US3285579A - Devices for homogenizing a mixture by ultra-sound vibrations - Google Patents

Description

United States Patent Ofifice 3,285,579 Patented Nov. 15, 1966 3,285,579 DEVICES FOR HOMOGENIZING A MIXTURE BY ULTRA-SOUND VIBRATIONS Robert lurin, 2 Rue des Marais, Viroflay, France F led May 5, 1964, Ser. No. 364,958

Claims priority, application France, May 9, 1963,

934,259 9 Claims. (Cl. 259-4) The present invention relates to devices for homogenizing by means of ultra-sound vibrations the mixture of a llqllld withat least one other fluid, either liquid or gaseous, of any viscosity and which may even be pasty and/ or contain solid particles, said other fluid being little miscible or nonmiscible with said liquid (as it is the case for suspensions or emulsions) and tending to separate from this liquid shortly after it has mixed therewith. The above ment oned vibrations are produced by projecting at least the liquid in the form of a jet upon the free end of a metal element capable of vibrating at an ultra-sound frequency, preferably under the mere effect of the impact of sa d et thereon, the other fluid being introduced in proxmity to said free end preferably through the intermediate ofthe jet itself, in which case said other fluid is mixed with the liquid before projection of the whole upon the metal element.

The chief object of my invention is to provide a device of the type above described which is capable of producing a mixture more homogeneous and more stable than up to this time.

The invention consists chiefly, in surrounding the metal element by a bell the bottom of which is fixed to the end of said element opposed to its free end and the edge of which is free, said bell being chosen in such manner that the fundamental sound of natural vibration thereof has a harmonic which at least substantially coincides with the ultra-sound generated by the system consisting of the liqu d et and the metal element, whereby the 'bell vibrates in resonance with the system consisting of the liquid et and the metal element, at least most of the annular space comprised between the metal element and the lziell being filled with the liquid mixture to be homogemze A preferred embodiment of my invention will be herevmaftendescribed with reference to the appended drawings, given merely by way of example, and in which:

FIG. l is an axial sectional view of a homogenizing device made according to the present invention;

FIG. 2 shows on an enlarged scale the portion of this devlce through which the mixture to be homogenized is lntroduced;

.FIG. 3 is a diagrammatic .part view showing some of the paths along which travel the particles of the jet introduced into the device.

It has already been proposed to homogenize a mixture of liquids which are little or nonmiscible together by pro ecting said mixture in the form of a jet upon the free end of a metal element capable of vibrating at an ultrasound frequency under the mere effect of the impact of said jet.

It has even "been proposed to surround said element by a klnd of nozzle provided at its downstream end with a throttled opening in order to create, by a cavitation effect, in the immediate vicinity of the vibrating element, an empty space capable of facilitating the vibrations of this element. But up to the present time no homogenizing .device based upon such a principle has been satisfactory in practice concerning in particular homogeneity, regularity and stability of the mixture to be obtained.

The present invention permits of obtaining these qualities at a high degree owing to the provision of a resonance between, on the one hand, the system consisting of the jet of mixture and of the metal element and, on the other hand, a bell to the bottom of which said element is secured. For this purpose the bell is chosen in such manner that its natural vibration fundamental sound, which is sharp in the range of audible sounds, has, as one of its harmonics, the ultra-sound emitted by the system consisting of the jet and the element, or an ultra-sound of nearly equal frequency. Thus, the amplitude of the oscillations of the disturbing system (consisting of the jet and the element) may reach its maximum values simultaneously with the amplitude of the oscillations of the disturbed system (bell), .both systems then vibrating in resonance. Furthermore, the annular space between the element and the bell is filled, at least mostly, with the mixture to be homogenized, whereby the ultra-sound vibrations of the jet and element system are transmitted to the bell both through the metal and through the liquid mass. The resonance ultra-sound oscillations then generated in said mass are of very high intensity and cause the individual particles of said mass to burst into extremely fine and stable micelles.

The liquid mixture to be homogenized is preferably made of constitutents which are little miscible or nonmiscible together, that is to say which have different surface tensions and high interfacial tensions, at least one of these constituents being in particular in a colloidal state. This mixture may be treated either in the cold or in the hot state, with or without the addition of stabilizing, dispersing, tension-active or similar agents. Such a mixture consists for instance of heating fuel (often called mazout) and water, with or without the addition of air, or of gasoline and water, or again of a suspension of paint, glue, a detersive product, a food product or any other suitable binder, either mixed or not with a gas ,and/ or with solid particles. In some cases it is possible, by means of repeated recycling, to transform the mixture into a gel.

The vibrations of the metal element might be generated through any suitable means of mechanical, hydraulic, pneumatic, piezo-electric, magneto-striction, or even optical kind, but it is preferred to produce them by the mere effect of the jet on the above mentioned element.

Said element might be a blade capable of vibrating like a reed, or a rod provided at its end with a bulb. However, preferably, said element is in the form of a body capable of deflecting the jet it receives toward the free edge of the bell. In particular said element comprises a rod provided at its end with a deflecting substantially conical head the apex of which is directed toward the jet.

The frequency of vibration of the system consisting of the jet and the element varies a little with the characteristics of the mixture that is fed. In practice, in order to obtain resonance with a given mixture I act upon the pressure and the flow rate of this mixture as it is being introduced into the apparatus (in particular by making use of caibrated feed nozzles of suitable size) until there is obtained the best possible dispersed mixture, the obtainment of resonance being shown by a very sharp improvement of this mixture.

Preferably the above mentioned bell is inverted so that the liquid mixture present therein escapes therefrom by overflow along its free edge, subjected to very intensive vibration. This bell then preferably has a considerable portion thereof immersed in the mixture to be homogenized, .the level of the free surface of this mixture around the bell being advantageously maintanied at a constant value through suitable means.

Advantageously I provide, in combination with said bell, another bell of smaller size, the respective centers of the bottoms of these two bells being secured together and the smaller one being on the inside of the larger one, with its bottom and its side wall at a distance from the bottom and side wall of the larger bell, respectively, thus forming an annular space filled with vibrating liquid mixture. The natural frequency of vibration of this second bell may be such that it produces a secondary resonance effect with the other vibrating system, but this is not a necessary condition.

Of course all the parts are made in such manner as to have a good mechanical resistance so as to avoid any risk of breaking thereof by the strong resonance oscillations.

In the embodiment of the invention illustrated by way of example, the homogenizing device comprises the following elements:

(a) a nozzle housed in a support 2 (FIG. 1) and capable of projecting in the downward direction, as illustrated by arrow F the liquid mixture 31 to be homogenized;

(b) a metal rod 9 the free upper end of which carries a deflecting head directed toward the orifice of the above mentioned nozzle so as to be struck by the jet of mixture 31, and

(c) an inverted bell 14 surrounding rod 9, the bottom 14 of which bell is fixed to the lower end of said rod 9 and the upper edge 14 of which is free.

The mixture projecting nozzle comprises a removable disc 3 (FIG. 2) provided at its center with a calibrated orifice 1 and secured in support 2 (which is provided with internal and external screw threads) by a nut 38. A filter 4 capable of retaining the impurities of the mixture is also secured by screwing in nut 38. Support 2 is also fixed by screwing in a coupling 5 provided with internal and external screw-threads and this coupling 5 is in turn housed in an adjustable manner, by screwing, in a fixed ring 6. This coupling 5 is secured in the desired position by an external nut 7. Coupling 5 is connected with a feed conduit 39.

The center of the bottom 14 of bell 14 is provided with a hole through which extends a threaded rod 15 forming an extension of an annular shoulder 13 itself disposed at the center of the bottom of a second inverted bell 11 smaller than bell 14. Mere screwing of rod 15 in a downwardly extending vertical bar 19, so that said rod 15 passes successively through bell 14, a Washer 40 and a supporting stirrup 16, permits of securing the respective bottom portions of the two bells together While keeping these bottoms at a distance from each other by means of shoulder 13. Bell 11 comprises a central finger 12 on which is force fitted the lower end 41 of rod 9.

Stirrup 16 is secured to a lid 18 and supports the whole along the vertical axis of a tank 17 which is covered by said lid with the interposition of a resilient packing 28 and of a metal ring 29.

A bell 20 having its free edge turned downwardly is secured to the lower end of bar 19 by means of a central screw 21 and receives through this bar the vibrations of parts 9 to 14.

A tubular sheath 30 carried by stirrup 16 is provided for collecting the liquid mixture overflowing from bell 14 and for guiding it by gravity toward the external face of bell 20. The free lower edge of said bell 20 is located at a small distance from the portion of tank 17 located opposite it.

The bottom of this tank 17 carries a nut 24 in which is screwed a plug 25 connected by screwing with an outlet pipe 26 for the outflow of the homogenized mixture.

In order to prevent the free surface 33 of the liquid mixture 32 contained in tank 17 from reaching the free upper edge 14 of bell 14 there is provided an overflow 27: The bottom of tank 17 may be closed, said overflow being then used as outlet for the homogenized mixture. magnet 3 carried by screw 21 retains the ferromagnetic particles which may be contained in the mixture.

Of course in order to avoid loosening under the effect of the vibrations, all the screwed parts are fixed by means of a glue consisting chiefly of an artificial resin such as that known under the trade mark Araldite.

The operation of the device is as follows:

The mixture to be homogenized is projected downwardly along arrow F onto the apex 8 of deflecting head 10. It is deflected in the form of a sheet toward the edge 14 of bell 14 (arrow F FIG. 3). The whole of this sheet and of head 10 vibrate at an ultra-sound frequency due to the more impact of the jet onto head 10. These vibrations are transmitted to hell 14 by conduction both through said sheet and through the metal of the rod and of the bell whereby this bell vibrates in resonance with the above described system.

A portion of the sheet that has struck the side wall of bell 14 is reflected in the direction of arrow F toward rod 9. Another portion of said sheet is reflected along arrow F against the outer face of the small bell 11, which vibrates also, whence it is again returned toward the outside and so on.

Bell 14 is filled with the mixture and this mixture overflows into sheath 30, travels by gravity along said sheath (itself subjected to ultra-sound vibration through the intermediate of stirrup 16 and of the mixture 32 itself) then along the external surface of hell 20 (which also vibrates), undergoes a last vibratory stress by flowing through the throttled annular interval between bell 20 and the lower edge of tank 17, and is finally evacuated through pipe 26 toward a utilization apparatus or a provisional storing device, or toward recycling.

Under normal working conditions, the level of the free horizontal surface 33 of the liquid mass 32 surrounding bell 14 advantageously remains stationary and is in particular slightly below the level of edge 14 Most of bell 14 is then immersed in the liquid. As a matter of fact, experience teaches that the conditions of resonance, and therefore the characteristics of the homogenization that is obtained, vary if said level varies.

In order to obtain a constant position of level 33, I advantageously make use of an overflow 27, which supposes a flow rate of injection slightly above the delivery flow rate. Preferably I make use of a regulation system comprising a float 34 capable of acting upon a valve 35 which controls the injection flow rate either directly or indirectly (for instance electrically by means of a circuitbreaker 36 mounted in the energizing circuit 37 of valve 35, which is supposed to be electrically controlled).

In what follows indications will be given merely by way of illustration concerning an embodiment of the invention according to the above description.

Element 9 is a rod of hard steel having a diameter of 2 mm. and a length of 35 mm. (its bottom portion being not included), carrying a head 10 of substantially conical shape with a pointed apex 8. It is capable of vibrating at an ultra-sound frequency of 20,000 Hz. approximately, under the impact of jet 31.

Bell 14 is made of bronze machined to the desired shape and includes a fiat bottom joined through a rounded portion to a cylindrical skirt the diameter and height of which are about equal to mm. The fundamental sound given by said bell has a frequency of about 4,000 Hz.

The mixture to be homogenized comprises, in volume, 50% of water and 50% of mazout.

It is injected under a pressure of 10 kg./cm. through a nozzle having a diameter of 2 mm. and located at 6 mm. from the apex 8 of head 10.

Under the impact of this jet the whole of the jet and of head 10 vibrate at about 20,000 Hz., which causes bell 14 to vibrate at its harmonic of the order of five when said bell is filled with the liquid mixture and immersed in said liquid up to the of its height.

The second bell 11, disposed in bell 14, is also made of bronze. The bottom of these two bells are at a distance from each other of 13 mm. and the side walls are at a distance of 7 mm. of each other. Bar 19 and bell 20 are made of steel. With this device I obtain a continuous flow of 200 liters per hour of a very stable and regular emulsion of mazout in water, the micelles of which have dimensions ranging from 0.1 to 0.5 micron. Such an emulsion is used to feed a mazout burner with an excellent efliciency and it may be preserved without inconvenience before its use for a considerable time which may reach and even exceed one hour. In particular if, during this time, the components thereof separate a little from each other, it sufiices to stir the mixture to restore the emulsion.

Likewise, experience teaches that a mere cooling permits of freezing the homogenized mass without separation of the constituents thereof.

In a more general manner the resonance ultra-sound frequency generally ranges from 10,000 to 100,000 Hz. and the pressure of injection from 3 to 30 -kg./cm. the diameter of the nozzle ranging generally from 0.5 to -5 mm. and its distance to the apex of the vibrating elements from 2 to mm.

Of course the device might be heated or cooled instead of being kept at the temperatures of the surrounding medium.

The number of obstacles (bells or the like) subjected to ultra-sound vibrations and along which flows the mixture to be homogenized might be different from that referred to in the above described example. The ultrasound vibration of the metal element may be obtained in any suitable manner, for instance electrically.

Several of the mixtures to be homogenized may be introduced into the device through distinct passages.

In a general manner, while I have, in the above description, disclosed what I deem to be a practical and eflicient embodiment of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of my invention as comprehended within the scope of the appended claims.

I claim:

1. A device for homogenizing a mixture of a liquid with at least one other fluid which comprises, in combination, a metal element having a free upper end capable of vibrating at ultra-sound frequency, means for projecting a jet of said liquid and said other fluid downwardly toward said metal element so as to impinge onto said free upper end thereof, a bell opposite said projecting means having a closed lower end fixed to said metal element at a point thereof located at a distance below said free upper end thereof, said bell having a top open end with a free edge surrounding said metal element upper end, the natural frequency of vibration of said bell having one of its harmonics substantially equal to the ultrasound frequency of the system consisting of said liquid jet and said metal element, whereby said bell vibrates in resonance with said system, at least most of the annular space between said metal element and said bell being filled during operation with the mixture to be homogenized.

2. A device according to claim 1 wherein the free end of said metal element is in the form of a deflector adapted to reflect said jet toward said free edge of said bell.

3. A device for homogenizing a mixture of a liquid and at least one other fluid which comprises, in combination, a vertical metal rod having its upper end free, said metal rod being capable of vibrating at an ultrasound frequency, means for projecting downwardly onto said upper end a jet of said mixture, an inverted bell surrounding said rod at least substantially coaxial therewith, and means for securing the bottom of said bell to the lower part of said rod, the top edge of said bell being free, the natural frequency of said bell having one of its harmonics subtantially equal to the ultra-sound frequency of the system consisting of said liquid jet and said metal rod, whereby said bell vibrates in resonnance with said system, the mixture to be homogenized filling during operation the annular space between said metal rod and said bell up to the edge of said jbell.

4. A device according to claim 3 comprising means for maintaining about said bell .an amount of said mixtur about most of the height of said bell.

5. A device for homogenizing a mixture of a liquid and at least one other fluid which comprises, in com bination, a vertical metal rod having its upper end free, said upper end forming a substantially conical head of revolution about the axis of said rod and having its apex turned upwardly, said metal rod being capable of vibrating at an ultra-sound frequency, means for projecting downwardly onto said apex a jet of said mixture, said means comprising a disc having a calibrated hole formed therein, an inverted bell surrounding said rod at least substantially coaxial therewith, and means for securing the bottom of said bell to the lower part of said rod, the top edge of said bell being free, the natural frequency of said bell having one of its harmonics substantially equal to the ultra-sound frequency of the system consisting of said liquid jet and said metal rod, whereby said bell vibrates in resonance with said system, the mixture to be homogenized filling during operation the annular space between said metal rod and said bell up to the edge of said bell.

6. A device for homogenizing a mixture of a liquid and at least one other fluid which comprises, in combination, a vertical metal rod having its upper end free, said upper end forming a substantially conical head of revolution about the axis of said rod and having its apex turned upwardly, said metal rod being capable of vibrating at an ultra-sound frequency, means for projecting downwardly onto said apex a jet of said mixture, said means comprising a disc having a calibrated hole formed therein, an inverted bell surrounding said rod at least substantially coaxial therewith, means for securing the bottom of said bell to the lower part of said rod, the top edge of said bell being free, the natural frequency of said bell having one of its harmonics substantially equal to the ultra-sound frequency of the system consisting of said liquid jet and said metal rod, whereby said bell vibrates in resonance with said system, a casing surrounding said bell, the mixture to be homogenized filling during operation the annular space between said metal rod and said bell up to the edge of said bell and means carried by said casing for keeping the level of said mixture about said bell at a constant position below the edge of said bell.

7. A device for homogenizing a mixture of a liquid and at least one other fluid which comprises, in combination, a metal element having a free upper end capable of vibrating at an ultra-sound frequency, means for projecting a jet of said mixture downwardly toward said metal element so as to impinge onto said free upper end thereof, a first bell opposite said projecting means having a closed lower end fixed to said metal element at a point thereof located at a distance below said free upper end thereof, said bell having a top open end with a free edge surrounding said metal element upper end, a second bell smaller than the first one and disposed therein, the closed lower end of said second bell being secured to a second point of said metal element, said second bell having its bottom and its side located at a small distance from the bottom and the side of said first bell, respectively, the natural frequency of vibration of said first bell having one of its harmonics substantially equal to the ultrasound frequency of the system consisting of said liquid jet and said metal element, whereby said first bell vibrates in resonance with said system, the mixture to be homogenized filling during operation atv least most of the annular space inside said first bell about said metal element.

8. A device for homogenizing a mixture of a liquid and at least one other fluid which comprises, in combination, a vertical metal rod having its upper end free, said metal rod being capable of vibrating at an ultrasound frequency, means for projecting downwardly onto said upper end a jet of said mixture, an inverted first bell surrounding said rod at least substantially coaxial therewith, means for securing the bottom of said bell to the lower part of said rod, the top edge of said bell being free, a second bell smaller than the first one and disposed therein, the bottom of said second bell being secured to the bottom of said first bell, said second bell having its bottom and its side located at a small distance from the bottom and the side of said first bell, respectively, the

up to the edge of said first bell, a vertical bar rigid with said rod and forming a downward extension thereof at its lower end, supporting means for said bar carried by said casing, a third bell carried by said bar at the lower end thereof, said third bell having its edge turned downwardly, an annular sheath open at both ends carried by said casing on the inside thereof and coaxially surrounding said bells on the outside thereof, and an outlet for said casing located below said third bell and substantially in the axis thereof. I

9. A device according to claim 8 wherein the lower edge of said third mentioned 'bell is located close to the inner wall of said casing so as to form a throttled passage for the homogenized mixture before it flows out through said outlet.

References Cited by the Examiner UNITED STATES PATENTS 2,657,021 10/1953 Cottell et al.

WALTER A. SCHEEL, Primary Examiner. I. M. BELL, Assistant Examiner.

Claims (1)

1. A DEVICE FOR HOMOGENIZING A MIXTURE OF A LIQUID WITH AT LEAST ONE OTHER FLUID WHICH COMPRISES, IN COMBINATION, A METAL ELEMENT HAVING A FREE UPPER END CAPABLE OF VIBRATING AT ULTRA-SOUND FREQUENCY, MEANS FOR PROJECTING A JET OF SAID LIQUID AND SAID OTHER FLUID DOWNWARDLY TOWARD SAID METAL ELEMENT SO AS TO IMPINGE ONTO SAID FREE UPPER END THEREOF, A BELL OPPOSITE SAID PROJECTING MEANS HAVING A CLOSED LOWER END FIXED TO SAID METAL ELEMENT AT A POINT THEREOF LOCATED AT A DISTANCE BELOW SAID FREE UPPER END THEREOF, SAID BELL HAVING A TOP OPEN END WITH A FREE EDGE SURROUNDING SAID METAL ELEMENT UPPER END, THE NATURAL FREQUENCY OF VIBRATION OF SAID BELL HAVING ONE OF ITS HARMONICS SUBSTANTIALLY EQUAL TO THE ULTRASOUND FREQUENCY OF THE SYSTEM CONSISTING OF SAID LIQUID JET AND SAID METAL ELEMEMT, WHEREBY SAID BELL VIBRATES IN RESONANCE WITH SAID SYSTEM, AT LEAST MOST OF THE ANNULAR SPACE BETWEEN SAID METAL ELEMENT AND SAID BELL BEING FILLED DURING OPERATING WITH THE MIXTURE TO BE HOMOGENIZED.

Images