick drawing of all of the surface collected oil down into the whirlpool's central rotating surface along the vertical axis 18 and out the outlet opening 24 to the preferred air-operated pump for transfer on to the sepa¬ rator 35 for final separation within the separator 35 where the coolant fluid and surface-collected free oil are further separated and removed from each other.

In the alternate embodiment shown in Figure 3, a portion of the fluid mixture discharged from the container opening 24 is returned to the container 20 prior to its entry into the separator 35. Most of the fluid mixture discharged through opening 24, however, proceeds directly to the separator 35 for final separation and subsequent discharge through respective separator outlets 65, 67 and 68. A two-way, diverter valve 32 directs a portion of the fluid into the conduit 33 where it is pumped back to the container inlet means 25, where it then enters the con¬ tainer 20 in a tangential direction with a velocity which creates with the centrally located opening 24 the fluid vortex forces discussed above.

The two modes of operation of the present inven¬ tion are thus a "recirculating method", shown schematically in Figure 1, which allows a number of passes of the fluid mixture through the system prior to the ultimate recovery of the coolant fluid from the system through the container tap 27, and a "single-pass" method, shown schematically in Figure 3, where a portion of the fluid mixture passes on to the separator while the remain- ing portion is recirculated in order to maintain the fluid vortex within the container for the recovery of the coolant fluid.

The final result from the present invention is that with the combination of the fluid vortex-creating container 20 and the centrifugal separator 35, the prior art oil skimming devices are eliminated from the coolant fluid recovery process. Furthermore, the present inven- tion accomplishes the "skimming" process in substantially less time and more effectively than was possible with the prior art devices.

Obviously modifications and variations of the present invention are possible in light of the above disclosure. Therefore, it is to be understood that within the scope of the following claims the invention may be practiced otherwise than as specifically described herein.

Claims

WHAT IS CLAIMED IS:

1. A system for separating a heavier liquid and a lighter liquid from a fluid mixture, comprising: a container adapted to receive said fluid mix- ture comprising walls defining a generally centrally located bottommost outlet opening, said container having a generally circular cross-section and inlet means for introducing a fluid into said container in a manner to create with said outlet opening a fluid vortex, said fluid vortex having a central portion defining a rotating sur¬ face extending through said fluid to said outlet opening; means for separating said heavier liquid from said lighter liquid; means for transferring fluid from said container outlet opening to said separating means; and means for recirculating at least a portion of said fluid back to said container through said container inlet means to maintain said fluid vortex, whereby said lighter liquid being carried upon the surface of the fluid is carried by said central rotating surface to said con¬ tainer outlet opening.

2. The system according to claim 1 wherein said container inlet means is a tangential inlet situated so that fluid flowing through said inlet is directed towards a side wall of said container near the fluid surface level of said container.

3. The system according to claim 1 wherein said container includes an open top portion for receiving said fluid mixture.

4. The system according to claim 1 wherein a bottom portion of each of said container walls slopes downwardly towards said centrally located outlet opening.

5. The system according to claim 4 wherein said downwardly sloping container wall portions define an inverted frustoconical bottommost portion of said con¬ tainer.

6. The system according to claim 1 wherein said heavier liquid is a .water-based coolant fluid, said lighter liquid is an oil, and said separating means is a centrifugal separator, said separator including inlet means for receiving fluid from said container, first outlet means for discharging recovered coolant fluid, and second outlet means for discharging separated oil from said separator.

7. The system according to claim 6 wherein said recirculating means includes conduit means for trans- ferring said recirculated fluid portion from said separator first outlet means to said container inlet means.

8. The system according to claim 1 wherein said recirculating means includes a valve disposed in said fluid transferring means and a conduit connected between said valve and said container inlet means, said valve having a first operative position allowing a portion of the fluid discharged from said container outlet opening to be recirculated through said conduit into said container, and a second operative position preventing the recircu¬ lating flow of said fluid portion through said conduit.

9. The system according to claim 8 wherein said transferring means includes pumping means capable of pumping fluid discharged from said container outlet open- ing to a remote location without substantial agitation of the fluid during the transfer.

10. A system for separating a coolant fluid and a lighter liquid from a contaminated fluid mixture, com¬ prising: a container adapted to receive said contaminated mixture, comprising walls defining a generally centrally located bottommost outlet opening and a portion of said walls sloping downwardly to said outlet opening, said con¬ tainer having a generally circular cross-section and inlet means for introducing a fluid into said container in a direction which creates with said outlet opening a fluid vortex; a separator mounted proximate said container for separating said coolant fluid from said lighter liquid, said separator including inlet means for receiving fluid mixture from said container, first outlet means for dis¬ charging recovered coolant fluid and second outlet means for discharging lighter liquid from said separator; conduit means for transferring fluid from said container outlet opening to said separator inlet means; and - means for introducing coolant fluid from said separator first outlet means into said container inlet means whereby said fluid vortex is maintained and said lighter liquid is carried upon the surface of the fluid being carried to said container outlet opening by said fluid vortex.

11. The system according to claim 10 wherein said container has a vertical axis extending through said outlet opening and wherein said inlet means is a tan- gential inlet in said wall whereby fluid flow passing through said tangential inlet into said container is initially directed towards said container side wall in a plane perpendicular to said axis.

12. The system according to claim 10 wherein said container has an open top portion.

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13. The system according to claim 10 wherein said downwardly sloping container walls define an inverted frustoconical bottommost portion of said container.

14. The system according to claim 10 wherein said conduit means includes an air-operated, diaphragm pump.

15. A process for automatically skimming, within a container having a generally circular cross section and a bottom outlet opening, a lighter liquid from a fluid mixture including said lighter liquid, while transferring both said lighter liquid and fluid mixture to a remote location, comprising the steps of: depositing a volume of said fluid mixture into said container; introducing a portion of said fluid into said container in a direction enhancing a fluid vortex within said container while permitting said lighter liquid to rise to the surface of said fluid vortex so that said lighter liquid is carried upon said fluid vortex surface to said outlet opening; and continuously transferring a flow of said fluid mixture and said surface carried lighter liquid to a remote location.

16. The process according to claim 15 wherein said fluid portion is introduced tangentially.

17. The process of claim 15 further including a step of recirculating a portion of the fluid mixture subsequent to its transfer from said outlet opening so as to enhance said fluid vortex.

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