US3544079A

US3544079A - Apparatus for mixing liquids

Info

Publication number: US3544079A
Authority: US
Inventors: Jacques Henri Dressler
Original assignee: Saint Gobain Techniques Nouvelles SA
Current assignee: Saint Gobain Techniques Nouvelles SA
Priority date: 1958-02-06
Filing date: 1965-06-04
Publication date: 1970-12-01
Anticipated expiration: 1987-12-01
Also published as: GB905232A; ES247017A1

Description

United States Patent [72] Inventor Jacques Henri Dressler Courbevoie, Seine, France [21] App1.No. 461,349 [22] Filed June 4, 1965 Continuation-impart of Ser. No. 790,900, Feb. 3, 1959, abandoned. [45] Patented Dec. 1, 1970 [73] Assignee Saint-Cobain Techniques Nouvelles Courbevoie, France [32] Priority Feb. 6, 1958 [33] France [31] No. 757,601

[54] APPARATUS FOR MIXING LIQUIDS 23 Claims, 2 Drawing Figs.

[52] US. Cl 2 5 9 /7; 23/267I23/271; 261/184 [51] Int. Cl B011 7/00 [50] Field of Search 152/359;

[5 6] References Cited UNITED STATES PATENTS 1,445,935 2/1923 Daman 259/96 1,645,614 10/1927 Monahan 259/96 1,949,696 3/1934 Schoneborn 259/96 2,501,467 3/1950 lttner 2,869,841 l/l959 Cowan Primary Examiner-Robert W. Jenkins Attorneys-Dale A. Bauer, John L. Seymour and Bauer and Seymour upwardly through a vertical pipe section opening through the bottom wall of a container and terminating in a flared upwardly facing frustoconical seat for a mixing rotor fixed to the lower end of a shaft and having a complementally shaped lower face. The shaft is journaled and rotated at the top end of the container, exteriorly thereof. The rotor has a central mixing chamber in communication with the upper end of the pipe section, from which lead radial bores. The liquids are drawn upwardly into the mixing chamber and impelled through the bores as the rotor spins. The intermingled liquids pass upwardly in the container, flow to a settling or decantation tank from which they are separately drawn off by outlets at different elevations. The vertical pipe section has an opening in its side wall which may be manually varied in effective size to selectively vary the proportions of mixed liquids recirculated through the opening. There may be several cycles of mixing and decantation each in a sequential one of a plurality of container-settling tank pairs.

Patented 1, 1970 INVENTOR.

JACQUES NENRI DRESSLER ATTORNEYS APPARATUS FOR MIXING LIQUIDS This application is a continuation-in-part of my prior copending US. Pat. application Ser. No. 790,900, filed Feb. 3, 1959, now abandoned, and relates to an apparatus and a process for circulating and mixing two or more liquids, particularly those which are ordinarily considered to be incompatible or immiscible. The method and apparatus for carrying it into practice are particularly useful in a battery of mixing decanters of the type which are horizontally related, for the abstraction of products dissolved in one liquid and removed by contact with another liquid.

A valuable use of the invention is in the separation of elements or of products which are used in the atomic industry. These elements are dissolved as salts in a liquid and are separated by means of a second solvent which dissolves one or more, but not all of the elements or products. The two solvents are circulated countercurrent through a battery of mixing decanters. In each mixer, because of contact between the liquids, the element or elements to be extracted pass partially from the first into the second solvent. In each decanter used in the particular process under discussion the enriched solvent and the stripped solvent are separated by decantation, the solvents used being chosen so as to be mutually insoluble and of different specific gravity so that the heavier liquid sinks to the bottom and is returned to the-preceding mixer, while the other and lighter liquid rises to the top and proceeds to the following or subsequent mixer. The difficulty with known apparatus and methods is that the elements to be separated, being strongly radioactive, impart this radioactivity to parts of the apparatus with which they are associated or with which they come into contact. Such parts are, for example, pumps, joints, and packing. Since such parts require repair and replacement from time to time, an element of danger to operating personnel is inherently involved. Furthermore, any leakage of the liquid may also create dangerous conditions.

it is an object of this invention to present an apparatus and a method which eliminate the chance of leakage where conventional pumps, joints, glands, and packing are used.

Another object is to provide a mixing and decanting apparatus wherein all moving parts which come into contact with the liquids, are or may be cornpletely sealed and which are so located and protected as to obviate dangers inherent in prior art apparatus which, once placed on stream, cannot be subsequently repaired or replaced without exposing operating personnel to dangerous radioactivity.

Yet another object is to provide an apparatus as aforesaid which is relatively simple and efficient, and unusually free of wear so that periods between necessary repair or replacement of parts are extremely long.

Another object is to provide a method of and an apparatus for assuring the efficient and intimate admixture of two liquids, particularly two mutually insoluble liquids of different specific gravity.

Still another object is to provide an apparatus and method by which two mutually insoluble liquids are intimately mixed and propelled at one and the same time so that the mixed liquids are moved by the force of the mixing movements to a region of relative calm where separation of the liquids takes place by settling and decantation.

Another object is to provide a method and apparatus of particular utility in fields of atomic energy, in facilitating the separation of elements or products thereof which are solutes in a liquid, by intimately mixing the solution with another liquid in which one or more but not all of the solutes are soluble, the other liquid being insoluble in the solvent, while simultaneously drawing the liquids into the mixing space and moving the mixed liquids to a place of quiet or relative calm, for decantation.

Other objects are to provide an apparatus which has a minimum of moving parts, a minimum number of packed joints and glands and which affords improved simplicity of control.

A still further and important object is to provide a method and apparatus by which two immiscible liquids are rapidly and intimately mixed by centrifugal force and at the same time impelled by a component of said force into a settling compartment where the intermixed liquids and their respective solutes may stratify as the result of difference in their relative specific gravities.

Supplemental to the immediately foregoing object it is a further object to control and direct the intermixed liquids so that a selectively variable portion thereof is recirculated and added to the discrete entering liquids to promote rapid and thorough intermixture thereof, and to control and direct the flow of completely mixed liquids into the settling compartment in a smooth and uniform manner for decantation.

Yet another object is to provide a novel apparatus by which decantation of the intermixed liquids is promoted and facilitated.

Other objects and advantages of the invention will become clear to those skilled in the art, after a study of the following detailed description in connection with the accompanying drawing.

In the drawing:

FIG. 1 is a vertical sectional view of one element of a battery of mixer decanters of the type useful in atomic industries;

FIG. 2 is a partial section on an enlarged scale of the impeller of a novel type used in carrying out the process.

Referring in detail to the drawing, 1 and 2 identify generally and respectively, a mixing compartment or tank and a settling or decantation compartment or tank. The two are connected at their tops by an overflow'passageway 12. A common cover 26 extends over the tops of both compartments,

The bottom wall of compartment 1 has an opening within 'which is sealed an upwardly projecting tube 5 terminating in an upwardly and outwardly flared frustoconical end 9. Tubes 3 and 4 connect with the lower end of tube 5 for the introduction respectively of two liquids to be mixed or intermingled. Midway'between its ends tube 5 is provided with an orifice 6 in and through its wall. The orifice is generally in the form of an inverted isosceles triangle, but its sides as developed, are not straight lines but are curved or convex inwardly in the form, for example, of portions of parabolas, and merge into a circumferentially disposed base. A sleeve 7 has a smooth sliding fit over and about tube 5 and an axial dimension equal to or a little greater than the altitude or axial dimension of the orifice. Means schematically shown as a pair of vertically disposed rods 8 are connected at their lower ends with sleeve 7 and extend upwardly through apertures in top 26 to the exterior, where they are provided with suitable means, not shown, for effecting and maintaining a selected vertical adjustment of the sleeve with respect to tube 5 and orifice 6 therein. The construction and arrangement are such that the sleeve may be vertically adjusted to selectively vary the effective size of the orifice and thus, for any given rate of flow of liquids into the tank through pipes 3 and 4, to vary the proportion of mixed liquids recirculated into pipe 5. The curved sides of the orifice as previously described, make it possible to vary the rate of recirculation directly with vertical adjustment of the sleeve. In its fully lowered position the sleeve completely obturates the orifice so that in such position no recirculation takes place. in this way a fine control of flow is provided between tube 5 and overflow passage 12 connecting the tops of the mixing and settling compartments. Of course, more than one aperture or orifice 6 may be provided in which case all are preferably of the same size and shape and equiangularly spaced about the tube, with their bases and apices in respective common planes normal to the axis of the tube.

Baffles 11 are fixed to the inner wall of tank 1 in vertical position, circumferentially spaced thereabout. As shown, each baffle extends from a position near the bottom of the tank to a location near the level of overflow passageway 12. These baffles serve to prevent the buildup of circular currents or swirl, and may be of any number and spaced as required for their intended purpose. Mixing tank 1 is also provided with horizontal baffles 13 which project inwardly for a limited distance from the wall thereof. Other baffles such as 14 shown centrally disposed and in as axially spaced relation with baffles 13, tend to divide the mixing compartment into upper and lower chambers and thus to prevent the establishment of excessively strong violent vertical currents which might otherwise extend upwardly to the level of overflow passageway 12 and thus adversely affect performance of the apparatus. Baffles 14 may radially overlap baffles 13. All baffles contribute to the thorough mixing of the liquids and assure that the flow of mixed liquids through passageway 12 is smooth, even and devoid of turbulence.

Impeller is shown upon FIG. 1 and in greater detail upon FIG. 2, as fixed to the lower end ofa vertical shaft 15 which is journaled by bearings not shown, for rotation on an, axis coincident with that of the flared end of tube 5. The shaft extends upwardly, passes with a smooth fit through an aperture in cover 26 and there connected with power-driven means not shown, by which it is rotated. A stirring device 16 may be connected with the shaft for rotation as a unit therewith within the tank, below the level of passageway 12. This stirrer assists in mixing of the liquids without, however, creating excessive turbulence, particularly that having a vertical component of motion.

Impeller 10 is shown as a frustoconical dished element having a lower surface shaped complementarily to and fitting the upper flared end of tube 5. The lower surface of the impeller is centrally recessed at 17 to provide a mixing chamber to receive liquids moving upwardly from pipes 3 and 4 into tube 5. A plurality of equiangularly disposed bores or passages 18 are formed in the impeller and extend upwardly and outwardly from chamber 17 to and through the rim of the impeller or rotor, each in a respective radial plane through the axis of shaft 15. Thus, in a way clear from inspection of the drawing, rotation of the impeller imparts a like rotation to liquid momentarily within the bores and impels the liquid outwardly by centrifugal force. Since the bores also have an upward and outward inclination, the force applied to the liquid has a component axially and upwardly with respect to the axis of shaft 15. This component generates ascending currents which result in a general flow of mixed liquids upwardly within the tank. Furthermore, due to the presence in recess 17 of both liquids from pipes 4 and 5, a portion of each is drawn into each bore and there mixed with the other as the two swirl violently outwardly to and through the open end of the bore. When orifice 6 is exposed wholly or partly by a corresponding adjustment of sleeve 7, a portion of the mixed liquids in tank 1 is drawn therethrough into tube 5 and recirculated, mingling with liquids entering from pipes 3 and 4 and further promoting complete mixture. A small portion of the liquid is impelled by centrifugal force between the interfaces of the flared end of tube 5 and impeller 10 so that the impeller in effect floats upon a film of liquid. The outwardly and upwardly moving streams ofliquid create a force upon the rotor which has a vertically downward component urging the impeller onto its seat upon flared end 9.

The apparatus thus described comprises a receptacle in which the mixing and upward flow of the mingled liquids is effected by an impeller having a vertical axis, and which is located above and coaxial with an injection tube. The impeller draws liquids to be mixed from the tube and impels them radially outwardly by centrifugal force having an upward component which, in turn, creates a smooth flow of mixed liquids about baffles ll, 13, and 14 to overflow passageway 12. At the same time the liquids are violently rapidly and thoroughly mixed.

After traversing passageway 12 the mixed liquids are first directed downwardly by baffle 20 which thus protects the contents ofthe tank from agitation by the incoming flow. In tank 2 the lighter of the two liquids floats on the heavier and overflows through apertures 21 in the top of standpipe 22 from whence it is returned to a preceding unit or, if desired, to such other destination as is required by the process being carried out. A vertical baffle 23 defines a chamber 24 within the tank and terminates short of the bottom thereof to thereby permit the heavier liquid to .pass to chamber 24, thence upwardly to and through the apertures in the top end of a second standpipe 25. From this pipe the heavier liquid with its solute. passes to a subsequent unit of the battery, or to other appropriate destination.

The operation is generally clear from the foregoing description. When the impeller is spun the liquid filling bores 18 is impelled radially outwardly and upwardly and into the surrounding body of mixed liquids. The outward flow creates a suction head in'tube 5 which draws further supplies of liquids through the tube. The absolute, subatmospheric pressure in the tube may be regulated by axial adjustment of sleeve 7 to vary the effective size of orifice 6. Raising of the sleeve, of course, increases the effective size of the orifice, raises the absolute pressure in tube 5 or, what is the same thing, reduces the suction therein, increases the rate of recirculation of liquids, other conditions remaining the same, and decreases the flow input from pipes 3 and 4. Sleeve 7 therefore plays an important part in securing the necessary intimate intermingling of liquids, while assuring maximum output per unit of given capacity. Furthermore, adjustments of sleeve 7 make it possible to adapt the apparatus for a wide range of versatility. For example, liquids which intermix readily may be treated with orifice 6 substantially fully obturated and at maximum flow rate to tank 2. At the other extreme, liquids which for one reason or another require more thorough and prolonged mixing, may require operation with orifice 6 at full effective opening while the rate of flow from pipes 3 and 4, and to tank 2 will be correspondingly reduced.

it has been determined that when, as shown, the flared upper end of tube 5 conforms to the shape of the lower surface of rotor or impeller 10, regulation ofthe spacing between the rotor and the flared end is made easier and is less critical. This regulation may be carried out in certain installations by raising and lowering shaft 15 by conventional adjustable thrust bearing means not shown. Where the interfitting parts or surfaces of 9 and 10 are as shown it has been demonstrated that the suction head within tube 5 does not vary greatly for relatively appreciable displacement axially, of the impeller with respect to the tube, nor for appreciable, eccentricity between the two axes thereof. To the contrary, when the upper end of the tube is simply a circular edge, a more precise and accurate adjustment is required because a small change in spacing between the tube and impeller creates substantial variations in head within tube 5.

The internal wall of the mixing tank is provided with projections, baffles, or the like which are wholly or partially immersed and which prevent the establishment of rotating currents and contribute to the turbulence of the liquid bath and the intimate intermixing of its constituents. The horizontal baffles have a similar function and effect with respect to prevention of undesirable vertical streams. The entire system acts to cause an intimate dispersion of one liquid within the other, producing even molecular contact of one liquid with the other. The mixer can be constructed with more than two vertical compartments if desired, each compartment having its own stirrer and impeller if needed.

One very important advantage of the invention is that it enables successful mixing and handling of dangerous or corrosive or toxic liquids because it contains no moving parts which pass through walls or glands below the liquid level. Thus there is no danger otherwise present where such liquids may escape through worn or defective glands, seals, etc. The mechanical devices which require occasional attention such as motors and shafts are located outside the liquid compartments in zones which can be protected so that repairs and replacements can be readily effected without danger.

As an illustration of one important use, the following example is given.

EXAMPLE The mixer substantially as shown upon FIG. 1 and occupying position N" in a battery of mixers, was fed through pipe 3 with an aqueous nitric solution containing uranyl nitrate and fission products. This solution came from mixer-decanter "N l. The organic phase, already enriched in uranyl nitrate and coming from decanter N l was introduced into said mixer through pipe 4. The organic phase consisted of tributyl phosphate.

ln mixer N" an emulsion of one phase in the other was made, part of which was again mixed with the two entering solutions, by means of orifices 6. The intimate contact into which these two phases were thus brought caused the aqueous phase to be deprived of part of its uranyl nitrate in favor of the organic phase whereas the fission products remained in the aqueous phase.

The emulsion was then caused to leave mixer N by means of overflow 12 into decanter 2 where both phases separated. The organic phase, enriched in uranyl nitrate, left through apertures 21 for mixer N 1" whereas the aqueous solution with the fission products was conducted through tube 25 into mixer N l The respective concentration of uranyl nitrate in the two outgoing phases were very close to the equilibrium concentrations.

Since many other uses, modifications, rearrangement of parts, and substitutions of equivalents will readily occur to those skilled in the art, after a study of the foregoing disclosure, the disclosure should be taken in an illustrative rather than a limiting sense. It is to be understood therefore that the invention is not limited to the specific embodiment shown.

lclaim:

1. Apparatus adapted to the mixing of incompatible liquids comprising a container, a settling tank, overflow means connecting said container with said settling tank and establishing a liquid level, a plurality of inlet conduits opening into said container beneath the liquid level, means to supply said conduits with liquids, a single conduit connected to said conduits and having a part provided with orifice means within the container, means to adjust the size of the orifice means, a flared conical end on said single conduit, a rotor having a conical face conforming to said end, and diverging channels in the rotor connecting the interior of said single conduit with the interior of the container below said overflow means.

2. The apparatus of claim 1 in which the lateral orifice means is triangular and the means to adjust is a movable sleeve which encircles the conduit.

3. The apparatus of claim 1 in which the rotor is solid, is provided with a central cavity, and the conduits are holes extending radially from the central cavity through the solid rotor.

4. The apparatus of claim 1 in which the tank is divided into upper and lower compartments by offset baffles, in the lower of which the rotor is located.

5. The apparatus of claim 4 in which the lower compartment has vertically arranged baffles.

6. The apparatus of claim 4 in which the rotor is mounted on a shaft which passes through the upper compartment and is provided therein with a stirrer.

7. Apparatus for mixing immiscible liquids which comprises a tank adapted to hold a body ofliquid, a plurality of conduits operatively connected to the tank beneath the liquid level for the introduction of a plurality of fluids which are to be mixed with the contents of the tank, a mixing chamber connected to the conduits, rotor means having radially directed tubes connecting in one place with the mixing chamber and in another place with the interior of the tank below the liquid level, thus acting to separate liquid from the mixing chamber into relatively small individual streams, and means to rotate the rotor means to centrifugally inject the individual streams into the body ofliquid in the tank.

8. Apparatus for mixing incompatible liquids comprising a container having means to establish a liquid level, contiguous conduits operatively connected to the container beneath the liquid level, a mixing chamber connected to said conduits, centrifugal injector means having projecting radial tubes connected to said mixing chamber and opening into the container below the liquid level, and means to rotate the injector to inject liquid from the mixing chamber into the container.

9. ln apparatus for injecting liquid beneath the level of a body of liquid, a tank, a conduit entering the tank below the liquid level, a flared conical end on the conduit, a rotor having a flared conical surface fitting the flared conical end, and internal cavity in the rotor connecting with the conduit, radial tubes connecting the cavity with the tank, and means to turn the rotor on the flared conical end of the conduit.

10. The apparatus of claim 9 in which the radial tubes are also angularly inclined.

11. In a mixer for liquids, a container, an impeller journaled in said container for rotation about an axis, said impeller including a plurality of passageways each generally radial of said axis and each in communication at its inner end with a central recess in said impeller, means to rotate said impeller about said axis, and means comprising a plurality of conduits each in communication with said central recess to supply discrete liquids thereto.

12. The mixer of claim 11, said last-named means including a vertically disposed tube having its lower end in communication with all of said conduits and a step bearing at its upper end on which said impeller is journaled, there being an orifice in the wall of said tube within said container, and means operable to selectively adjust the effective size of said orifice.

13. In a mixer for liquids, a container, means forming a mix ing chamber in said container, a plurality of conduit means in communication with said chamber each for supplying thereto a respective discrete liquid, and impeller means rotatable about an axis and positioned within said container, said impeller means including a plurality of passageways each (a) extending generally radially of said axis, (b) in communication at its inner end with said mixing chamber, and (c) opening at its outer end into said container.

14. The mixer of claim 13, said axis being vertical, said impeller including a shaft coincident with said axis and extending upwardly beyond the top of said container for connection with a source of power for rotating said impeller.

15. In an apparatus for mixing liquids, a container, means forming a mixing chamber in and adjacent the bottom of said container, a plurality of conduit means in communication with said chamber each to supply a discrete liquid thereto, an impeller, means mounting said impeller in said container adjacent the bottom thereof, for rotation on a vertical axis, said impeller comprising means forming a plurality of discrete angularly spaced bores generally radial of said axis, each said bore communicating at its inner end with said chamber and at its outer end opening into said container.

16. In an apparatus for mixing liquids, a container, means forming a mixing chamber in and adjacent the bottom of said container, a plurality of conduit means in communication with said chamber each to supply a discrete liquid thereto, an impeller, means mounting said impeller in said container adjacent the bottom thereof, for rotation on a vertical axis, said impeller comprising means forming a plurality of discrete angularly spaced bores generally radial of said axis, each said bore communicating at its inner end with said chamber and at its outer end opening into said container, said mixing chamber including a single vertical tube extending upwardly from the bottom of said container and having a flared upper end having an upper surface forming a surface of revolution about said axis, said impeller having a lower surface of revolution complementary to and fitting the surface of said flared end, said chamber comprising a recess in and centrally of said impeller, each said bore opening into said recess at its radially inner end.

17. The apparatus of claim 16, each said bore having a central axis extending radially outwardly and upwardly at an acute angle with said axis.

18. The apparatus of claim 17, said surface of revolution being conical, rotation of said impeller irnpellingv outward movement of liquids by centrifugal force, said force having a component vertically downward to urge said impeller onto said flaredend.

19. An apparatus for mixing liquids comprising a container, tubular means forming a mixing chamber in and adjacent the bottom of said container and having an upwardly facing first bearing surface of revolution about a vertical axis, an impeller journaled in said container for rotation on said axis and having a second and lower bearing surface complementary to and fitting said first bearing surface, said impeller including a central recess in said second bearing surface and a plurality of bores each generally radial of said axis and in communication at its inner end with said recess, and opening at its outer end into said container, and a plurality of pipe means each communicating with said tubular means to conduct respective discrete liquids thereto.

20. The apparatus of claim 19, and a shaft fixed with said impeller and extending upwardly in coincidence with said axis above the top of said containerfor connection with a source of power exteriorly of said container.

21. In an apparatus for mixing liquids, a container, tubular means in and adjacent the bottom of said container and having an open distal end therein, an impeller in and adjacent the bottom of said container and having a vertical axis of rotation and a plurality of liquid passageways generally radial of said axis and each in communication at its inner end with the open distal end of said tubular means and at its radially outer end opening into said container, valve means in said tubular means for direct passage ofliquid thereinto from the lower portion of said container, and operable to selectively vary the recirculation of mixed liquids, and a plurality of pipes each in communication with said tubular means, to conduct thereto discrete liquids to be mixed. 7

22. The apparatus of claim 21, and liquid seal means between said tubular means and said impeller.

23. A mixer and decanter for liquids, comprising, means forming first and second containers, a passageway connecting said containers adjacent the tops thereof, a tube in said first container adjacent the bottom thereof and having afirst upwardly facing bearing surface symmetrical about a vertical axis, an impeller having a second and lower bearing surface complementary to and fitting said first surface, said impeller including aplurality of angularly related discrete generally radial passageways each in communication at its inner end with said tube and each opening at its outer end into said first container, a plurality of pipe means each communicating with said tube to supply discrete liquids thereto, respectively, means connected with said impeller to spin the same about said vertical axis, a partition in said second container dividing the same into first and second compartments in communication at the bottom of said second container only, said first compartment receiving flow directly from said passageway, a first standpipe in said first compartment and having it open upper end a little below the level of said passageway, a second standpipe in said second compartment and having its open upper end below the level of the upper end of said first standpipe, and first and second conduit means each connected with a respective one of said standpipes to conduct liquid therefrom.